Gravel Removal Studies in Arctic and Subarctic Floodplains in Alaska

Biological ServicesProgram FWSIOBS-80108 June 1980 Gravel Removal Studies in Arctic And Subarctic Floodplains in Alaska

NORTH SLOPE

I I SWARD PENINSULA

NORTHERN INTERIOR

Interagency Energy-EnvironmentResearch and DevelopmentProgram OFFICE OF RESEARCH AND DEVELOPMENT SOUTHERN INTERIOR U.S. ENVIRONMENTAL PROTECTION AGENCY and

Fish a.nd Wildlife Service ~~~~~~~~~~~ D@@2968 L""" ""

"" U.S. Department of the Interior "" "" -" .. The Biological Sewices Program was establishedwithin the U.S. Fish and Wildlife Service to supply sclentific information and methodologies on key environmental issues that impactfish and wildlife resources and their supporting ecosystems.

Projects have been initlated in the following areas: coal extraction and conversion; power plants; mlneral development; water resource analysis, including stream alterations andwestern water allocation; coastal ecosystems and Outer Continental Shelf development; National Wetland Inventory; habltatclassification and evaluation; inventory and data management systems; and information management.

The Blological Services Program consists of the Office of Biological Services in Washington, D.C., which is responsible for overall platming and management; National Teams, which provide the Program's central scientific and technical expertise and arrange for development of information and technology by contracting with States, universities, consulting firms, andothers; Regional Teams, which provide local expertise andare an important link betweenthe National Teams and the problems at 'the operating level; and staff at certain Fish and Wildlife Service research facilitles, who conduct in-house research studies. FWSIOBS-80108 June 1980

GRAVEL REMOVAL STUDIES IN ARCTIC AND SUBARCTIC FLOODPLAINS IN ALASKA Technical Report

Woodward=ClydeConsultants 4791 Burlness Park Blvd., Suite 1, Anchorage, Alaska99503

Contract Number FWS-14-16-oo08-970

' Norval Netsch, FWS Project Officer Water Resources Analysis Project Biological Services Program US. Fish and Wildlife Service 1011 E. Tudor Drive Anchorage, AK 99503 This study was funded in part by the Interagency Energy-Environment Research and Development Program Office of Research and Development U.S. Environmental Protection Agency

Performed for the Water Resources Analysis Project Office of Biological Services U.S. Department of the Interior Washington, DC 20240 DISCLAIMER The opinions, findings, conclusions, or recommendations expressed in this report are thoseof the authors and do not reflect the views of the Office of BiologicalServices, Fish and Wild- life Service or the Office of Research and Development, U.S. Environmental Protection Agency. EXECUTIVE SUMMARY

A 5-yeargravel removal study was initiatedin mid-1975 toevaluate the effectsof gravel removal from arctic and subarcticfloodplains in Alaska. The primarypurpose of the project was toprovide information that will assistresource managers in minimizing detrimental environmental effects resultingfrom floodplain gravel mining. To achievethis objective 25 material sites werestudied by a team of scientists andengineers. Two major productsof the project are a TechnicalReport which synthesizes and evaluatesthe data collected at the sites, and a Guidelines Manual thataids theuser in developing plans and operatingmaterial sites to minimize envi- ronmentaleffects.

Datafrom the 25 studysites were collected and analyzedby the follow- ingsix disciplines:

RiverHydrology and Hydraulics

0 AquaticBiology TerrestrialEcology Water Qual ity e Aesthetics GeotechnicalEngineering

DataAnalysis compared thePhysical Site Characteristics (drainage basin size,channel width, channel configuration, channel slope, and stream origin) and theGravel Removal AreaCharacteristics (type of gravel removal method, locationof gravel removal, andage ofthe gravel removal site) with themeasured effects of mining activities.

iii The generalconclusion reached was thatproper site select'ion and projectdesign facilitate gravel mining with minimal effects onthe habitats andfauna of floodplains. The keyto the successful mitigation of potentialdetrimental effects is to carefully matchthe material site design and operation (site location, configuration, prof i le,schedule, and rehabi I- itation)with the Physical Site Characteristics of the selected floodplain.

VARIABLES INFLUENCING MIN ING EFFECTS

PhysicalSite Characteristics

Among thePhysical Site Characteristics, channel configuration was themost important. Potential floodplain chahge is least for a braidedriver and greatestfor a straightriver. Size of channel is an importantfactor, withthe least change to beexpected in a largesystem and thegreatest in a smallsystem (assuming equally-sized material sites). Combining these two var-iables(channel configuration and sire),gravel removal operations can be expectedto have the least effect on large braided rivers and thegreatest effect on smallstraight rivers.

Otherinfluencing Physical Site Characteristics, which are related to configuration and size,are the availability and sizeof unvegetated gravel bars,floodplain width, and the distance that can be maintainedbetween the miningsite and theactive channel. For example, in a smallstraight river systemthe floodplain is narrowand gravel bars are neither plentiful nor large. Thus, toextract gravel, either a significantlength of active floodplain or theadjacent inactive floodplain and terrace mustbe disturbed.In thelatter case thenarrowness of the floodplain forces the operation to closelyencroach upon theactive channel. In large river systems these problems can beless significant because gravel bars are larger and, if the inactivefloodplain or terraceare used,the wider floodplain allows maintenance of a broaderundisturbed buffer zonebetween the material site and activefloodplain. Gravel Removal AreaCharacteristics

All ofthe Gravel Removal AreaCharacteristics were found to signifi- cantlyinfluence the effects of gravel mining. The location of thematerial siterelative to the active channel is considered to bethe most important factor. Whethera materialsite is scraped or pit-excavated is important, butoften pits are located away from an activechannel, avoiding the types ofchanges that can beassociated with scraping in active floodplains.

The majoreffects of pit sites located in inactive floodplains and terracesare the loss ofvegetated habitat, the possibility for the occurrenceof fish entrapment, a change inthe appearanceof the floodplain, and long-termdelay in the re-establishment of predisturbanceconditions. Where pitsites are situated close to active channels, particularly on the inside bends in meanderingsystems, the possibility exists for diversion of the channelthrough the pit, eventually forming a channelcutoff in the meander. Thishighlights the importance of providing a bufferbetween the material site and theactive channel. Where pitsites are of suitable size, of sufficientdepth, and havecontoured perimeters, they can increase local habitat diversity and provideconditions suitable for fish and variousspecies of terrestrial fauna.

Scrapedmaterial sites in active floodplains have minimal effects onthe floodplain environment when onlyexposed gravel bars are excavated abovethe water level, and when slope and contoursare maintained (resew blingthose of natural bars). Removal ofvegetated areas or banks, which resultsin decreasedlateral stability of active channels or allows waterto spreadover a largearea, isnot desirable. Decreased water depth'and veloc- ityincreases sedimentation rates, alters water temperature, and alters dissolvedoxygen levels. These changes in aquatic habitat usually affect the localdistribution andcomnunity structure of benthos and fish,

The effectsof scraping in vegetated areas of inactivefloodplains and terracescan be similar to those described for pits. However, long-term closedsite will facilitatere-establishment of pre-mining vegetation con- dit ions.

Ifmaterial sites are located andoperated toprevent or greatly mini- mizeeffects onchannel hydraulics, and to utilize only exposedgravel bars,the probability of major localized changes to a floodplaingenerally is greatly reduced. Where exposedgravel bars are not available or are inadequate, a tradeoffdecision between sites must be made thatweighs the potentialeffects of aquatic disturbances against terrestrial disturbances. Inthese cases, minimization of hydraulic change to active channels should beimportant in the decision -- majorhydraulic changes can have a greater long-termeffect on terrestrialsystems than the controlled disturbances associatedwith a sitelocated in a vegetatedinactive floodplain or terrace

RECOMMENDEDFUTURE S;FUD IES

Duringthe present study a number ofsubject areas were identified thatshould be investigated.

I. Evaluationof gravel mining from coastal and uplandsources; and, preparationof guidelines for users of these sources. These alternatives to sourceshave not been studied.

2. Evaluationof the effects of multiple sites onone river system. Such an investigationshould be aimed at determining the critical, spatial, andtemporal relationshipsof multiple sites. Gravel replenlshment rate predictionsshould be an integralpart of this investigation.

3, Severalfloodplain gravel removal sites should be investigated before,during, and after mining to assess the adequacy ofthe Guidelines Manua I .

4. Severaltopics of the Guidelines Manual shouldbe studied in detail to assesstheir adequacy, (i.e., buffers, pit design, and active channel dredg i ng 1 .

vi Thisreport was submittedin fulfillment of Contract Number 14-16- 0008-970 by Woodward-Clyde Consultants,Anchorage, Alaska, under sponsor- shipof the Office of Biological Services, U.S. Fish and WildlifeService. Work was completedas of June1980.

vi i TABLE OFCONTENTS

Page

EXECUTIVE SUMMARY ...... iii LISTOFFIGURES ...... xi i LISTOFTABLES ...... xix ACKNOWLEDGMENTS ...... xxi i INTRODUCTION. E . H . Follmann ...... BACKGROUND ...... PHILOSOPHY ...... PROJECTDESCRIPTION ...... REFERENCES ...... APPROACH ANDMETHODOLOGY. E . H . Follmann ...... II SITESELECTION ...... II DATAREVIEW ...... 17 FIELD STUDYOF SELECTEDMATERIAL SITES ...... 17 DATABASE ...... 29 TECHNICAL REPORT ...... 30 GUIDELINES MANUAL ...... 31 REFERENCES ...... 33 DESCRIPTION OF STUDY RIVERS. L . L . Moulton. Ed .... 35 SEWARD PENINSULA ...... 35 NORTH SLOPE ...... 42 NORTHERN INTERIOR ...... 51 SOUTHERN INTERIOR ...... 58 REFERENCES ...... 66 EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND HYDRAULICS. L. A . Rundquist ...... 67 INTRODUCTION ...... 67 METHODS OF DATA COLLECTION ...... 70 METHODS OF DATAANALYSIS ...... 71 HYDROLOGY ...... 71 HYDRAUL ICs ...... 72 QUANTIFICATION CHANGESOF ...... 74 RESULTS AND DISCUSSION ...... 81 CHANNEL CONFIGURATION ANDPROCESS ...... 81 HYDRAULICS ...... 99 SEDIMENTATION ...... 115 ICE CHARACTERISTICSICE ...... 122 HYDROLOGY ...... 127 SUMMARY.AND CONCLUSIONS ...... 134 CHANNEL CONFIGURATION ANDPROCESS ...... 134 HYDRAULICS ...... 135 SEDIMENTATION ...... 135 ICECHARACTERISTICS ...... 136 HYDROLOGY ...... 136 RECOMMENDATIONS ...... 136 REFERENCES ...... 138 EFFECTS OF GRAVEL REMOVAL ON AQUATIC BIOTA. L . L . Moulton ...... 141 INTRODUCTION ...... i41 METHODSOF DATA COLLECTION ...... 144 METHODS OF DATA ANALYSIS ...... *.. 145 RESULTS AND DISCUSSION m rn . rn . . rn .... 148 MAJOR GRAVELREMOVAL HABITATALTERATION ...... 148 EFFECTS OF HABITATALTERATION ON FISH POPULATIONS .... 167 EFFECTS OF HABITATALTERATION ON AQUATIC MACROINVERTEBRATES ...... 198 SUMMARYAND CONCLUSIONS . . . . rn 0 .... 209 EFFECTS OF GRAVEL SCRAPING ON RIVERINEHABITATS . .... 209 EFFECTS OF INUNDATED PIT FORMATION ON THE ASSOCIATEDRIVER BIOTA ...... 211 RECOMMENDATIONS ...... 213 REFERENCES ...... 214 EFFECTS OF GRAVEL REMOVAL ON TERRESTRIAL BIOTA. M.R.Joyce ...... 215 INTRODUCTION ...... 215 METHODS OF DATA COLLECTION . . . . rn 218 METHODSOF DATA ANALYSIS . rn rn . . rn . . . . 220 RESULTS AND DISCUSSION ...... 222 VEGETATIVE CO”UNITIE$ OF STUDYAREA FLOODPLAINS rn . . 222 VEGETATIVE COMMUNITY CHANGES AT GRAVELREMOVAL SITES ...... 225 FACTORS AFFECTINGVEGETATIVE RECOVERY RATE . e 0 rn 24 I FAUNAL COMMUNITY CHANGES AT GRAVELREMOVAL SITES .... 248 FACTORS AFFECTING RECOVERY RATE OF FAUNALCOMMUNITIES . . 253 PERMANENTLY PONDED SITES . rn . 0 rn rn . 254 SIMILARITIES OF RESPONSE BETWEEN BIOTA ANDSTUDY SITE PARAMETERS . . . . . rn . . 259 SUMMARYAND CONCLUSIONS . . . rn . 268 VEGETATIVE REMOVAL ...... 268 MINING DEPTH AND LOCATION . . rn 268 OVERBURDEN ...... 269 PERMANENTLY PONDED HABITATS ...... 269 RECOMMENDATIONS . . . . 270 REFERENCES ...... 271 EFFECTS OF GRAVEL REMOVAL ON WATER QUALITY. L . L . Moulton ...... 273 INTRODUCTION ...... 273 RESULTS AND DISCUSSION ...... 276 POST-MININGEFFECTS OF GRAVEL REMOVAL OPERATIONS . . 276 SUMMARYAND CONCLUSIONS ...... 284 REFERENCES ...... 285

ix Page

EFFECTS OF GRAVEL REMOVAL ON AESTHETICS. D . K . Hardinger ...... 287 INTRODUCTION ...... 287 SCENICQUALITY ...... 289 VISUALSENSITIVITY ...... 289 DEGREE OF VISIBILITY ...... 290 APPROACH ...... 291 THE VISUAL RESOURCESOF THE STUDY REGIONS ...... 292 SEWARD PENINSULA ...... 292 NORTH SLOPE ...... 295 NORTHERN INTERIOR ...... 297 SOUTHERN INTERIOR ...... 300 EFFECTS OF GRAVEL REMOVAL ON VISUAL RESOURCES ...... 304 SEWARD PENINSULA ...... 304 NORTH SLOPE ...... 305 NORTHERN INTERIOR ...... 306 SOUTHERN INTERIOR ...... 306 SUMMARY ...... 308 GEOTECHNICAL ENGINEERING CONSIDERATIONS OF GRAVEL REMOVAL. H . P . Thomas and R . G . Tart. Jr ...... 311 INTRODUCTION ...... 311 APPROACH ...... 314 SITESELECTION AND INVESTIGATION ...... 315 PRELIMINARYSITE SELECTION ...... 315 SITEINVESTIGATION ...... 317 FINALSITE SELECTION ...... 318 MININGPLAN PREPARATION ...... 319 SITE PREPARATION ...... 321 ACCESS ...... 321 OVERBURDENREMOVAL ...... 324 CHANNEL DIVERSION ...... 324 SETTLING PONDS ...... 325 SITEOPERATION ...... 326 EXCAVATION ...... 326 TRANSPORTATION AND STOCKPILING ...... 327 PROCESSING ...... 328 SITE REHABILITATION ...... 329 REFERENCES ...... 330 INTERDISCIPLINARY OVERVIEW OF GRAVEL REMOVAL. E . H . Follmann ...... 331 INTRODUCTION ...... 331 PHYSICALSITE CHARACTERISTICS ...... 333 CHANNEL CONFIGURATION ...... 333 DRAINAGE BASIN SIZE (CHANNEL WIDTH) ...... 348 CHANNEL SLOPE ANDSTREAM ORIGIN ...... 350 GRAVEL REMOVALAREA CHARACTERISTICS ...... 354 TYPE OF GRAVEL REMOVAL ...... 354 363 LOCATION OF GRAVEL REMOVAL . . rn m m DIKES AND STOCKPILES ...... 376

X Page

SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS ...... 379 SUMMARY ...... 379 RECOMMENDATIONS ...... 382 RECOMMENDED FUTURE STUDIES ...... 384

APPENDICES A . SCIENTIFIC NAMES ...... 385 B . GLOSSARY ...... 395

xi LIST OF FIGURES

Number Page

I Locationof the 25 gravel removalstudy sitesin Alaska ...... 13 Typical Seward Peninsulaterrain ...... 37 ArcticCoastal Plain wetlands ...... 43 Northernportion of the Arctic Foothills , . . . . . 44

Typicalview of theWhite Hills section ofthe Arctic Foothills ...... 44

6 M. F. KoyukukRiver valley looking upstream . . . . 52

7 Typicalterrain of theKokrine-Hodzana Highlands . . 53

8 Typicalterrain thein Yukon-Tanana UplandSection 59

9 Elaciofluvialdeposits inDry Creek floodplain . . . 60 IO Typicalview ofAlaska Range section ...... 61

II Aerialphotograph showing the two gravel removallocations at Sinuk River considered separatelythein hydrology/hydraulics analysis . . 75

12 Aerialphotograph of Washington Creek showing theupper andlower gravel removal areas . . . 77

13 Aerialphotograph of Oregon Creek showing theupper and lower gravel removal areas ...... 78

14 Aerialphotograph of Aufeis Creek showing upperand lower gravel removal areas ...... 79

15 Aerialphotograph of Middle Fork Koyukuk River- Upstreamshowing upper and lower gravel removal areas ...... 80

16 Schematicdiagram of theplan view and cross sectionof a typical braidedriver ...... 83

17 Maximum depths and correspondingtop widths of undisturbedmajor, side, andhigh-water channelsat four braided study sites ...... 84

xi i -Number Page 18 Schematicdiagram of the plan view and cross sectionof a typicalsplit channel river ...... 85

19 Maximum depths and correspondingtop widths of undisturbedmajor, side, and high-waterchannels atfour split channel study sites ...... 86

20 Schematicdiagram of the plan view andtwo crosssections of a typicalmeandering river . . ... 87

21 Maximum depths and correspondingtop widths of undisturbedmajor, side, and high-waterchannels at 15 studysites with meandering, sinuous, and straightconfigurations ...... 88

22 Schematicdiagram of the plan view and cross sectionof a typicalsinuous river ...... 90

23 Schematicdiagram of the plan view and cross sectionof a typicalstraight river ...... 90 24 Schematicdiagram of an alluvialfan ...... 91

25 Comparativeaerial photography of the Nome Rivershowing change in channel configuration resultingfrom gravel removal activitles ...... 96

26 Aerialphotograph of the Ugnuravik River pit site showingthe insufficient buffer zone . . ... 98

27 Aerialphotograph of the Tanana River-Upstream sitewith substantial buffer zoneseparating thepit from the active side channel ...... IO0

28 Aerialphotograph of the Prospect Creek pit showingwlde buffer zone separatingthe pit fromthe active channel ...... 101

29 Schematicdiagram illustratingdefinitions of channelgeometric and hyraulicvariables ...... I02 30 Averagehydraulic geometry of river channels expressedby relations of width, depth, and veloc - ityto discharge at two locationsalong a river (modifiedfrom Leopold, Wolman, and Miller 1964) ... I04

31 Schematicdiagram showing change inwater surfaceslope in response to a change in waterdischarge ...... I05

xiii Number Page

32 Schematicdiagram i I lustrating the effects of a flowobstruction on the local hydraulics .... 107

33 Comparativeaerial photography of the Penny Rivershowing change in hydraulic characteristicsresulting from gravel removal activities ... 113

34 Schematicdiagram illustrating anexample of a change inlocal water surface slope resultingfrom an in-channelgravel removal operation ... 114

35 Schematicdiagram showing degradation process .... 116

36 Upstreamview of thermal and fluvialerosion inthe access road atUgnuravik River, acting as a long-termsediment source to the river ..... 123

37 View oferosion of a diversion dam whichacts as a long-termsediment source to Skeetercake Creek. Dunes inforeground are atypical of the undisturbedriver ...... 123

38 Largearea of aufeisat the upper gravel removalarea at Washington Creek as it appeared inearly June ...... 125

39 Aerialphotographs of Washington Creek (top) and Aufeis Creek(bottom) showing material site locations and approximatechannel locations before thedisturbance ...... 133

40 Siltationresulting from extensive aufeis field at OregonCreek mined study area, 20June1977.,...... 149

41 Removal of bank coverat Oregon Creek as observedon 24 June 1977 ...... 152

42 Removal of bankcover at Skeetercake Creek as observedon 18 June 1977 ...... 153

43 WashingtonCreek upstream and mined area on 9 September 1977 showingreduction of instream cover due togravel removal operation (flow level [o. I I m3/sec] = 20 percentof mean annualflow). Other habitat alterations include increasedbraiding, siltation, and intergravel flow...... 154

xiv Number Page

44 Reductionof instream cover as providedby bouldersat Sagavanirktok River, 3August 1978 (flowlevel, 60 mS/sec, = 155% ofestimated mean annualflow)...... I55

45 Increasedbraiding at Sagavanirktok River study site causedby mining mid-channel gravel bars and a vegetatedisland in the active channel (miningoperation conducted during the winter of 1974-1975) ...... I 57

46 Response ofcross-sectional wetted perimeters topercentage of mean annualflow and percentage ofcross sections comprised’of selected depthintervals at mean annualflow at three gravelremoval study sites ...... I 58

47 Low velocitybackwaters formed by gravel removal at Dietrich River-Downstream (13 July 1978) and MiddleFork Koyukuk River-Upstream (18 July 19781, noteextensive silt depositionin both cases .... I 59

48 Creationof low velocityside channels and inundatedpit following gravel extraction ..... I 60

49 Sequence ofaerial photographs showing effects ofovermining the inside of a meanderbend at MiddleFbrk KoyukukRiver-Upstream. Immedi- atelyfollowing mining (b) there was an increase in backwaterareas, The nextyear (c) the meander was partiallycut off, creating a varietyof low velocityhabitats ...... I63

50 Temperatureand dissolved oxygen profiles at four deep gravelpit study sites ...... I65

51 Ponded areaat Kuparuk River study site where threeseine hauls captured 61 Arcticgrayling and 2 slimysculpin, 9 August 1978 (pool I in Table 21) ...... I 79

52 Ponded areaat Middle Fork Koyukuk-Upstream study site whereone seine haul captured 28 Arcticgrayling, 3 roundwhitefish and 3 slimy sculpin, 18 July 1978 (pool 2 inTable 21) ..... I 79 53 Potentialmigration blockages, aufeis fields at WashingtonCreek and Oregon Creek, June 1977 . I82

54 Regionwhere Aufeis Creek went subsurface creatingmigration blockage due tolack of surfaceflow...... I 83

xv Number Page

55 ProspectCreek study site - shallowpond habitat supportingArctic grayling, chinook salmon juveniles,round whitefish, northern pike, burbot, and slimysculpin, 12 August 1978 ...... I88

56 West ForkTolovana River study site - deep pond withextensive shallows providing northern pike and Arcticgrayling habitat, 29 July 1978 ...... I88

57 Tanana River-Upstreamupper pit showingexten- sivevegetation beds, 18 August 1978. Note differencein the extent of vegetative development inthis 13-year old pit as compared tothe 2 and3-year old pits in Figures 55 and 56 ...... I 90

58 Potentialoverwintering area at Willow Creek. Thisspring-fed tributary, openthroughout the winter,had previously entered Penny River at a deep pool ...... I 92

59 Creationof a potentialoverwintering area at West ForkTolovana River downstream from pit , . I .. I 96

60 Densitiesof selected aquatic macroinvertebrates atAufeis Creekstudy areas during 1977 sampling trips ...... 206

61 Penny Riverundisturbed floodplain showing typical NorthSlope and Seward Peninsulafloodplain characteristicsof sinuous channel bordered with dense shrubthickets with incised outside meanderbank, and narrowgravel point bar on inside meander . . .. 224

62 West ForkTolovana River showing typical South- ern and Northerninterior medium riverflood- plaincharacteristics with shrub thickets and whitespruce-paper birch stands along the riparian zone ...... ". 224

63 West ForkTolovana River showing permanently floodedpit excavated adjacent to the active floodplainwith a downstreamconnection ...... 226

64 A view of OregonCreek looking downstream throughthe mined area showing site conditions thatremain 13 yearsafter gravel removal . . .. 229

65 Penny Rivermined area looking upstream. Note theflooded conditions within the disturbed area, and theoverburden piles in the center of thesite ...... 290

xv i -Number Page 66 Close-upview of an overburdenpile in the Penny Rivermined area. Note the development of herbace- ousand woody vegetationduring the II years followinggravel removal ...... 234

67 WashingtonCreek mined area showing vegetative recoveryonly present on the overburden pile 13 yearsafter gravel removal ...... 234

68 Woody revegetationoccurring throughdevelop- ment ofadventitious stems ...... 235

69 Distribution of woody slashdebris andother organicsover the ground on the edge of the gravelremoval area at Aufeis Creek ...... 236

70 View ofthe upper pit at Tanana River-Upstream showingdiversity of shorelineconfiguration anddevelopment of woodyand herbaceousvegetation 13 yearsafter gravel removal ...... 237

71 Viewof the lvishak River floodplain looking downstreamshowing typical braided channel characteristicswith extensive gravel bars and isolated,vegetated islands ...... 239 72 View ofboth undisturbed (background) andmined (foreground)reaches of theShaviovik River. Notethat gravel removal maintained natural pointbar contours andshapes and didnot disturbriparian>vegetative zones ...... 240

73 Compacted surfacegravels in an accessroad leadingto the Oietrich River-Downstream site .... 244

74 inorganicoverburden piled on the edge of the OregonCreek sitewhich supported no vegetation 13 yearsafter gravel removal ...... 244

75 Close-upof dense and diversevegetative development in an area of surfacebroadcast of woody slash and organics.Note the willow adventi- tiousstem development ...... 246 76 Distantview of a largesilt depositional areaat the Sagavanirktok River study site ...... 247 77 A siltdepositional area of the Kavik River support i ng a we I I -deve 1 oped p i oneer vege tat ive community ...... 247

xvi i Number Page

78 Close-upof a concentra tionof willow seedlings atthe shoreline of the JimRiver ponded area .... 248

79 Vegetatedorganic mats thatwere washed downstream andgrounded during high water on Toolik Riverfloodplain gravel bars ...... 249

80 TananaRiver-Upstream showing shoreline diversity and vegetativedevelopment in the upper pit ... 256

81 Undisturbedbuffer along the original stream channelat Aufeis Creek (downstream disturbed areaonly) ...... 264

82 Gravel fill rampused toprotect the incised bank atthe Sagavanirktok River study site ...... 266

83 Thermal and hydraulicerosion of permafrost inducedby multiple passes of a trackedvehicle across an unprotectedincised floodplain bankand adjacent tundra ...... 267

84 Armoredbank protectingthe West ForkTolovana Riverpit from a channeldiversion into the mined site ...... 267

85 Typical Seward Peninsulalandform at Penny River ... 293

86 Typicalview of an Arctic Coastal Plain floodplain . . 295

87 DietrichRiver valley ...... 298

88 Lower MiddleFork Koyukuk River valley ...... 298

89 McManus Creek valley ...... 301

90 PhelanCreek valley ...... 302

91 Gravel ramp atShaviovik River site providing accessover a permafrostriver bank ...... 322

92 Thermalerosion near Ugnuravik River resulting fromcompaction and destructionof the vegetative mat overlyingice-rich permafrost soils ... 323

91 Configurationsofstudy rivers ...... 335

xvi i i LIST OF TABLES

Number Pagl

I Major VariableMatrix ...... 15

2 MethodsUsed forMeasuring Water Quality Parameters with the Number ofReplicates Taken perStudy Area ..... 21

3 AquaticBiology Sampling Methods Used at EachStudy Site. 24

4 Sire and QuantityValues of the 25 StudySites ..... 36

5 QuantificationRatings of Change in Channel Configuration CharacteristicsResulting from the Gravel Removal Operationat Each ofthe 25 Sites ...... 93

6 Values of Exponentsfor Hydraulic Geometry Power Relations I06

7 Quantificationof Change inHydraulic Variables Resulting fromthe Gravel Removal Operationat Each ofthe 25 Sites ...... I 09

8 Quantificat on Ratingsof Change inSedimentation Character sticsResulting from the Gravel Removal Opera t i on at Each of the 25 Sites ...... I19 9 Quantification Ratings of Change inAufois -Potential thatResul tedfrom the Gravel Removal Operationat Each ofthe 25 Sites ...... I 26

IO Mean Annual Flow Estimates at Each ofthe 25 StudySites. I 29

1 II CalculatedDischarges in m’/s Correspondingto Selected RecurrenceIntervals for Each ofthe 25 StudySites . . I 30

12 QuantificationRatings of Change in Quantity of Intergravel Flow Resul t ing from theGravel Removal Operation at Each ofthe 25 Sites ...... 131

13 Major HabitatAlterations Observed at Sites Mined by Scraping ...... I 50

14 Percent of Pit Area Composed ofSelected Depth Intervals. I 64

15 Effects of CumulativeHabitat Alterations on Fish Populationsin the Mined Area of Study Sites Mined byscraping ...... I68

xix Number Page

16 EstimatedDensities andBiomass of Arctic Charand Slimy Sculpinat Washington Creek Study Site Based on RepeatedElectroshocking of Blocked Sections of Stream 21-23June1977...... I 72

17 EstimatedDensities and Biomass of Arctic Charand Arctic Graylingat Kavik River Study Site Basedon Repeated Electroshocking of BlockedSections of Stream, 1976 . I 74

18 Comparisonof Fish Densifies in Mined and Undisturbed Areas as Determined by ElectroshockingBlocked Sectionsof Stream at Kavik River Study Site, 1976 . . I 75

19 Catch of ArcticGrayling per Angler Hour atKavik RiverStudy Areas Ouring Summer 1976 SamplingTrips . . I 76

20 Change in Catchper Effort and PercentComposition of IndicatorSpecies at Selected Study Sites ...... I77

21 Sumnary ofCatch from PondedWater Areas Isolatedfrom ActiveChannels at Two StudySites ...... 181

22 Mean ForkLengths of Coho SalmonCaught by Minnow Trap at the Penny RiverStudy Site During 1977 ...... I 86

23 Differences of Coho Salmon Mean Fork LengthBetween Sample Areasand Associated Significance Levels, Penny River StudySite During 1977...... I87

24 PhysicalConditions at Pits Visited During Winter .... I93

25 Response of Aquatic Riffle Macroinvertebrate Taxa to HabitatAlterations Observed at Selected Study Sites . I 99

26 Changes inAquatic MacroinvertebrateDensities at Sites Exhibiting Type I and 2 SubstrateAlterations ..... 203

27 Densities of Aquat ic Macroinvertebrates Collected at Inundated Pit Si tes, 1976-1978 ...... 208

28 Quantitative Changes inSelected Terrestrial Biological Parametersat Gravel Removal StudySites ...... 223

29 Location, ResponseTime, andCommunity Characteristics of VegetativeRecovery at SelectedStudy Sites ...... 232

30 Quantificationof Change inSelected Hydrology Parameters Which Were ImpedingVegetative Recovery at Study Sites 243

31 QualitativeEvaluation of HabitatQuality andFauna Use at Permanently Ponded Gravel Removal Sites ...... 255

xx Number PEge

32 BirdObservations by Habitat Type Withinthe Control and DisturbedAreas at TananaRiver-Upstream 3-7 June, 1978. Numbers Indicate Minimum Individuals Known to Occur in Each Habitat Type ...... 257

33 BirdObservations by Habitat Type Withinthe Control and DisturbedStations at West ForkTolovana River 9-11 June, 1978. Numbers IndicateTotal Individuals Known to Occur in Each Habitat Type ...... 258

34 TwoWay CoincidenceTable Displaying a HierarchialClus- teringof Similar Sites and SimilarBiotic Parameters . 260 35 SelectedAlaska Water Quality Standards ...... 2 74

36 Water QualityParameters Measured at Gravel Removal Sites WhichExceeded Alaska Water Quality Standards ..... 275

37 Changes inTurbidity andSuspended Solids BetweenSample Areasat Selected Study Sites ...... 278

38 Relative Change of Water QualityParameters Between Up- streamand Downstream Sample Areas atSelected Study Sites ...... 28 I

39 AverageMeasured Values of SelectedWater Quality Param- etersat Study Sites with Inundated Pits ...... 283

40 InterdisciplinaryRating of CumulativeEffect of Scraping, UsingVarious Indices of Change onStudy Sites Visited from 1976to 1978...... 3 38

41 InterdisciplinaryRating of Effects of Pits onAssociated Floodplainsat Selected Study Sites Visited from 1976 to 1978 UsingVarious Indices of Change ...... 3 59 A-l VegetationIdentified inthe Text ...... 386 A-2 Mammals Identifiedinthe Text ...... 387 A-3 BirdsIdentified inthe Text ...... 388

A-4 FishSpecies Reported and Caught or Observed inMajor GeographicalAreas Represented by the Twenty-five Sites...... 390

A-5 AquaticMacroinvertebrates Caught at Study Sites During 1976-1978 FieldSampling ...... 392

xx i ACKNOWLEDGMENTS

Woodward-Clyde Consultantsappreciates the contributions of anumber of scientists and engineers.

Dr. A. 0. Ott, now withthe Alaska State Pipeline Coordinator's Office, conceivedthe aquatic biology field program and was responsiblefor much ofits implementation. He alsoserved as a principalinvestigator onthe studyfor oneand one halfyears of the field phase.

BrentDrage, now with R & M Consultants, was responsiblefor early implementation of thehydrology field program.

Otherscientists whose contributionshave benefited the study are, J,ames A. Glaspellof the Alaska Department of Fish and Game; Michael A. Scottof the U. 5. Bureau of Land Management; and Dr. Keshavan Nair, Dr. UlrichLuscher and Robert Pitt of Woodward-Clyde Consultants.

A number of Woodward-Clyde personnelassisted in the field at various times,including Donald 0. McKay (now withthe U. S. Fish and Wildlife Service),Kenneth E. Tarbox,Jonathan lsaacs, and Jerry P. Borstad.

Thanksare also due toAlyeska Pipeline Service Company and theAlaska Departmentof Transportation for use of their photographs of some mining sites and theuse of their mining plans.

We arealso grateful to Susan Ogle forgraphics production and Marnie lsaacs foreditorial review. And finally, we aredeeply indebted to -Jean Borstadand Jayne Voorhisfor report production.

xxi i The U. S, Fish and WildlifeService Project Officer appreciates the technical and administrativeassistance provided by Summer Dolethroughout the project and to Dr. Norman Benson fortechnical advice during the data collection and analysisphases. We thankthe following individuals who reviewedand commented on some portionsor all of thereport in draft form: Bob Bowker, Hank Hosking,Ronald Kin,nuner, Jim Lewis,Lou Pamplin, John Stoutand Jerald Stroeble, all withthe U. S. Fish and WildlifeService, various stations; -Bill Gabr ie1 andEar I Boone w i th the Bureau of Land Management, Anchorage, A I aska; Joe Childers and Bob Madisonwith U. S. GeologicalSurvey, Anchorage, Alaska; Dr. Alvin Ott withthe State Pipeline Coordinators Office, Fairbanks, Alaska; BruceBarrett and Carl Yanagawa withthe Alaska Department of fish and Game, Anchorage,Alaska; Brien Winkley, U. S. Army Corps of Engineers,Vicksburg, Mississippi; and W. P. Mett and A. W. Schwarz with ARC0 Oil and GasCompany, Anchorage,Alaska,

xxi i i INTRODUCTION E. H. Follmanna

ThisTechnical Report and theaccompanying Gravel Removal Guidelines Manual forArctic and SubarcticFloodplains (Guidelines Manual) present data analyses and conclusionsresulting from a 5-yearstudy of 25 floodplain materialsites in arctic and subarcticAlaska, and provideguidelines to insureminimal environmental degradation when siting,operating, and closing floodplainmaterial sites. This study, its results andconclusions, and thesereports directly relate only to floodplains, although several aspects may also be applicablein nonfloodplain locations.

BACKGROUND

A common denominator in all resource and industrialdevelopment is theneed for granular material; gravel is used worldwide for construction projects and transportationroutes. In thearctic and subarctic, however, thepresence of permafrost creates special construction problems that place additional demands onthe supply of gravel.

Even slightalterations in the permafrost thermal regime caused by surfacedisturbances can cause thawing, thermokarst formation, subsidence, and erosionalprob lems. Maintenanceof the therma I regime is essen.t ial when buildingor operatingin permafrost areas, but especially in regions characterized by finegrained soils with high water content. These latter areasare highly susceptibleto subsidence when surfacedisturbance alters

a E. H. Fol lmann is presentlyassociated with the Institute of Arctic Biologyof the Universityof Alaska.

I thethermal regime. In these cases, the thawed ground becomes a morass in whichvehicle passage can be impossible andmai ntenanceof structural stability of facilities becomes difficult.

The currentmajor solution for eliminating or greatly reducing permafrost thaw is to usegravel as either pads for structures or asroadways. Althoughthese demands existelsewhere, the thickness of gravel required inpermafrost areas is far greater than in nonpermafrost areas. The gravel pad inpermafrost areas replaces the insulative function of the vegetative mat that was removed or compressedby the gravel fill. Since theinsulative qualityof the vegetative mat is greaterthan that of anequ i valentthick- nessof gravel, a gravelpad must be considerably thicker to maintain an equivalentthermal regime. Under these circumstances the mos t important considerationsfor determining pad or road thickness are: cI i maticfactors, soilsurface temperatures, permafrost temperatures, and subgrade soilproper- ties(McPhaiI et al. 1975). The objectiveis to establish the freeze front in or slightlybelow the fill (McPhaiI et al. 1975). Where thisis accom- plished,potential thawproblems can be greatlydiminished.

Arctic and subarcticregions have been thefocus of attention during thepast several decades because of the wealth of natural resources known orthought to occur in these regions. The discoveryof oil and gas onNaval PetroleumReserve No. 4 (now theNational Petroleum Reserve-Alaska) in the1940's, at Prudhoe Bay in 1968, and innorthern Canada hasstimulated thisinterest andexpanded it toinclude metallic minerals and coal. Expan- sionof exploration activities can be expectedto continue.

As resourcedevelopment in remote arctic and subarcticareas becomes moreeconomically feasible the region's resources will be utilized to meet society'senergy and material needs.These futureprojects will require increasedquantities of gravel to facilitate construction and toprovide stablesubstrates for various permanent andtemporary facilities.For example,the gravel requirement for the Trans-Alaska Pipeline System was about 3 49 millioncubic meters (m 1 (MichaelBaker, Inc. 1977). Smaller projects requiringgravel, such as exploratory well drill pads and associated camps,

2 3 typically use up to 75,000 m . If, however, airstrips and roadsare associatedwith these sites, quantities can increase to several hundred thousand cubicmeters. Basedon experience constructing the Yukon Riverto Prudhoe Bay Haul Road (HaulRoad), approximately 31,000 m3 ofgravel are required perkilometer of roadconstruction, and maintenancerequirements average 3 about 700 m perkilometer (km) per year for about the first 5 years(Alson personalcommunication). Alyeska Pipeline Service Company requestedabout 1.5 mi I lion m’ ofgravel for maintenance of their project over a 5 year period. The figurespresented above for the large pipeline projects repre- sentgravel needs from both upland and floodplain sites. About half of the gravelused on the oilpipeline was fromfloodplains.

Alluvialdeposits found in broad floodplains offer one ofthe prime sourcesof gravel in northern areas. Individual material sites vary consider- ablyin size, as indicatedby the range of those considered for study in 3 thisproject: 7,738 to 631,000 m of material removed. Severaldifferent sites may benecessary tosupply material meeting the required project specifications becauseone site may notcontain all typesof material needed.For example, not all potentialsites will havematerial suitable for topping.Also, since road and pipeline construction projects need materials throughouttheir lengths, one site or a seriesof sites in onearea will notsatisfy the demands ofthese projects. A hauldistance of 6.5 km or lesshas been estimated to be economically efficient for construction in Alaska, and hauldistances of I3 to 16 km orless are planned for maintenanceof the Trans-Alaska Pipeline System (Alson personal communication). Therefore,material sites for these types of projectsnecessarily must be locatedat regular intervals due to economicconsiderations.

To protect an environmentfrom unacceptable disturbance, the elements comprisingthe environment must be known, thevarious elements of the proposed activity mustbe known, and theeffects of the activity on the environ- mentalelements separately andas a wholemust be known.Where thisinfor- mat-ion isavailable, guidelines to conduct the proposed activity with a min imum ofenv ironmentalperturbation can be developed. Where informationon one ormore of theseelements islacking or is only partly understood, any

3 guidelinesthat are developed are based on estimates and assumptions whose validity is dependenton the experience and predictive powersof those developingthe guidelines. The lattercondition is therule in mostcas@s whereenvironmental impacts are concerned. Impacts from resource exploration anddevelopment have not been studied as much as is necessary to make intel- ligentdecisions regarding environmental impacts. This lack of research is particularlytrue in arctic and subarcticregions. Theremoteness of the area and thehigh cost of conducting research have not facilitated an ade- quatedescription of theenvironmental elements. Studies of the environ- mentaleffects of development have been similarly hindered.

Extensiveliterature review revealed that the specific impacts of gravelremoval had seldom been studied and, therefore,were poorly understood.Description of impacthad been attempted inonly a fewcases (Bull andScott 1974, FederalWater Pollution Control Administration 1968, Forshageand Carter 1973, Sheridan1967); and these studies dealt specif- icallywith only oneaspect, e.g., fisheries.LaBelle (1973) reviewed gravel andsand availabilityin the Barrow area of the National Petroleum Reser V e- Alaska and made recommendationson gravel extraction and evaluationsof potentialenvironmental impact, Northern Engineering Services Company Limited and AquaticEnvironments Limited (1975) evaluated the material s t es associatedwith the Trans-Alaska Pipeline System with reference to aquat C habitat.In addition, several reports identified problems associated with gravelextraction as one of many sources of environmentalperturbations that couldbe expected from new and continuedexploration anddevelopment inthe north (Bliss and Peterson 1973, Klein 1973, Weeden and Klein 1971, West 1976). None ofthese latter reports presented results of any materialsite studies.

Therehave been few studies on the environmental effects resulting fromconstruction of the Trans-Alaska Pipeline System.The JointState/ FederalFish and WildlifeAdvisory Team (JFWAT) prepared a reporton surveil- lanceexperience with gravel mining recommendations (Burger and Swenson 1977). The JFWAT also produced a seriesof reports dealing with experiences onthe pipeline, including environmental effects studies. However, themajor

4 responsibilityof the majority of JFWAT staff was environmentalsurveillance ofconstruction, not research on environmental effects.

Weeden and Klein (1971:481) stated: "As with so many otherproblems oftundra management, thedesign of criteria for mining operations in gravel lagsfar behind present need because detailed knowledge of fish populations -- wherethey are, when theymigrate, where they spawn, theirvulnerability to added silt loadingsof river waters, etc. -- islacking". By early 1975, thestate of knowledge had not progressed or expanded greatly. This fact, coupledwith the dependenceon gravelfor arctic and subarcticconstruc- tion,stimulated the U.S. Fish and WildlifeService to initiate a project toinvestigate the effects of gravel removal on floodplainsystems. The projectobjective was toprovide a comprehensiveinformation review and data synthesisto form the basis for future mining of river and floodplain gravels. The purposeof the project is to provide an informationbase that will assistresource managers to formulate recommendations concerning oper- ationsthat will minimizedetrimental environmental effects of gravel removalfrom arctic and subarcticstreams,

PHILOSOPHY

Little is known aboutthe natural changes which occur in riverine systems inarctic and subarcticregions. Therefore, determining the effects ofresource exploitation in these regions is often difficult because of the interplayof natural changes andman-induced disturbances. The basisfor thisstudy was theassumption that gravel removal operations in a floodplain causechange, themagnitude of change depending primarily on the floodplain characteristics,the location of the site, and themethod of gravel extraction.Since almost all riverine systems in arctic and subarcticregions have evolvedto the present through natural change and.without man-induced disturbances, all changesdue togravel removal identified in this study were consideredundesirable. To maintain a river system inits natural or near- naturalstate was consideredthe essence of guidelines development and providedthe best conceptual base from which to minimize environmental degradation. However, it isrecognized that there may be situations where

5 resource managers may wishto exercise other options. Any sitecharacter- isticsor methodsthat facilitated rapid recovery to predisturbance con- ditionswere considered for implementation as guidelines.

The presuppositionthat all changesdue togravel removal are undesirable does not,by necessity, cause the data analyses andrecommendations to beimpractical. It is a foregoneconclusion that changes will occur when gravelis removedfrom a floodplain. To notethat changes from the naturalstate were less at one site than another suggests that the former site was operatedmore consistently with characteristics of the system thanthe latter, thereby reducing the magnitude of change. The floodplain and gravelremoval characteristics at sites that produced these minor changesformed the primary basis for development of constructive guidelines tominimize change,Conversely, the floodplain and gravelremoval characteristicsat sites with major changessupported development of guidelines primarilyof a precautionarynature.

The analysesin succeeding chapters treat the changes that were meas- uredat individual study sites. There are sites, for example,where species diversityincreased as a resultof site disturbance. In some contexts, thisincreased diversity would beconsidered a beneficialeffect of gravel removal. However, inthe context of thisproject, this effect initially was evaluatedequal to one which caused an equivalent decrease in species diversity because it reflected a changefrom the naturally evolved condition.

Thisproject treats all changesconsistently and objectively as a changefrom the natural, and special interest perspectives are neither recommended norencouraged, However, it isrecognized that a resource man- agerin certain circumstances may begreatly influenced by the need to consider a sitefrom a multipleor optimal use standpoint. For example, subsequent togravel removal a deeply dug sitemight beconsidered as a watersource in areas where winter supplies of water are minimal. Several studysites were deep pitsthat contained water throughout the year. For- mationof a pit represents a majorchange from the natural situation and the site will notrevert back to a naturalsituation for many years, if at all.

6 Inthe context of this project, pits represent a majordivergence from the natural. However, when consideredfrom the standpoint of multiple use or habitatdiversification, a resource manager may electto recommend or ap- prove a permitfor this form of gravel removal. In these situations the resource manager will beable to predict the results of such an operation by reviewof the following sections in this report.

PROJECT DESCRIPTION

A 5-yeargravel removal study was initiatedin mid-1975 toevaluate theeffects of gravel removal from arctic and subarctic streams in Alaska. The primarypurpose of the project was toprovide an informationbase that will assistresource managers informulating recommendations for minimizing detrimentalenvironmental effects of removing gravel from arctic and subarctic streams. To achievethis the following objectives were met:

A comprehensiveliterature review and synthesis was conducted to evaluate known and conjecturedeffects of gravelremoval and other similardisturbances on floodplainenvironments.

Physical,chemical, and biological characteristics of seven sites inhabitedby fish after gravel removal were evaluated in moderate detail on a short-termbasis.

Physi.cal,chemical, and biologicalcharac teristicsof 18 sitesthat reflectedvarious removal methods, stream types, and timessince completionof operations were determined ingross detail andon a short-termbasis.

a Relationshipsbetween parameters related to grave I remova I operations, geomorphiccharacteristics of streams,water qual ity, and biota were evaluated.

The studyof three sites prior to, during, and immediately after gravel removal was an originalproject objective that was eliminated due to a lack of suitablesites meeting project schedules.

7 A thorough and broad-spectrumevaluation of the impacts gravel removal canhave infloodplains requires assessmentfrom a number of disciplines. To lookat only oneelement could lead toconclusions and recommendations thatmight cause major changes to a riverine systemon a long-termbasis. Therefore,the approach taken in this study included analyses in the follow- ingsix disciplines:

RiverHydrology and Hydrau I ics AquaticBiology a TerrestrialEcology Water Quality e Aesthetics

0 GeotechnicalEngineering

Thisapproach not only allowed analysis by individualdiscipline, but per- mittedconsideration of the interdiscipline trade-offs inherent in evaluations of disturbancesto natural environments. for example, gravel mining techniquesthat would avoid effects on aquatic biota could require removal ofimportant floodplain habitat used by terrestrial faunaor be impractical fromgeotechnical considerations.

These disciplines wereselected for the study because they were believedto cover the various impacts that were known orsurmired to be associatedwith gravel removal. Due to a paucityof background information, it was notpossible to beassured that all significant impacts were addressed bythese disciplines.

Althoughthe main purpose of this gravel removal study was toprovide an informationbase for recommendations to be made by resource managers, anotherimportant contribution is to provide abase for subsequentlong- termstudies. For example,a problemneeding extensive study is the effect ofremoving gravel from many sites in one river system,as occurs along highways and pipelines when theyparallel floodplains for routing or geo- technicalreasons. This problem is not treated in the present study and, infact, was consciouslyavoided when sites wereselected.

8 REFERENCES

Bliss, L. C., and E. B. Peterson. 1973. The ecologicalimpact of northern petroleumdevelopment. Fifth International Congress. Arctic Oil and Gas: Problemsand Possibilities.Le Havre. 26 pp.

Bull, B., and K. M. Scott. 1974. Impact ofmining gravel from urban stream beds inthe southwestern United States. Geology 2(4):171-174.

Burger, C., and L. Swenson. 1977. EnvironmentalSurveillance of Gravel Re- movalon theTrans-Alaska Pipeline System with Recommendations for FutureGravel Mining. Joint State/Federal Fish and WildlifeAdivsory Team SpecialReport No. 13. Anchorage,Alaska. 35 pp.

FederalWater Pollution Control Administration. 1968. Sand andGravel Waste EvaluationStudy, South Platte River Basin, Colorado.

Forschage, A., and N. E. Carter, 1973. Effects of GravelDredging on the BrarosRiver. Texas Parks and Wildlife Department, Inland Fisheries Research

Klein, D. R. 1973. The impactof oil development inthe northern environment.Proceedings lnterpetroleum Congress 3:109-121. Rome, Italy.

LaBelle, J. >C. 1973. FillMaterials andAggregate Near Barrow Naval Petro- leumReserve No. 4, Alaska. The ArcticInstitute of North America for theOffice of Naval Petroleum and Oil ShaleReserves. Washington, D. C. 146 pp.

McPhaiI, J. F., W. B. McMullen,and A. W. Murfitt. 1975. Design andcon- structionof roads on muskeg in arctic and sub-arcticregions. Six- teenthAnnual Muskeg ResearchConference. Montreal, Quebec, Canada. 51 PP.

MichaelBaker, Inc. 1977. Accounting of satelfree usepermit materials. Preparedfor Alyeska Pipeline Service Company. Anchorage,Alaska.

NorthernEngineering Services Company, Ltd. and AquaticEnvironments, Ltd. 1975. Reconnaissanceof the Alyeska Pipeline-Material Source Borrow Methodsand an Evaluation of These Methods with Respect to Aquatic Habitats.Canadian Arctic Gas Study,Ltd. Calgary, Alberta, Canada.

Sheridan, W. L. 1967. Effectsof Gravel Removal on a SalmonSpawning Stream. U. S. Department of Agriculture,Forest Service. 26 pp.

9 Weeden, R. B., and 0. R. Klein, 1971. Wildlife and oil: a survey of cri- ticalissues in Alaska. The PolarRecord 15(9):479-494.

West, G. C. 1976. Environmental problems associatedwith arctic development especiallyin Alaska. Environ. Conserv. 3(3):218-224.

IO APPROACHAND METHODOLOGY E. H. Foilmanna

SITE SELECTION

The siteselection process began inJuly 1975 and initial workin- volvedcontacting various agencies andgroups tolocate potential study sites. Among thosecontacted, the main sources of information were the Bureauof Land Management, theAlaska Pipel-ine Office, the Alaska Division of Lands,and theState Pipeline Coordinator's Office. In addition, the AlaskaDepartment of Highways (now Alaska Department of Transportation and PublicFacilities) provided a considerable amount of information.

A totalof 575 potentialsites were identified andsubdivided into threeareas north of Latitude 66' -- theNorth Slope, the Yukon RiverBasin, and the Seward Peninsula -- toobtain representative sites throughout arctic and subarcticAlaska. Later in the project the Yukon RiverBasin sites wereseparated into Northern Interior andSouthern Interiorsites. Following identificationof these sites, field reconnaissance was initiated to assess thesuitability of the sites for the study and tocharacterize those sites consideredpotential candidates for thestudy. Sixty-four site5 remained ascandidates following field reconnaissance.

To augment thedrainage and materialsite descriptions developed in thefield for the 64 sites,additional information on gravel removal activities and watershedcharacteristics was obtainedfrom various agencies,

a E. H. Follmannis presently associated with the Institute of Arctic Biologyof the University of Alaska. topographic maps, and otherdata sources. Based on more complete site descriptions,preliminary variables were established with which to compareand selectsites.

Site comparisons were restricted to sites within the same region to insureadequate representation of theNorth Slope, the Northern Interior, SouthernInterior, and the Seward Peninsula.Six sites were selected to representthe Seward Peninsula,eight for the North Slope, six for the NorthernInterior, and fivefor the Southern Interior (Figure I). The sites werecategorized by the presence or absence of fish on the basis of field observation and reliablebackground information. The sitesthat were known tocontain fish after gravel removal were compared todetermine which should receiveadditional study.

All siteswere previously mined. As statedearlier, sites could not be identifiedwhich would allow studies (within project schedules) before, during, and aftergravel removal operations. All siteswere named in ac- cordancewith the U.S. Boardof Geographic Names. However, two sites oc- curredon unnamed streamsand were assigned project names ofSkeetercake Creek(unnamed tributaryto the Toolik River) andAufeis Creek (unnamed tributaryto the KuparukRiver). When twostudy sites occurred on the same river,they were designated upstream anddownstream respectiveto their locations.

MajorVariable Matrix

Followingsite selection the preliminary variables used to compare sites werereviewed to determine which should be considered major variables. Initially,nine major variables identified as either site characteristics or miningcharacteristics were selected to describe each ofthe 25 sites (Woodward-Clyde Consultants 1976). Theseparameters were chosen because theywere thought to be important from the standpoint of assessinggravel removaleffects, they best described the sites, and theyallowed selection ofsites which exhibited the greatest variety of variables. The variety was especiallyimportant because it insuredthat sites were different, thus

12 Figure 1. Location of the 25 gravel removal study sites in Alaska. permitting assessment ofthe effects of various gravel removal procedures on siteswith different physical and biologicalcharacteristics.

The majorvariables were again reviewed following the field investigation, when detailed site characteristics were available to determine whichwere stillsuitable for comparing the 25 materialsites. The seven variablesselected for the final Major Variables Matrix included:

e Drainagebasin size, e Channel$ width, e Channel configuration, e Channelslope, e Stream orlgin,

0 Type ofgravel removal, and e Location of gravelremoval.

Theseparameters were categorized as either Physical Site Characteristics orGravel Removal AreaCharacteristics. Each ofthe sites was characterized accordingto these variables (Table I). Definitionsof these variables areincluded in the Glossary.

PhysicalSite Characteristics. Drainage basin size andchannel width aresignificant becausethe impact of gravel removal could differ depending onthe amount of disturbancein proportion to the size of stream and floodplain.Also, systems having greater discharge andbed load movement could beexpected toregenerate a material site more rapidlythan a systemwith smallerdischarge and lessbed load movement assumingthe amount of mining disturbance is proportionatein the twostreams. Categories used were small, medium, and largebased on the drainage area above the site and small, medium, and largebased on the channel top width within the study reach at mean annualflow. Although from a hydrologicalstandpoint categorization onlyaccording to drainage basin area would have been sufficient, we considered it importantto include channel width because width is a tangible measurement that canbe observed at a sitelocation.

14 SWARD PENINSULA Gdd Run crak X X X X X X x xx X 11 Sin& River X X X X X X X xxx ..X 10" WahirgtonCreek X X X X X x xx xx X 13 0r-n Creek X X X X X x xx xx 13 Penny River X X X X X x x xx xxxx xx 11 Nom River X X X X X xx x xx 2M NORTH SlOE - UgnwavikRivar X X X X X xx xx x 7 AuWi Creek X X X X X x xx xxx xx x 5 Kupwuk Rinr X X X X X X x 9 Skaemc& Creek X X X X X xx xx x x It Slgmnilktok River X X X X X X X xx X 3 lvishak River X xx X X X X 3 s)uviarik Rlwr X X X X X X xx 6 Kavik Riw X X X xx x x xx xxx 7&P MORTHERN IMERDR Diich Rivsr-US 'X X X X X xx X X X 2 Diarich River" X X X X X X X X x3 M.F. Koyulndc RiwrUS X X X X X X X xx x x 4 M.F. KWukRiverOS X X X X X X X X X 2 Jim Rh X X X X X X X x xx x2 Creek X X X X X X X xx X 2

SOUTHERN INTERIOR W.F. Tolwana RM X X X X X X X X X 3 "amr creek X X X X X X X X I8 T ananr River-DS Tananr X xx X X X K 4 Tarunr River-US X xx X xx X 13 P helan Creek Phelan X X X X X x %X xx 3

%e Kavik River was mind during two periods: tSGs -1589 ad 1873 -1074. Channel configurationsvary from straight mountain streams to braided rivers.Factors associated with various types of streams such as bed load movement, bank erosion,and water fluctuation were considered important. Configurationsincluded in this stu,dy werebraided, split, meandering, sinuous,and straight.

Channelslope, along with other variables, is a majorfactor governing watervelocity, discharge, andsediment transport, Therefore, streams with slopes,categorized as mild,moderate, and steepwere included.

Stream origin was consideredbecause it governsaspects of stream hydrology.Stream origin also influencesthe amount ofbed load material availablefor transport, thereby indicating the regenerative capacity of a stream,and the availability of suspended sediment that could deposit in a gravelremoval area. Categories used were mountain, foothill, coastal plain, and glacial.

Otherfactors such as stream bed material, bank vegetation, and watershed characteristicsare important, but were not considered as majorvariables. To a largeextent these factors are accounted for by the major variables and thephysiographic provinces occurring within the regions.

Gravel Removal AreaCharacteristics. Two majortypes of gravel removal operationsused in floodplain areas are pits andscrapes, distinguished primarily bydepth of excavation andpermanent inundation by water after siteclosure. During site visits it was apparentthat pits were either connected or notconnected to an activestream channel. Becausemagnitude of change to a systemcould be greatly influenced by this factor, pits werecharacterized as either connected or not connected.

Location of gravel removal sites within a floodplaininfluences the degreeof impact and the regenerat ivepotential of a site.Therefore, dis- tinctionswere made between sites locatedin a channel,adjoining a channel, andseparated from a channel.

16 To determinethe impact of gravel removal over time and theregenera- tivecapacity of various types of streams, it was necessary toobserve sitesthat were active during different years. Information was notavailable forsites associated with construction activity early in this century, but was forsites ranging back tothe late 1950's.

Specificdescriptions of the regional characteristics, physical Site characteristics, and characteristics of thegravel removal operation at the 25 studysites occur in a subsequentsection.

DATAREVIEW

Availableinformation regarding the effects of gravel removal and othersimilar disturbances in floodplains was reviewed,Information was solicitedfrom many Federal andmost Stateagencies, from various Canadian groups,and from literature sources. Due to a minimum ofinformation on theeffects of gravelremoval, particularly in arctic and subarcticregions, some ofthe processes involved had to be discussed from a theoretical standpoint.

The results of this workwere included in a PreliminaryReport prepared in 1976 (Woodward-Clyde Consultants 1976). Thisreport should be referred to if a reviewof available literature is desired.

FIELD STUDY OFSELECTED MATERIAL SITES

Preparationfor the field program began inSpring 1976 and thelast site was visited in March 1979. Site visits were splitover three summers with 7 sitesstudied in 1976, IO sitesin 1977, and 8 sitesin 1978. In addition,seven sites were visited during the winters of 1977-1978 and 1978-1979 todetermine the presence or absence of fish, to record water qualityparameters, and todescribe the occurrence of icing conditions.

Duringthe 1976 field program field teams representingRiver Hydrology andHydraulics, Aquatic Biology, and Terrestrial Ecology worked each site

17 simultaneously. The AquaticBiology team alsocollected water quality data. Simultaneouseffort of field teams was consideredadvantageous during the first field season toinsure coordination of workwhere necessary. In addition,simultaneous work permitted on-site discussion of methodology

changesby all disciplines,thus further insuring coordination and CO- operation.During subsequent field seasons, some ofthe sites were visited byindividual field teams, butall teams visitedthe sites during the same summer. These individualvisits allowed eachteam tovisit sites during peak eventsfor parameters associated with their discipline. Data andsample collectionareas were flagged to facilitate collection of dataat the same sitesduring subsequent visits by eitherthe same ordifferent teams. In addition,the hydrology and hydraulics and terrestrial teams placedsemi- permanentposts at each sitefrom which to initiate surveys for future studies.

The followingsection includes a review of thefield and laboratory programsconducted during the field effort. Programs are described only forRiver Hydrology and Hydraulics,Water Quality, Aquatic Biology, and TerrestrialEcology because these were the only disciplines for which data werespecifically collected. Geotechnical Engineering and Aestheticsrelied completely on fieldinformation collected byother groups.

RiverHvdroloav and Hydraulics

Introduction.Emphasis of the field program was on describinglocal fluvial geomorphicprocesses, obtaining evidence of past flood histories, measuringriver hydraulic parameters, investigating sediment transport properties of thechannels, describing river processes, and investigating specificeffects of gravel removal on these factors. Photographs were taken fordocumentation of significantfeatures, Hydraulic and hydrologicaldata collectionwere coordinated with the water quality, aquatic biology, and terrestrialecology studies.

Hydrological and geomorphologicalliterature pertaining to each site and its drainagebasin, e.g., hydrologicalrecords, surficial geology,

18 and aerialphotographic interpretations were also used in the analys s of each site.

Geologyand Geomorphology. Using topographic maps, stereoaeria photography, and surficialgeology maps, a briefanalysis of eachdrainage basin was made toevaluate the geomorphology of the river valley, the river terraces, and thepresent and pastregime of the river. The morphologicalfea- turespertaining to the general area around the material site were verified inthe field.

Hydrology. The U.S. GeologicalSurvey Water Resources Records were reviewedfor flow measurements within a studysite's drainage basin. Where flow measurementswere representative, various key discharges with the respectivestages were estimated anddocumented. Inthe field, evidences offloods were investigated. Where sufficientdata could be obtained at thestudy site or near vicinity, a stage-dischargerelationship and flood frequencyanalysis were included in the data package. For the rivers that hadno past flow records, the hydrology was synthesizedusing a regional flowanalysis (Lamke 1979).

Hydraulics.Hydraulic parameters for,each river channel and floodplain weremeasured inthe field. At eachstudy site cross sections were surveyed upstreamfrom, within, anddownstream from the area of gravel removal (in conjunctionwith the aquatic ecology program) to measure the following hydraulicparameters: width, depth, andarea. All crosssection locations weredocumented and elevationsreferenced to temporary benchmarks.The longitudinalslope of the water surface and, wherepossible, the bed were surveyed. All surveysused standard surveying techniques. The dischargeat thetime of thesurvey was measuredusing standard techniques (Buchanan and Somers 1969).

Materials and-Sediment. Representative samples of the river's flood- plainsurface material were obtained upstream anddownstream from the gravel removalarea using the photographlc-grid method (Kellerhals 1971). These wereconsidered to be representative of the channel bed material. The sire

19 distribution was determinedby the frequency-by-number method. Inaddition, theunderlying material was measuredusing hydraulic sieves and thesize distributiondetermined by percentage-by-weight.

The river bank materialswere described at cross section locations basedon a subjectiveevaluation andphotographed for documentation. Ma- terial gradation samplesof riverbank materials were not obtained.

ChannelProcesses. The fluvialmorphology at each site was assessed usingcomparative aerial photography. In the field, fluvial morphological featureswere verified anddocumented in more detail, e.g., gravelbar types,bed formations, scour holes, andsediment deposition. Degradation and/oraggradation upstream from, and downstream from the gravel removal site wereinvestigated.

RiverIce. In thefield, evidences of ice processes (breakup jams, icescour, gouging, and aufeis)were documented to help evaluate the role ofice onthe river morphology.

Water Oua I i tv

0 Water qualityparameters measured were temperature ( C), dissolved 2 oxygen(ppm), conductivity (micromhos/cm ), turbidity (JTU), suspended solids(mg/&), oxidation-reduction potential (MV), and pH (Table 2). Water quality measurementswere taken atthe aquatic macroinvertebrate sample sites.Usually the measurementswere taken along a transectacross the river or pit with the number ofreplicates with,in a siteadjusted to the size of thewater body. Themeasurements were normally within 30 cm ofthe water surface,although depth profiles were taken in pits.

AquaticBiology

Introduction.Field emphasis was placed on aquaticinvertebrates, changes infish distribution in relation to the gravel mined area, and potentialfish spawningand rearinghabitat during the ice-free period.

20 Table 2. MethodsUsed forMeasuring Water Quality Parameters with the Number ofReplicates Taken perStudy Area

Rep I i cates Methodof perstudy Par ame t er determination area

Dissolvedoxygen YSI Model 57 DO meter 3 - 15

Temperature YSI Model 57 DO meter 3 - 15

Conductivity Hach Model 2510 conductivitymeter 3 - 15

Turbidity Hach Model 21 OOA turbidimeter 2 - II

Suspended solids Mi I I iporefi terprocedure 1-3 (5 pm f Iter)

Oxidation-reductionDelta Scient i fic 1212-P2 ORP 2-5 pote ntial meter potential

PH Delta Scientific 1212 pH meter 1-5 Hach pH kit I

21 Additionalvisits were conducted to specific sites if potential over- winteringhabitat or suspectedspawning areas were present within the mined area.

Studysites were categorized into two groups. Eighteen sites were visited onceduring the open water season. Seven sites with known fish utilizationin the mined area were subject to additional field study. These sevensites were visited on three separate occasions during open water conditionsof I calendaryear. In addition, seven pit sites where winter utilization by fish was suspectedwere visited to document overwintering.

The 18 sitessubject to a less intensi ve field" programwere visited only once.

Selectionof SamDle Areas.Three samp I e areaswere selected at all sites: upstream, withinthe mined area , anddownstream. Selection of upstream anddownstream sample areas was basedon similarityto the aquatic and terrestrialcharacteristics exhibi tedin the mined area prior to gravel removal.Selection of sample areas was made so thatsubstrate, depth, width, velocity, and pool:riffle ratio weresimi arat the upstream anddownstream locations,

Theupstream area was typicallyloca ed atleast 400 m abovethe mined area and the downstreamarea was between 400 and 800 m belowthe mined area.Selection of the 400 rn criteria was basedon the assumption that thehydrological effect of gravel removal would be minimal that far upstream.Selection of a downstreamarea between 400 and 800 m belowthe minedarea was basedon the probability that changes occurred in this area eitherdur ing or immediatelyafter gravel removal.

At sites with morethan one mined area, additional sample areas were selectedto assess effects. Similar selection criteria were used.

Selectionof SampleGear. Fish andaquatic macroinvertebrate sampling gearwere selected relative to the types of habitat present. Features such

22 as width,depth, stream velocity, shoreline configuration, stream bank vegetation,obstructions, channel substrate, andpresence of pits affected thegear selection process. Samplegear used at eachstudy site is listed inTable 3.

SampleProgram. Informationrecorded in the field included stream name, sample location and description,description of the disturbed area, and thedate, time, and existing weather conditions. Visual surveys were conductedwithin sampling areas to describe habitat and torecord the presenceof fish.

Sample Collection,Disposition, andAnalysis. A varietyof seines with square mesh (3.2 mm), 6 to IO m longand 1.8 m deep, wereused. Seines wereextended across the stream from bank to bankand pulled downstream innarrow streams. In larger streams and pits the quarter-haul technique was used.Experimental, multifilament gill nets 15 x 1.8 m, withpanels of 12.7, 25.4, 38.1, 50.8, and 76.2 mm square mesh, wereanchor-set inpits, and, in onecase, inthe deep, slow-movingsection of a largeriver.

A backpackshocker, one of the least selective of all active fishing methods, was used inappropriate watercourses. Stream width permitting, a preselectedlength of stream was blockedwith seines and theenclosed areashocked repeatedly until fish were no longer captured or observed. The areaof the shocked section was usually measured toallow for density estimation.

Minnow trapsselective for juvenile and smalladult fishes were used to sampleaquatic habitats. Traps were located In pools, riffles, and pits andwere baited with salmon eggs. Traps were usually fished from 12 to 24 hours.

A dipnet was used at one siteto capture juvenile fishes for identification.Visual surveys were made at each siteto record distribution andunusual events or criticalhabitats, suchas spawning areas.

23 Table 3. AquaticBiology Sampling Methods Used at Each StudySite

Macroinvertebrate samp I igear ngFish sampl gearing SurberPonarMinnow Gill Electro- Hook & Set Study site samp grabI er trap Seine netshocker line I ine

Sewar d Pen i nsu I a

Gold Run Creek + SinukRiver + + WashingtonCreek + OregonCreek + + Penny River + + Nome River +

North S I ope

UgnuravikRiver + + Aufeis Creek + + KuparukRiver f "b SkeetercakeCreek 4" Sagavan irk tokR i ver + + + lvishakRiver + + ShaviovikRiver -k + KavikRiver + + f

NorthernInterior

Dietrich River-US + -e + Dietrich River-DS + M.F. KoyukukRiver-US + M.F. Koyukuk-River-DS + + Jim River + + + ProspectCreek + +

SouthernInterior

W.F. TolovanaRiver + + + + McManus Creek + + f + TananaRiver-DS + + + Tanana River-US + + + + Phe I an Creek + + 4-

24 Capturedfishes were identified, measured (fork length), weighed, and releasedexcept when preservedfor reference. Data collected were used todetermine species composition, sire distribution, and relative abundance; estimatesof density were made. These evaluationswere compared within andbetween gravel removal sites.

Macroinvertebrates. A 30-cm squareSurber sampler was used to collect macroinvertebratesin riffle areas. Sampling areas were stratified by depth, bottomtype, current velocity, and othervariables that may havebeen corre- latedwith benthic distribution. At moststudy areas three sampling sites wereselected and five replicate samples were collected at eachsampling site. Two samplingsites were selected in a fewcases where there were multiplemined areas or wherethe river was not directly affected bygravel removal,e.g., a pit site away fromthe stream channel, with five replicates takenper site.

A Ponargrab was used tocollect macroinvertebrates in pits. Single grabswere taken at several stations spaced to cover the main depth regions withinthe pits. Ponargrab samples were cleaned, separated (the slurry passedthrough a U.S. Standard No. 30 sieve), and placedin labeled con- tainers.

Samples collected.withthe Surber sampler were placed directly into labeledcontainers. All samplecontainers were filled with 70 percental- coholto preserve specimens for later examination. Sampleswere picked and sortedin the laboratory. Organisms were sorted into major categories and placedinto labeled vials containing 70 percentalcohol. Identification was tothe lowest practical taxonomic level.

Datafrom quantitative samples were used to obtain total and individual taxondensity. Data on standing crop and number of taxawere evaluated; comparisonswere made within andbetween sample sites.

Pit SamplingProgram. Four pits,werevisited during March 1978 to assess thepotential for fish entrapment and overwintering.During the

25 following summer thesepits, plus three additional ones,were visitedto assess if fish werepresent. The pits werethen revisited during the 1978-79 winterto assess if fish remained in the pit after freezeup or moved into theriver. If fish remained in the pit, subsequent visits were made to determine if fishcould survive the winter. Sampling was conductedwith a varietyof gear types including minnow traps,set lines, gill nets, hook and line, and observation.In addition, an underwatertelevision system was usedfor surveillance under the ice at two pits. Dissolved oxygen and temperaturewere measured when water was present. Ice thickness,presence or absenceof flowing or openwater, or both, and formationof aufeis - by over- flowwere recorded.

TerrestrialEcology

Introduction. The terrestrialfield programidentified habitats affected by gravelremoval operations andassessed the impact of habitat modification onassociated wildlife. Qualitative and quantitativesurveys wereconducted during a 3-day fieldeffort to characterize the plant communities and seralstages present on disturbed and undisturbedareas. WiId- lifeutilization of these habitats also was evaluated. The undisturbed sites encompassed seral stageslikely to develop with time on thedisturbed site, and werebelieved to be most representative of the disturbed areas priorto gravel removal.

The program was expanded to 5 days at one representative study site (regionalrepresentative site) in eachof five geographical areas: Arctic CoastalPlain (North Slope), Arctic Foothills (North Slope), Seward Penin- sula,Northern Interior, and SouthernInterior. The increasedtime at these studysites allowed for additional sampling efforts using the same sampling procedures.

-Soils.Soil sampling was conductedwithin each habitat on disturbed andundisturbed sites to evaluate the growing conditions and thepotential forrevegetation. Within each habitator definable soil unit, the character ofthe upper horizon, depth of organic layer, surface drainage, anddomi-

26 nantvegetation were recorded. Approximately I5 subsampleswere collected with a soil auger-tubesampler from the ground-cover rooting zone (approxi- matelythe upper 20 cm).These subsamples were combined to formone composite sample for each soilunit. Composite samples were air dried andana- lyzedfor pH, percentorganic matter, and percentnitrogen, phosphorus, and potassium. A particle size distribution analysis was conducted todeter- minethe percent sand, silt, and clayin the composite sample.

Vegetation,Vegetation surveys delineated the major cover 'types withinthe study area. Within each habitat, the seral stage of development was noted and theplant species were recorded.

Qualitative site descriptions wereaugmented by limited useof quan- titativesampling methodsthat employed a systematic,nested plot design (James 1978). Strandor patch habitats required "spot" location of nested plotsor qualitative description only.

Description of theoverstory vegetation included the following parameters:dominant and subordinatetree species, average height and DBH (diam- eterat breast height) of thestand and standcomponents, and representative agesby species and heightclass. A limited number ofcircular plots (0.04 ha)were used toquantitatively sampleeach habitat.Forester's calipers or a diametertape, or both, were used to determine tree DBH; treeheight was estimated andan increment borer or cross-sectioning method was employed to determinethe age of woody plants.Increment cores and cross sections werereturned to the laboratory for staining andage determination when necessary.

Shrubgrowth within each habitat was descr'ibedby identifying species composition and relativedensity, average height by species, and representative agesby species and heightclass. Stem andclump densitycounts were conductedon a limited number ofsystematically located, 0.004-ha circular plots.Selected shrubs were agedby cross-sectioningabove the root collar. Evidenceof herbivore browsing was noted.

27 Groundcover sampling identified species composition within eachhabi- tat and provided an estimateof percent surface coverage for eachtaxon. Percentsurface coverage was visuallyestimated in systematically located, 0.0004-ha plots.Fjercent surface coverage was estimatedas follows: if onlyone plant of a giventaxon was present and its coverage was very sparse, it was rated at I percentcoverage; if morethan one plant of a giventaxon was present,but its coverage was lessthan IO percent of the plot'ssurface area it was ratedat 5 percentcoverage; the percent coverage of all othertaxa was estimatedin increments of IO.

Wildlife.Evidence of wildlife use of disturbed and undisturbedareas was recordedat each site.Direct observations andevidence of use (tracks, trails,nests, dens,runways, food caches, and scats) were keyed totheir presence in specificseral stages. Historical use of a covertype was noted (i.e., hedgedgrowth form of preferred browsespecies) and seral stages criticalto certain life history stages of wildlife were inspected. The disturbedarea was examined forthe presence of specialattractants or deter- rents to wildlife useof the site.

An aviancensus was conductedin disturbed and undisturbedhabitats at all studysites; attempts were made tovisit the five intensive study sitesduring the peak avianactivity period. The census in homogeneous habitats employed a ModifiedStrip Plot technique for three consecutive mornings(five mornings at the intensive sites) to obtain data on thespecies present and habitatutilized. Small, isolatedhabitats were qualitatively surveyedto ascertain avian species occurrence. Waterfowl, shorebirds, and game birdswere inventoried by totalcounts when areasof concentration were clearly visible.

Small mammals (shrews,voles, and lemmings) were inventoried at all sitesin disturbed andundisturbed habitats using a trap andremoval technique. A *'I ine"or *tspot" trapping configuration was used in a1 I cover types.Trapping was conductedfor two nights at nonintensive sites and four nightsat regional representative sites with the traps checked,baited, and reset eachday. The species,sex, age, and weight of capturedspecimens wererecorded to assess occurrence and characteristics by habitat.

28 Collectionof terrestrial invertebrates was conductedat all fish intensivesites and atthe regional representative sites. Collections were made adjacentto the watercourse at the disturbed site and nearthe upstream aquaticsampling station to assess theavailability of potential food sources for theaquatic environment. Sweep netswere used to collect invertebrates.Specimens were preserved in 40 percentalcohol and returnedto thelaboratory for identification.

DATA BASE

The data base, thethird endproduct of thegravel removal study, (theTechnical Report and Guidelines Manual arethe first two endproducts) consistsessentially of all informationcol ectedduring site selection and fielddata collection. Information for each ofthe 25 study s itesincludes:

0 Case historyinformation including min ng plans andperm its,if avail- ab le;

a Biological,hydrological, and waterquality field data;

0 Geotechnicalevaluations;

e Tabulation of data summat ions;

Computer printoutsfor aquatic ecology and hydrology and hydraulics;

0 Draftsite description reports;

Sitephotographs, including both ground and aerial;

e Topographic maps showing sitelocation; and

e Depiction of actualdata collection areas within each site.

29 The information is in a formto a low any professionalto evaluate where thedata was collected,what data was col I ected, and thegeneral conclusions oftha original investigator.

Thisdata base is on file wi h the U. S. Fish and WildlifeService. It will notbe distributed routinely with theTechnical Report and Guide- lines Manual. Due tothe mass ofinformation available, a specific need will have to be identifiedbefore the data relevant to that needcan be prov i ded.

TECHNICAL REPORT

Analysesof field data, beyond the immediate data reduction after sitevisits, began inwinter 1977-78. Thisinitial effort prepared descrip- tionsof each of thestudy sites visited in previous summers andanalyzed dataspecific to each site.Brief summaries ofessential information rele- vantto each of the 25 materialsites studied during this project are includedin the subsequent chapter. These are included to orient the reader forthe discussions that follow in the individual discipline chapters.

Datasyntheses for all sitesdid not begin until after the 1978 field season.Analyses of combined sitedata are contained totally in this report. Each ofthe six disciplines included in the project, (River Hydrology and Hydraulics,Aquatic Biology, Terrestrial Ecology, Water Quality, Aesthetics, andGeotechnical Engineering), is discussedin separate chapters. These chaptersinclude some integrationwith other disciplines. For example, AquaticBiology is dependent,for some ofits data interpretation, on the Water Qualityparameters measured,and on thephysical changes that are describedin the River Hydrology and Hydraulicssection.

An interdisciplinaryoverview of the effects of gravel removal fol lows thediscipline chapters. This chapter reviews the analyses of the six disci- plinesin terms of the similarities and differencesthat are evident. An importantaspect of thischapter is discussion of thetradeoffs and com- parisonsbetween disciplines that must occur with respect to the siting,

30 operation, and closingof material sites. Where possible,the similarities in approachof the varigus disciplines to minimize disturbance from gravel removalare emphasized because these conditions maximize protection of floodplainenvironments.

GU I DEL I NES MANUAL

The Guidelines Manual (printedseparately) is basedon the evaluations andrecommendations contained inthe Technical Report, on the preliminary guidelinesdeveloped in an earlier phase of thisproject (Woodward-Clyde Consultants 19761, andon stipulations andrecomnendations used bycertain resourceagencies when reviewingmaterial site applications and projects.

The guidelinesare intended to provide guidance to the persons responsiblefor writing material site permits and forplanning resource or indus- trial development inlocalized areas. The guidelines also arehelpful to potentialapplicants for material site permits because they will helpin planning a projectcharacterized byminimal environmental perturbations.

The guidelinesare not designed as stipulations to beattached to eachpermit granted. If used inthis manner contradictionsin siting, operational, and rehabilitationprocedures could occur, thus negating the value of theguidelines. It is intendedthat the guidelines user evaluate the proposedproject within the context of the guidelines, and theproposed areafor the material site, to insure that it will develop in an environmen- tallyacceptable manner.

The guidelineswere developed for use by personnelwith some background in an environmentalscience. Ease ofuse was considerednecessary because, atleast on largeprojects such as pipelines androads, permit agencies can be inundatedwith applications requiring quick consideration. A setof guidelinesthat are cumbersomeand inefficientto use,under these circumstances,could foster disregard of theguidelines or their misuse e.g., attachingthe guidelines as stipulations to B permit.

31 The guidelines, as mentioned,were developed with the assumption that thepotential user has some experiencewith environmental problems and issues and, thus,appreciates the potential complexities associated with a materialremoval project. It isstrongly recommended thatthe user read theTechnical Report and understand why and how theguidelines were developed. A comprehensionof the total proJect is considerednecessary for intellioent.efficient. andexDeditious use ofthe auidelines. Without this ...... understanding,the guidelines could be viewed out of context and used inap- wow i ate I v.

32 \ REFERENCES

Buchanan, T. J., and Somers, W. P. 1969. DischargeMeasurements at Gaging Stations. Book 3, Chapter A8. Techniquesof Water-Resources Investi- gations of the U.S. GeologicalSurvey. 65 pp.

James, F. C. 1978. On understandingquantitative surveys of vegetation. Am. Birds32(1):18-21.

Kellerhals, R. 1971. Samplingprocedures for coarsefluvial sediments. J. HydraulicsDiv. ASCE 97(HY8):1165-1180.

Lamke, R. 0. 1979. FloodCharacteristics of AlaskanStreams. U.S. Geolog- icalSurvey Water Resources Investigations 78-129. Anchorage,Alaska 61 PP- Woodward-Clyde Consultants. 1976. Preliminary Report - Gravel Removal Studiesin Selected Arctic and Sub-ArcticStreams in Alaska. U. S. Fish and WildlifeService. FWS/OBS 76/21. Wash. D. C. 127 pp.

33 DESCRIPTION OF STUDY RIVERS L. L. Moulton, Ed.

As previouslymentioned, 25 sites wereselected for study. These sites occurredin four geographical regions of Alaska and include a widevariety of PhysicalSite Characteristics andGravel Removal AreaCha.racteristics (Table I). Site locationsare shownon Figure 1. Table 4 sumnarizesdis- turbedarea sire, volume of gravelremoval, and period of activityat each site.

SEWARD PENINSULA

General Oescr ipt ion of Region

The regionof Seward Peninsulacontaining the six study sites is in the foothills of theKigluaik Mountains, characterized bybroad rounded hills with elevations of 250 to 700 m (Figure 2). The surficialgeology at SinukRiver, Washington Creek, and Nome Riveris dominated byremnants of highlymodified moraines and associated drift resulting from Pleistocene glaciation. Gold Run Creekhowever, isjust outside the northern edge of glacialinfluence andthe surficial geology is fine-grained alluvial and colluvialdeposits with rare bedrockexposures. At OregonCreek and Penny Riverthe surficial geology is Characterized by coarse andfined-gralned deposits of alluvium and colluviumassociated with moderate to stesp-sloped mountains and hills. Bedrockexposures are cmon onthe upper slopes and crests. The regionis generally underlain with permafrost of variablethick- 0 ness.Normal temperatures range from 3 to 13 C inthe summer and -23 to -13OC inthe winter. The annual precipitationof the region is about 30-40 cm, includingapproximately 130 cm as snow.

35 Table 4. Size and QuantityValues of the 25 StudySites

Drainage basArea in of GravelvolumeVolumelDrainage Average Per iod of are a gravel ramoval removedbasinramovalgravel area i ndexa depthgravel removal 2 3 (km .I lhal IIOCX, m I Iml

Seward Pen i nsu t a Gold Run Creek 67 4 8 I .2 0.2 t963-65 Sinuk River 540 88 1 74 3.2 0.2 I96066 Wash i ng t on Creek 29 3 49 17.0 I .6 1960-63 OregonCreek 31 7 27 8.8 0.4 196065 Penny River 62 15 58 8.2 0.3 1960-65 Nome River 130 2 -- " " 1950's Late

NorthSlope UanuravikRiver 279 1 < 23

NwthernInteriw Dietr ich River-Upstream 520 35 63 1 12.0 I .8 1974-77 Dietrich River-Downstream 667 8 I29 I .9 I .7 I975 Middle ForkKoyukuk River-Upstream 2400 20 I77 0.7 0.9 r 974 MiddleFork Koyukuk River-Downstream 4100 28 215 0.5 0.8 1975-76 Jim River 687 I1 I35 2.0 I .2 1974-76 ProspectCreek 248 6 e4 3.4 I .4 1974-75

SouthernInteriw West Fwk Tolovana River 754 a I 32 9.8 I.? I975 McManus Creek 14 4 < 75 < 54.0 < 1.9 1961 Tanana River-Ownstrean 44,600 e 310 1.0 3.9 1971 Tanana River-Upstream 313,700 9 I 35 t .o I .5 1962-65 Phe I an Creek 83 95 57 5 70. Q 0.6 1975-76 Figure 2. Typical Seward Peninsulaterrain.

Vegetationwithin the floodplains consists of densemature willow thicketsinterspersed with less advancedmixed woody-herbaceous communities. The valleywalls contain occasional willow and alderthickets in the moist ravines and pockets, and shrub-tussocktundra on the slopes. The river systemscontain both anadromousand residentfish s,pecies.Typical anad- romousspecies 'include Arctic char, pink, chum, coho,and sockeye salmon and variouswhitefish species. Typical resident species include Arctic grayling, residentArctic char, northern pike, Alaska blackfish, and slimysculpin.

Descriptionof Study Rivers - Location and Gravel Removal Area Characteristics

Gold Run Creek.Gold Run Creek is a small,sinuous river which originatesin the foothills of the Kigluaik Mountains at an elevationof 427 m and flowsthrough rolling hills for 23 km to its confluencewith the Blue- stoneRiver. The studysite is approximately 7 km fromthe mouth at an

37 elevationof 100 m. Gravel was removedfrom thissite for construction of the Nome-Tel ler Highway.Gravel removal occurred by sha I low scrapingover approximately 3.5 habetween 1963 and 1965 with 7,738 m3 ofmaterial extracted.Scraping occurred in the active channel, on mid-channel and lateral bars, and on a vegetatedisland between the active channel and a high-water channel.Approximately I ha of riparianwillow thickets and anaccompanying 0.5-m layerof overburden were removed prior to gravel removal. This organic overburden was placedin a stockpile on the edge ofthe scraped area along theright (northern) floodplain bankdownstream from the highway bridge. An additionaloverburden pile, composed primarilyof sand, was locatedat the downstream limit ofthe scraped area. Both stockpiles still remainedduring thesite visit. A 50-m longgravel access road also was presentleading from thehighway to the scraped area located upstream from the highway bridge. The floodplain bank atthe floodplain end ofthis access road was incised and approximately I m high.Rehabilitative measureswere not conducted aftercompletion of gravel mining activities.

SinukRiver. The SinukRiver is a medium, splitriver which originates inthe Kigluaik Mountains at an elevationof 425 m. Itflows through a narrow,steep-walled valley before entering a broadvalley containing the studyreach. The lower sectionflows across a relativelyflat coastal plain for26 km beforedischarging into Norton Sound. The studysite is approximately 19km fromthe mouth at an elevationof 30 m.

3 Between 1960 and 1966, 174,221 m ofgravel were extracted for highway construction by shallowscraping within the active floodplain and adjoiningthe active channel of the Sinuk River. Access to the floodplain was gainedvia two short(about 30 m) gravelroads leading from the highway. Scrapingextended approximately 1,500 m upstreamand downstream from the SinukRiver bridge andencompassed 88 ha.

Materialwithin the Sinuk River floodplain was describedfrom highway departmentanalyses as stream-depositedsandy gravel with less than 25 percentgreater than 50 mm insize (coarse gravel) andabout 2 percent exceeding 250 mm (boulders).Several (three or four1 islands were removed

38 duringthe mining operation. These islandswere heavily vegetated with willow thicketsaveraging 1.2 m inheight. These islandscomprised approximately 35 haof the site. Stripping of 0.15 m ofoverburden was necessary in thesevegetated areas. In addition, approximately 150 rn ofincised floodplain bankand 1.2 to 1.6 haof adjacent tundra were removed from the north- eastside of the floodplain to expose gravel deposits. Also, withinthe activefloodplain, debris and soilfrom vegetated islands were pushed into a longnarrow overburden pile (approximately 450 m inlength) in the middle of thematerial site to exposeunderlying gravel deposits. The watertable was encounteredat about 0.75 m belowvegetated sand bars with seasonal frost presentin the floodplain and' permafrostencountered at depths of 0.9 to 2.4 m inadjacent terraces. It doesnot appear that this material site was shaped,contoured, or rehabilitatedin any way followinggravel removal. Variousaspects of this site are shown inFigures 2 and II.

WashingtonCreek. Washington Creek is a small, sinuouscreek which originatesin the foothills of the Kigluaik Mountains at an elevationof about 265 m and flowsthrough a wide, V-shaped valleyfor about 13-km before enteringthe Sinuk River. The studysite is approximately 5 km fromthe mouthat an elevationof about 105 m.

Thisstudy site consists of two gravel removal areas approximately 1,000 m apart on WashingtonCreek. Both areas were developed between 1960 and 1963 duringconstruction of the Nome-Teller Highway. The lower site was stillbeing used in 1978 tosupply gravel far road maintenance.

Gravelat both sites was removedby scraping the Washington Creek floodplain and thealluvial fan deposits formed near the confluences of two unnamed tributaries of WashingtonCreek. A reported 8,000 m3 of ma- 3 terials wereremoved from l ha inthe upstream site, while 41,000 rn had beenremoved from 2ha inthe downstream site.

Clearingof large amounts ofoverburden was requiredfor the development ofboth sites. Overburden was notremoved from the material sites but was collectedinto large mounds whichwere still presentat the time

39 ofour visit. Large stockpiles of cleangravel were also seen at both sites. Effortsto rehabilitate the floodplain or to maintain the natural character of thechannel were not observed during the field study. Dikes, however, wereconstructed in the downstream mined area to maintain the course of the mainchannel inits pre-mining location. Various aspects of this site are shown inFigures 12, 38, 39, 43, 53a, 53b, and 67.

OregonCreek. Oregon Creek is a small,straight river which originates inthe foothills of the Kigluaik Mountains at an elevation of 380 m and flowsapproximately 7 km through a V-shaped valley to a confluencewith CrippleRiver. The valleywalls are steeply sloped over the upper half of its length;the lower half is flankedby moderately sloped hills. The Crip- pleRiver headwaters lie at an elevationof about 300 m andthe river flows in a broad V-shaped valley for 40 km beforedischarging into Norton Sound. TheOregon Creek confluenceoccurs 15km downstreamfrom the headwaters of CrippleRiver at an elevationof 80 m.

The material site was developedby scraping gravel bars within and adjoiningthe active channel near the Oregon Creek-Cripple River confluence.Scraping of angulargravel and cobbles was conductedwest of the Nome-Tel ler Highway in OregonCreek from 1960 to 1963 when 20,500 m3 of materialwere removedfrom approximately 5.5 ha. Vegetation was removedfrom 4 ha atthe downstreamend ofthis site. Mounds ofvegetated overburden alongthe banks of thebroadened channel and stockpiled gravel within the activefloodplain were observed during site inspection. Between Juneand September 1965, 6,000 m3 ofgravel were excavated from I ha inthe Cripple Riverimmediately downstream from the highway bridge. Various aspects of thissite are shown inFigures 13, 40, 41, 53c, 64, and 74.

Penny River. ThePenny River is a small,sinuous river which originates in the foothills of theKigluaik Mountains at an elevationof 230 m and flowsapproximately 23 km beforedischarging into Norton Sound. In its upperreaches, the Penny Riverflows in a narrow V-shaped valley. The valley broadensdownstream and the valley floor typically reaches widths of 350 m

40 betweenmoderately sloping hills in the vicinity of thestudy reach. The studyreach is approximately 8 km upstreamfrom the mout,h at an elevationof 28 m.

The material site was developedby scraping within the active floodplain and excavationof a pitadjacent to the main channel of the river. Material removedfrom the 15-ha site was primarily sandand gravel alluvium with some colluvialdebris along the southeast edge ofthe working limits. Rock typeswere quartz mica schist, limestone, and quartz;rock fragments were subangular to roundedwith 3 to IO percentgreater than 50 mm insize and I essthan I percentgreater than 250 mm.

Clearing and strippingwere necessary to remove the dense willow (that cover edapproximately 12 ha)and an average 0.6 m ofoverburden. The water tablevaried from 0.8 m to morethan 1.5 m deep with nopermafrost encountered up to a depthof 2.1 m. Scraping was conductedduring 1960-63 when 3 3 3,646 m wereremoved and during August and September, 1965 when 47,034 m wereextracted. The 1965 operationyielded some selectmaterials, indicating that a processingplant probably operated within the site. A small 0.6-ha pit was excavated inthe southeast corner of the material si t e duringthe 1965 operation.This pit averaged I to 1.5 m indepth during the site visits and was directlyconnected to the main channel. Small stockp I es were pres- entwithin the disturbed area during field inspection. The s te was not shaped, contoured,or rehabilitated in any way followinggravel removal. Thus, many shallowdepressions, which are not sloped to drain toward the river,collect standing water. In addition to the 0.6-ha pit,scraping occurredto below the water table in several small isolated pockets, and theseareas were covered with standing water during site visits. Four organicoverburden piles and thegravel access road remain on the site. Var- iousaspects of this site are shown inFigures 33, 58, 61,65, 66, and85.

Nome River. The Nome Riveris a medium, sinuousriver which originates inthe Kigluaik Mountains at an elevationof about 230 m and flowsthrough a broadvalley for about 57 km to its mouth atNorton Sound.The Nome River drainagebasin is longand narrow, with an averagewidth of about 8 km. The studysite lies about37 km fromthe mouth at an elevation of about 58 m.

41 Thismaterial site was developedby scraping 1.9 haacross the entire floodplainwidth. Scraping apparently occurred in the active channel andon adjacentmid-channel and lateralbars. Vegetative and overburdenclearing was notnecessary because the site ,was sparselyvegetated prior to gravel removal.Mining was conducted atthis location in the late 1950's during constructionof the Nome-TaylorHighway. Access was via a short 60-m gravel roadleading from the highway. A gravel fill ramp protectedthe 1.5-m incisedfloodplain bank.There was noevidence of siterehabilitation; the accessroad remains and its endhas been eroded by the river. Material stockpiles and overburden bermswere not observed inthe floodplain. Various aspectsof this site are shown in Figure 25.

NORTH SLOPE

GeneralDescription of Region

Eightgravel removal sites from two North Slope physiographic provinces,the Arctic Coastal Plain (ACP) and ArcticFoothills (AFH),were includedin this study (Wahrhaftig 1965). Both provinces are underlain bycontinuous permafrost. The studysites at Ugnuravik River and Kuparuk Riverare in the TeshekpukSection of the ACP whilethe Skeetercake Creek siteis in the White Hills Section. Aufeis Creek,Sagavanirktok River, and KavikRiver sites are in the Northern Section of the Arctic Foothil Is Prov- incewhile the lvishak River and ShaviovikRiver sites are near the border betweenthe two provinces. TheTeshekpuk Section of the ACP Province is flat and poorlydrained, being very marshy in the summer (Figure 3). The poor drainageresults in part from a continuouspermafrost layer From 0.2 to 1.2 m beneaththe surface. Ice wedge polygons,beaded streams, and elongated thawlakes are common inthis area.Pingos and incised river channels providethe only relief to the flat terrain. The studysites in this section arein an areaof coastal delta deposits of interstratified alluvial and marinesediments with some localglacial drift deposits.

Inthe White Hills Section of the ACP Province,the surficial geology containsareas of undifferentiated alluvium and colluviumconsisting of

42 Figure 3. ArcticCoastal Plain wetlands.

fine-graineddeposits associated with greatly sloping hills. Bedrock out- cropsare rare in this area. The NorthernSection of the AFH Provinceis characterizedin its northernarea by gently rolling terrain with occasional isolatedhills and in its southernarea by rolling plateaus and low linear mountainswith broad east-trending ridges (Figure 4). The surficialgeology ofthe AFH is morecomplex than that in the ACP Province. The Aufeis Creek studysite is near a geologiccontact between eolian silt deposits and undifferentiatedalluvial and colluvialdeposits while the Kavik River and SagavanirktokRiver sites are flanked by remnants of moraines and associated drift. The topographysurrounding the lvishak River site, near the border of the ACP and AFH Provinces, is more typicalof that of the White Hills Sec- tion(Figure 5) whilethe Shaviovik River site is rightat the interface of the twoprovinces. The areato the south andwest ofthe Shaviovik River site is flatwhile that to the north andeast is predominated by mildly sloping hills up to 360 rn.

43 Figure 4. Northernportion of theArctic Foothills.

Figure 5. Typical view of theWhite Hills Section Of theArctic Foothills.

44 The climateof the North Slope is Characterized by long winters, cold temperatures, and frequentwinds. Normal temperature ranges are from 2 0 to l3OC inthe summer and -30 to -22 C inthe winter. Annual precipitation alongthe Arctic Coastal Plain is approximately 13-15 cm, whichincludes 30-120 cm as snow, whilein the Arctic Foothills, the annual precipitation is about 25 cm, including 140 cm as snow.

The Teshekpuk Sectionof the ACP Province is characterizedby flat topography,wet tundra, and numerous lakes and ponds. All plants,including woody formssuch as willow andheath, are low growing.In most areas tundra vegetationoccurs up tothe stream banks and woody thicketsare not present. The vegetationof the Northern Section of the AFH Provinceconsists oftundra species with small stands of taller riparian shrub thickets (2-5 m inheight) along the river systems.

Small river systems of theNorth Slope contain primarily resident fishspecies, such as Arcticgrayling, resident Arctic char, round whitefish,burbot, and slimysculpin, with estuarine species, such as fourhorn sculpin,ninespine stickleback, and possiblywhitefish species, entering lowerreaches. Larger river systems, such as the Sagavanirktok-lvishak drainage,also contain anadromous species,including Arctic char, chum and pinksalmon, broad whitefish, humpback whitefish,least cisco, and Arcticcisco, as wellas the resident species.

Descriptionof Study Rivers - Location andGravel Removal Area Characteristics

UgnuravikRiver. Ugnuravik River is a medium, sinuousriver which originates on theArctic Coastal Plain at an elevation of 100 m and flows acrosscoastal plain tundra for 65 km beforeemptying into the Beaufort Sea. Itis primarily confined to a singlechannel except for a few short beaded sectionsin the upper reaches. The studysite is approximately 6 km fromthe mouth at an elevationof 2 m.

45 The study site was developedby pit excavation and scrapingapproxi- mately I ha within and adjoiningthe active channel of the Ugnuravik River. Gravelremoval was conductedduring the winter from 26 March to I April 1969 with an unknown quantityof sand and gravel extracted from the site. Twenty- threethousand cubic meters had been approved for removal, but the permittee foundthat the gravel was only a veneerand not insufficient quantities for their needs.During thisshort period of operation, gravel was removedfrom belowthe water table. Silt accumulation was notedin the gravel removal area;overburden had been stripped and piled along both banks of the river; andbackhoe teethwere observed near the working limits. Variousaspects of thissite are shown inFigures 26,36, 83, and 92.

AufeisCreek. Aufeis Creek is a medium, meandering riveroriginat- ingin the foothills near the lmnavait Mountains at an elevationof 670 m and flowsapproximately 100 km beforejoining the Kuparuk River. The study site lies at an elevation of 275 m approximately 60 km upstreamfrom the confluencewith the Kuparuk River.

Material removedfrom this site was usedfor the construction of facil- itiesassociated with oil exploration. Facilities constructed include a 1,341-m airstrip, acamp workand storage pad, and access roads of approximately 7 km inlength connecting the stream with the airstrip and camp pad. An est i ma ted 288,000 m3 ofmater ial wereremoved during the win terof 1972.

There are twolarge and distinct gravelremoval areas separated by approximately 3,130 m ofundisturbed stream. The upstreamgravel removal areacovers 46 ha a ong a 2,260 m reachof the stream. The entiref-Iood- plain was scraped, ncludingthe channel bed itself. Clearing andremoval of approximately 20 ha ofvegetation and overburden were required. There is no evidence of rehabi I i tationfollowing mining.

Miningat the downstream gravelremoval area was lessextensive and includedscraping the inactive floodplain, and in some areas,the adjacent terracesalong a 600 m reach of thestream. Deep and shallowscraping, as

46 well as pitexcavation, were utilized to removegravels. The mainchannel ofthe creek was apparentlynot disturbed at the downstreamarea. Clearing andremoval of vegetation and overburden were required in the downstream area.Dikes were also constructed, possibly to protect the integrity of themain channel and prevent its spreadinginto the mined area. Various aspectsof this site are shown inFigures 14, 39, 54, 68a,68b, 69, 75, and 81.

KuparukRiver. The KuparukRiver is a large,braided river which originatesin the Brooks Range foothills and crossesthe Arctic Coastal Plain beforedischarging into the Beaufort Sea. The studysite is locatedapproximately 9 km upstreamfrom the mouth of the Kuparuk River at an elevationof lessthan IO m.

The materialsite was developedby scraping unvegetated mid-channel and lateralbars within the active floodplain of the Kuparuk River. Approx- imately 41,300 rn3 ofgravel was removedfrom 14 habetween Apri I andAugust 1969 toprovide material for drill site pads, roadways,and airstripsnear thesite. The site was scrapedto within or slightly below the existing watertable. The 5-m incisedfloodplain bank was protectedwith a gravel fill ramp. Small mounds ofstockpiled material were noted within the material site.Various aspects of thissite are shown inFigure 51.

SkeetercakeCreek. Skeetercake Creek is a smal I, meanderingstream whichoriginates in the northern edge ofthe foothills of theBrooks Range at an elevationof about 300 m and flowsapproximately 40 km to its confluence withthe Toolik River. The studyarea lies at an elevationof about 160 m, approximately 15 km upstreamfrom the confluence.

Material removedfrom Skeetercake Creek was used for oil drilling operations.Gravel extraction at the site was accomplishedduring December 1965 byscraping IO haof floodplain deposits on three consecutive meanders. Approximately 38,000 m3 of gravelwere reportedly removed, much of which apparently was not used; theunused material was pushed intolarge stock- pileswhich still r.emain inthe upstream gravel removal area.

47 Vegetativeclearing, overburden removal, andberm constructionwere conductedat each ofthe three gravel removal areas. At theupstream area theoverburden was formed into an earthendike, the purpose of which is unclear. The gravelremoval areas were not rehabilitated following disturbance.Various aspects of this site are shown inFigures 37, 42, and48a.

SagavanirktokRiver. The SagavanirktokRiver is a large,sinuous river (atthe study site) which originates in the Philip Smith Mountains of the Brooks Range at an elevationof approximately 1,500 m and flowsthrough mountains,foothills, and coastalplains approximately 300 km beforeenter- ingthe Beaufort Sea. The studysite, at an elevation of 335 m, is located about It km downstreamfrom Pump Station Number 3 onthe Trans-Alaska Pipe- line, 16 km downstreamfrom the mouth of Ribdon River, and 21 km upstream fromthe mouth of Lupine River.

Gravelremoval occurred in 1974 and 1975 byscraping vegetated and unvegetatedgravel bars totaling approximately 35 ha.About 15 hahad been vegetatedwith mature riparian willow thickets. The originalmining plan called for scraping to an averageof 1.5 m indepth with an averageof 15 cm ofoverburden removal required prior to gravel extraction. Approximately 3 3 283,000 m and 148,000 m ofgravel were removed from the upstream and downstreamgravel removal areas, respectively. Access to the floodplain was gainedvia a gravel ramp whichprotected the floodplain incised bank.

Prior to site abandonment in 1976, existingstockpi les andberms were leveledand contoured, and thegravel fill ramp protectingthe bank was to beremoved. Various aspects of this site are shown inFigures 44, 45, 76, and 82.

lvishakRiver. The lvishakRiver is a large,braided river which originatesin the Philip Smith Mountains at an elevation of 1,829 m and flows 80 km throughthe mountains and45 krn throughthe foothills before entering theSagavanirktok River. The studysite lies I1 Rm upstreamfrom the conflu- enceof the Sagavanirktok River.

40 Material removedfrom the lvishak River was used forthe constructionof facilities associated with oil exploration. Gravel extraction was accomplishedby scraping unvegetated, mid-channel gravel bars within the activefloodplain of the lvishak River. Two separatewinter gravel removal operationswere conducted at this location with 115,000 m3 extractedduring March and Apri I 1972 and 3,800 m3 extractedduring November and December 1974. Informationpertaining to the size of the gravel removal area is not availablebecause removal occurred on randomly located gravel bars within thepermit area; however, theaverage depth of excavation planned for the 1972 operationwould require approximately 40 ha of exposed material.

Threeseparate gravel removal areas were observed in the field. The upperarea islocated upstream from the airstrip in the left quarter of theactive floodplain. The middlearea lies in the middle of the flood- plaincovering an areaequivalent to the upstream one-third of theair- strip. The lowerarea lies aboutone-third of the way acrossthe floodplainfrom the left bank, just downstreamof the downstream end of the airstrip.

Vegetativeclearing, overburden removal, or dikeconstruction were notnecessary at the site. Gravel ramps were used for access to the flood- plainover the river bank at most pointsof entry, however, atthe down- streamaccess point the 2-m incised bank was cutinstead of protected by gravelfill. Two gravelhaul roads 90 to 150 m longconnect the airstrip tothe material site. During 1972 and 1974 doterswere used to rip and stockpilematerial for front-end loader transfer to scrapers and trucks. Maximum excavationdepth was tothe existing water level at the time of thegravel removal operation.

Rehabilitation measuresused in 1972 and 1974 weresimilar: depres- sionswere filled, stockpiles were leveled and gravel ramps were removed prior to breakup.Various aspects of this site are shown inFigure 71.

ShaviovikRiver. The ShaviovikRiver is a medium, sinuousriver which originatesin the Brooks Range at an elevation of 909 m and flowsfor 95 km

49 beforeemptying into the Beaufort Sea. The studyarea is 95 km fromthe mouth at an elevationof 230 m.

Gravel was scrapedfrom unvegetated gravel bars within the active floodplain. The gravel was used inconstruction of oilexploration facil- itiesincluding a drilling pad, campsite,supply pads, and landing strip. The proposedextraction area encompasssed approximately 2.4 km offloodplain.Gravel removal was conductedduring the winter of 1972 with 3 116,000 m extractedbetween March and springbreakup. Vegetative clearing and overburdenremoval were not necessary before gravel removal. Material was stockpiledwith a dozerand loaded into dump truckswith a front-end loader.Excavation below the water table was notpermitted under the provisions of themining plan. Access over the river bank tothe mined area was bygravel ramp.

Upon completionof gravel removal all excavatedsites were to be smoothedby back-blading with a dozerand the gravel access ramp overthe stream bank was to beremoved, At thetime of site inspection the gravel rampwas stillpresent and essentiallyintact. Various aspects of this site are shown inFigures 4, 72,and 91.

KavikRiver, The KavikRiver is a medium riverflowing in split channel configuration.It originates in the Brooks Range at an elevationof 1,200 m and flows 125km toits confluence with the Shaviovik River. The studysite is 60 km fromthe confluence with the Shaviovik River at an elevationof 180 m. Downstreamfrom the study reach the floodplain widens and takeson a braidedconfiguration.

Approximately 40 hawere mined by scraping mid-channel and lateral gravelbars within the active floodplain of the Kavik River. Gravel was usedfor construction of an airstrip and road, and for developmentof four oil we1 I pads. Approximately 196,000 m3 wereremoved in 1968-1969 with 3 another 50,000 m extractedin 1973-1974.The initialgravel removal activity at this site was a trespassaction and a miningplan is notavailable. Gravelremoval was conductedduring the winter with scrapers and belly

50 dumps; gravelremoval was completedprior to breakup. Most disturbed gravel barscontained sparse vegetative cover consisting of herbaceous plants and scattered young willows;however, one 2-ha islandvegetated with a mature willowthicket was removed.The overburden and slashfrom this island were piledwithin the gravel removal area.

Diversiondikes were constructed to direct flow from the gravel removal area,and a 2-ha gravelstockpile was locatedon the edge ofthe floodplain. The 2-m incisedfloodplain bank was cutin five locations to gain access to thefloodplain or to reach underlying gravel deposits. Approximately 375 m of bankwere disturbed. Rehabilitative measures were not employed following theactivity, hence all dikes,stockpiles, overburden piles, and cut banks remainedduring the site visit. Various aspects of this site are shown in Figures 5 and 77.

NORTHERN INTERIOR

GeneralDescription of Region

All sixstudy sites in this region are located in the KoyukukRiver watershed.Four sites, Dietrich River-Upstream, Dietrich River-Downstream, MiddleFork Koyukuk River-Upstream, and Middle Fork Koyukuk River-Down- stream,are in the Central and EasternBrooks Range Section of theArctic 'MountainsPhysiographic Province, while Jim River and Prospect Creek, are in theKokrine-Hodzana Highlands Section of theNorthern Plateau Physiographic Province(Wahrhaftig 1965). The Centraland Eastern Brooks Range Sectionis characterizedby flat-floored glacial valleys and east-trendingridges that riseto elevations of approximately 1,800 m (Figure 6). Minortributaries typicallyflow east andwest, parallelto the structure imposedby the belts of sedimentary and volcanicrocks. Valley walls are dominantly coarse rubble depositsassociated with steep sloped mountains which have a highpercentage ofbedrock exposures. The valleybottom in the vicinity of theMiddle Fork Koyukuk Riverstudy sites consists of unmodified moraines and associated drift. The area is underlain bycontinuous permafrost. The JimRiver and ProspectCreek sites, in the Kokrine-Hodrana Highlands, are in an areaof

51 Figure 6. M.F. Koyukuk Rivervalley looking upstream.

coarse and fine-graineddeposits associated with moderate to steep sloped mountains and hills;bedrock exposures are limited to upper slopes and crestlines(Figure 71. The area is underlain bydiscontinuous permafrost.

Normal temperatureranges in the Northern Interior are from 2 to 2OoC 0 inthe summer and -30 to -8 C inthe winter. The annual precipitation is about 28-38 crn, whichincludes 190-210 cm as snow.

The valleysin the Dietrich River-Middle Fork KoyukukRiver region areheavily wooded withboth steep, timbered slopes and gentlysloping terracesadjacent to theriver. The slopesare vegetated primarily with standsof white spruce and paper birch. In the Jim River-ProspectCreek area,the valleys are heavily wooded withwhite spruce an'd paperbirch and a thickunderstory. Resident fish species found in the Koyukuk River systeminclude burbot, Dolly Varden or Arctic char, Arctic grayling, longnosesucker, northern pike, slimy sculpin, round whitefish, inconnu, and

52 Figure 7. Typicalterrain of theKokrine-Hodzana High- I ands.

otherwhitefish species. Anadromous speciesinclude chum andchinook salmon and possibly anadromous whitefishspecies.

Description of StudyRivers - Locations andGravel Removal Area Characteristics

DietrichRiver - Upstreamand Downstream. The DietrichRiver is a medium, braidedrfver which originates in the Endicott Mountains of the Brooks Range at an elevation of approximately 1,500 m and flowssouthward throu,ghmountainous terrain for 110 km, joiningthe Bettles River to form theMiddle Fork Koyukuk River.

The upstreamstudy site is locatedapproximately 4 km, 14 km, and 25 km upstreamfrom the confluence with Big Jim Creek, Snowdon Creek,and BettlesRiver, respectively. The downstream site is located 17 km and 6 km

53 upstreamfrom the confluence with the Bettles River and Snowdon Creek, respectively, and 8 km fromthe upstream site.

Theupstream site was excavated,in an alluvialgravel deposit within theactive floodplain of theDietrich River. Between late summer 1974 and early 1977, 631,000 m3 of gravel was removedfrom the 35-ha site for constructionof the Trans-Alaska Pipeline. A dike was constructedacross an intermittentchannel north of the gravel removal area to divert active flow orseasonally high water away fromthe material site.

Two methodswere used to removegravel. Most of the site was scraped to an averagedepth of 3 m while a pit was excavated by draglinein the southernend of the work area. This pit is approximately 240 x 90 m and was excavated to an averagedepth of an additional 2 m belowthe scraped portionof the gravel removal area. Within this pit twodeeper holes approximately 9 m deep wereexcavated. Ground springs were encountered during the scrapingoperation. The groundsprings have been divertedthrough two chan- nelsinto the deep pit.Aufeis formation Was a naturaloccurren,ce in this areabefore gravel removal and was observeddownstream from the pitdrainage channelduring the first winter following excavation.

A screening-crushingoperation was used to producepipeline padding and beddingmaterial; stockpiled processed material also was storedat this location. The materialsite was utilized as a concretefabrication area in August 1975 to producecement castings of pipeline weights.

Inthe summer of 1977 thearea was slopedand contoured to drain water intothe gathering channels leading to the deep pit. The southern and north- ernportions were then reseeded with annual grasses. The centralportion was left open foraccess to stockpiled maintenance and operationgravel for the Trans-AlaskaPipeline.

The DietrichRiver-Downstream site was workedby shallow excavation of a graveldeposit within the active floodplain of the Dietrich River. 3 Gravel was removedfrom the 7.5-ha sitewith 128,590 m ofmaterial ex-

54 tractedduring 1975 forconstruction of the Trans-Alaska Pipeline. Over- burdenwithin the working limits requireddisposition and stabilization outsidethe active floodplain. Permit provisions required a 90-m undisturbedbuffer between the working limits of the material site and active channelsof the Dietrich River. Braided channels that flowed east of the materialsite were diverted west of the site by an upstreamdike to pre- ventactive flow during excavation. Fine to coarse gravel with sand and a trace of silt was excavatedto a 0.9 m depth.Rehabilitation measures conductedafter mining included sloping of all aliquotsto the southwest. Various aspects of this site are shown infigures 47aand 73.

MiddleFork Koyukuk River - Upstreamand Downstream. The MiddleFork Koyukuk Riveris a large,sinuous river which originates in the Brooks Range at theconfluence of the Dietrich and BottlesRivers and flows 116 km before joiningthe North Fork Koyukuk toform the Koyukuk R ver. The MiddleFork Koyukuk Riverflows in inconsistently spaced reaches ofbraided and single channelpatterns.

The upstreamstudy site is located about 92 km romthe confluence of theMiddle Fork Koyukukand North Fork Koyukuk Riversat an elevation of 365 m. The downstreamstudy site is 45 km fromthe confluence with the North Fork Koyukuk River and47 km downstreamfrom the upstream study site at an elevationof 282 m.

At theupstream study site gravel extraction was accomplishedby shallow excavationof sparsely vegetated gravel bars associated with the active channeland excavation to the same elevationin the contiguous, vegetated 3 alluvialterrace. FromAugust to November 1974, 135,000 m of gravel was removedfrom about 20 ha.

The materialsite is comprised of two parcels; the upper area encom- passes a high-waterchannel while the lower area is situated on theinside bendof the next meanderdownstream. The upperarea was unvegetatedprior togravel removal. Scattered stands of shrubthickets occurred within the activefloodplain portion of the lower ar,eaand theadjacent alluvial ter- racehad to be cleared of maturewhite spruce andbalsam poplar prior to gravelremoval. Overburden was notpresent on the active floodplain area, however, 15 cm oforganic silt were stripped from the alluvial terrace and disposedof southeast of the lower area.

An undisturbed 30-rn buffer was maintainedbetween the active channel and theworking limits of thelower area; natural depressions and minor channelsthrough the buffer were augmentedby constructionof perimeter dikesnot exceeding 0.3 m abovethe natural buffer elevation. Caterpillar tractors with rippers and self-loadingbottom dump scraperswere used to excavateto depths of 0.9 m inthe active floodplain and 3.0 rn inthe adja- centalluvial terrace area. The upperarea was scrapedto a depthof 0.9 rn.

Materialextracted from the active floodplain was seasonallyfrozen, sandy, fineto coarse rounded gravel. The alluvialterrace provided frozen, interlayeredsilty andsandy gravel tothe water table. Screening and stockpiling of selectmaterial was conductedon the floodplain. Permit provisions requiredthat unused materialof si1 t size and finer bedisposed of outs i de theactive floodplain; unused coarse materialfrom the screening process couldbe evenly spread in the gravel removalarea.

Duringsite rehabilitation the disturbed area was graded to an even bottomwith cut faces no steeper than 2:1, stockpileswere removed,and outletchannels were constructed at the downstreamend toallow high-water drainage.Revegetation within the active floodplain was notattempted due tothe likelihood of periodicflooding. Various aspects of thissite are shown inFigures 15, 47b, 49, 52, and 88.

The MiddleFork Koyukuk River-Downstream site was developedby shallow scraping of a sparselyvegetated lateral gravel bar within the active floodplain. The gravelremoval operation was conductedduring the winters of 3 1975 and 1976 with 215,000 m of materialremoved from 28 ha. Permitpro- visionsrequired overburden encountered within the working limits to be disposedof and stabilized outside the active floodplain.

56 A materialsite investigation conducted prior to removing gravel report- edwell-rounded gravel with someseams offine sand andan absence of perma- frostin test pits. Approximately 38,000 m3 ofselect material was produced from a screeningoperation and stockpiled outside the material site working limits. Rehabilitation of thesite following completion of the gravel removal activitydid not include seeding or revegetation of the leveled gravel due tothe likelihood of periodic flooding. Various aspects of this site are shown inFigure 6.

Jim River. The JimRiver is a medium, sinuousriver which originates at an elevation of 880 m andflows about 96 km beforeemptying into the SouthFork of the Koyukuk River. The study area is located 37 km fromthe mouth at an elevationof 275 m.

Material removedfrom this site was usedfor the construction of facili- tiesassociated with the Trans-Alaska Pipeline. An accessroad (90 m in length) was constructedconnecting the site to the Haul Road. Vegetative cover and underlyingorganics were removed.Gravel extraction was accomplishedby scraping about I I ha, yielding an estimated 200,000 m3 ofgravel. The site was workedduring winter to a levelbelow the water table. As a result,the site was inundatedduring summer, leaving,at the time of the survey, a shallowpit consisting of two ponded segments, approximately 5 and I ha insize with amaximum waterdepth of 1.2 m. The formerhigh-water channel now flowscontinuously through the site thus connecting the pit area withthe main Jim River.

Restoration began duringthe fall of 1976. The site was contoured, includingsloping the banks on the south, north, andwest sidesof the site, and revegetated. The excavateddepression was filled in restricting water to theeast side of the gravel removal area and reducingthe inundatedpit area to I haby 1978. Variousaspects of this site are shown in Figures 7, 48b, and 78.

ProspectCreek. Prospect Creek is a medium, meanderingstream which originatesat an elevationof about 600 m andflows 40 km to its conflu-

57 ence withthe Jim River. The studysite lies at an elevationof 270 m approximately 5 km fromthe mouth of Prospect Creek. The site was workedby scrap- ingsurface gravel deposits over 6 haof gently sloping terrain adjacent to ProspectCreek. In addition, a I-ha pit was excavatedon the northern edge (lowestpoint) of the gravel removal area to act as a sedimentcatch basin. Gravelremoval was conductedintermittently from April 1974 throughApril 3 1975 with 63,636 m ofgravel removed forconstruction of the Trans-Alaska Pipeline System. A 45-m widebuffer was maintainedbetween Prospect Creek and thegravel removal area, however, a 90-m wideswath was clearedthrough thisbuffer zoneon 22 May 1974.

Gravelremoval was accomplishedby ripping frozen material prior to conventionalloading and hauling methods. Material varied from clean to silty‘fine to coarse gravel. An averageworking depth of 2.7 m was planned forthe catch basin pit withadditional excavation permitted if suitable material was presentbelow this level. A screeningoperation to produce selectmaterial was conductedin the pit.

The pit has filledwith water as a resultof intergravel flow during the summer months.During the site visit, this pondedwater averaged approximately I m in depth. The pit doesnot have an inlet, however, an outlet leadingto Prospect Creek from the northwest corner was constructedduring site rehabilitation activities to allow unimpeded fish passage into andout ofthe pit.

Additionalrehabilitation measuresincluded grading the material site to I percentdownslope, ensuring that all cutslope faces were no steeper than 2:1, and levelingof temporary stockpiles to blendwith the natural terrain.Various aspects of this site are shown inFigures 28 and 55.

SOUTHERN INTERIOR

GeneralDescription of Region

All fivestudy sites in the Southern Interior were located in the Tanana Riverdrainage, which empties into the Yukon River. The studysites

58 arelocated in three physiographic provinces - the Yukon-Tanana Upland Sectionof the Northern Plateaus Province (WestFork Tolovana River and McManus Creek),the Tanana-KuskokwimLowland Section of the Western Alaska Province(two Tanana Riversites), and theeastern portion of the Alaska Range Sectionof the Alaska-Aleutian Province (Phelan Creek) (Wahrhaftig 1965).

The Yukon-Tanana UplandSection is characterizedby rounded ridges and flat,alluvium floored valleys (Figure 8). Surfacedeposits tend to

Figure 8. Typicalterrain in the Yukon-Tanana Upland Section.

coarse and fine-grainedalluvium and colluvium.Bedrock exposures are gen- erallylimited to upperslopes and ridges. The area is underlain bydiscon- tinuouspermafrost and is subjectto extreme temperature ranges, from -45OC 0 inthe winter to 32 C inthe summer. The average annu.aI precipitation is 33-35 cm, whichincludes 130-150 cm as snow.

59 The Tanana-KuskokwimLowland Section in the vicinity of the Tanana Riverstudy sites is characterized by extensiveglaciofluvi'al deposits and largealluvial fans (Figure 9). The area is immediatelysouth of the

Figure 9. Glaciofluvialdeposits in Dry Creek floodplain.

Yukon-Tanana Uplandsection. The Tanana Riverbasin lies in an areaof discontinuouspermafrost. The climateis typified bycold, dry winters and warm, relativelymoist summers with an annual precipitationof around 32 cm, includingabout 90 cm as snow.

The Alaska Range Section is characterzedby glaciated ridges between mountainsto 2,900 m (Figure IO). Unmodifiedmoraines and associateddrifts dominatethe surficial geology. The areais underlain by discontinuous 0 permafrost.Normal temperatures range from 2 to 17 C inthe summer and -33 to I 0C inthe winter. An annualprec'ipitation of 43 cm includes 275 cm as snow

60 Figure IO. Typicalview of Alaska Range Section.

The vegetationat the Southern Interior study sites varied because of differencesin climate, elevation, andgeology of the three physiographic provinces, The West ForkTolovana River site is in a valleyheavily wooded withwhite spruce and paper birchwith a thickunderstory, particularly alongthe river. At McManus Creek,the surrounding hillsides have thin stands of whitespruce with dense underbrush. The floodplainareas devoi d of whitespruce are covered with willow thickets with woody andherbaceous groundcover. At the two Tanana Riversites the adjoining hillsides are coveredwith densestands of aspenand paper birchwith scattered white sprucewhile islands in the floodplain are covered by IO to 20 m tall st ands of whitespruce with scattered paper birch. The Vegetationsurrounding the PhelanCreek siteconsists of subalpine tundra, upland thickets associated withthe drainages, and scattered,open stands of white spruce.

Residentfish species found inthe Tanana Riversystem include Arct ic gray1ing, northern pike, burbot, longnosesucker, slimy sculpin, various

61 whitefishspecies, and scatteredDolly Varden populations. Anadromousspe- ciesinclude coho, chum and chinooksalmon, and variouswhitefish species. Speciesof whitefish found in the drainage include Bering cisco, broad whitefish, humpback whitefish,least cisco, round whitefish, andinconnu. Mostof these species show substantial movements withinthe Yukon River drainage and distribution andanadromy has not been well documented for many ofthe species.

Descriptionof Study Rivers - Locationand Gravel Removal Area Characteristics

West ForkTolovana River. The West ForkTolovana River is a medium, meanderingriver originating in the foothi I Is ofthe White Mountains in the Yukon-Tanana UplandSection at an elevationof 915 m. The confluence ofthe West ForkTolovana River andTolovana River, a tributaryto the Tanana River,lies 6 km downstreamfrom the study site. The materialsite is located on theeast side of the river with an undisturbed 60-m buffer strip betweenthe site and theriver. The miningoccurred in an abandoned channelwith the upstream end of thechannel plugged toprevent water flow throughthe site. The outlet, however, is open to a backwaterarea of the river. The8-ha site was workedin 1975 by a draglinewith 101,500 m3 of material removed, stockpiled, and screenedto produce the required quantitiesof select materials. The pit filled with groundwater and hasdepths inexcess of 6 m. The unfloodedportions of thegravel removal area were contoured and slopedto drain toward the pit in 1976. Mostof these areas were also reseededby Alyeska Pipeline Service Company withannual grasses. Variousaspects of thissite are shown inFigures 48c, 56, 59, 62, 63, and 84.

McManus Creek. McManus Creek is a small,sinuous stream which originatesin foothills at an elevationof 1,000 m and flows 25 km toits confluence withSmith Creek, forming the Chatanika River. The studysite lies at an elevationof 675 m, approximately 20 km from its confluencewith Smith Creek.During the course of its development, McManus Creekhas tended to migratelaterally southward, causing a slightlysteeper valley wall on the leftthan on the right.

62 The material site was developedduring construction of the Steese Highwayby scraping gravel deposits within and adjoining the main channel of McManus Creek.A.smaII gravel pit was also dug alongthe northwest boundary ofthe site, in an areawhere the floodplain meets the valley wall. During gravelremoval operations, it was necessary toclear and removethe dense 3 vegetationat the 3-ha site. An estimated 75,000 m ofgravel were made availablefor use by these efforts, although a considerablysmaller amount is thoughtto have actually been removed. Large mounds of removedoverburden andunused gravels were left within the site. Site rehabilitation was not performedfollowing mining activities. The revegetationthat has occurred is attributedto natural reinvasion. Various aspects of this site are shown in Figure 89.

Tanana River - Downstreamand Upstream. The Tanana River is a large, braidedriver fed by many glaciersin the Alaska Range. The Tanana River- Downstreamstudy siteis adjacent to the Richardson Highwayapproximately 57 km downstreamfrom the Tanana River and Delta River confluence at an elevation of 260 m. The site was developedby pitexcavation of the central portion of a vegetatedisland located within the active floodplain of the Tanana River.Excavation was conductedafter March 1971 withapproximately 3 310,000 m ofmaterial removedfrom withinthe 8-ha workinglimits. Cleared and strippedsurface materials were disposed of in waste areas along the bordersof the pit. Permit stipulations required a minimum 91 m bufferalong thehighway and a minimum 30-m undisturbedbuffer along adjacent sidechannels of the Tanana River. Maximum depthof excavation in this unconnected,water-filled pit was approximately 9.4 m. The site was notreha- bi I i tated.

TheTanana River-Upstream study site is adjacentto the Richardson Highwayapproximately 9 km downstreamfrom the Tanana River and Delta River confluenceat an elevationof 290 m. The gravelremoval area was developed by pitexcavation of a vegetatedgravel deposit adjacent to an activeside channel of the Tanana River. The pit was excavatedin two parcels herein calledthe upper and lowerpits, which are segregated from the river by a 30 to 40-m widevegetated buffer. A singlechannel at the downstreamend of the

63 lower pitconnects the excavated area to the Tanana River.Mining operations wereconducted between 1962 and 1965 duringreconstruction of the Richardson Highwaybetween Shaw Creekand DeltaJunction. The actual amount ofgravel 3 removed is unknown but 133,600 m wereapproved for removal at this location. The upper and lower pitstotal about 7.5 ha.Access tothe site was via a 100-m gravelroad from the Richardson Highway.

Clearingof dense willow and alder and scatteredwhite spruce and paperbirch was necessarybefore stripping of 0.6 to 0.9 m ofbrown silt, fine sand,and organicmaterial. Coarse gravel was presentbelow the over- burdenwith IO to 15 percentoversized material. Small stockpiles of gravel werenoted along the south edge ofthe pit. In the upper pit the excavation occurredin an irregularpattern over about 3.5 ha, creating numerous islands and spits. The lower pit onthe other hand was minedcontiguously over 4 ha, is of greateraverage depth, and containsno major elevated land forms within its mainboundaries. It didnot appear that the site was rehabil- itatedfollowing gravel removal. Variousaspects of this site are shown in Figures 27,57, 70, and 80.

PhelanCreek. Phelan Creek i s a small,braided river which originates at an elevation above 1,200 m at theGulkana Glacier and flows 19 km through themountainous terrain of the A aska Range beforejoining the Delta River. The studysite is locatedapprox mately 3 km upstreamfrom the Richardson Highway crossingof Phelan Creek and 9 km downstreamfrom the terminous of theGulkana Glacier.

The material site was workedby scraping unvegetated exposed deposits inthe active floodplain of Phelan Creekduring construction of theTrans- AlaskaPipeline System. Approximately 152,000 m3 wereremoved from the 25-ha original workarea between July and October 1975;a 70-ha upstreamexpansion 3 was approved inlate October and yielded an additional 423,000 m .

Severalhigh-water channels traversed both the original work limits and thearea encompassedby plannedexpansion to the east, The majoractive channelsof Phelan Creek flowed through the original working area at the timeof the survey.

64 Vegetativeclearing and overburden removal were not necessary for theremoval of the sandy gravel with some cobbles and boulders. A 15-m buffer was maintainedbetween the work area andmain channel of Phelan Creek; thisnatural buffer was augmentedby dikesacross depressions and minorchannels. A dike was constructedat the upstream end of the site to divertintermittent channel flow andan outletchannel was providedat the downstreamend ofthe gravel removal area to facilitate drainage. Material was removed to a0.9-m workingdepth with conventional loading and hauling methods;permafrost was notpresent but ripping with dozers was necessary forexcavation of seasonally frozen ground. Similar working depths, excavation methods,and diversion/bufferprocedures were used during development ofthe upstream expansion.

The siteapparently was notrehabilitated, because several dikes and onestockpile remained during the time of the site visit in 1978. Various aspectsof this site are shown inFigure 90.

65 REFERENCE

Wahrhaftig, C. 1965. PhysiographicDivisions of Alaska. U. S. Geological Survey.Prof. Paper 482. 52 pp.

66 EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND HYDRAULICS L. A. Rundquist

INTRODUCTION

The purposeof the hydrology and hydraulicsstudy was toevaluate theeffects of floodplain gravel removal on the river configuration, hydraulics,sedimentation, ice characteristics, and hydrologyat the 25 study sites. The locationsof these sites are shown inFigure 1. The characteris- ticsdescribing the physical aspects of thesite and thegravel removal methodsare listed in Table I. Generaldescriptions of the sites are pro- videdin DESCRIPTION OF STUDY RIVERS.

Previousstudies of gravel removal from river floodplains are limited in number. A preliminaryreport for this project (Woodward-Clyde Consultants 1976a)reviewed literature on gravel removal up tothat time. Significant results of thatreview are included and expanded upon inthis section. Other pertinentliterature identified since 1976 areincluded in this section.

A fewgeneral statements (from Woodward-Clyde Consultants 1976a) con- cerningthe behavior of rivers are given in the following paragraphs to provide a basisfor the information presented in subsequent sections.

A rivercontinually changes its position andshape as a consequence of hydraulicforces acting on its bed and banks. These changes reflect the dynamiccondition of thenatural environment; they may be slow, gradual processes or suddenmorphological changes resulting from an extremeflood event. A river systemalways strives toward a stateof equilibrium in order to conveythe water andsediment delivered to it.

67 Similarly, whena stream isaltered locally, the change oftencauses modificationof the channel characteristics for considerable distances both upstreamand downstream. The riverresponse to changes is quite complex,but all riversare governed by the same basicforces. From a review of available literature on riverresponse to alterations, some generalstatements can be made onthe basis of past research results (Karaki et al. 1974).

Depth is directlyproportional to water discharge and inversely proportionalto sediment discharge.

a Channel widthis directly proportional to water discharge and to sedimentdischarge.

a Channelshape (width:depthratio) is direct ly related to sediment discharge.

0 Meanderwave lengthis directly proportiona I towater discharge and to sedimentdischarge.

Riverslope is inversely proportional to water discharge and directly proportional to sedimentdischarge and grainsize.

o Sinuosityis proportional to val eyslope and inverselyproportional to sedimentdischarge.

Althoughthese relationships canno be used topredict the exact re- sponseof a riverto alterations, they do revealthe interdependency of the riverparameters.

Localmodifications to a river caninduce short-term andlong-term responses.During excavation, channel morphology and sedimentationcharacteristics may bechanged. Afterthe operation has ceased,the river will tendto readjust to the geometry and patternthat it hadpreviously; ifthe magnitudeof the modification is large enough, thereadjustment may take many decades to complete. The short-termresponses are usually observable

68 and may bemeasurable; however, the long-term response may be so gradual thatthe changes will notbe noticeable for decades.

Inaddition to these general statements pertaining to all rivers, a few characteristicsof arctic and subarcticrivers are introduced below. Flow stopsin many rivers for much ofthe winter. Those riversthat continue toflow in the channel beneath the ice or in the gravel beneath the channel havethe potential to develop aufeis, which is ice that forms upon itselfby a series of overflows. The remainingflow is consideredvital to fish overwinteringareas.

At breakup,the water levels of large snowmelt floods are often in- creasedby ice jamming or aufeis in the channel. After the snowmelt flood, flow may decreasesignificantly for the rest of the summer except for a few shortduration events in response to summer storms.Very low summer flow is especially common onthe North Slope, which is semiarid,receiving only 150 mm ofprecipitation annually.

In subarcticAlaska, glaciers feed many r vers,resulting in generally more un iformflows through the summer. Diurnal fluctuationsare evident in these r ivers near theirheadwaters. Associated withglaciers are glacier dammed lakesthat can empty rapidly causing ex ensiveflooding downstream.

69 METHODS OF DATA COLLECTION

The hydrology and hydraulicsfield program was Conducted toprovide informationfor the evaluation of gravel removal impacts anthe physical characteristics of theriver within the study reach. Three consecutive dayswere available at each of the 25 studysites for collection of these data. The site visit was duringthe summer when thewater level was relatively low sd thatthe channels could be more easilycrossed. Details on theprocedures used canbe found in APPROACHAND METHODOLOGY.

70 METHODS OF DATA ANALYSIS

The evaluationof changes resulting from gravel removal operations atthe 25 studysites was based primarily onsubjective judgement. A few hydrologic and hydraulicanalyses were performed to enhance thedata base formaking further evaluations and biologicalanalyses. A table was prepared thatlisted quantitative values for the subjective evaluation of changes, and was used to compare sites and, thereby,to evaluate the relative change. The followingsubsections describe briefly the methods used in theanalyses.

HYDROLOGY

Mean annualflows and flood frequency curves were developed for the 25 studysites. There were no U. S. GeologicalSurvey gaging stations at thestudy sites. Nine sites were near enough togaging stations to use thegaging station data, although none of the station records exceeded 12 yearsin length. Standard regional regression techniques were difficult to usebecause of the sparse gaging station network in arctlc and subarctic Alaska. The hydrologicanalyses thus include a significant amount ofjudge- ment;thus, the resuI,ts should be considered as roughestimates.

Mean AnnualFlow

The mean annualflows at six U. S. GeologicalSurvey gaging stations wereused as a basisfor the analysis. The unit mean annualflow (mean annualflow per square kilometer of drainage basin) was computed for these stations.Nine of thestudy sites were near enough tothe stations to use thestation's unit mean annualflow. At theremaining 16 sites,the unit mean annualflow from the nearest gaging station was modifiedafter con- sideringthe difference in mean annual precipitationof the drainage basins for thegaged river gnd thestudy site.

71 FloodFrequency Analysis

Floodfrequency curves for ea,ch ofthe study sites were generated byapplying a regionalanalysis technique described by Lamke (1979). Dischargesfor the 1.25-, 2-, 5-, IO-, 25-, 50-, and100-year recurrenceintervals were computed. In order to improve these estimates, floodfrequency data based on the application of the LogPearson Type Ill distribution wererequested from the U.S. GeologicalSurvey for 17 gagingstations on or in the general area of thestudy sites. The re- gressionequations presented by Lamke were also usedon these gaged rivers and theratio of the Log PearsonType Ill dischargesto the dischargescalculated from the regression equations were computed. These ratios werethen applied to thestudy sites if the sites were (1) onthe same riverbut upstream or downstreamfrom the gaging site, (2) a similarsite to that of the gaged river, and (3) ifthe drainage basincharacteristics such as headwaterslocation, aspect, and drainage basinshape were similar, The resultingdischarges were used to develop floodfrequency curves for each of the study sites.

HYDRAULICS

Threeanalyses were included in the hydraulic investigation: backwateranalysis, uniform flow analysis, and hydraulicgeometry analysis. Each ofthese are discussed in the following separate subsections.

BackwaterAnalysis

A backwateranalysis was performedfor most of the rivers included inthe study using the standard step method (Chow 1959). Inputdata to theprogram included a selecteddischarge, a correspondingwater sui" faceelevation at the control section, cross-sectional geometry of each crosssection in the study reach, distances between cross sections, and roughnesscoefficients for each subsection of each cross section.

72 Uniform Flow Analysis

Inaddition to the flood flow computations performed in the backwater analysis,values of some geometric and hydraulicparameters at low flows werecomputed inorder to relate these parameters to the corresponding discharge and toprovide data for the aquatic habitat evaluation. Use of the backwaterprogram was notappropriate for lowflows because of the small number and widespacing of cross sections in the study reaches. The flowsat thesurveyed cross sections were assumed to beuniform and computationswere made usingthe Manning equation (Chow 1959).

The inputdata to the uniform flow program included the cross-sect i ona I coordinates,roughness coefficients, energy slopes, selected discharges , and initialestimates of stage. The surveyedwater surface slope was used a s an estimateof the energy slope becausemost surveys took place when rivers werecarrying flow similar in magnitude to the mean annualflow. Similarly, theroughness coefficient was calculatedfrom the measured discharge and geometryrather than from estimates used in the backwater analysis. This calculationtechnique was used becauseroughness would I ikely begreater at low flowsthan that at flood f lowsdue tothe greater influenceof the bed roughnessat small depths.

Hydraulic Geometry Analysis

Valuesof the coefficients and exponents inthe power relationsfor the hydraulicgeometry (including mean velocity) at a cross sectionwere com- putedfor disturbed and undisturbedcross sections at five selected study sites. Power curvefitting was completedfor the geometric and corresponding dischargedata which were determined by the hydraulic analyses discussed in theprevious subsections. The resulting coefficients and exponentswere compared withthe values obtained for other rivers in Alaska and otherparts ofthe United States. In addition to this quantitative comparison, a quali- tativecomparison of power relationcoefficients andexponents for disturbed andundisturbed cross sections was made basedon plots of the power curves for each crosssection of other sites having insufficient data range for a quantitativeanalysis.

73 QUANTIFICATION OF CHANGES

At each ofthe 25 studysites an attempt was made toquantitatively ratethe degree of change ofselected river characteristics due tothe gravelremoval operations. When quantifying changes,the selected charac- teristicshould be comparedbefore and afterthe gravel removal operation undersimilar flow conditions. Whenever possible,this was done usingaerial photographs.Aerial photographs often did not provide the necessary detail, orthe lack of information concerning flow conditions in the photographs made suchcomparisons less meaningful. Thus, theupstream sample area was assumed torepresent the undisturbed condition for many ofthe comparisons. Aftercomparisons were made,a ratingscale was appliedto establish the relative degree of change occurringin physical characteristics at the varioussites.

A scale was selectedranging in value from 0 to IO, with 0 being a verylarge decrease in the quantity of a characteristic, 5 indicatingno change,and IO being a verylarge increase in the quantity of a characteristic.Intermediate values reflect various degrees of changebetween the extremevalues. More specific meanings of the degree of change for each characteristicare given in the following RESULTS AND DISCUSSION section.

All siteswere rated using the rating scales. Sites with morethan onephysical response to the gravel removal activity were given morethan one rating. These sitesincluded Sinuk River, Washington Creek, Oregon Creek,Aufeis Creek, and MiddleFork Koyukuk River-Upstream. At all other sites,the physical changes resulting from the gravel removal operation were similarthroughout the site. The gravelremoval areas for all sitesare discussed ingeneral in the previous section (DESCRIPTION OF STUDY RIVERS).The separationof the gravel removal areas for the hydrologic and hydraulic analysesat selected sites is describedin the following paragraphs.

At SinukRiver, different responses to gravel removal were observed for twogravel removal locations. These locations are shown inFigure II. An islandthat split the channel upstream of the highway bridge was completely

74 Scale in Meters 17 June 19T3 0- 38-l

75 removed (thisarea is designatedArea A). The otherlocation (Area 81, in and adjacentto high-water channels upstream anddownstream from the highway bridge, was separatedfrom the main channel.

At WashingtonCreek, two gravel removal areas were separated by approximately I km of undisturbedriver (Figure 12). The upper(upstream) and lower (downstream)gravel removal areas are designated A and B, respectively.

At OregonCreek the major area of disturbance was immediatelyupstream of its confluencewith Cripple River (Figure 13, Area A). The unvegetated gravelbar (Area B) immediatelydownstream from the highway bridge was also usedfor gravel extraction.

At theAufeis Creek site,the two major gravel removal areas were separatedby over 3 km of river channel(Figure 14). The upperand lower sitesare designated A and B, respectively.

Gravelremoval at the Middle Fork Koyukuk River-Upstream site was locatedin a high-waterchannel and on a pointbar (Figure 15). The upper andlower sitesare designated areas A and 6, respectively.

76 Scale in Meters 17 June 1973 0- 254 Figure 12. Aerialphotograph of WashingtonCreek showing the upperand lower gravel remove1areas.

77 8L Scale in Meters 7July1977 I 0 305

Figure 14. Aerial photograph of Aufeis Creek showing upper and lower gravel removal areas.

79 Scale in Meters 11 July1977 0-5 0-5 Figure 15. Aerialphotograph of Middle Fork Koyukuk River-Upstream showingupper and lowergravel removal areas.

80 RESULTS AND DISCUSSION

The followingsubsections present and discussthe results of thedata analysisfor the 25 studysites. The fivesubsections represent five cate- goriesof river characteristics which exhibited changes resulting from gravelremoval operations. These include:

e Channe'l configuration and process,

0 Hydrau I i cs, e Sedimentation, a Icecharacteristics, and e Hydro Iogy.

Each subsectionincludes background information that provides the reader with a knowledgeof selected characteristics of undisturbedrivers anda descriptionof changeswhich occurred in these river characteristics as a resultof gravel removal operations.

CHANNELCONFIGURATION AND PROCESS

The channelconfiguration of a riveris the shape of theriver channel(s) when lookingvertically down at theriver. Configurations represented bythe 25 studysites include braided, split, meandering, sinuous, and straight. A sixthconfiguration, beaded, isunique to northern environments, but was notinvestigated during this study; beaded systems are typically very small and arenot likely to contain much gravel.Associated with the channelconfigurations are processes of sediment erosion and deposition which form featurescharacteristic of the configuration. The fivechannel configurationsthat were used to describe the studied sites are described in subsequentparagraphs.

81 The channelconfiguration is a functionof river stage (water level); theoptimum stage for defining the channel configuration is at law flow. The channelconfiguration is also a functionof location along the river; a rivercould conceivably exhibit all channel configurations between its headwatersand its mouth. The channelconfigurations describing the 25 studysites are those only through the reach studied. Configuration combinations,local spatial variations, and variationsover time complicate channelconfiguration selection.

UndisturbedCondition

BraidedConfiguration. A braidedriver typically contains two or more interconnectingchannels separated by unvegetated or sparsely vegetated gravelbars (Figure 16). Itsactive floodplain is typically wide and sparselyvegetated, and contains numeroushigh-water channels and occasional vegetatedislands. Active channels are typically wide and shallow and carry largequantities of sedimentat high flows. Bars separating the channels are usually low, gravelsurfaced, and easilyerodible. The lateralstability of thechannels is quite low; channelsshift bybank erosionand/or by channel diversioninto what was previously a high-waterchannel. The lateralactiv- ityof channels within the active floodplain of a braidedriver that carries largequantities of bedload, is expectedto be high because gravel deposits may partiallyor fully block channels, thereby forcing flow out of the channel. Maximum depthsand corresponding top widths of undisturbed major, side, andhigh-water channels, at four braided study sites, are plotted in Figure 17.

SplitConfiguration. A split channel river hasnumerous stableislands whichdivide the flow into two channels (Figure 18). The banks of the channelsare typically vegetated andstable. The splitriver floodplain is typically narrow relative to thechannel width. There are usually no more thantwo channels in a given reach and otherreaches are single channel. One ofthe twochannels in a spli t reach may bedry during periods of low flow. The channelcross section is narrowerand deeper than a braidedriver with similarflow characteristics. Maximum depths and correspondingtop widths of

82 PLAN VIEW

SECTION A-A

Figure 16. Schematic diagram of the plan view and cross section of a typical braidedriver.

83 LEGEND *Aollve Channol DHlgh-Water Channol

A n

a nn a

m. AD

Figure 17. Maximum depths and correspondingtop widths of undisturbed major, side, and h.igh-waterchannels at four braided study sites.

04 PLAN VIEW

SECTION A-A -

Figure 18. Schematicdiagram of the plan view and crosssection of a typical split channel river.

undisturbedmajor, side, and high-waterchannels, at four split channel studysites, are plotted in Figure 19. Sedimentdischarge is typicallyless thanthat of a braidedriver. Bed load is depositedat low flowto form

gravelbars along the sides or in the middle of the channels. These bars are typically more erodiblethan the banks. The bars,rather than the banks , are I erodedduring subsequent floods, resulting in a laterallystable channe 1.

MeanderingConfiguration. A meanderingriver winds back and forth withinthe floodplain (Figure 20). The ratioof the channel lengthto the downvalleydistance is called the sinuosity ratio, or SinuOs ity.Meandering rivers have a sinuositygreater than 1.5. Flow is contained in a single a

LEGEND a

.Active Channel

oHlgh-Water Channel

.Side Channol

A% A a n

D a

I A I I 11 I IIII 1 1 I 4 i 67Q910 d0 30 do do 120 lMl80210 CHANNELFULL TOP WIDTH (m)

Figure 19. Maximum depths and correspondingtop widths of undisturbedmajor, side, andhigh-water channels at four split channelstudy sites.

86 rpointBars-l

PLAN VIEW

High" Channel /--Point Bar

SECTION A-A SECTION B-6

'igure 20. Schematicdiagram of theplan view and two crosssections of a -ypical meanderingriver.

87 channel,with very few islands. At eachbend, thetypical cross section contains a pointbar on theinside of the bend and a pool on theoutside of the bend, resultingin a triangular shapedcross section. Point bars arethe primary area of sediment deposition in a meandering river. Between thebends is a crossing,which typically has a wide and shallowcross sec- tionsimilar to that of a singlebraided channel. Since the width of the channel inthe crossing is similar to that in the bend, theaverage velocityis often greater through the crossing. Maximum depths and corresponding tapwidths of undisturbedmajor, side, and high-waterchannels at 15 study sites with meandering,sinuous, and straightconfigurations are plotted inFigure 21. A meandering rivershifts in the downvalley direction by

LEGEND *Active Channol &High-WaterChrnnoi 4. 4%. e WEC 18ida Channol a A e AA n A A a P n$

Figure 21. Max imum depthsand corresponding top widths of undisturbedmajor, side, andhigh-water channelsat 15 studysites with meandering, sinuous, and straight configurations a continuousprocess of erosion and deposition;erosion takes place on theoutside bank,downstream from the midpoint of the meanderbend and depositionoccurs on the downstream end ofthe next point bar downstream. The rateof downvalley shifting varies from one riverto another. The rate and directionof shifting is much more predictablethan the lateral shifting of braidedchannels. A result of nonuniformshifting is channel cutoffs.

Thef loodplain width of a meandering river is of ten roughly equal tothe meander beltwidth, which is the average width from the outside of onemeander bend tothe outs de ofthe next opposite meanderbend (Figure 20). High-waterchannels on the insideof point bars are typical onmeander- ingrivers. Sediment transport n meandering rivers is typically moderate.

SinuousConfiguration. A s nuous river is similarin plan view to a meandering riverexcept that its sinuosity is between 1.1 and 1.5 (Figure 22). Insinuous rivers, point bars are smaller and downvalleyshifting isgenerally less than that of a comparable-sizemeandering river. Other thanthe greater stability, sinuous rivers are quite similar in form and hydrauliccharacteristics to meandering rivers.

StraightConfiguration. A straightriver flows in a singlechannel I with a sinuosityless than I. I (Figure 23). The thalweg, or deepestpart of thechannel, typical ly wanders back and forth within the Ghannel wi.th alternateground bars formed bysediment deposition opposite those locations wherethe thalweg approaches the side of the channel. The alternatebars may or may not beexposed at low flows. Riverswith a ,long reachof straight channelpattern are much less common thanrivers with other configurations. Banks of straightchannels are expected to be relatFvely stable. Sediment transportis likely to be lightto moderate in these systems.

OtherProcesses. Rivers with any configuration may befound innarrow mountainvalleys andon alluvialfans. Rivers in these locations have dif- f erent processes of erosion anddepos i t ion than those descr i bed for the’? typicalriver with the same configuration. Channel configurations of moun- tainousrivers are typically not controlled by alluvialprocesses, but

09 PLAN VJEW

SECTION A-A Figure 22. Schematicdiagram of theplan view and crosssection of a typica sinuous river.

I PLAN "IEW

SECTION' A- A Figure 23. Schematic diagram of theplan view and crosssection of a typici I straight river.

90 r,atherare controlled by geological and morphologicalfeatures of the valley.Mountainous rivers commonly havevery little or no floodplain and consequently,have small quantities of gravel.Alluvial fans develop when a steepgradient stream flows onto a substantiallyless steep terrain; Its sedimenttransport capacity is significantly reduced causing sediments to be deposited.This deposition fills the channel, thus forcing the flow to develop a new channel.This may occurby a gradualmigration process or bya rapid abandonment of one channel to develop a new channel. Such processes develop a partial cone-shaped depositof gravels with the apex beingnear the end of thesteep gradient river valley (Figure 24). The fan may or may not be vegetated;denser vegetation implies greater stability.

Changes Due toGravel Removal

Themost cmmn change tothe channel configuration resulting from gravelremoval wasa shifttowards a morebraided configuration as indicated,in part, by an increasein the number' ofchannels, A decreasein lateralstability of the channels was oftenassociated with changes to

91 morenumerous channels. These changes were most prevalent inscraped sites andmost prominent insingle channel sites. Gravel removal at many scraped and pit excavatedsites caused a diversionor a highpotential for diversion offlow through the gravel removal site. These observed channel configuration changeswere given quantitative ratings for comparative purposes (Table 5). thesechanges in channelconfiguration are discussed in more detailin the following sections.

BraidingCharacteristics. The twobraiding characteristics considered werethe number and stabilityof the channels. Themost significant changes inthese characteristics resulted from scraping operations in straight, sinuous, split, and meandering riverswith lesser changesobserved inscraped braidedrivers. This difference was expected,because braided rivers had suchcharacteristics prior to gravel removal, thus, anychange was compara- tively less significant. The locationsof the gravel removal operations that causedthe most significant change in the braiding characteristics were thosewhich disturbed the bars adjacent to active channels or those which causeddiversion of flow into the material s i te.

Disturbanceof the bars adjacent to active channels can hypotheti- callyreduce the flow within the channel during floods because flow spreads outthrough the mined area. The reducedflow within the channel would reduce theability to transport sediments; sediment deposition within the channel may result.This deposition would potentially aggravate the problem by furtherreducing the cross-sectional area available to the flow. This pro- ce5scan result in widening the channel and thedevelopment of mid-channel bars.Although the potential for this hypothetical process exists, it was notobserved at the study sites.

Braidingcharacteristics increased at many sites due tothe diversion of flowthrough the site and thelack of a well-definedchannel to confine theflow. The flowthus spread through the material site and likelydid nothave sufficient scour potential to develop a new channel,Thus, numerous poorly-definedchannels flowed through the site.

92 Grave I Diversion Diversion remova t NO. of Chan ne 1 a b througkthrough River channelsstabiarea I ity scrape pit

Got d Run Creek 5 5 6 SinukRiver 4 3 9 - - 7 WashingtonCreek IO 0 IO 5 4 6 OregonCreek 9 0 9 7 5 6 Penny River 9 0 IO Nome River IO 0 IO 0 Ugnurav Riverik 6 3 9 w Aufeis Creek A 9 0 10 B 5 4 6 KuparukRiver 7 3 7 SkeetercakeCreek 5 I IO Sagavan irktok River IO 4 9 lvishak River 8 4 7 ShaviovikRiver 6 5 6 KavikRiver 8 2 9 D ietri ch R i ver-Upstream 5 5 7 Dietr i ch River-Downstream 6 5 7 MiddleFork KoyukukRiver-Upstream A 5 5 6 3 10 0 10 MiddleFork KoyukukRiver-Downstream 8 4 7 Jim River 5 5 7 ProspectCreek 5 5 - West Fork TolovanaRiver 5 5 - McManus Creek 5 5 6 Tanana River-Downstream 5 5 - Tanana River-Upstream 5 5 - Phe tan Creek 4 5 IO

(Footnotes oh followingpage) Table 5. Footnotes a Number ofchannels ratings: Number ofactive channels in the mined area B= R Number ofactive channels upstream from the mined area

IO 3< BR 9 2.5 < BR 23 8 2

6-10 Notused 5 No change in channel stability 4 Slightdecrease in stability, but within natural stability variationof the river 3 Moderatedecrease in channel stability due togravel removal 2 Largedecrease in channel stability due togravel removal I Substantialdecrease in channel stability due togravel removal 0 Verysubstantial decrease in channel stability due togravel remova I

C Flow diversion rat in S:

IO Highpotent al forriver to divert all its flowpermanently throughthe site 9 Diversion o f a significantquantity of flow through the site occurred with i n severalyears 8 Moderate potentialfor river to divert all of its flow permanently through the site 7 Moderate to highpotential for some of theriver flow to divert permanen tlythrough the site or for flowdiversion through the site dur ingflood events 6 Low potentialfor river diversion through the site 0-5 Notused

94 Ten sites hadmore than twice as many channelsin the material site as wereupstream. At fourof these sites, Washington Creek, Nome River, SagavanirktokRiver, and MiddleFork KoyukukRiver-Upstream, the numbers of channelsincreased more than three times due togravel removal operations. Most sites (7 of 101 withlarge increases in numbers ofchannels also had a verysubstantial apparent decrease in the lateral stability of those channels.Lateral stability evaluations were based on subjective judgements of I stabilityindicators. Lateral stability indicators included the height and erodibilityof the gravel bars at the edge ofthe active channels, the bed loadtransport characteristics evident atthe t ime ofthe site visit, and thechannel configuration.

The Nome River is an example of a materia sitewith increased braided characteristics(Figure 25). Inthis s inuous r ver,single channel flow was prevalentprior to the gravel removal operation; exceptions to this arethe split in the channel immediately downstream from the material site location andtwo high-water or small activeside channels adjacent to the materialsite location. Approximately 20 yearsafter the gravel was removed, theriver was flowingin numerous, poorly-definedchannels through the materialsite. The riverapparently diverted into the scraped area soon afterthe operation was completedand has attempted to develop a well- definedchannel since it diverted. The state of equilibriumbetween erosion and depositionin the Nome River was disturbedby the gravel removal operation. To restoreequilibrium it will probablytake several decades from thetime of theinitial disturbance.

FlowDiversion Through Site. Gravel removal operations caused flow diversionor a highpotential for flow diversion at 12 ofthe 25 study sites.Sites with a highpotential for the diversion of all ofthe flow permanentlythrough the site included upper Washington Creek, Penny River, Nome River,upper Aufeis Creek, Skeetercake Creek, lower Middle Fork Koyukuk River-Upstream, and PhelanCreek. At most ofthese sites, all of the flow hadalready diverted when the site was visited. All of thesesites were scrapedand the lower Middle Fork Koyukuk River-Upstream site was theonly site where a buffer was known to havebeen used toseparate the site from

95 August 1950 Scale in Meters 0- 130

Figure 25. Comparativeaerial photography of the Nome Rivershowing change in channelconfiguration resulting from gravel removal activities.

96 theactive channel. The vegetatedbuffer was approximately 30 m wide and roughly I m inheight; vegetation was missingin and adjacentto a high- waterchannel which crossed the buffer. Low (0.3 m) dikeswere used to blockoff this high-water channel. Flow began to divertthrough the material siteduring the first breakupfollowing the removal of gravel. The buffer breached,apparently caused by overtopping and subsequent erosion of thetop anddownstream face during the flood. At thetime of the site visit in 1978, 34 yearsafter the mining took place, 85 percentof the flow was going throughthe material site. Scraped sites with a large amount, butnot all, ofthe flow diverted through the material site by the time the site was visitedincluded Sinuk River (in-channel site), upper OregonCreek, UgnuravikRiver, Sagavanirktok River, and KavikRiver. None ofthese sites had a vegetatedbuffer.

A majorconsequence of flowdiversion through scraped sites was the developmentof braiding characteristics, as was discussedin the previous section.Another consequence was thatflow in the former main channel(s1 was eliminatedor significantly reduced, thus affecting their hydraulics and theirregime. Flow through scraped sites that had the potential to aidthe replenishment of gravel within the site occurred at Sinuk River (in-channelsite), Washington Creek, Oregon Creek, Ugnuravik River, Aufeis Creek,Kavik River, and PhelanCreek. At othersites, such as Penny River andMiddle Fork Koyukuk River-Upstream, flow through the site was probably eroding moresediments than it was depositing.

Most (6 of 7) pit excavatedsites had vegetated buffers separating thematerial site from the active channel(s1. The exception is Ugnuravik River(Figure 261, whichhad only a 5- to IO-m widegravel bar sepafating thematerial site from the active channel. Therefore, the potential for flowdiversion through this pit is high; flow has divertedthrough the siteduring floods, but the diversion has not yet been permanent.

The two pitexcavated sites onthe Tanana Riverwere judged to have moderate tohigh potential for some ofthe flow diverted permanently through thesite within several decades followingsite closure. Both sites had

97 Scale in Meters 7 July 1977 0 76

Figure 26. Aerialphotograph of the Ugnuravik River pit site showing the in- sufficientbuffer zone.

98 approximately 30 m to 40 m widevegetated buffers. The mainchanne I of the Tanana Riverhas the capability to erode through such a buffer inless than a year. The sidechannel at the Tanana River-Upstream site (Fi gure 27)eroded 3 m ofthe wsidest partof the buffer between early June and mid-September of 1978. At eitherof the Tanana Riversites, it couldtake severalyears or several decades for the river to breachthe buffer and flow throughthe pit, the length of time depending on the lateral direction oftravel. of the mainchannels.

The Prospec t Creekand West ForkTolovana River sites were judged to have a modera te potentia 1 forall of the flow to d’ivertthrough the pits.Both sites hadvegeta tedbuffers that included portions of abandoned channels. The upstreamend of the abandonedchannel, inboth cases, causes a zoneof weakness inthe buffer. Eventhough, atboth sites, the width and heightof the buffers were likely sufficient to preventbreaching for several decades,zones of weakness Inthe buffers at the abandoned channels andchannel aufeis development in the active channel may causeearlier flowdiversion and bufferbreaching. At the West ForkTolovana River site, theupstream end was dikedoff and heavilyriprapped; however, in spring of 1979, flowapparently overtopped the dike and scouredthe channel lead- inginto the pit, leaving a largedelta gravel deposit in the pit. Flood stage was probablyhigh because of aufeis development in the channel. Channel -aufeis developrneut alsoinfluenced the Prospect Creek site(Figure 28). -Aufeisdeveloped in the channel reach upstream from the material site, reducingthe channel capacity during the snmelt runoff period. The runoff thusflowed directly down thevalley, rather than following the ice-filled channel. The waterflowed through the pit causing headcutting of the upstream edge.The edge was subsequentlyriprapped to prevent further headcutting.Doyle and Childers(1976) documented thisApril 1976 occurrence.

HYDRAULICS

Hydraulics, as used inthis investigation, is the study of those param- eterswhich influence the mechanics of waterflow through the study reach. The hydraulicparameters which were considered include hydraulic geometry,

99 channelslope, and local flow characteristicsat flow obstructions. Hy- draulic geometry isdefined as the geometric and hydraulicvariables at a crosssection that vary with changes in discharge. The hydraulicgeometry variablesdiscussed are top width, hydraulic depth, and mean velocity. Chan- nelslope (gradient) is the reduction of the water surface elevation in the downstream direction. A generaldiscussion of thesehydraulic parameters is presentedin the following subsection, followed bya descriptionof the effects onthese parameters due togravel removal.

UndisturbedCondition

The hydraulicgeometry parameters considered herein are top width, hydraulicdepth, and mean velocity. The topwidth is the width of thewater surfaceat a givencross section anda givendischarge (Figure 29). The

Fiure 29. Schematic diagram illustratingdefinitions of channel gaanetric an% hydrau I i c var i ab I es. hydraulicdepth is defined as the cross-sectional area of flowdivided by thetop width. The mean velocityis defined as the ratio of discharge to cross-sectionalarea of flow. An estimateof the carrying capacity of the channel isthe conveyance,which isdefined by:

t 02 K = CAR' (1) where K = conveyance C = a coefficientrelated to the roughness of the channel A = crosssectional area of f low R = hydraulic radius x = a fractionalexponent

The discharge is directlyproportional to the conveyance withthe proportion- alityconstant being the energy slope to a fractional power, usually f.

The variationin the hydraulic geometry as a functionof discharge at a rivercross section is an indicatorof the shape ofthe channel cross section. The shape primarilyreflects the magnitude of the bank-full dis- chargewhich typically has sufficient sediment carrying capacity to shape a channel and occursfrequently enough tomaintain the resulting shape. The topwidth, hydraulic depth, and mean velocityat a crosssection are often expressedas a functionof discharge in the form of power relations:

b W=aQ f D=cQ V=kQm where W = topwidth D = hydraul ic depth

V = mean velocity Q = discharge a, c, k = coefficients b, f, m = exponents

Typicalrelations for a hypotheticalriver are shown inFigure 30. Sub- stitutingthe power relationsfor the hydraulic geometry variables into the flowcontinuity equation iI lustratesthe interdependence of the variables:

Q=AV=WDV b = (a Q 1 = (a c k

I03 Thus, forcontinuity,

axcxk=l and b+f+m=l

Note: All Scales Are Loaarithmlc

Figure 30. Averagehydraulic geometry of river channels expressed byrelations of width, depth, and velocityto discharge at two locationsalong a river(modified from Leopold, Wolman, and Miller 1964).

If a coefficient or exponentfor one hydraulic geometry variable changes due tothe gravel removal operation, at least one of theother variables must

I04 also change tomaintain continuity of flow. Generally speaking, if a channel is widened, it oftensatisfies continuity bybecoming shallower. Similarly, if a channelslope, or gradient, is increased,thus increasing velocity, continuityis commonly satisfied by a reductionin depth.Exponent values forselected study sites and otherrivers are given in Table 6. The ex- ponentsexhibit a widerange of variability for different rivers; Rundquist (1975) foundthat the exponents and the coefficients can be expressed as functionsof the bank-full discharge. The coefficient c andexponent f in the power relationfor hydraulic depth were found in addition to be a functionof the median bed material size. The exponents inthe power relations may change at a givensite for discharges above bank-fullbecause of the typicallyabrupt change in bank slope atbank-full conditions.

The slopeof the water surface profile for a typicalriver generally will parallel the bedslope at low flow,often producing a sequenceof riffles and pools. At floodflows, the pool-riffle sequence is notapparent in the water surface prof i le (Figure 31 1.

Figur'e 31. Schematicdiagram showing change inwater surface slope in responseto a change inwater discharge.

Naturallyoccurring flow obstructions in rivers can include vegetation, rockor snow avalanches,aufeis, and boulders. The effectof an obstruction on thehydraulics is to cause a localincrease in velocity which often

I05 Table 6. Values aIf Exponentsfor Hydrau I ic Geometry Power Relationsa

Undisturbed Disturbed areas areas River bf m b f rn

Kupar uk R i ver 0.43 0.28 0.29 0.48 0.28 0.24 SagavanirktokRiver 0.25 0.40 0.35 0.32 0.42 0.26 ShaviovikRiver 0.40 0.33 0.27 0.52 0.29 0.19 MiddleFork Koyukuk River-Upstream 0.29 0.44 0.27 0.44 0.33 0.23 MiddleFork Koyukuk River-Downstream 0.54 0.28 0.18 0.37 0.29 0.34 Averagevalues, midwestern b United States 0.26 0.40 0.34 b BrandywineCreek, Pennsylvania 0.04 0.41 0.55 Ephemeralstreams insemiarid b United States 0.29 0.36 0.34 Averageof 158 gagingstations b in United States 0.12 0.45 0.43 b IO gagingstations on Rhine River 0.13 0.41 0.43 Average of 17 stations in SouthcentralAlaska' 0.19 0.39 0.42 Average of 30 stationsin Upper d Salmon Riverarea, Idaho 0. I4 0.40 0.46

a b W=aQ f D=cQ V=k Qm bCompi led by Leopold, et al. \I9641

C Emmett (1972) dEmmett (1975)

I06 resultsin erosion of theobstruction or bed scour adjacent to t,he obstruction(Figure 32). Completechannel relocation is also a potentialresponse to flow obstructionsblocking a highpercentage of thechannel's cross- sectionalarea.

Changes Due to Gravel Removal

Substantialchanges in hydraulic geometry, slope, and flow obstructions resultedfrom gravel removal operations at roughly 60 percent of thesites. Typicalhydraulic geometry changes in the mined area included increased channeltop width, reduced hydraul ic depth, reduced mean vel'ocity, and increasedconveyance. Changes inslope due togravel r,emoval operationstook

I07 thefarm of increases through the mined reach resulting from channel cutoffs and localslope redistributions affecting the pool-riffle sequence.Flow obstructionsin the forms of material stockpiles, diversion dikes, and overburdenpiles have the potential for causing local scour, ice jam formation, and siltation.

HydraulicGeometry. Gravel removal operations caused changes in the naturalcross-sectional shape of the active channels of approximately half ofthe rivers included in the study. The backwateranalysis was notcomplete enough at some sitesto confirm the hydraulic geometry changeevaluation. A comparisonof power equationexponents for cross sections in disturbed and undisturbedareas (Table 61 indicated a variedresponse to gravel removal. The coefficientsin the power equationsmust also be considered tounderstand the effects of gravel removal. For example, atthe Middle ForkKoyukuk River-Downstream site,the top width increased at a slower ratewithin the gravel removal area than outside of it. However, thecoef- ficientsin the power relationswere greater for the disturbed than the undisturbedcross sections indicating that the top widths were larger at lowflows in the disturbed areas than the undisturbed areas and weresimilar inboth locations at higher flows. A qualitativeevaluation of this effect canbe made bycomparing the relative channel widths in the material site at low flow and floodflow (Channel width and Floodedarea, Table 7).

The coefficientin the power equationfor the top width was greater forthe disturbed cross section than the undisturbed cross sections at eightof the sites; this difference resulted from a consistentlygreater top widthat all discharges considered in the hydraulic analysis. The sitesat whichthis occurred were Gold Run Creek,Washington Creek, Nome River, Aufeis Creek,Skeetercake Creek, Sagavanirktok River, and both sites on the MiddleFork Koyukuk River. At SinukRiver the exponent of the power relation forthe top width was observed to begreater at the disturbed cross section thanat the undisturbed cross section. This difference indicates that the gravelremoval area had smaller top widths at low flows,but larger top widthat high flows, than the undisturbed cross section.

I 08 Grave I Loca I removalChannel Flooded Ponded Overal I s FlowI ope a a R i ver area w i d th"area area stopeb redistribution'obstruction

Go1 dRun Creek 7 6 5 6 5 8 SinukRiver 6 7 6 5 7 8 - 9 8 - - a Wash ington Creek a IO IO 8 7 9 6 8 IO 5 5 8 OregonCreek IO 9 8 6 7 a 5 6 5 5 5 5 Penny River IO IO IO IO 5 9 Nome River IO IO 7 7 5 7 - Ugnurav ik R i ver 7 IO a 7 5 7 0 Aufeis Creek A 8 IO 10 7 7 7 UI 0 6 6 6 5 5 5 Kupar uk R i ver 6 7 6 5 5 7 SkeetercakeCreek 5 8 IO IO 5 IO SagavanirktokRiver 8 IO 6 6 5 5 lvishakRiver 6 6 6 5 5 5 ShaviovikRiver 5 6 5 6 5 7 KavikRiver 6 7 6 6 7 IO Dietr i ch River-Upstream 5 5 5 5 5 7 Dietr i ch River-Downstream 6 7 7 5 IO 5 MiddleFork Koyukuk R-US A 5 6 9 5 5 5 B 7 9 8 IO 5 5 MiddleFork Koyukuk R-DS 9 IO 7 7 5 5 JimRiver io io 6 5 7 5 ProspectCreek 5 5 5 5 5 5 West ForkTotovana River 5 5 5 5 5 5 McManus Creek 5 IO 6 7 5 8 Tanana River-Downstream 5 5 5 5 5 5 TananaRiver-Upstream 5 5 5 5 5 5 Phel an Creek 4 2 6 5 5 9

(Footnoteson fol lowing page) Table 7. Footnotes

‘Widthand arearatings: Parameter inthe mined area w=R Parmeter upstream from the mined area

wherethe parameter is:

0 topwidth of thechannellsl during the survey period for Channel Width

0 topwidth of thechannslIs1 during floods of approximatelybank-full floodmagnitude for Flooded Area e areaaf ponded water,excluding pits, for PondedArea.

IO 3 < WR 9 2.9 < WR 5 3 8 2 < WR 5 2.9 7 1.5 < WR 5 2 6 I < W 5 1.5 or other W values if theyare within the natural range 07 variationof the river R 5 WR I orif other data indicates no change 4 0.67 5 WR < I or other WR values if theyare within the natural rangeof variation of theriver

3 0.50 WR C 0.67 0-2 Notused bOveral I slope ratings: ofdisturbed reach after removal L~ = Length gravel Length ofdisturbed reach before gravsl removal

LR < 0.71 .4 or 0.11 5 LR 0.77 .3 or 0.77 5 LR < 0.83 .2 or 0.83 5 LR < 0.91 .I or 0.91 5 LR < 1.0 or ifother data indicate nochange

‘Local sloperedistribution ratings:

IO Veryoteop slope followed by a verylong pool 9 Steepslops followed by a long pool 8 Moderateslope follaned by slightly longer than average pool 7 Slope and pool lengthslightly more than that inthe undisturbed aroas 6 Sano localslope redistribution detected or likely to haveoccurred butnot likely that of the natural river 9 No local sloperedistribution 0-4 Notused dFlw obstruction ratings: 10 Obstructionsin an activeIw-water channel Such thatflow is diverted 9 Obstructionsadjacent to an active low-waterchannel 8 Obstructionsin or adjacentto high-water channels 7 Obstructions in thefloodplain but away from any developedchannels 6 Smallobstructions not much different in sizefrom those Occurring naturallyin the floodplain 5 No obstruclions 0-4 Notused

I 10 Associatedwith the trend towards larger top widths in the grave I removalareas, the hydraulic depth in seven of these areas decreased. Sites withsmaller hydraulic depths, in the mined area, for all discharges I n- cludedWashington Creek, Nome River,Aufeis Creek, Skeetercake Creek, SagavanirktokRiver, and bothsites on the Middle Fork Koyukuk River.

The mean velocity was consistentlyless at the disturbed cross section thanat the undisturbed cross section at nine of the sites for the range of dischargesincluded in the backwater analysis. These sites included Gold Run Creek,Washington Creek, Ugnuravik River, Aufeis Creek, Skeetercake Creek, SagavanirktokRiver, Dietrich River-Downstream, and both of theMiddle Fork KoyukukRiver sites. At two sites,the rate of increaseof velocity with discharge was differentin the disturbed area than in the undisturbed area. At SinukRiver, the velocity increased at a lesserrate at the disturbed crosssection than at the undisturbed cross section. At MiddleFork Koyukuk River-Downstream,the reverse was found.

Theconveyance, orcarrying capacity of the channel, was consistently greaterin the gravel removal area of eight sites compared with conveyances atundisturbed cross sections. These sites were Gold Run Creek,Sinuk River, WashingtonCreek, Aufeis Creek, Sagavanirktok River, Kavik River, Oietrich River-Downstream,and Middle Fork Koyukuk River-Upstream. The SinukRiver had a largerexponent or, equivalently, a more rapidincrease in conveyance withdischarge than cross sections which were not disturbed by the gravel removaloperation. Conversely, the conveyance at the downstream site on theMiddle Fork Koyukuk River increased with discharge at a slowerrate than didthe conveyance of the undisturbed cross sections.

Significant changes inhydraulic geometry were observed primarily at s iteswhich were scraped, although not all scrapedsites showed a signif- i can t increase.Most of the significant changes were observed at meandering, sinuous,and straightrivers. Although no single gravel removal location caused a significantlygreater change inhydraulic geometry than others, mostof the sites that had significant changewere those sitesthat were excavatedby scraping in-channel and immediatelyadjacent-to-channel loca- t ions.

I IJ Thearea of ponded water, which includes those low-lying areas which accumulatewater but are not effective in the conveyance of flow, was increasedat roughly half of the study sites. This ponding indicated that the site was notsmobthed during restoration, was excavatedtoo deeply, or was notproperly drained. Table 7 liststhe relative effect of this parameter at the 25 studysites. The impactof the ponding to the hydraulics ofthe systems was notgreat. However, it was a concern toaesthetics and fishentrapment evaluations.

ChannelSlope. Channel slope changes took the form of an overall increasein slope or a localredistribution of slope. An overallincrease inslope wascommonly due tothe formation of a meander cutoff. A redistri- butionof slope without changing the overallslope occurred when theslope was increasedleading int o thegrave removalarea and decreasedthrough thegravel removal area. Table 7 ind catesthose sites which had slope changes.

Studysites exhibiti ngan overa I increasein slope due togravel removalwere generally in small, nonbraided river systems that were excavatedby scraping techniques. The locationof gravel removal wasan importantfactor affecting the overall slope of the system. Sites such as upper WashingtonCreek, Penny River,Skeetercake Creek, and lowerMiddle Fork KoyukukRiver-Upstream, that were excavated on theinside of bends, meanders,and islands most significantlyaffected the overall slope of the river system.This influence was expectedbecause significant increases in slope aremost likely to result from the development of a meander cutoff(reducing channellength and increasingslope).

ThePenny Rivergravel removal operation caused a sign if icantincrease inoverall slope (Figure 33). The photographof the site af terthe grave I was removedshows thatthe main channel flows in a relatively stra ight coursealong the inside of two broad meanders that were cut offin the excavationprocess. The channellength was reducedby a factorof two in the process,equivalent to doubling the overall slope through that reach. Doublingthe slope has the effect of increasing the mean velocityby roughly 40 percent.

I12 Scale in Meters August 1950 July 1977 0 191

Figure 33. Comparativeaerial photography of the Penny Rivershowing change in hydrauliccharacteristics resulting from gravelremoval activities.

I13 Gravelremoval from active and high-waterchannels generally caused local sloperedistribution. Removing gravelfrom bars and banksimmediately adjacentto channels also appeared to cause a localredistribution of the watersurface slope. An exampleof a localslope redistribution, which is similarto the situation at the Dietrich River-Downst,ream site, is schemat- icallyillustrated in figure 34.

After Gravel Remwal

FlowObstructions, Flow obstructionsin the form of material stockpiles,diversion dikes, and overburdenpiles had a largerpotential for hydraulicdisturbance on smallrivers than those onmedium and largerivers. Thislarger potential exists because the flow obstructions would have to be placedcloser to the active channel due tothe typically smaller floodplain width.There were no significant hydraulic impacts observed due toflow

I14 obstructions,but the potential exists for bedscour at the base of the obstruction,erosion of the obstruction, and ice jamming atthe obstruction. Erosionof a dikeat Skeetercake Creek increased siltation as discussed in thefollowing section.

SEDIMENTATION

Sedimentationincludes the processes of erosion, transportation, and depositionof sediment. These are complex processes related to sediment andwater flow properties. Attempts to quantify: these processes provide, atbest, estimates of the quantity. A verybrief discussion of sediment sizedistribution, channel erosion, andsediment transport are given in thefollowing section. Changes to thesesedimentation characteristics due togravel removal are then briefly discussed.

UndisturbedCondition

SedimentSize Distribution. An importantfactor influencing most sedi- mentationproblems is thesire distribution of the sediments. The typical descriptors of thesize distribution of sediment are themedian diameter and graduationcoefficient of the material. Natural sediment distribution tends to belog-normal, which is a twoparameter distribution. Themedian diameter of a distribution has 50 percentof the material smaller by weight and 50 percentof the material larger. by weight. The secondparameter, the gradationcoefficient, gives the slope of the straight line resulting from plot- tingthe distribution on log-probabilitypaper. It is defined as

where u is thegradation coefficient and D is theparticle diameter for X which x percent of thematerial is finer. The gradationcoefficient is relatedto the standard deviation of the material. The materialcan be describedas uniform if its gradationis less than 1.3 orgraded if its gradationis greater than 1.3.

I15 The mediansediment size in the floodplain generally decreases in thedownstream direction along a river. Thus, themedian size may becobbles inthe headwaters and finegravel near the mouth.However, themedian size cansignificantly vary around this general average within a smallarea at a specifiedpoint along the river. This variation is a consequence of thevariation in hydraulic forces from one pointin the floodplain to another.

ChannelErosion. Channel erosion in rivers is generallyconsidered to beeither local erosion (scour) or degradation. Both result from an increasein the sediment transport capacity, or a decreasein the sedimentload entering the area, or both.

Localscour is most commonly a resultof local increasesin velocity due to flowobstructions or contractions. The increasedvelocity increases sedimenttransport capacity. Degradation can result if the channelbed is steepenedin a shortreach by, for example, a meander cutoff. The sediment transportcapacity would be increased through this reach causing erosion and a generalupstream progression of the steepened slope (Figure 35).

Upstmm Progl.ggsion of Steepened Slope

Figure 35, Schematicdiagrwn showing degradation process.

The progressiveerosion continues upstream until equilibrium is reached.In theory,equilibrium is reached when the slope is equal tothe slope prior to theoccurrence bf the cutoff, which would require the steepened slope to migrateto the headwaters. In practice, the steepened slope is reduced

I 16 during its upstreammigration and graduallyreaches an equilibrium condition. However, thedegradation may extendover a longreach before equili- briumis achieved.

SedimentTransport. Sediment transport is the movement ofsediments past a specificcross section of a river. The sediment may betransported assuspended load or bedload. Suspended load is sedimentthat is trans- portedlong distances suspended in the water column. Bed loadis sediment thatis transported by saltation (bouncing), or by rollingor sliding along theriver bed. The sedimentsize distinction betweenbed load andsuspended loadvaries with variations in discharge. At low flows, assumingthe sedi- mentswere available, silts and clays may betransported in suspension andsands and gravelstransported as bedload. During floods, suspended load may includeclays, silts, sands,and gravels,with cobbles and boulders transported as bedload. Often, the suspended load is assumed toinclude clays, silts, andsands and thebed load includes gravels, cobbles, and bou I ders.

Changes Due toGravel Removal

Very little sedimentdata were collected at the study sites. Direct measurementsor observations of bed or suspendedtransport were not made because site visits werescheduled during periods of low flow when thesites wouldbe most workable. Because the sedimentation characteristics prior to gravelremoval were also unknown, theupstream cross section was usually usedas the undisturbed cross section. The effects of gravelremoval were evaluatedby comparing sedimentation features in the gravel removal area to thosein the undisturbed upstream area.

At sixsites, a decrease inthe median sizeof the surface layer, or armor layer, was observed in themined area as compared withthe undis- turbedarea. Similarly, an increase or decrease was observedin the median diameterof1 the material underlying the armor layerat eight sites. In many cases it was difficultto evaluate whether the variationin mediandiameter was a resultof the gravel removal operation or simply a resultof the

I17 naturalvariation of the mediandiameter at a site.Degradation was also observed at a few sitesalthough at other sites only causative evidence was availableto indicate that this process can occur. Sediment transport changeswere suggested atseveral sites where there were observations of bedformsin or downstream from the gravel removal area, observations of changes inthe bed materialsize, computations of changes in shear stress, or observationsof sediment sources which remained from the gravel removal operation. The effectsof gravel removal activity on these sedimentation characteristicswere evaluated and givenquantitative ratings for com- parativepurposes (Table 8).

SedimentSize Distribution. The most common significant change in "...... sedimentsize distribution resulting from gravelremoval was a decrease inthe size causedby finematerial depos itionin the material site. This change was reflectedin the surface mater ialat six sites and thesubsurface materialat six sites. OregonCreek, Penny River, and UgnuravikRiver had significant changes inboth surface and subsurfacematerial sizes. At Sinuk River,fine andmedium sizedgravels were nearly missing from the subsurface samples inthe material site, causing an increasein the mediansize. The explanationfor this is unknown. At WashingtonCreek, the subsurface ma- terialsire was largerin the material site eventhough finematerial depositionin the site reduced the median sizeof the armor layer.

A patternof correlation was notevident between increases or decreases in armor layermedian diameter resulting from gravel removal and physical site or gravelremoval area characteristics. One reasonfor this lack of correlation is that armor layerdevelopment is a complexfunction of several interrelatedfactors including degree of development of undisturbedarmor layer,flooding history since gravel was removed, and flowcharacteristics inthe gravel removal area. If the undisturbed size distribution of the armor layer was notsignificantly different from that of the material underlying it, therelative changedue togravel removal would have been less and thetime required for recovery to the undisturbed condition would also be less. The timefor recovery is also a functionof the floods during the recoveryperiod; one large recurrence interval flood may be sufficientto

I 18 Grave I Armor Subsur face removalcoat material Channe 1 Bed Suspenied a a River area size sizedegrada t i onb I oad I oad

Go1 d Run Creek 4 6 8 a SinukRiver 4 5 3 6 - - - - WashingtonCreek 2 io 3 3 3 5 5 5 OregonCreek 2 5 3 8 - 5 4 5 Penny River 2 5 3 8 Nome River 2 5 4 4 - UgnuravikRiver 2 5 5 8 rg Aufei s Creek A 6 5 5 5 B - 5 5 5 KuparukRiver 4 5 a 6 SkeetercakeCreek 5 5 9 a Sagavan i r ktok River 7 5 5 5 Iv i shak River 6 5 5 6 ShaviovikRiver 7 5 8 5 Kav ik River 7 5 IO 3 DietrichRiver-Upstream 5 9 5 5 Dietrich River-Dcwnstream 5 8 4 3 Middle Fork KoyukukRiver-Upstream A 5 5 5 5 8 I 6 9 5 Midd I e Fork Koyukuk River-Downstream 5 5 4 3 Jim River - 5 5 6 ProspectCreek 3 5 5 5 West ForkTolovana River - 5 5 5 McManus Creek 4 8 5 5 TananaRiver-Downstream - 5 5 5 TananaRiver-Upstream - - 5 5 5 Phe I an Creek 7 5 6 5 5

(Footnotes on following page) fable 8. Footnotes '$adiment site distribution ratings: Median sirein the ravel removal area DR Median size upstre: from thegravel removal area

IO 10 C, DR ldue to gravelremoval activityl 5 D 10 Iduotogravel removal activity) 9 2 R. 8 1.2 5 P < 2 ldueto gravel rmval activityl R 7 1.25 OR (cause uncertain1 6 I 5 OR < 1.2 5 DR I 4 0.E < DR 5 I 3 0 c 0.8 (cause uncertain) R- 2 0.5 C DRC 0.8 (dueto gravel removal activityl I 0.2 < D < 0.5 ldueto gravel removal activityl R- 0 DRC0.2 ldue to gravel remvu1 activtty

'Channel degradationratings:

IO Verysubstantial deyadation upsfreom of the disturbed area 9 Substantialdegradation upstream of thedisturbed area B Large amunt of degradationupstream of thedisturbed srea 7 A noticeableMount of degradationupstrqm of thedisturbed area, but notunlike degradation wh-ich could occur naturally 6 Slightdegradation upstream of disturbed araa &servedor implied; may notbe a result of gravelremoval 5 No degradationobserved or implied by ttrh dots 0-4 Notused

'Sed load ratings:

IO Substantiulincrease in bed load byerosion in tho g%vel remval area 9 Large increaseIn bed load by eroslcnin the gravel removal area 8 Increase IR bedload by erorrlon inthe gravel removal ares 7 Bedload Increase due togravel remoral activityexpected but not verified by eirect evidence 6 Slightbee load increase potentially due to gruvol removal activity 5 Ma bedload change svldent 4 Slight bed load decrease by Ceporitlon ln the gravel rmval area J Moderatobed load decrease by deposition in thegrwml removal area 0-2 Not used' dSurpende4 1 old rati ngs :

9-10 Nnt used 8 Largetemporary andlor moderate long term fncroade In suspended I oad 7 Tlmporory incruase In suspendedload as a result of disturbance of armorcoat 6 Potentialslight increase in suspendedload resulting from gravel rmvolactivity 5 KO apparentchange in suspevCed lucd 4 Potentlslslight drcrease In suspendedload resulting from depcjsition 3 Moderate amount of deposition of suspended matwial 0-2 hot used

I 20 develop anarmor layercomparable to that in the undisturbed area. The developmentof anarmor layerin the gravel removal area is alsogreatly dependenton the location of the area relative to theactive channel and the resultingflow characteristics through the site. The location and extent of gravelremoval may besuch that anarmor layer may notdevelop until thearea fills in sufficiently to haveappropriate hydraulic character- isticsfor armorlayer development.

ChannelErosion; Channel erosion in the form of local scour was not observedat any ofthe study sites. The potentialexists for localscour to develop as a result of flowobstructions in the form of materialstockpiles, overburdenpiles, and diversiondikes. This potential was discussedin the previoussection discussing hydraulics.

Channel degradation was observedat four sites and may havebeen devel- opingat three other sites. At Washingtonand McManus Creeks,obvious degradation hadoccurred upstream from the site in the main channel. At thetwo DietrichRiver sites, degradation was occurringin high-water channels; at thedownstream site, one of the high-water channels developed into an active sidechannel after work completion. Channel degradation resulting from gravelremoval activity has been documented elsewhere (Woodward-Clyde Consultants 1976b, Li andSimons 1979). Li andSimons (1979)suggest that theinstallation of check dams can restrictupstream degradation. Sheridan (1976) discussesin-channel gravel removal, noting that the pits filled in withsediment; a similarsituation occurred on Sinuk River with noapparent degrada t i on.

SedimentTransport. Changes in sedimenttransport due togravel removal were difficultto evaluate. The ratingsgiven in Table 8 arethus highly subjective. A few possiblechanges which were suggested by the sedimentary featuresin andaround the material sites are discussed below. It is likely that most scrapedsites exhibited anincrease in suspended load during the firstflood event and possiblyduring one or twosubsequent events as the materialin the gravel removal area was washed cleanof the fine grain sites.This increase was thuslikely a temporaryincrease common atmost scrapedsites. Long-term increases in suspendedload were implied at sites withdisturbed areas which contributed fine materials to the flow. Examples ofsuch long-term increases were the access road degradation at Ugnuravik River(Figure 361, thediversion dam atSkeetercake Creek (Figure 37), and severalsites with overburden piles or berms containingfine-grained materials.Similar increases in suspended load could occur from accelerated bank erosionat the site. Deposition of f ine-grainedsediments in several of thegravel removal areas was also observed,Sites with changes in suspended load showed no patternwith the physical site or gravelremoval area characteristics.

Apparentchanges in bedload were observed at some sitesin the form of graveldunes or loose gravel deposits in anddownstream from the gravel removalarea. When thesedeposits occur in the gravel removal area, they couldindicate the inability of the flow through the area to carry the sedimentload delivered to it orgenerated within it. Depositionoccurring downstreamfrom the gravel removal area would imply that the flow through thearea is sufficientto erode the loose gravel from the gravel removal area. It is possiblethat when thesegravels reach the main channel they are transportedin the form of another bed form or possibly in suspension. Bed loadchanges occurred most often at scraped sites in active and high-water channels, and inlocations immediately adjacent to such channels.

ICE CHARACTERISTICS

UndisturbedCondition

Icejamming can occur during breakup when icefloes moving down the riverare blocked, thereby blocking subsequent ice floes and eventually creating a surface dam tothe flow of ice. Ice jamscan cause scour due to increasedvelocity beneath the ice dam; theycan also causethe water level to rise,resulting in increased flooding. Ice jamsare normally caused by a constrictionin the channel width or depth, a reductionin flow velocity, or manmade structuresin the floodplain.

I22 Figure 36. Upstreamview of thermal and fluvialerosion in theaccess road at Ugnuravik River, acting as a long-term sedimentsource to the river.

Figure 37. Viewof erosion of a diversion dam whichacts as a long-termsediment source to SkeetercakeCreek. Dunes in foregroundare atypical of theundisturbed river.

I23 Aufeisis defined as areasof ice which have developed by asequence of eventsof overflowing water on top of the previous ice surface. The general mechanism forthe growth of aufeis involves an increasein the hydrostatic pressure due to a reducedflow area; when thepressure exceeds the elevation ofthe ice surface, overflow onto this surface results and subsequently freezes. The overflowcauses the pressure to decrease and cesurface ele- vationto increase. This sequence continues to repeat unti thesource water cannotproduce sufficient pressure to exceedthe elevation ofthe ice surface.Three requirements for the formation of aufeis are g i venby Carey (1973); (1) significantground water or under-ice flow, (2) growthof ice to thechannel bed or near the bed,and (3) subsurfaceconstriction such as bedrock,less pervious soil, or permafrost.

Changes Due to Gravel Removal

An organizedprogram of winter and springobservations of aufeis and breakupwere not included in this study. Therefore, much ofthe following discussionis based on observations of aufeis and icejamming potential, ratherthan of actualaufeis and ice jams.However, at two sites,Washington Creek (Figure 38) andOregon Creek, largeareas of aufeis were observed in early June, Incidentalwinter observations at a few othersites documented theexistence of aufeis.

Ice jams couldbe caused by several aspects of floodplain gravel removal.In rivers which are increased in width and depthby the gravel removal,such as byin-channel mining, the velocity would decrease causing the icefloes to gather. At thedownstream end of the gravel removal area these floescould jam where the channels constrict back to the natural width, This icejam could cause flooding in andupstream from the gravel removal area and possible bedscour beneath the ice jam. Riverchannels which are widened causingshallower depths, such as byremoving bars adjacent to the channel, couldcause ice jamming by grounding the ice floes. Another potential mechanism forice jam formation resulting from a gravelremoval operation is the blockingof ice floes by flowobstructions in the form of overburden piles, stockpi les, or dikes.

I24 Figure 38. Largearea of aufeis at the upper gravel removal areaat Washington Creek as it appeared inearly June.

Inevaluating the potential for aufeis development - at each of the studysites, it was assumed thatwide, shallow channels were more likely to developaufeis t han narrow, deep channels.This assumption isprobably valid because shal low channelsare more likely to freeze to their bed and to have a shallowtalik (unfrozenzone) than deep channelscarrying equivalent flow. The results of t hisevaluation of aufeispotential .are listed in Table 9, alongwith the identification of those rivers with aufeis activity or po- p tential,aufeis -activity prior to the gravel removal operation.

Mostof the observations of increases or potentialincreases in aufeis activity wereassociated with mining activities in straight and sinuous rivers,although some activitiesin braided, split, and meandering rivers also causedpotential increases. Increases in aufeis activity were associatedwith scraping operations. Increased aufeis -activity or potentialaufeis activityoften occurred at those sites where the gravel removal operation was locatedin active or high-water channels and inlocations imnediately fable 9. QuantificationRatings of Change inAufeis Potential that Resulted frm theGravel Removal Operation at Each of the 25 Sites

Grave I remova I Aufeis River area potential'

Gold Run Creek 6 SinukRiver 5 6 WashingtonCreak IO 6 Oregon Cr eok io 5 Penny R i ver 6 Horne River 6 Ugnurav ik R ivcr Aufeis Creek A B Kupar uk River SkeetercakeCreek 5 SagavanirktokRiver lvishskRiver ShaviovikRiver KavikRiver DietrichRiver-Upstream Dietrich River-Downstreem MiddleFork Koyukuk River-Upstream A B MiddleFork Koyukuk River-Downstream Jim River ProspectCreek westFork Tolovana River McManus Creek Tsnana River-Downstream tanana River-Upstrom Phel an Craek

'Aufeis- potential ratings:

10 Large aufeis developmentobserved inthe disturbed area whmra no aufeis was przly rocorded 9 Moderate sized aufeis developmentobserved in thedisturbed area where no aufeis was pmsly recorded 8 Smameis developmentobserved or a strongpotential for aufeis Occur- rence isfntarred 7 Relocation of an exiltfngaufeis area by gravel I-smOVal activity 6 Potentialincrease in aufeisivity resulting from gravelr6mVal activitv 5 No change in aufeis chwacttristlcs 0-4 NotUled bRiverswith a highpotential for icingactivity prior to the gravel r.moval aperatlon.

126 adjacentto the channels. Such locations, when excavatedfor gravel, tend to increasechannel width, decrease depth, and allowfor freezing down tothe channelbed.

As notedearlier, large areas of aufeis were observed in the Washington Creekand Oregon Creek study sites.Both of these sites had been extensively scrapedand that caused numerous channelsto form and loss ofsurface flow tointergravel flow because of looselycompacted gravels. The aufeis may be retardingthe recovery of the surface flow by protectingthe loose gravels fromthe flood flows during the snowmelt runoff period. At bothsites, the channelsflowing during the survey were not flowing where the channel had previously been; it is thuslikely that the talik was not as deep beneath thenewly formed channels, thereby providing the aufeis requirement of a subsurfaceconstriction. The shallowchannels would likely freeze to the bed, therebysatisfying another requirement for aufeis formation. The third requirement, a watersource, was alreadyavailable. Thus, atthese two sitesthe gravel removal operation changed the channel location and cross sectionsufficiently to provide two ofthe three requirements for aufeis format i on.

HYDROLOGY

Hydrologyis the study of the origin, distribution, and properties ofwater during the time it is ator near the earth's surface. Of concern inthis sect'ion is thedistribution of the water. More specifically, this sectiondiscusses briefly the quantity of water that can be expected at the 25 materialsites during low flowand flood flow conditions andpoten- tialeffects onthe quantity due tothe removal of gravel.

UndisturbedCondition

The mean annualflow of a riverat a specificpoint is, as the term implies,,the mean flowduring any 12 monthperiod. It is an indication oftotal annual runoff and may alsobe used as an approximationof the typical low summer flow.Estimates of mean annualflow for the 25 study

I27 3 sitesare listed in Table IO. They rangefrom 0.09 rn /s at McManus Creek to 540 m3 /5 at TananaRiver-Downstream.

Floodfrequency curves show theexpected frequency of occurrence.of differentmagnitude floods at a specificpoint on a river. The frequencyof occurrence is commonly referredto by therecurrence interval of the flood, which isthe average number ofyears between floods of that magnitude. The reciprocalof the recurrence interval is the probability of occurrence of a givenmagnitude flood in any year.Flood frequency curves were developed for eachof the study sites. Discharge values corresponding to selected fre- quenciesof occurrence are shown inTable 11.

Changes Due toGravel Mining

Hydrologiccharacteristics are, to a largeextent, governed by basin- wideparameters such as climate andgeology. Gravel removal operations did nothave a significanteffect on these characteristics. However, local changes in the ratio betweensurface flow and subsurfaceflow occurred at severalsites, The localchanges were not measured; quantitativeratings shown inTable 12 wereassigned based on a subjectiveevaluation. A local reductionin mean annualflow occurred at the upper Washington Creek and upperAufeis Creek sites as a resultof a loss ofsurface flow to intergravelflow. At WashingtonCreek, the flow entered the gravel removal area andspread out through loose, uncompacted gravel; a largepercentage reductionin surface flow resulted at low flows.This intergravel flow component was still evidentin the site 13 yearsafter the site was worked. The rela- tiveeffect of the loss ofsurface flow during flood events was likely minimal. At Aufeis Creek,surface flow appeared to ceaseentirely for a period of 2 years,although continuous surveillance was notavailable to verifythis. Thus, the mean annual flow ofAufeis Creek inthis local region was reducedto near zero for 2 years. The effect on floodflows wasunknown.

Two othersites, the upper Oregon Creek andPenny Riversites, had a potentialfor a similar,but not as extensive,decrease of surface flow lostto intergravel flow. No observationsor measurementswere available

I20 Table 10. Mean AnnualFlow Estimates at Each of the 25 StudySites

Un i t mean annual f low Mean annual flow 3 2 3 River (rn /s/km 1 (m 1s)

Gold Run Creek 0.013 0.9 SinukRiver 0.033 18.0 WashingtonCreek 0.018 0.5 OregonCreek 0.023 0.7 Penny River 0.023 I .4 Nome River 0.033 4.3 Ugnur av i k R i ver 0.0023 0.6 Aufeis Creek 0.0044 1. I Kupar uk R i ver 0.0045 38 SkeetercakeCreek 0.0035 0.3 SagavanirktokRiver 0.0083 39 lvishakRiver 0.0066 24 ShaviovikRiver 0.0040 I .6 KavikRiver 0.0062 5.5 DietrichRiver-Upstream 0.006 3. I Dietrich River-Downstream 0.006 4.0 MiddleFork KoyukukRiver-Upstream 0.0054 I3 MiddleFork KoyukukRiver-Downstream 0.0054 22 Jim River 0.010 7. I Prospect Creek 0.010 2.6 West ForkTolovana River 0.0062 4.7 McManusCree,k 0.0062 0.09 Tanana River-Downstream 0.012 539 Tanana River-Upstream 0.012 468 Phe I an Creek 0.063 5.2

I29 3 Table II. CalculatedDischarges in m /s Correspondingto Selected RecurrenceIntervals for Each of the 25 Study Sites

Recurrenceinterval 4 years 1 R i ver I .255 2 IO 25 50 IO0

Gold Run Creek 11.2 19.2 32.1 42.8 53.6 70.2 91.0 SinukRiver I13 171 256 323 391 48 I 589 Wash i ng ton Creek 2.58 5.63 10.7 16.6 28. I 39.5 54.9 OregonCreek 6.21 11.1 19.4 26.3 33.5 44.8 59.3 Penny River 18.2 23.7 31.7 37.0 43.7 50.2 57.0 Nome River 32.4 53.3 86.3 I14 I 42 182 232 Ugnur av i k R i ver 31.4 46. I 71.5 92.1 121 I49 I 80 AufeisCreek 39.2 56.8 89.3 I16 I 60 196 235 Kupar uk R i ver 905 I355 2165 284839064840 591 2 SkeetercakeCreek 10.6 16.7 28.4 54.638.4 69.8 87.0 SagavanirktokRiver 376 462 592 665 785 970 863 lvishakRiver 26 7 333 432 489 579 641 7 26 ShaviovikRiver 35.8 59.6 98. I I 30 164 212 272 KavikRiver I 08 171 27 I 353 444 559 701 DietrichRiver-Upstream 35.6 58.6 I02 140 I95 322 253 Dietrich River-Downstream 46.9 75.9 131 178 247 402 318 MiddleFork Koyukuk R-US I 26 I89 302 396 534 661 808 MiddleFork Koyukuk R-DS I 90 276 428 552 736 896 1079 Jim River 101 I25 I56 178 204 251 228 ProspectCreek 33.3 43.6 57.6 67.3 78.5 90.4 102 West ForkTolovana River 63.9 89.2 I 30 159 203 282 242 McManus Creek I .65 3.32 7.48 12.0 20.6 29.8 42. I TananaRiver-Downstream I562 I752 1992 2120 2356 2460 2619 TananaRiver-Upstream 1341 1518 I738 1857 2069 2169 23 I8 Phe I an Creek 49.3 65.3 92.8 I14 146 171 I97

I 30 Table 12. QuantificationRatings of Change inQuantity of IntergravelFlow Resulting from the Gravel Removal Operationat Each ofthe 25 Sites

a River GraveRiver I removalntergravel Iflow area

Go1 dRun Creek 5 SinukRiver 5 5 WashingtonCreek 9 5 OregonCreek 7 5 Penny R i ver 7 Nome River 5 Ugnurav i k River 5 Auf e i s Creek A IO B 5 KuparukRiver 5 SkeetercakeCreek 5 SagavanirktokRiver 5 lvishakRiver 5 ShaviovikRiver 5 KavikRiver 5 DietrichRiver-Upstream 3 Dietrich River-Downstream 5 MiddleFork KoyukukRiver-Upstream A 5 B 5 MiddleFork KoyukukRiver-Downstream 5 Jim River 5 ProspectCreek 5 West ForkTolovana River 5 McManus Creek 5 Tanana River-Downstream 4 TananaRiver-Upstream 4 Phe I an Creek 5 a lntergravelflow ratings:

IO All surfaceflow converted to intergravel flow for one summer or more 9 Substantiallong-term loss of surface flow to intergravel flow 8 Moderatelong-term loss of surface flow to intergravel flow 7 Impliedlong-term loss ofsurface flow to intergravel flow 6 Small quantitiesof surface flow lost to intergravel flow 5 No apparentchange 4 Impliedincrease of surface flow and decrease of intergravel flow 3 Known increaseof surface flow and decrease of intergravel flow 0-2 Not Used

131 toestimate the magnitude of the decrease. The location of thegravel removalarea may provide an explanationfor the significant intergravel flow at WashingtonCreek and AufeisCreek. At thesetwo sites the scraping occur- rednear the downstream end of a sharp meanderbend (Figure 39). It appeared thatthe scraping in this location caused most of the flow to leave the confinementof the channel. The lackof a welldefined channel caused the flow to spreadover the gravels in the material site and depositthe sediment load that it was carrying,These deposits were quite loose and unstable, and thuswere very conducive,to intergravel flow. Other sites having a similarspecific location of scraping were slightly different in configur- ationfrom that shown inFigure 39; eitherthe bendupstream from the scrapedarea at these sites was notas sharp or thescraping occurred further downstreamon the bend, thusallowing some ofthe flow and likely much ofthe bed load to be retained in the original channel.

Threepossible explanations for the continued loss ofsurface flow at WashingtonCreek are (1) thatthe suspendedload is notsufficient to fill theopenings in the gravel, (2) thepresence of aufeis in the site protectsthe gravels from the significant snowmeltfloods, and (3) water freezesin the gravel, expanding and separatingthe gravels in the process.

Pit sites,such as Dietrich River-Upstream and the twoTanana River . sites, had a potentialto locally increase the mean annualflow as a result ofintercepting intergravel flow and allowing it tosurface at the pit. However, thepercentage increase in the mean annualflow at these sites is probablyquite small.

I32 Figure 39. Aerialphotographs of Washington Creek, (tap) and AufeisCreek (bottom)showing material site locations andapproximate channel locations beforethe disturbance. SUMMARYAND CONCLUSIONS

Variousphysical characteristics of arctic and subarcticrivers were affected bygravel removal operations. These characteristicswere divided intofive categories:

I. Channel co,nf iguration and process, 2. Hydrau I ics, 3. Sedimentation, 4. Icecharacteristics, and 5. Hydrology.

One or more characteristicsfrom these categories were observed to have changedas a result of removinggravel from the 25 floodplainstudy sites.

CHANNELCONFIGURATION AND PROCESS

Channel configuration and processcharacteristics that changed as a resultof gravel removal operations included braiding characteristics, suchas increase in the number ofchannels and decrease inlateral stability of thechannels, and the potential for diversion of flowthrough the gravelremoval area. The greatestchanges in braiding characteristics occurredat 10 studysites and resultedfrom gravel removal operations thatdisturbed the bars adjacent to active channels or that diverted flow throughthe material site. Flow diversionthrough the mined site resulted fromhaving insufficient buffers or no buffersat all. Gravel removal operationscaused flow diversion or a highpotential for flow diversion at 12 ofthe 25 studysites.

I34 HYDRAULICS

Hydrauliccharacteristics exhibiting changes as a resultof gravel removaloperations included the hydraulic geometry (including width, depth, velocity, andconveyance), overall channel slope, local slope redistribution,flow obstructions, and areaof ponded water. Increases in channel width,conveyance, overall slope, flow obstructions, andponded water weretypical responses to gravel removal, as weredecreases in channel depth and velocity. One or more ofthese effects from gravel removal were observedat all ofthe sites except those pit excavatedsites that were separatedfrom the active channels by a buffer.Small river systems typically hadsmaller floodplains which forced the gravel removal operation closerto active or high-water channels, causing hydraulic changes.

SEDIMENTATION

Sedimentationcharacteristics which appeared to have changed as a result of gravelremoval operations included armor layer and subsurface materialsite distributions, channel degradation, andsuspended and bed loads. The most common significant change insediment size distribution resultingfrom gravel removal was a decreasein the size caused by fine materialdeposition in the material site. This change was reflectedin thesurface material at six sites and thesubsurface material at six sites, three of whichwere different from those with surface material changes. Channel degradation was observedat four sites and may havebeen develop- ingat three other sites. Changes in sedimenttransport due togravel removalapparently took the form of increasesas well as decreases,with apparentchanges occurring at II sites. Mostchanges inthe sediment characteristicsresulting from gravel removal operations occurred at scraped sitesin or immediately adjacent to active andhigh-water channels and atthose sites where fine sediment sources were left in the floodplain nearthe channel ,

I35 ICE CHARACTERISTICS

Two icecharacteristics were identified as potentially being increased as a resultof gravel removal activity. They areice jamming and aufeis formation. Thesecan be affectedby a wideningof the channel followed by a rapidreduction in width, a reductionin depth, obstructions in the floodplain, and relocatingthe channel through an areawhich was previously dry.Aufeis formation was observedat four study sites.

HYDROLOGY

The onlycharacteristic related to the hydrology of theriver which was identified as potentiallychanging as a resultof gravel removal operations was a changefrom surface flow to groundwater flow or vice versa. Thischange, although relatively minor at most sites, can have a local effecton the mean annualflow, flow duration curve, and potentially, onthe flood frequency curve. Significant reduction of surface flow occurredat twostudy sites.

RECOMMENDATIONS

Listedbelow are several recommendations concerning gravel removal operations,the purpose of which is toreduce the number ormagnitude of changes tothe physical characteristics of rivers:

I. Small riversshould not be considered as gravel sources.

2. Braidedrivers should beconsidered as primary gravel sources; otherriver configurations, listed in order or likelihood of caus- ingthe least physical change,are split, meandering,sinuous, and straight.

3. Pit excavationsshould be located on terraces or possibly inactive floodplains and shouldbe separated from the active floodplain by a bufferdesigned to maintain this separation for two or more decades.

I36 4. Materialsites within the active floodplain should:

e Not disturbthe edge ofthe active channells);

e Malntain a high-waterchannel shape, withinthe material site, similarto that which enters and leavesthe site;

Notincrease the bed slope of active or high-water channels locally to morethan that of naturallyoccurring slopes;

Form new high-waterchannels through the site if flow is expected throughthe site;

Be shapedand contoured toprovide proper drainage;

0 Have materialstockpiles, overburden piles, and dikes removed from nearactive channels unless they have a specificpurpose for beingthere and aredesigned to withstand the hydraulic forces; and

0 Be protectedfrom low flow channels until the occurrence of the first flood afterthe site is completed.

I37 REFERENCES

Carey, K. L. 1973. IcingsDeveloped from Surface Water and Groundwater. U.S. Army ColdRegions Research and Engineering Laboratory. Mono- graph I I I-D3.71 pp.

Chow, V. T. 1959.Open-Channel Hydraulics.McGraw-Hill BookCompany, New York , 680 pp.

Doyle, P. F., and J. M. Childers. 1976. ChannelErosion Surveys Along TAPS Route,Alaska, 1976. U.S. GeologicalSurvey Open-File Report. 89 PP.

Emmett, W.W. 1972. The Hydraulic Geometry of Some AlaskanStreams South of the Yukon River. U.S. GeologicalSurvey Open-File Report. Anchorage.July. 102 pp.

Emmett, W. W. 1975. The Channelsand Waters of the Upper Salmon River Area,Idaho. U.S. GeologicalSurvey Professional Paper 870-A. 116 pp,

Karaki, S., K. Mahmood, E. V. Richardson, D. B. Simons,and M. A. Stevens. 1974. Highways inthe River Environment - Hydraulic and EnvironmentalDesign Considerations. Prepared for Federal Highway Administration by CivilEngineering Department. Colorado State University.Fort Collins, Colorado. 453 pp.

Lamke, R. D. 1979. FloodCharacteristics of AlaskanStreams. U.S.Geo- logicalSurvey Water Resources Investigations 78-129. 61 pp.

Leopold, L. B., M. G. Wolman, and J. P. Miller. 1964. FluvialProcesses in Geomorphology. W. H. Freemanand Company,San Francisco,Cali- fornia. 522 pp.

Li, R. M., and D. 8. Simons. 1979. Mathematicalmodeling of erosion and sedimentationassociated with instream gravel mining, pp, 420-429. InConservation and Utilization of Waterand Energy Resources. ASCE Hydraulics/Energy Division Conference. San Francisco. 8-11 August.

Rundquist,L. A. 1975, A Classification and Analysis of NaturalRivers. Disser'tation.Colorado State University. Fort Collins, Colorado. 377pp.

Sheridan, W. L. 1976. Effects of Gravel Removal on a SalmonSpawning Stream. U.S. Department of Agriculture.Forest Service. 26 pp.

I 38 Woodward-Clyde Consultants.1976a. Preliminary Report - Gravel Removal Studiesin Selected Arctic and Sub-arcticStreams in Alaska. U.S. Fish and WildlifeService. FWS/OBS 76/21. Wash. D. C. 127pp.

Woodward-Clyde Consultants. 1976b. AggregateExtraction Management Study,County of Yolo California.Prepared for the County of Yolo. PlanningDepartment. Aggregate Resources Management Committee. 128 pp.

I 39 EFFECTS OF GRAVEL REMOVAL ON AQUATIC BIOTA L. L. Moulton

INTRODUCTION

Populationsof organisms are controlled by physical and chemical factors,often termed their environment, andby biologicalfactors, including predation and competition.Environmental constraints on a particularspecies determinethe usable habitat available to that population andthe site of thepopulation is often restricted by the amount of usablehabitat. After the maximum number of individuals a particularhabitat cansupport (termed thecarrying capacity) has beenreached, the population cannot increase without an increasein usable habitat. Predation andcompetition can act on a populationto limit numbersbelow the carrying capacity, thus undisturbed populationsare not necessarily fully utilizing the available habitat.

Alterationsto the habitat can alter the quality of the habitat, leadingto direct changes inthe carrying capacity, and consequently,to reductionsin the affected populations. Decreases in habitat diversity may reduce thecarrying capacity for onespecies while leaving that for another un- changed. Ifthe twospecies were in competition, the reduction or removal of one may allowthe other species to increase, Generally, decreases in habitat diversity will resultin an increasedcarrying capacity of one species which isable to efficiently utilize the moreuniform habitat. Conversely, increasesin habitat diversity generally cause increases in the number of speciesor life history stages present as new habitattypes are added.These speciesincreases are often accompanied by decreases in the populations whichhad formerly been utilizing the moreuniform, less diverse, habitat.

141 The decreases may bedue either to ess availablehabitat or to competition fromspecies which more efficiently uti Iizethe newly created habitats.

The typesof habitats present na riverare determined by thelocation,size, configuration, and waterquality characteristics of the river. Featureswhich define specific habitats include depth, velocity, substrate, andcover. Alterations to a riverwhich affect any ofthese features will alsoaffect the habitat available in the river and may impacthabitats downstreamfrom the alterations. Habitat alterations may affectthe quality ordiversity of the habitat, or both.Reduced habi tatquality makes thearea lessdesirable to the species present prior to alt eration,while altered habitatdiversity may favorone species or I ife hi storystage over another. Reduced habitatquality implies alteration of a single habitat type whereas reducedhab i tatdiversity implies reduction in the number ofavailable habitats bu t thetwo responses are not independent.

Severa I typesof habitats may be used inthe life cycle or even sea- sona I cyc I e of an organism,and there is often a criticalhabitat which controlsthe size ofthe population. In the arct ic and subarcticenviron- ment, thecritica I habitatfor fish populations is often the amount of overw i n ter i ng hab itat.Other critical habitats often controlling fish populationsare spawn ing and rearingareas. Critical habitats vary from stream to streamand species to species depending on the characteristics of the streams and thelife cycle requirements of the species.

Recentstudies have been aimed at quantifying the effects of habitat alteration onstream populations (Stalnaker and Arnette 1976, Boveeand Cochnauer 1977, Binns andEiserman 1979)..Two of the basic requirements of theseefforts are detailed measurementsof appropriate habitat parameters andan intimateknowledge of thehabitat requirements of the species in question. The emphasisof the present study was on a multiple-disciplinary surveyof the effects of floodplain gravel removal on a broadgeographical scale.Because of thelimited data on many species andcomplete lack of data on many ofthe river systems studied, a detailedhabitat analysis was not possible. The 3 to 4 day surveysat each site allowed for gathering of basic

I42 physical and biologicaldata but not the type of detail required for sophis- ticatedcorrelation analysis. For these reasons the present analysis was confinedto analysis of trends and subjectiveevaluations of habitat alterations and theireffects onaquatic organisms.

The material sites were visited 2 to 20 years aftermining was complete,thus the immediate effects of gravelremoval operations were not studied. Thechanges evaluatedduring the present study were those which persistover a number ofyears rather than those affecting the biota during theyear of disturbance. A literaturereview of impacts at the time of actualgravel removal was presentedby Woodward-CIyde.ConsuItants (1976).

I43 METHODS OF DATA COLLECTION

A5 detailedin APPROACH AND METHODOLOGY a variety of standardsampling methods were utilized at eachstudy site with the specific methods used dependent-onthe type of river systemand habitatbeing studied.

I44 METHODS OF DATA ANALYSIS

The datafrom each of the 25 sites were firstanalyzed on a site- by-sitebasis to determine the effect of gravel removal operations on the aquaticenvironment at each study site. These individual site evaluations providedthe basis for further analysis to identify trends and correlations relatingto major site variables (Table I, MajorVariable Matrix). These individualsite evaluations are not included because of space limitations butare part of the permanent data base maintained by the U. 5. Fish and WildlifeService.

The variousphysical and biological parameters measured at thedif- ferentsites varied greatly in magnitude andthe variation made thodirect comparisonof data among sitesimpractical. The variousparameters recorded atthe study sites were standardized on a scaleof 0 to ,IO to obtain a relative measure ofthe degree of change. A rating of 5 indicatesthat a parametermeasured inthe mined area had not changed from the same parameter inthe upstream area; ratings of 0-4 and 6-10 indicatedecreased and in- creasedparameter values in the mined area relative to the upstream area. The rating was determinedby calculating the percentage change in the mined arearelative to the upstream area for each site and subjectively assigning ratingvalues to various percentage intervals such that all or most of the 0-10 scale was utilizedfor those sites at which the parameter was evaluated.Data from study sites with similar ratings were examined for similar alterationsthat might lead to a simi larparameter response.

The analysisof habitat alteratioh was basedon fieldnotes from the site surveys,ground and aerial photographs, direct measurement ofhabitat parameters,results of hydraulicanalysis, and visualobservations. Habitat parametersconsidered in the analysis included changes in substrate type,

I45 substrateporosity, configuration of adjoining banks,bank and instream cover, number ofchannels, pool-riffle frequency, depth, velocity, and wettedperimeters at different flow levels. Additional habitat alterations werenoted where appropriate, such as excessivesiltation, aufeis formation and creationof new aquatichabitats. Much ofthe analysis was subjective because many habitatparameters were difficult to quantify, consequently, theanalysis was keptconservative. The results of hydraulicanalysis, as describedin the EFFECTS OF GRAVELREMOVAL ON RIVER HYDROLOGY AND HYDRAULICS, allowedfor a certain amount ofhabitat parameter quantification andthese resu Itssupported the subjective evaluations whenevercomparisons wereavai lable, indicatingthat subjectivity was not a majorsource of error.

Analysisof changes in fish populations was accomplishedby evalu- atingthe types of habitatalterations occurring in the mined area relative tothe upstream area. Then the measuredparameters that appeared to be mostimportant at the particular site were examined to determine if there hadbeen a change infish distribution, as indicated by a differencein catchrate between the upstream and minedareas. In this manner thecombi- nationsof habitat alteration could be evaluated for their cumulative effect onthe population of fish present during the site visit. Additional effects werepostulated based on known lifehistory requirements of the various species.

The large number ofbenthic sample replicates obtained at eachstudy siteduring the field surveys allowed for an analysisof vari'ance to determine ifsignificant differences existed in the densities among sample areaswithin a studyreach. All Surbersample data were computer coded and thedensities were subjected to an analysisof variance and multiple classi- ficationanalysis (Nie et al. 1975). A nonparametericprocedure, the Mann- WhitneyU-test (Zar 19741, was also used toevaluate differences in density. The resultsof the two testswere comparedand, where theresults of the two testsdiffered, the more conservativenonparametric test was used.Addi- tional computeranalysis included the calculation of various indices of diversity and similarity,such as the Bray-Curtis and Raabe similarity

I 46 indices, and Shannon-Weaver andSimpson densityindices. The indicesrespond differently to changes indensity and diversity andwere used primarily to searchfor changes in the aquatic macroinvertebrate assemblages vulnerable to Surbersamplers.

Because thelevel of identification was tothe generic level at best and oftenonly to family or order, the indices were applicable only to the presentstudy. Comparison with results of otherstudies and extensiveanal- ysis of thedata are not justified. Often multiple species within a genus wererecognizable but the absence of suitabletaxonmic aids for arctic aquaticmacroinvertebrates inhibited identification. A listof collected taxonomicgroups by phyletic classification, with associated comn names, is includedin Appendix A.

I47 RESULTS AND DISCUSSION

MAJOR GRAVEL REMOVAL HABITAT ALTERATIONS

HabitatQuality

Alterationsof habitat quality observed at many of thesites consisted primarilyof substrate alteration andremoval of bothinstream andbank cover.Siltation, commonly associatedwith instream disturbances, was observed at a few sites,but was not a majorfactor because most of the sites werevisited several years after mining hadbeen completed. At threesites where siltation was observed it was causedby eroding berms (Kavik River) ormelting aufeis fields (Washington Creek,Oregon Creek) (Figure 40).

Two typesof substrate alteration were observed: (1) a shiftfrom a moderatelycompacted gravel substrate to a veryloose, unconsolidated sand- gravelsubstrate, usually with considerable intergravel flow and (2)a shiftfrom a smooth,paved substratewhich produced near laminar flow to a moreporous, irregular substrate producing turbulent flow. Most of the substratealterations recorded were Type I alterationswith only twoType 2 alterationsobserved. Type I alterationsoccurred at four of theeight sites wherescraping was conductedin an activechannel (Washington Creek, Oregon Creek, Penny River, McManus Creek)and atfour where flow subsequently increased or divertedto inundate a scrapedarea (Sinuk River, Kuparuk River,Sagavanirktok River, lvishak River) (Table If). The effectsof this typeof alteration appear to belong-term, because thisalteration was noticeableat McManus Creek 16 yearsafter mining. The effect on the substrate was caused by removal of the armor layer,loosening of the gravels, andsubsequent washing out of fine materials. Formation of ice in the mined areasappeared toprolong the recovery time of thistype of alteration.

I48 a) Sedimentbeing released by meltingaufeis.

b) Silt depositedin substrate downstream from aufeis field. - Figure 40. Siltationresulting fromextensive aufeis field at OregonCreek mined study area, 20 June 1977.

I49 Table 13. MajorHabitat Alterations Observed at Sites Mined by Scraping (5 = No Change, 6-10 = TrendTowards Parameter, 0-4 = Trend Away From Par arne t er 1

Seward Pen i nsu I a a Gold Run Creek -5 5 0 5 6 5 SinukRiver 75 0 - 6 9 8 WashingtonCreek IO 5 IO IO IO IO IO OregonCreek IO IO5 IO 9 9 8 Penny River 95 IO 8 9 IO IO Norne River -5 5 - IO 10 7

North S Iope Ugnurav i k R i ver 58 5 5 6 IO 8 Aufeis Creek -5 5 8 9 IO IO KuparukRiver 85 5 5 8 7 6 SkeetercakeCreek -5 9 0 5 8 IO SagavanirktokRiver 95 5 9 IO IO 6 lvishakRiver 65 5 5 8 6 5 ShaviovikRiver 53 5 5 6 6 5 KavikRiver -5 5 9 8 7 5

NorthernInterior DietrichRiver-Upstream 55 5 5 5 5 5 Dietrich River-Downstream 55 5 5 6 7 7 M.F. KoyukukRiver-US 55 IO 5 IO 9 9 M.F. KoyukukRiver-DS 55 5 5 8 IO 7

SouthernInterior McManus Creek 75 5 5 5 IO 5 Phe I an Creek 55 5 5 4 2 5 a Dash means parameternot evaluated at this site.

I 50 Type 2 substratealterations were documented at two locations,both on medium sizeNorth Slope rivers (Table 13). In onecase, Ugnuravik River, theupstream area showednear laminar flow that was changed toturbulent flowwhile in the other case,Shaviovik River, the reverse occurred - the upstreamflow was turbulentwhereas the flow through the mined area was laminar. Such changeswould be expected naturally where localized substrate orslope differences alter flow characterlstics.

Bank cover isprovided by structures on or features of the stream bank thatprovide shelter from surface predation and reducevisibility. Ex- amplesof bank cover include overhanging vegetation and incised or undercut banks,thus bank cover was eliminated when miningremoved these features (Figures 41 and 42). These typesof bankcover were typically present in straight,sinuous, meandering or split channel rivers, but were less common inbraided rivers, Significant bankcover loss was observedat 6 ofthe 21 scrapedsites, Sinuk River, Washington Creek, Oregon Cre'ek, andPenny River sites on the Seward Peninsula, at theSkeetercake Creek site on the North Slope,and atthe Middle Fork KoyukukRiver-Upstream inthe Northern In- terior(Table 13).

Instreamcover is createdby obstructions, such as bouldersor logs, thatprovide slack water where fish can hold position with minimal energy expenditure and reducepredation from ebove by being less visible. Water depthcan also function as cover,because deep pools and runsoffer more overheadprotection and oftenlower velocities than shallow riffles. Certain species,such as Arctic char and Arcticgrayling, are often associated with instreamcover. Instream cover was reducedat five sites, Washington Creek, OregonCreek, Penny River,Kavik River, and SagevanirktokRiver, as a result ofdirectly removing boulders and largecobbles or altering flow such that new channelsdid not possess this habitat (Figures 43 and 44). At sixsites, Gold Run Creek,Washington Creek, Oregon Creek, Aufeis Creek, Skeetercake Creek,and Sagavanirktok River, the channel configuration was altered so thatthe channel was wider and shallowerin the mined areas, thus the instreamcover provided by depth was reducedby lowering the ratio of pools to riffles,

151 'I a) Undercutvegetated bank typical of OregonCreek upstream studyarea.

b) OregonCreek mined study area - notice lack of bankcover, multiplechannels.

Figure 41. Removal of bank cover at Oregon Creek as observed on 24 June 1977.

I 52 a)Skeetercake Creek upstream study area - noteundercut vegetatedbank.

b) SkeetercakeCreek mined study area - bankcover absent, flow spread over wide, shallow area.

Figure 42. Removal of bank coverat Skeetercake Creek as observed on 18 June 1977.

I53 b) WashingtonCreek upper mined study area, note spread of flow,multiple channels, lack of surfacewater.

Figure 43. WashingtonCreek upstream and mined area on 9 September 1977 showingreduction of instreamcover due to 3 gravelremoval operation (flow level [O.II m /sec] = 20 percent of mean annual flow).Other habitat alterations include increasedbraiding, siltation, and intergravel flow.

I54 a) Sagavanirktok River upstream study area, note predominance of boulders.

b) Sagavanirktok River mined study area showing extensive sedimentation and backwaters.

Figure 44. Reduction of instream cover a5 provided by boul ers at Sagavanirktok River, 3 August 1978 (flow level, 60 m !l/sec, = 155% of estimated mean annual flow).

I55 HabitatDiversity

The resultof decreasing habitat diversity, that is, creating uniform habitats bygravel removal operations, was tofavor certain species or life historystages over others. One of themain indicators of reduced habitat diversity was increasedbraiding in the mined area caused where gravel depositswere scraped to below the water line or where flow subsequently increasedto inundate the mined area. Phis type of habitat alteration occurredat 10 studysites (Washington Creek, Oregon Creek, Penny River, Nome River,Aufeis Creek, Kuparuk River, Sagavanirktok River, lvishak River, KavikRiver, and MiddleFork Koyukuk River-Downstream) (Figures 43 and 45, Table 13). The channelsin a braidedarea usually have a uniformdepth, velocity, and substratewith minimal bankcover. The areaswere generally characterizedby increased wetted perimeter, reduction in channel depth, and reduced mean velocities(Figure 46). At WashingtonCreek (Figure 46a), for example,the cross section in the upper mined area (Cross Section 3) hadthe greatestwetted perimeter at all flowlevels, but most of this was inshal- low openchannels with little cover. Similarly, at OregonCreek (Figure 46b)the wetted perimeter at cross sections in the mined area (Cross Section 2 and 3) was considerablygreater than that in the upstream area and ap- proachedor exceeded that of the Cripple River cross sections, a river withgreater than three times the estimated mean annualflow of Oregon Creek.Again, the Oregon Creek mined area channels were wide and shallow, providing low quality andlow diversityhabitat. The final example, SagavanirktokRiver (Figure 46~1, showed a similarpattern with the mined areacross sections having a greaterwetted perimeter, but a shallowerdepth profilethan cross sections in undisturbed areas.

Habitatdiversity was increasedin some othermined areas by the creationof new habitats.Three types of new habitatswere usually found: (1) low velocitybackwater areas, (2) a sidechannel off the main river, and (3) a floodedpit forming a pond habitat(Figures 47 and 48). Low velocity backwaterareas were found at five sites (Sinuk River, Skeetercake Creek, SagavanirktokRiver, Dietrich River-Downstream, and MiddleFork Koyukuk River-Upstream);side channel formation occurred at three sites (Skeetercake

I56 a) 27 July 1973 - pre-mining b) 2 August 1976 - postmining

Figure 45. Increasedbraiding at Sagavanirktok River study site caused by miningmid-channel gravel bars and a vegetatedisland in the active channel (miningoperation conducted during the winter of 1974-1975).

I57 MAF = 0.53 m3/~ Cross Section 2 3 4 5 6 US UM BM LM DS 26% 88% 42% 53% 30% 22 12 26 26 28 19 18 10 14 15 7 10 11 l13 4 6 6 0.4 2 0.7

% OF MEANANNUAL FLOW a. Washington Creek

Cross Section 2 3 4 5 6 C- O-UM 0-LM Bridge GLM C-E 88% 64% 24% 29% 31 % 32 2924 21 28 4 Q19 16 24 0.215 15 15 15 11 2 8 2 0.4

o/o OF MEAN ANNUALFLOW b. Oregon Creek Cripple River - crossseetion 2 3 4 UM LM 06 23% 21% 21 % 21 19 19 18 17 17 11 14 14 10 11 11 6 10 7 3 6 5 1 2 3 0.2 0.4 2 1 1 3 02 0.07 KEY us Upsfreern UM Upparmlnsd BM Between Mlned LM Lower Mlned OS Downstream Oh MEANANNUAL FLOW 0 Oregon Creek c Crlppls Rlvqr c. Sagavanlrktok River 'MAF .MMn Annual Flow Figure 46. Reyponse of cross-sectionalwetted perimeters to percentage of mean annual flow and percentage of cro,sssections comprised of selected depthin4ervaIs at mean annual flow atthree gravel removal study sites.

I 58 a) Dietrich River-Downstream - inundatedmined study area.

b) Middle Fork Koyukuk River-Upstream - backwaterin lower minedarea.

Figure 47. Low velocitybackwaters formed by gravelremoval atDietrich River-Downstream (13 July 1978) and MiddleFork Koyukuk River-Upstream (18 July 19781, noteextensive silt depositionin both cases.

I S? Cut- off channel created by mining Original channel

a) SkeetercakeCreek showing cut-off channel, 4 September1975.

b)Jim River showing side channel created by mining in a high- waterchannel, 12 August 1978.

c) West ForkTolovana River pitcreated by deep excavatingin an abandonedchannel, 29 July 1978.

Figure 48. Creationof low velocityside channels and inundated pitfollowing gravel extraction.

I 60 Creek,Middle Fork KoyukukRiver-Upstream and Jim River); and flooded pits werecreated at seven sites (Penny River, Ugnuravik River, Dietrich River- Upstream,Prospect Creek, West ForkTolovana River, Tanana River-Downstream, andTanana River-Upstream),

The changes inhabitat diversity were determined by the location of mining and, to some extent,the type of mining. Braiding (decreasing habitat diversity)occurred where the majority of flow went through a minedarea, suchas where a meariderwas eliminated(two sites: Penny River,Middle Fork KoyukukRiver-Downstream), an inchannelisland or gravelbar was removed (fivesites: WashingtonCreek, Kuparuk River, Sagavanirktok River, lvishak River,Kavik River) or where excavation occurred in an active channel (five sites:Washington Creek, Oregon Creek, Penny River, Nome River,Aufeis Creek). Removal ofgravel in active channels created braided areas in what hadpreviously been pool-riffle habitats, thus, in these cases there was often a loss ofinstream andbank cover, substrate alteration, depth alteration,spreading of flow combined with decreased velocity, and loss ofpools and riffles.Habitat diversity increased at two siteswith incomplete meander cutoffsforming backwater andponded areas or side channels (SkeetercakeCreek, Middle Fork Koyukuk River-Upstream) and with gravel removal in a high-waterchannel to belowthe water table such that it contained pondedwater (Sinuk River) or annual flowing water (Jim River).

Habitatdiversity also increasedat three sites where recent gravel extractionor channel changes created low velocitybackwater areas and braidedcharacteristics were not well established (Sagavanirktok River, Dietrich River-Downstream,Middle Fork Koyukuk River-Upstream). Ponded areas or low velocitybackwaters were characterized by a sand to silt substrate. Thelow velocitywith associated clear water often allowed increased growth offilamentous algae. Water temperatures were usually increased over those inthe active channel because of thedark substrate andpoor circulation. Similareffects, although not as great in magnitude, were observed where sidechannels were formed at Jim Riverand Middle Fork Koyukuk River- Upstream.Water velocitieswere reduced and increased silt deposition was observedin the main channel.

161 The threesites with increased habitat diversity due torecent flow were 3 to 4 years old and, in twocases (Dietrich River-Downstream and MiddleFork KoyukukRiver-Upstream), flow had only entered the site within a yearor two of thesite study (Figure 49). The habitatdiversity in these areas will probablydecrease within a fewyears as meander cutoffsare completedand braiding characteristics are established.

Inundatedpits were formed when gravelremoval was conducted away fromthe active channel and thedepressian, usually deeper than I m, filled withwater either by directconnection to the river or through intergravel flow.These areas developed characteristics typical of pond habitats,i.e., mud bottom,rooted aquatic vegetation around shorelines, high density plank- toncommunities, and mac'roinvertebratestypical ly associated with a lentic environment. Two typesof pits were included in the study: shallow (< 2 m) and deep (> 2 m) pits(Table 14). Shallow pits (Penny River, Ugnuravik River,Prospect Creek) normally froze to the bottom in the winter while deep pits(Dietrich River-Upstream, West ForkTolovana River, Tanana River- Downstream,Tanana River-Upstream) contained water year-round.

Two ofthe deep pits (WestFork Tolovana River, fanana River-Upstream) showed dissolvedoxygen and temperaturestratification in the summer of studywhile the other two (Dietrich River-Upstream, TananaRiver-Downstream) didnot (Figure 50). The timeat which stratification would be mostpro- nounced was missedat Dietrich River-Upstream andTanana River-Downstream and it is possiblethat there was some stratification mid-summer; however, the TananaRiver-Upstream and West ForkTolovana River were thermally strati- fiedfrom early June to mid-September. All pits exceptthe Tanana River- Downstream pit wereconnected tothe associated rivers. TheTanana River- Downstream pit was on a vegetatedisland and connection to the river was inundatedonly during annual high water events. This pit had clear water (bottomvisible to deeperthan 5 m), very little mud or silt even inthe deepestarea, and virtuallyno thermal stratification. Aquatic vegetation was absentexcept along the shoreline, despite the extreme water clarity. Four of thefive deep pits hadextensive shallow areas, with over 25 percent ofthe area less than I m deep. Only atthe Tanana River-Downstream was a majorityof the area deeper than 2 m (Table 14).

I62 a) 16 September 1972

b) 2 August1976

c) I1 July 1977

Figure 49. Sequenceof aerialphotographs showing effects of overmining theinside of a meanderbend atMiddle Fork Koyukuk River-Upstream. Immediatelyfollowing mining (b) there was an increasein backwater areas.The next year (c) the meanderwas partiallycut off, creating a varietyof low velocityhabitats.

I63 Table 14. Percent of Pit Area Composed of SelectedDepth Intervals

Depth Dietrich R West Fork Tanana R TananaR-Upstream i n termI Penny R UpstreamProspect Ck Tolovana R Downstream Upper Lower (ml (%I ($1 (4;) (4;) ($1 I%) ($1

0- I 70.0 54.0 28 23 1-2 21 .o 32 .O 35 38 si 2-3 0 4.4 0 6.2 34 45 3-4 0 I .3 0 4.2 I1 0 0 4-5 0 0.6 0 3.0 13 0 0 >5 0 2.2 0 0.7 41 0 0

Meandepth (m) 0.6 t .o 0.6 4.5I .5 I .6 * 1.7

Max imum depth (ml I .5 7.5 I .5 6.4 9.4 2.7 2.9

Totalarea (ha) 0.6 I .8 t .O 4.25 4.5 7.5 a Estimated. T andDO TandW

0 a. Dietrich -Upstrearn,lO July1978

T and DO T and DO

c.Tanana- Downstream, 9 Sept.1976 d.Tanana-Upstream,lS Aug.1978

I65 Water Qual i ty

Water quality measurements reflectedhabitat alterations in several ways. First,dissolved oxygen and temperatureresponded in a predictable fashionto increased braiding. The spreadingand shallowing of flow and loss ofcover led to an increasedrate of heat exhange, withthe temperature, and thereforedissolved oxygen,responding more quickly to ambient air tern- peraturesin the mined area than in the upstream area. Similarly, areas with pondedwater showed increasedtemperatures and reduced dissolved oxygen (SkeetercakeCreek, Dietrich River-Downstreaml. An increasein dissolved oxygenand decrease intemperature which was notcaused by flow alteration was recordedat Dietrich River-Upstream where a spring was uncoveredduring gravelremoval operations. As mentioned,inundated pits functioned as pond habitatswith corresponding water quality characteristics. Theseincluded highertemperature andlower dissolved oxygen than the associated rivers and in some cases,thermal and oxygen stratifications.

A secondtype of water quality change was a change inconductivity betweenthe upstream andmined areas. A change inconductivity may indicate theexistence of a springwater source near or exposed by the gravel removal operation. Such changeswere recorded at Aufeis Creek, Skeetercake Creek, DietrichRiver-Upstream andPenny River. As alreadymentioned, the Dietrich River-Upstream wasan identifiedspring exposure. ThePenny Riverhad a spring-fedtributary entering the floodplain in the mined area. Springs were notrecorded at Aufeis Creek or Skeetercake Creek, but the conductivity changes may indicatetheir existence.

A thirdtype of waterquality changewas alterationin turbidity or suspendedsolids, or both, in the mined area compared tothe upstream area. Thesechanges probably indicate erosional or depositional characteristics of themined area, but the sampling was insufficientto reach definite conclu- sionson an individualsite basis.

I66 EFFECTS OF HABITATALTERATION ON FISH POPULATIONS

Observed Alterationof Summer Distributionsor Densities

Severaltypes of changes in summer fishdistribution wereobserved inthe mined areas; specific types of distributional changes were related to certaintypes of habitat alterations caused by gravel removal. These changes included: (1) reductionin the numbers ofall fishes in a disturbedarea, (2)replacement of one species byanother species, (3) replacement of one age groupby another age group , and (4) increasein the number offish or species,or both (Table 15). A list ofall species caught during the s tudy and theirscientific names is includedin Appendix A.

DensityReductions. Reductions in numbers of all fishpopulat i ons occurredat Washington Creek, Aufeis Creek, and KavikRiver sites. The habitatin the upper mined area of Washington Creek was alteredin sever a I ways, reducinghabitat quality and diversityto anextent that few organ i sms couldutilize the newly created habitat. The density andbiomass of Arct i c char was significantlyreduced downstream ofthe upstream sample area (Table 16). The slimysculpin density andbiomass was alsoreduced in the upper minedarea, but increased in the lower sample areas todensities exceeding thosein the upstream area. The sculpinbiomass remained low, indicatingthe slimysculpin captured below the mined area were smaller than those captured above.Thus, there was a replacementof Arctic char habitat by a habitat more suitablefor slimy sculpin in the lower three sampleareas. Thespe- cifichabitat alterations that led to a loss ofArct-ic char habitat were removalof bank and instream cover and possibly reduced water quality (i.e., increasedturbidity) caused by siltation from the melting aufeis f-ield.

At theAufeis Creek site, there was onlyone lifehistory stage of Arcticgrayling present during eachsampling trip, thus anychanges would have to bedensity reductions rather than species or age-group shifts. Densityreductions were recorded in the upper mined area during the first trip and al I disturbedareas in the second trip. Specific habitat alterationsthat led to reductions in Arctic grayling habitat were: (I) thereduc-

I67 00 -tn om OB ta, L em 0 ._ *- u ta, mc

-a mc --noc i u to m am 0 *- (UCLO, tt EL m *- 0 c alt " L a" (0- D r 3- E vvmm u) .- L 1) L L o *. 0 +-Y m CL mmc wm ma,ot CL OL--~ 00 JQCC ~n

.- - L

x a, L a, a, L L > m u ._ > Ly L x % C a, c 0 L a, (3 v, 0 a

I68 Y I om 0 h tal -m co I m- im L C mal 3 " 0 0 -c Y x mal L .- 3 L3 @E W rn-0 t + - C oa, m m .- .-tm 01 -In OX mLI LV3 to C aoo 0 .- 0 tt m I k- 03 L a v a a0 W u ta + m 0 + L* ms W C mm .cu) L yr .- 0 0 WY z S

W m m "I - .'" I C .5 L a a, m L L

cs c V .-0

- cc n i .- alE t wtm m .-t n 10 I

-0 al 3 L (I W *- > c .- C I IX 0 aJ V > Y L .- Y 0 01 lx a, t > a, x .- .-Y LT > m L 3 C rn 3 3 a

I 69 Table 15. IContinued)

Effects of totalalteration to Study site Habitatalterations caused bymining fish populations inmined area

ShaviovikRiverScraped point bars; increased laminar No measurablechanges ftow,slight braiding, andbackwater i ncrease

Kavik RiverScraped floodplain; increased silta-Arcticchar and Arcticgrayling tion,braiding, backwaters, ponded bothdecreased water;decreased instream cover

NorthernInterior

Oietrich River-US Scrapingin high-water channel , ex- Creation of overwinteiingarea posed spr i ng water

Oietrich River-DS Scraping in high-water channe I ; Some useby Arcticgrayling, po- increasedbackwaters and ponded tentialfor stranding water - newlyflooded depression

M.F. KoyukukRiver-US Part i a I meander cutof f; i ncreased Alteredspecies composition, round braiding,backwaters, ponded water; whitefish andlongnose sucker in- decreasedbank cover creased,documented stranding, overal I habitat diversity increased

M.F. KoyukukRiver-DS Scrapingin high-water channel; in- A I tered species composi t ion - creasedbraiding, backwaters, ponded roundwhitefish, slimy sculpin wa t er increased,Arctic grayling decreased,potential for stranding

Con t i nued om +a 01 V +

+& mc 'E cf - C m .- -m mc +o ++0 e- m u" 03 looQ

m .-E .-K E r n -0 a lo 3 Io u lo K .-0 + m L -+01 lu + m .-c .a m I

E -m a c a

171 -0 ro

U a, (FI- a, nw- LE E am m -

m N

'0 (FI .- !! a, E L L ._ (FI E r '0 3 c t 01 v, m

I72 tion of thepool-riffle frequency, and (2) increasedbraiding characteristics wi ththe associated loss of bank cover and alteredflow regime.

At theKavik River site, habityt quality was altered bythe erosion of berms I eft in and alongactive channels, Channelizing one section of the river, and creationof a morebraided configuration. The densitiesof Arctic char and Arcticgrayling for eachstudy area were estimated by repeated shockingof blocked channels (Table 17). Total fish densities in the mined areawere reduced by a factorof three or greater when compared to the undisturbedareas (Table 18). The catchof adult Arctic grayling, as determinedby angling, was also lower inthe mined area (Table 19). The densityreductions occurred in both Arctic grayling and Arcticchar with neitherspecies apparently favored by the habitat alteration. Removal of instrearncover appeared to be a majorhabitat alteration affecting reduction offish densities because a channelthat contained boulders adjacent to the minedarea supported densities of both species comparable to those in undisturbedareas.

Speciesand Age Group Alteration.Species shifts were observed at nine sites(Washington Creek, Oregon Creek, Penny River,Kuparuk River, SagavanirktokRiver, lvishak River, Dietrich River-Downstream, Middle Fork KoyukukRiver-Upstream, and Middle Fork Koyukuk River-Downstream) because alterationsin the type of habitatallowed other species to populate an area (Table 20). A similarresponse is a change inthe age structureof fish inhabiting a reachof river, as was observedat Kuparuk River, Skeetercake Creek, and MiddleFork Koyukuk River-Upstream. In these areas newly created habitatsfavored or excluded certain age groupsin the areas affected by gravelremoval operations. On KuparukRiver, the mined area had a more uniformhabitat than the upstream area andnumerous smallchannels of simi- larvelocity. Age-0 and age-l Arcticgrayling andseveral age groupsof slimysculpin were present in the upstream area while only age-l Arctic graylingwere captured in the mined area. At theSagavanirktok River, Arctic graylingjuveniles were confined almost exclusively to the mined area, while theupstream area catch was dominatedby round whitefish andan unmined channeladjacent to the mined area contained adult (-300mm) Arcticgray- ling.Again, the mined area was changedfrom a largesingle channel to an

173 o f AreaNo. of No. of ArcticArctic char gray I i ng b sections samp I edpasses/w Avg dens i ty Avg b iornassbAvg dens i t yb Avg Biomass 2 a 2 2 lfish/100m2) (gm/100m2 S tudy areaStudy samp I ed Im shocker tfish/IOOrn 1 (grn/100m

22 - 25 JUIV

I " " " Ups trem "

Mined 2 366 4 0.5 8.4 0 0 10.51 17.7-8.7)

Downstream 2 228 6 3.0 I II 4.0 I IO 12.6-3.5) (80-142) IO.9-7.01 (25-I951

4 - 8 Auaust

Upstream I 285 6 0.7 12 0 0

Mined 6 2,190 20 0.3 17 0 0 10-0.7) 0-68

Downstream 9 2,344 24 0.3 4 0.8 3 10- I .O) (0-17) 10-4.2) IO-20 I

28 Auaust - 4 Seotember

Upstream 2 822 8 I .7 30 0.9 35 ( I. 1-2.2) (24-36 1 10.7-1. I) I 8-5 I

Mined 9 2,452 32 0.7 19 0.5 5 (0-2.2) IO-79 1 10-2.21 0-30

Downs tr earn 6 I ,548 30 0.9 63 3.5 9.5 f0-3.91 IO-28 I I 10-10*9) 0-95

aNumber of timesblocked section of stream was sampled withelectroshocker. bValue inparentheses represents range of estimated values. i m .-c X V 0 L Ln 0 uc L c e- c V 3s W

Y - N E

L n

u) ucu 00.- - 01

I a3 N4NN

I 75 Table 19. Catch of ArcticGrayling per Angler Hour atKavik River Study AreasDuring Summer 1976 SamplingTrips

Per i ods Average Total number of of hours perof fish Area fishing effort anghour I er a

22 - 24 July

Upstream 3 4.7

Mined 3 7.9 2.6 ( 1.3-3.6)

Downstream 4 5.6 4.8 (2.2-6.0)

4 - 0 August

Ups t r eam 2 4.5 3.6 (2.25-4.9)

Mined 2.2 2.3

Downstream 2.6 3. I

28 - 31 August

Upstream 6.0 1.7

Mined 3.0 0

Downstream 0

a Valuein parentheses is range of estimatedvalues.

I76 Spocimm canporltion Dbwved Catch por effwt SmploMlnnw trmp Solno t IKtrerhock Mi nnalt '::',+m- Ma jw apec im

Penny R - June U 0.W 0- M 0.20 s3 - P 0.50 3- D c - *

KUDIruk R U .o"

Sognvanlrktok R U - 0.M M - 1.12 D - 0.14

ivlanok R 3. I - 00 I7 3.f . 87 e +At I .9 - 87 Y +At

u = uprtrem UM - upper mined BM Drtwwn intnoa D * dwnntrean LM 1 iwer minod P I pit OC - wiginel channol + - ~nerramdrelative to upstrma - * d*Croa$*d rrlativetouprtrom 55 rllmy sculpin t5 Coho SOImn RW - round whitefish At - Arctic char LNS = longnow mucker

I77 areacriss-crossed with numerous shallow small channels. At Skeetercake Creek,gravel removal inthe uppermined area created an extensive backwater which was utilized byadult Arctic grayling; at the middle mined area, bank cover and pools wereremoved and this led to a reductionin the population densityof Arctic grayling. At thelower mined area of the Middle Fork KoyukukRiver-Upstream site, the single-channel sinuous configuration of the river was changed to a split channelwith extensive backwater areas. The catch and speciespresent were similar between mined and undisturbed areas, butthe age structure was morecomplex inthe areas affected by gravel removal. Age-0, age-I,and age-2+ Arcticgrayling, age-0 roundwhitefish, andage-I and adultlongnose sucker were captured in the mined areas while the.speciescaught in undisturbed areas were primarily represented by a single age group.Only round whitefish exhibited a more diverse age struc- turein the undisturbed areas. Similarly, at the Middle Fork Koyukuk River- Downstream site the river was changedfrom a singlechannel to a multiple channelbraided system with numerous backwater areas. Arctic grayling domi- natedthe catch at the upstream area, but were replaced in the mined area by roundwhitefish and slimysculpin.

Potentialfor Entrapment, Gravel removal in active floodplains created areasof ponded water which were isolated from the active channel. Typically theseponded areas were inundated during high water and became isolated as thewater level receded (Figures 51 and 52). Fishoften entered these ponded areasduring high water and became stranded as thewater level dropped, The mortality rate of thesefish was assumed to behigh because they were subjectedto increased temperature, decreased dissolved oxygen, greater vulner- abilityto surface predation, desiccation if the area dried completely, and freezing.There were 13 scrapedareas at which ponded areas were observed: SinukRiver, Washington Creek, Oregon Creek, Penny River, Nome River, UgnuravikRiver, Aufeis Creek, Kuparuk River, Skeetercake Creek, SagavanirktokRiver, Dietrich River-Downstream, Middle Fork Koyukuk River- Upstream,and MiddleFork KoyukukRiver-Downstream (Table 13). Sampling in theseponded areas revealed significant entrapment at some sites. At Sinuk Riverthe mined &rea was notheavily utilized byfish. Pink and chum salmon spawn in the river and considerable numbers of chum salmon frywere captured

I78 Figure 51. Ponded areaat Kuparuk River study site where threeseine hauls captured 61 Arcticgrayling and 2 slimy sculpin, 9 August 1978 (pool I inTable 21).

Figure 52. Ponded areaat Middle Fork Koyukuk-Upstreamstudy site whereone seine haul captured 28 Arcticgrayling, 3 roundwhitefish and 3 slimysculpin, 18 July 1978 (pool 2 in Table 21).

I79 aboveand below the mined area, Pink and chum salmonare often associated with low velocitywater and there was highpotential for entrapment of downstreammigrants of these two species. The same twospecies, plus coho salmon,were vulnerable to entrapment at the Penny Riversite. At Washington Creek,Oregon Creek, and Penny River,the dominant species, Arctic char, are probablynot greatly affected by entrapment because they are generally associatedwith high velocity water and instreamcover and wouldtend to avoidthe type of areas which are prone to ponding. At theKuparuk River site, a naturalponded area, apparently enlarged by gravel excavation, contained a highdensity of age-l Arctic grayling (Table 21, Figure 51). At thelatter site both natural andponded areas created by gravel removal were presentin the study reach. At theMiddle Fork KoyukukRiver-Upstream, considerablestranding was documented when severalisolated pools were sampled(Table 21, Figure 52). The primaryspecies subjected to entrapment inthe Middle Fork KoyukukRiver system was Arcticgrayling.

MigrationBlockage. Two typesof potential mining-induced migration blockageswere observed during the study: (1) blockage due toaufeis formation, and (2) blockage due tolack of surface flow. Possible temporary migrationblockage due toaufeis formation may haveoccurred at the Wash- ingtonCreek andOregon Creek sites(Figure 53). The principalmigrations thatcould be affectedin these particular systems would be upstream and downstream movements ofjuvenile Arctic char and juvenile cohosalmon moving fromoverwintering areas to feeding areas and downstream migrations of adult Arcticchar returning to the sea from upstream overwintering areas, if present. A short-termdelay in these migrations may nothave a critical effecton these particular species, but a similarblockage for another species,such as an upstreamspawning migration of Arctic grayling, may have a greateffect onthe population in the river, A blockage due tolack of surfaceflow can occur where flow is spreadover a widearea and thereis considerableintergravel flow. Under such conditions, all surface flow may cease. Such a conditionoccurred at the Aufeis Creek site (Woodward-Clyde Consultants 1976) (Figure 54) and possiblycould occur at the Nome River site (K. Tarbox,personal communication). The potentialfor such a blockage

I80 Table21. Summary of Catch from PondedWater Areas Isolated From ActiveChannels at Two StudySites

No. of haul perCatch sein e Arcticseine Slimy Round Lonanose Loca t i on Poolhauls gray1 ingsculpin whitefish suiker

Kup aruk RiverKuparuk t 3 20.3 0.7 0 0

MiddleFork 2 I 28 3 3 0 Koyukuk River- 3 I 20 I 0 *I Upstream 4 I 0 0 0 0 5 I 0 0 0 0 6 I 2 0 0 0 7 2 9 0.5 0 5

181 a) Washington Creek -aufeis field, 21 June 1977.

b) WashingtonCreek aufeis -field, 21 June 1977. Note sedimentlayer on iceinside cavern.

c) OregonCreek aufeisfield, 7 June1977. Note sediment layer on meltingice in foreground.

Figure 53. Potentialmigration blockages, aufeis -fields at Washi-ngtonCreek and Oregon Creek, June 1977. a)Aerial view of AufeisCreek middle mined study area, 21 July 1977.

b) AufeisCreek upper study area where surface flow disap- peared for threeyears, 22 July 1977.

Figure 54. Regionwhere Aufeis Creek went subsurface creating migrationblockage due tolack of surfaceflow.

I83 existedat several additional sites, such as Washington Creek, Oregon Creek, Penny River, andSkeetercake Creek, but a specificblockage was not observed.

Creation of New Habitats

New aquatichabitat was createdat eight sites where mined areas separatedfrom the active channel were flooded subsequent to site closure. These includethe Dietrich River-Downstream and Jim Riversites as well asthe pit sites at Penny River,Dietrich River-Upstream, Prospect Creek, West ForkTolovana River, TananaRiver-Downstream, and Tanana River- Upstream. At theDietrich River-Downstream site, a wideshallow backwater was createdin the spring immediately prior to the site survey, 3 years aftermining, and was quickly utilized byround whitefish and Arcticgray- ling.Less mobile species, such as slimypculpin, i had not moved intothe I areaby the time of the survey (12-13 July)but would probably immigrate intothe mined area over the summer period,In the river, the most abundant species was juvenileArctic grayling; the second and third mostabundant wereslimy sculpin and roundwhitefish. Removing gravelin an abandoned channelat the Jim Riversite created a largepool habitat that contained a highdensity of adult Arctic grayling during the summer. Otherspecies capturedincluded juvenile chinook salmon, burbot, and slimysculpin. In the mainriver, the catch was dominatedby Arctic grayling.

The presentconfiguration of the Penny Riverapparent I y resu I t ed from twoseparate periods of mining.Originally, the floodplain was scraped adjacentto the channel. The channelsubsequently diverted throughthe scrapedsite and gravel was removedfrom the original channel, leaving a shallow pit. Duringthe site visit the present Penny Riverchannel, formed by flowdiversion through the original scraped area, was heavilyutilized by Arcticchar juveniles. The pit,created byexcavating in the original channel,provided rearing area for coho salmon juveniles andspawning and rearingareas for Alaska blackfish and ninespine stickleback. The catchin undisturbedareas was dominatedby Arctic char andcoho salmon withArctic char dominantin the spring and coho salmon dominant in the fall. The occurrence

I 84 of bothspecies in undisturbed areas, compared tothe single species dom- inancein the mined areas, again reflects the reduced habitat diversity in areasdisturbed by gravel removal.

ThePenny Riverpit provided coho salmon rearing habitat, which was Iim- itedin the river. Arctic char appeared to bemore suitedto the river environmentthan coho salmon, and avoided the pit. The pitthus provided idealrearing conditions Forcoho withlittle competition from Arctic char. There was a significantdifference in size of cohousing the pit ascompared to thoseusing the river possibly indicating increased growth rate bythose inthe pit (Tables 22 and 23). Duringthe winter the coho left the pit and moved toother areas where they possibly would be in direct competition with charfor space. If overwinteringspace is limiting in this river system,the increased number oflarger coho could lead to displacement andsubsequent reductionin the numbers ofchar. The ProspectCreek pit, a shallowpond habitatpreviously not present in the immediate area, was used as a rearing area by Arcticgrayling, round whitefish, chinook salmon, burbot, and slimy sculpin, and also provided a feedingarea for adult northern pike (Figure 55). Inthe upstream area of ProspectCreek the catch in 1977 was dominated byround whitefish, Arctic grayling, and slimysculpin listed in diminishing order of abundance. In 1978 juvenilechinook salmon appeared to dominate the fish populationsin the creek.

The DietrichRiver-Upstream pit and associated channels provided a deep-water,spring-fed system utilized principally by adult Arctic grayling and Arctic char while the main river contained juvenile Arctic grayling, slimysculpin, and roundwhitefish.

TheWest ForkTolovana River pit contained extensive vegetated shallow waterareas which sloped off rapidly to deep waterareas up to 6 m deep, thuscreating excellent spawning, rearing, and feeding areas for northern pike and feedingareas for adult Arctic grayling (Figure 56). Arcticgray- ling werethe only species captured in the river during three sampling trips,while northern pike were abundant in the pit. The onlyArctic gray- lingcaptured in the pit were adults longer than 225 mm; smallerArctic

I 8.5 Table22. Mean ForkLengths of Coho SalmonCaught by Minnow Trapat the PennyRiver Study Site During 1977

Age-0 Age- I Mean Mean tength StandardtengthSample length Standard Sample Area (mml deviationsize (mm) deviation size

4 - IO Auaust

Up stream 46.3 2.85 46.3 Upstream 21 76.7 7.59 27

49.9 3.56 96 Pit 3.56 49.9 85.4 9.29 35

Min ed (scraped) 47.8 2.86 47.8(scraped) Mined 50 80, I 6.78 38

Do wn stream 46.4 2.03 46.4 Downstream 18 79.7 5.70 20

9 - I3 SeDtember

Upstream 51 .O 5.45 90 85.6 7.33 5

Pit 57.3 5.02 387 89.665 7.55

Downstream 52.8 4.47 19 83.3 3.51 3 Table 23. Differences of Coho Salmon Mean Fork LengthBetween Sample Areas and Associated Sig- nificanceLevels, Penny RiverStudy Site During 1977 (UsingStudent's T-Test of Differences Among Lengthsin Table 22)

Age-0 Age- Age-0 I Lengthd i f f erenceSign i f icance Length difference Significance Areas (mn) I eve I Imml leve I

Pit-upstream 3.6 p < 0.01 8.7 p < 0.01 Pit-mi ned 2. I p < 0.01 5.3 p < 0.01 - Pit-downstream 3.5 p < 0.01 5.7 p < 0.05 (D Mined-upstream I .5 p < 0.05 3.4 NS 4 Mined-downstream I .4 NS 0.4 NS Upstream-downstream 0. I NS 3.0 NS

9 - 13 September

Pit-upstream 6.6 p < 0.01 4.0 NS Pit-downstream 4.5 p < 0.01 6.3 NS Upstream-downstream I .8 NS 2.3 NS Figure 55. ProspectCreek study site - shallowpond habitat SupportingArctic grayling, chinook salmon juveniles, round whitefish,northern pike, burbot, slimy sculpin, 12 August 1978.

Figure 56. West Fork To lovanaRiver study site - deep pond withextensive shallows providingnorthern pike and Arctic graylinghabitat, 29 Ju ly 1978.

I88 graylingeither were not entering the pit or were consumedby pikesoon afterentering. Northern pike were apparently spawning in the pit because many age-0 pikewere caught or observed in the shallows throughout the summer. During September, age-0 pikewere observed in the river in a large poolopposite the pit outlet, apparently moving from the pit to the river. Thus, thepit may beincreasing the number ofpike in the river system in general and, giventhe high density of agelo and age-l Arctic grayling observedin the river near the pit, may leadto a localizedincrease in the densityof river-dwelling northern pike near the pit. Studies by Alt (1970) and Cheney (1972) indicatethat movements ofnorthern pike in the rivers of thenearby Minto Flats region may notbe extensive. On a smallriver, such asthe West ForkTolovana River, a localincrease in the northern pike population may leadto 'local reductions in the Arctic grayling population.

The upper pit at the TananaRiver-Upstream site had a similarhabitat and alsoprovided a spawning,rearing, and feedingarea for northern pike as well as a feedingarea for least cisco and humpback whitefish(Figure 57). On a largeriver, as at the TananaRiver-Upstream pit,the effects of the / increased numbers ofnorthern pike mustbe minimal when compared to the riverpopulation. The maineffect of a deep pit on thistype of river system is providing a clearwater feeding area that increases the availability of desirablespecies to sport fishing. The lower pit was a more uniformdepth withminimal littoral area and was usedas a spawningand feeding area by longnosesucker. The connectionbetween the two pits, a shallow (8 cm deep) Stream, was usedby longnose sucker fry, lake chub, and juvenile chum salmon as a rearingarea. The lower pit was alsoutilized as a feedingarea by humpback whitefish,least cisco, northern pike, and burbot.

TheTanana River-Downstream pit was a deep(maximum depth = 9.4 m) clearwaterpit with apparently very low productivity.Fish species captured inthe pit werelongnose sucker, Bering cisco, and chinooksalmon. There was noconnection to the river, thus, the fish apparently immigrated during highwater and became trappedafter the water level dropped.

I89 a) UpperTanana River-Upstream Pit, noteextensive shallow areas.

b) UpperTanana River-Upstream Pit - area of highnorthern pikedensity.

Figure 57. Tanana River-Upstreamupper pit showingextensive vegetationbeds, 18 August 1978. Notedifference in the extentof vegetative development in this 13-year old pit as compared tothe 2 and 3-year old pitsin Figures 55 and 56.

I90 Effects on OverwinteringAreas

Possibleeffects of gravel removal on fish overwintering areas were observedat several of the study areas. Potential overwintering areas were createdat the deep pit sites -- DietrichRiver-Upstream, West ForkTolovana River, Tanana River-Downstream, andTanana River-Upstream -- bythe pits themselves. The DietrichRiver-Upstream pit has been reported as an overwinteringarea (W. Anderson,personal communication to A. Ott). Inaddition, outflowfrom the West ForkTolovana River pitcreated a potentialoverwinter- ingarea approximately 50 m downstreamfrom the outlet where a deep natural poolwith a 1-2 cm icecover existed into March 1979. A possibleoverwinter- ingarea on the Penny River was altered as a spring-fedtributary; Willow Creek,that had previously entered the main channel at a deep pool, now enteredthe river through the scraped area in a seriesof shallow braided channels(Figure 58).

The patternof freezing observed during winter studies on six of the pitsites indicated that fish entrapment was not a problemduring the 1978- 1979 winter(Table 24). Inthose pits studied, the outlet remained open wellinto winter with outlet flow velocities increasing as the still water atthe edgesof the pit froze, reducing the volume of thepit. Fish appeared to move tothe openwater found at the outlet areas and theincreased velocities may haveinduced the fish to move downstream to areasof reduced velocity.If fish wereholding at an outletpool and theoutlet closed downstreamfrom the holding fish, entrapment could occur. The ou tletarea in thepits examined was generallyquite small. However, the number offish affected compared tothe numbers usingthe pit in the summerwou Idbe minimal.

The outletsof the Prospect Creekand Jim Riversites remained open at leastuntil late January and possiblyinto early February, thus fish had ample opportunityto emigrate as flowdecreased during freeze-up, Fish were present(caught and observed)at both sites in early November butwere not evidentin late January. Both sites were frozen to the bottom in March. At the Penny Riverpit site, fish werecaught in the pitin late December and

191 11 Willow Creek, a tributaryof Penny River,showing flow diversionfollowing gravelremoval operations, September 1975.

b) Willaw Creek as it entered Psnny River on 20 March 1979.

Figure 58. Potentialoverwintering area at Willow Creek.This spring-fedtributary, openthroughout the winter, had pre- viouslyentered Penny Riverat a deep pool.

I92 Table 24. Physical Conditions at Pits VisitedDuring Winter

Penny R i ver J ia River Prospect Creek West Fork TolovanaRiver

IC0 Ice L ce Ice thlcknes sl thickness! thlcknessl thickness! thlcknessl thickness! thlcknessl Water Watw Dissolved Water Water Dissolved bter Water Olsroived WaterWater Oissolvsd depth temperature oxygen taaperaturodepth oxygen depth terrperature oxygen depth temperature oxygen Date tall’ PCP (Ppalb tun1 1% 1 PP”) 4-1 t°C1 I Ppmj tun) ( Ppm1

~~ ~~

16-20 Narch 1976 I55123 0.0 3.5 a015300.1 0.0

18 Decsrbw 1976 76/15 -0.6 12.4

24 January 1979 33136 -1.0 18.2 107f30 0.0 10.6

9 64larch 1979 75f534 O.Of3.5 5.8i5.8 *

83-14 #arch t979 90110 -0.5 5.a 11OfO i - -

open through January open through January closed by late blovsmber ctosed In March closedIn March f low through 4- into March

pirst nuhw = maximom Ice thickness, second numb- = l~xlmmwatar depth from bottm of ice to bottcn of plt. Flrst Q one nmber = surface measur-t, second nubw = bottm tlleasurment. Table 24. IConclvdedl

Ice Ice Ice thickness! thickness/ thlcknessl Water water D I ssol ved Wster Water Dissolved Wafer Water D I sso tved de pth temperature depth oxygen tompgrature depth oxygen depth tqratwe oxygen Daf e I cmb roc ! twml t cml I CI IPPIJ (at t CJ PPnj

16-20 March I978 33) 122 0.0 3.2 a.oi6.6

6 November1978

27-29 November 1978 201 loo 0.010.0 3.112.9 2Uf 165 2. I f3.5 6.2f5. t

18 December 1978

24 January 1979

Ur 6-8 March 1979 75/900 -1 -013.0 6.2f6.0 l05/ 100 0.0 6.0 90/ 163 0.5 11.4 P 13-14 March t979

20 March 1979

State of outtet no out I et c losed in Hovember open through Hovsnbsr open In brch closed in March theoutlet was flowingat that time. By March all flowin the pit hadceased and the pit and outletwere frozen to the bottom. The spring-fedtributary, WillowCreek, however, remained open and flowing into March, but fish were notdetected either in the tributary or in the Penny River downstreamfrom wherethe tributary entered the mined area. At West forkTolovana River, the outlet was blockedat the time of the first winter visit, 29 November 1979, becausethe deep, low velocity arm connectingthe pit to the river was frozen and theother arm flowedthrough a beaver dam. Flowout of the pit throughthe beaver dam persistedthrough March (Figure 59). Fishwere not detectedduring any ofthe winter visits. There was sufficientwater and dissolvedoxygen to support overwintering fish in mid-March 1979 andthe persistingoutflow through the beaver dam indicatesthe pit may bereceiving Some intergravelflow from the river.

The Tanana River-Downstream pit was visited only on 6-7 March1979; fish werenot captured but as emigration after the previous September visit was notpossible, fish were probably present. The dissolvedoxygen should nothave been depletedbecause of thedepth, limited phytoplankton production, andabsence of littoralvegetation, and, infact, was 6.0 mg/R in March(Table 24). At thetwo TananaRiver-Upstream pits, a moredynamic pattern of freezing was observed. On 27-28 November 1978, theconnection betweenthe two pits was frozensolid, thus isolating the upper pit. The surfaceof the ice in the upper pit was approximately 1.5 m higherthan the surfaceof the lower pit. A burbotand possible lamprey were observed with anunderwater television system, The outletof the lower pit was open tothe Tanana Riverwith a schoolof juvenile salmon and twospecies of whitefish holdingin the outlet current. Burbot were captured by setline in the lower pit. On 6-7 March 1979, theice surface of thelower pit had risen to the levelof the upper pit and theconnection between the two pits was open, approximately 30 cm deep and flowingat about 0.1 m/sec intothe lower pit. The outletto the lower pit was frozensolid. Dissolved oxygen at the upper pit had increasedfrom 3.4 to 6.0 ppm between November andMarch. Fishwere notdetected in either pit in March.

I95 a) Flowout of beaver dam atpit outlet, 29 November 1978.

bl Deep pool !>I rn) withthin ice cover approximately 50 m downstreamfrom beaver dam, 15 March 1979.

Figure 59, Creationof a potentialoverwintering area at West ForkTolovana River downstream from pit.

I 96 Theabove observationsindicate that after November theoutlet froze, thenthe side channel of the Tanana Riveradjacent to the pit started flow- ingthrough gravel into the upper pit, opened the connection between the two pits and flowedback into the side channel through an intergravelpathway. The raisingof the surface of the lower pit appeared to have been caused by overflowon top of the existing ice andsnow. Oxygen depletion wasa potential problemat the upper pit becauseof the dense stands of aquatic vegetation(the March 1978 dissolvedoxygen was 3.2 ppm) butthese were absent inthe lower pit and thedissolved oxygen was consistentlyhigher than that ofthe upper pit. The neteffect was thecreation of oneand possiblytwo overwinteringareas, depending on the minimum winteroxygen levels at the upper pit.

Assumingan adequate water depth, the main factor determining the suitabilityof a pit as an overwinteringarea is an adequatelevel of dissolvedoxygen through the winter. A pitwith sufficient depth for over- winteringbut with an extensive,heavily-vegetated littoral area may experience an anoxicperiod following the initial snow cover.Barcia and Mathias (1979) foundthat winterkill in eutrophic prairie lakes was closely correlatedto the mean depthof a lake anddeveloped a method toestimate thepotential for winterkill based onthe initial oxygenstorage, rate of oxygendepletion and the mean depth. The critical mean depthfor the lakes studied was approximately 2.0-2.5 m. Lakeswith an averagedepth less than 2.0 m experiencedregular winterkill, lakes 2.0-2.5 m experiencedoccasional winterkill, and lakeswith an averagedepth greater than 2.5 m generallydid notexperience winterkill. The indicationswere that a productivepit with anaverage depth of less than 2.5 m may havemarginal utility as an overwinteringarea, especially during years of early heavy snowfall.

The upperTanana River-Upstream and West ForkTolovana River pits had thecharacteristics to fitthis type of pit(Table 14). The 6 m deep areain the latter pit may haveprovided sufficient volume tomaintain a suitable dissolvedoxygen level, but both of these pits should be considered marginal overwinteringareas. lntergravel flow from the adjoining river, however, adding a continual supply ofoxygenated water, could maintain sufficient

I97 oxygenlevels throughout the winter. The lower Tanana River-Upstream pit did notcontain a greataverage depth, 1.7 m, butthe lack of littoral vege- tationreduced the probability of oxygen depletion. The waterin the pit was turbidduring the summer, limitingproduction of aquatic vegetation. The lower pitmaintained higher dissolved oxygen than the upper pit during the winter(Table 24). The DietrichRiver-Upstream andTanana River-Downstream pitsboth contained deep, clearwater regions and did not have well-developed littoralvegetation. Oxygen levelsprobably remained high throughoutthe year. The depth and lackof productivity combined to make thesetwo pitsexcellent overwintering areas; the same featureslimited the'ir value as rear i ng areas

Thereare other possible effects of gravel removal on overwintering areas,but they are difficult to assess because of the absence of dataon thestudy sites before gravel removal. A primaryeffect is the loss of overwinteringareas due to diversion of flowfrom an originalchannel, as occurredat four sites (Penny River, Dietrich River-Downstream, Middle Fork KoyukukRiver-Upstream, and MiddleFork Koyukuk River-Downstream). In these cases,complete or partial diversion of flow could lead to loss or reduction ofoverwintering habitat. Another effect is the loss ofoverwintering habitat due to increasedbraiding and theassociated changes -- loss ofpool- riffle sequenceand reductionsin depth and velocitywhich promote rapid freezing.In some areas,gravel removal created or aggravated the formation ofaufeis fields, thus leading to a reductionin water available for overwintering downstream(Washington Creek, Oregon Creek, McManus Creek,possibly some ofthe North Slope sites).

EFFECTS OF HABITATALTERATION ON AQUATIC MACROINVERTEBRATES

Observed Effects on Densityand Species Assemblage

Habitatalterations expected to affect.assemblages of riffle macro- invertebrateswould be changes in velocity, substrate, depth, and water quality.During the present study, habitat alterations resulting in a change ofeach of these parameters were accompanied by changes in the riffle community(Table 25).

I98 * W .- tu V -Im .-U .-0 L e, m J= C t .-0 U + .a a 1110 I tup al c c .- - nLm a XVE + mc m I- a- .-+ n n I +0 .. x+ +o .- C mmo c a,.- vnn(uL+ L mc al c .- +

v W J .-c L

0) m alc WE W-I I.- - .- - .- C nu nu a-a .- Q *- 10 a- Lo .- U cm tm cn .- m u)L WL mL a C cn ~n cn L .- Y 3 2 n Q KC . i, .- UP, U Y "I- .- E WC 01 0 Q+ mm u) cmx RIL m W .- L n #+ W u) no Lu) L c m+u vn V 0 I-01 CY C a om -m I u) 3 111 c1:

L W 111 C n 3 c 7 E c I a 01 X UJ W 111 I I L L 0, 0 .-> C L1: 0 rn 0, L 0

I99 W m .-U

.- *E mo LC 20 OL a, W XVE E *- El c mc WL 0 0 I" *- TU z z

u- ro

m t W W m 0 U L 'c1 V - a! 9, 0, 3 3 .- E c 0 - .* ,- v, t z 0 m C 0 0

U 9, a, mm 0 + "ID c m .- L I I mL 0 c m m tu .- t .- tm tm m mc m --P - c - C c c .- I .- .- .- .- .- .* .- 3 n mm mu mu cc L .* ._ 0 .- U wn wm um t .- E W W alL 0,L mt m m. ma mn tmh m me m m ._ i a, alo 0,- 0,- no L L .- LC LC mtw V ut 00 uo r- 9) c em *- E .- mm - t -t -4- 3 m V

01 .-t I I I m [1: r Y U .- 3 > t m m Y

200 Tu- t'0 .- c ~COO c a, .- 0, LC umm L .-r a- -t

P) C 0 Z

.- 3 owcn; LtnL mmo a, '7 BLa XVE ma, I-u

a, a.c

KC 0 .- c .- F mt wm COL

I a, n E L a a, v, I

20 I Response toSubstrate Alteration. The twotypes of substratealter- ationsobserved during the study (a shiftto unstable substrate andchange fromlaminar to turbulent flow) significantly affected the total numerical densitiesof aquatic macroinvertebrqtes in the mined area as compared to undisturbedareas (Table 26). At WashingtonCreek, Oregon Creek (June and

August 1 I al I Penny River,Kuparuk River, and McManus Creek(May) site visits,macroinvertebrate densities in minedareas were significantly less thanthose in the upstream area. At all fivesites there was a shiftfrom a moderatelycompacted gravel substrat e to a veryloose, unconsolidated sand- gravelsubstrate (Table 25). A simil arhabitat change atthe Sagavanirktok River and lvishakRiver sites resulted in a significantincrease in the densityof aquatic macroinvertebrates. In five of the eight cases in which therewere total density decreases, there were density reductions in the ephemeropterangenus Cinygmula while in seven of the eight cases, there were reductionsin the dipteran family Chironomidae. The densityincreases at the SagavanirktokRiver and lvishakRiver sites both contained density increases inthe ephemeropteran subfamily Baetinae and dipteranfamily Chironomidae, aswell as some othertaxa.

At two sitesthere was a changefrom laminar flow toturbulent flow causedby substrate alteration. At bothUgnuravik River and ShaviovikRiver sites,there WBS a significantdecrease in total macroinvertebrate density, primarily becauseof a decreasein Simuliidae densities. At UgnuravikRiver, thelaminar flow was inthe upstream (control) area, while at Shaviovik River,laminar flow occurred in the mined area.

At threeof the five sites where there were decreased densities in the minedarea (Washington Creek, Oregon Creek, McManus Creek)there were also aufeisfields associated with the mined area (Table 25). All threesites were visited early in the summer so that any -aufeiseffects would have been measured attheir greatest magnitude. Later visits at two of the sites (OregonCreek, McManus Creek)indicated that densities in the mined area increasedto levels similar to thosein the upstream areas. At OregonCreek, the summer recoveryfrom aufeis effects was notcomplete for population densitiesof Nemoura andCinygmula, which remained below the densities

202 203 reachedby the same generain the upstream area. The Augustand September populationdensities of Capnia and Baetinae,however, exceeded those recordedin the upstream area.

At McManus Creek,the mined area densities of Oligochaeta and

Rhyacophiladid not reach those recorded in the upstream area; the mi ned areadensities of Alloperla, Chironomidae, and Tipulidae exceeded the UP- streamarea densities on each of the twosucceeding trips. The fai lure of themined area densities of some taxato reach upstream densities, while thoseof other species exceeded the upstream densities, indicated thatthere wasa long-termhabitat alteration which has led to an alterationin species composition of themined area. Another site which showed a similarresponse, butwhere an aufeisfield was notidentified, was the Penny Riversite, wheremined area densities of Oligochaeta, Nemoura, Cinygmula,Chironomidae, and otherswere generally lower than upstream densities. In the Penny River minedarea, population densities of Tipulidae and, attimes Capnia, Baetinae,Ephemerella, and Athericidaewere higher than those in the up- streamarea. The shift in taxaat the above sitesappeared to be related to theoccurrence of unstable substrate possibly aggravated by an aufeisfield.

Othersites with a similarsubstrate alteration (Washington Creek, KuparukRiver) also showed densityreductions of most organisms but the site wa5 onlyvisited onceand thisprecluded any analysis of recoveryor sea- sonalpatterns, At KuparukRiver, densities of allspecies were lower in the minedarea than in the upstream area while at the Washington Creek upper minedarea, only Tipulidae densities exceeded those in the upstream area. In

' summary, certaintaxa, primarily Oligochaeta, Nemoura, Cinygmula, and Chironomidaewere reduced in areas of unstable substrate while others, primarilyTipulidae, but also Capnia and Baetinae, showed increased den- sit ies.

Response toIncreased Braiding. Aquatic macroinvertebrate responses to thesealterations were colonization by taxa which are more suitedto lower velocitywaters with higher organics. Clinging ephemeropterans, as found in thefamily Heptageniidae (Cinygmula, Epeorus), were replaced by sprawlers

204 andclimbers, e.g., Baetidae,Trichopterans often increased in these areas and thedipteran family Tipuliidae was oftenassociated with the finer sedimentsfound in mined areas. At two siteson large rivers showing increasedbraiding as well as alteredsubstrate (Sagavanirktok River and lvishakRiver1 there was an increasein the density of virtually all taxain themined area as compared tothe upstream area (Table 24). The riffles in themined area in these two cases were in small shallow channels with extensive riffle areawhile the riffles in the upstream area were in large channels,were less extensive, and composed of a morecoarse material. The rifflesin the minedarea had greater detrital accumulation, and the decreaseddepth and velocityassociated with the braided areas may have allowedgreater periphyton production. Such a situationwould increase the qualityof the habitat for most of thespecies unless a critical parameter, such as velocity,had been lost or altered. The increasedbraiding at other sites, suchas Oregon Creek and Penny River, may havecontributed in a similar manner tothe altered species composition.

The increasedbraiding at many ofthe sites led to changes inthe water temperature and dissolvedoxygen in the mined area. An examinationof the seasonalvariation in the riffle macroinvertebrates at Aufeis Creekrevealed a patternof density changes which indicated a possibleeffect of the alteredtemperature and dissolvedoxygen regime on the apparent densities of certainmacroinvertebrates (Figure 60). Inthe ephemeropteran taxa, Baetinae andCinygmula, the densities in the upstream area increased from the July to August tripwhile those in andbelow the mined area decreased. Simuliidae densitiesdecreased between the two trips in the upstream area with simu- Iiids absentin and belowthe mined area in August. The temperatureat the areabetween the two mined areas was 2.8OC (July) and 1.2'C (August)higher thanthat in the upstream area. The immaturestages of the three taxa apparently emerged earlierin the areas affected by gravel removal than in the unaffectedupstream area. The alteredwater quality parameters may have alteredthe emergence timesof these three taxa because temperature and dissolvedoxygen can affect developmental rates (Hynes 1972).

205 Q

July August

Figure 60. Densities of selectedaquatic macroinvertebrates at Aufeis Creek studyareas during 1977 samplingtrips.

206 An indicationof a similareffect was seen at McManus Creekwhere

Alloperla nymphs werepresent in the upstream area in densities exceeding thosein the mined and downstreamareas. An emergence ofadult plecopterans was occurringin the mined area during the site visit, however,and this probablycaused the reduced densities of nymphs. Thus, thelow nymphal densitiesof Alloperla in the mined anddownstream areas may have resulted from an earlier emergence timerather than a lackof suitable habitat. The observeddensity differences between upstream andmined areas, at sites whichwere only sampled once,must be viewed withcaution because of the possibility that emergence periodswere altered due to an alteredthermal regime. A majorperiod of emergence may haveoccurred in one area just prior to .the sitevisit, thus leaving the area with low densitiesrelative to an areawith a later emergence period. At presentthere is not enough informationon the natural emergence patterns,and the effects of temperatureand dissolvedoxygen on those patterns, to predict how thearctic macroinverte- bratespecies would respond to changes in these habitat parameters.

Creation of Pond Habitat. The creationof pond habitats allowed aqua tic macroinvertebratestypically found in a lentichabitat to colonize these areas(Table 27). Inthese cases the change was fromterrestrial to aquat ic habitat so there was not a directeffect on river Communities. Indirect effectscould beenrichment of downstream communities by phytoplankton and nutrientsbeing carried out of the pit. The SouthernInterior deep pits (WestFork Tolovana River, Tanana River-Downstream,Tanana River-Upstream) had a higherdiversity of organisms than the pits in other regions, probably reflecting a more stablehabitat. Theage ofthe pit did not seem toexert much effect becausethe West ForkTolovana River andupper Tanana River- Upstream pit both had similarconfiguration and similarfauna and density butthe former was IO years newer thanthe latter. Thelow productivityof the TananaRiver-Downstream pit was evident;the density of chironomidsat the TananaRiver-Upstream pits,about 50 km upstream, was 5 to 20 times greaterthan those at the downstream pit at a similartime of year.

207 Table 27. Oansitles of Aquallc Ikero1nvertebratesCollected st Lnundated Pit Sltes. t976-1976 IDensities In 0rganlsns/m2, from Ponar Sampler)

Hemiptera Calxldse Coleoptera Dytlscldae Hallplldas Tr I choptera D Le;;t;l t a Phryganea Polycentropus Ciptera Ceratopogonidae Chironanldae Elpididw SImul i idae Mollusca

we Planabidae Yalvata Pl8idlun G-r 1 dae Hydracar Ina

Total 2374 998 803 7025 606 3747 16,602 780 1843 7259 10,090 2271 1919 2635 No. of taxa 5 3 3 1 4 9 7 14 I2 96 14 a 7 a SUMMARY AND CONCLUSIONS

EFFECTS OF GRAVELSCRAPING ON RIVERINE HABITATS

Gravelremoval by scraping in floodplains resulted in a number of alterations to aquatichabitats with the biota showing a varietyof responses tothese habitat alterations. Important hab itatalterations included: (1) thecreation of braidedchannel areas w ithassociated changes in varioushabitat parameters, (2)removal of bankand instreamcover, 13) increasedhabitat diversity, (4) creationof potent ialmigration blockages, and (5) creationof potential entrapment areas.

IncreasedBraiding Characteristics

Thishabitat alteration occurred at 15 studysites where active channel depositswere scraped to below the water line or where flow subsequently increasedto inundate the mined area. The maineffect of braidingon spe- cifichabitat parameters was toreduce velocity and depthby spreading flow over a widerarea. The populationsof both aquatic macroinvertebrates and fishutilizing these areas were altered with shifts in species and life historystages, The reductionin velocity led to increased detrital accumulation,deposition of fine materials, and oftenaltered the temperature and d i sso I ved oxygenregime. The alteredtemperature regime led to a I tered emergence periodsof aquatic insects; the effect of thisalterat ionon reproduct ivesuccess and overallpopulation stability is unknown.

Fish populationsresponded to increased braiding in a number of ways, butthe general pattern was a reductionin the diversity of the fish community. Thenumber ofspecies andage groupsusually decreased in the braided areas.

209 The increasedbraiding also increasedthe probability of aufeis forma- tionin the mined areas. This effect was documented at WashingtonCreek and OregonCreek and was indicatedat McManus Creekand Penny River.There may havebeen additionalice formation at some of theNorth Slope sites, such as KuparukRiver, Sagavanirktok River, and lvishakRiver. The formationof aufeisfields seemed toprolong the recovery of the site as thechannels and substrateremained unstable and siltation persisted during the melting process. In addition,the water needed to create the aufeis field became unavailable downstream, thusreducing water available for overwintering, oftenthe factor limiting fish populations in arctic rivers.

Removal of Bank andlnstream Cover

Reductionof bank cover occurred whenever a portionof incised or undercutbank was removed. At siteswith this habitat alteration, the bank was scraped to removeoverburden inorder to accessunderlying gravel deposits. The former bank withcover was changed to a gravelbar following removaloperations. Certain species, such as Arcticchar and Arcticgrayling werestrongly associated with bank cover and the loss ofthis cover led toreduced population densities in the mined areas. Similarly, loss of instreamcover led to reduceddensities in mined areas.

IncreasedHabitat Diversity

Habitatdiversity increases were documented atthree scraped sites, but thesewere viewed as temporaryincreases at newly inundated sites. The habitatdiversity will decreaseas braiding characteristics are established, thechannel cutoffs are completed, and thehabitats become more uniform.

MigrationBlockages

The combinationof increased wetted perimeter and decreaseddepth in minedareas created a situationthat could lead to migrationblockages duringperiods of law flow. Such a situationoccurred at the Aufeis Creek

site and possiblycou Idoccur at the Nome Riversite. The PO tential for

210 migrationblockage was presentat sites, including OregonCreek and WashingtonCreek, where the entireactive channel was scraped.Because of the known complexityof fish movements throughoutarctic watersheds, migrationblockages can have a significant,but as yetunstudied, effect on popu I ations.

PotentialEntrapment Areas

The potentialfor fish entrapment was highat areas with extensive backwater,as was foundat newly ,inundated areas (Dietrich River-Downstream, MiddleFork KoyukukRiver-Upstream) and areas with increased braiding (many sites,including Sinuk River, Kuparuk River, Sagavanirktok River, lvishak River, and MiddleFork KoyukukRiver-Downstream). At thesesites, areas of pondedwater became isolatedfrom the active channel as thewater level dropped,trapping fish and invertebratesthat had moved or been carriedinto thesedepressions during the high water. Mortality of stranded fish and invertebrates is assumed to behigh because they are subjected to high summer watertemperatures, low dissolved oxygen, increased predation from terrestrialpredators, winter freezing, and total loss ofaquatic habitat as theisolated pools often dry up ifthe river continues to drop.

EFFECTS OF INUNDATED PIT FORMATION ON THEASSOCIATED RIVER BIOTA

The direct effects of pit excavation onthe river biota were difficult to assessbecause the river habitat was notdirectly affected; inundated pits werecreated from previously terrestrial habitat. Because of this, the pitsrepresented a new habitat and thefauna inhabiting the pits was con- siderablydifferent from that inhabiting the associated river.

Summer utilization bv Fish

Two ofthe pits, Dietrich River-Upstream andTanana River-Downstream, were deep clearwater pits with low productivity and fish utilization. At TananaRiver-Downstream this low utilization was easilyexplained because there was noconnection to the river and immigrationinto the pit occurred

21 I onlyat infrequent high water levels. The DietrichRiver-Upstream pit, however, was connected tothe active channels but fish were apparently not utilizingthe pit for feeding. Benthic macroinvertebrate densities in both thesepits werelow when compared.tothose of other pits. The spring-fed channelsupstream from the Dietrich River pit were utilized by adult Arctic grayling andthe pit itself was reportedto bean overwinteringarea, All otherpits were highly productive and heavilyutilized by fish as summer rearingareas. The shallowpits, Penny River,Prospect Creek, and Jim River sidechannel (this site had sme characteristicsof a pit) supportedhigh densitiesof juvenile salmon (coho in the Penny River,chinook in the latter two) as well as some speciesassociated with both a lacustrineenvironment (Alaskablackfish, burbot, northern pike) and stream environment (round whitefish,Arctic grayling, slimy sculpin). The productiveSouthern Interior deep pits, West ForkTolovana River andtwo Tanana River-Upstream, contained a more lacustrinefish fauna with northern pike dominating the fauna and humpback whitefish,least cisco, and burbotalso present in the Tanana River-Upstreamcomplex.

Potentialfor Winter Mortality andWinter Survival Areas

The creationof shallow pits and subsequentheavy summer usage by fish createdthe possibility for entrapment during freezeup and subsequentwinter mortality when thepit freezes solid or decay of vegetation consumes the dissolvedoxygen. The pattern of freezingobserved during winter studies indicatedthat during the year of observation,entrapment WBS minimal and probablynot a significantproblem.

The creation of deep pits connected to theriver could create overwinteringareas; this was documented orsuggested at severalstudy sites. All pitsstudied, with the exception of TananaRiver-Downstream, however, had a mean depthinsufficient to preclude winter mortality. Intergravel flow appeared tomaintain the ability of some pitsto support winter fish survival,but this is an unpredictablefactor in the design of pits.

212 RECOMMENDATIONS

I. It is recornmended thatmining practices leading to an increasedbraided configuration tie avoided.This is bestachieved by avoiding active channels andby miningabove the water table.

2. Undercut and incisedvegetated banks should not be altered.

3. Criticalhabitats, such as spawning and overwintering areas should be avo i ded.

4, Formationof isolated ponded areas that cause entrapment should be avoidedby contouring and sloping to provide drainage.

5. Pits should be excavatedto a sufficientdepth to precludewinter mortality.Generally, amean depthof at least 2.5 m shouldensure winter survival.

213 REFERENCES

Alt, K. T. 1970. Sheefishand pike investigations of theupper Yukon andKuskokwim drainages with emphasis on Minto Flats drainages. Alaska Dept.of Fish and Game. Fed. Aidin Fish Restoration, Annu. Prog.Rept. 1969-1970, Proj. F-9-2, 11:321-330.

Barcia, J., and J. A. Mathias. 1979.Oxygen depletion and winterkill riskin small prairie lakes under extended ice cover. J. Fish. Res. Bd. Canada 36(8):980-986.

Binns, N. A., and F. M. Elserman. 1979. Quantification of fluvialtrout habitatin Wyoming. Trans. Am. Fish. SOC. 108(3):215-228.

Bovee, K.D., and f. Cochnauer. 1977. Developmentand Evaluation of WeightedCriteria, Probabi lity-of-UseCurves for lnstream Flow Assess- ments:Fisheries. lnstream FlowInformation Paper No. 3. Coop. lnstream Flow Serv.Group, Fort Col Iins,Colorado. 39 pp.

Cheney, W. L. 1972. Lifehist oryinvestigations of northern pike in Tanana Riverdrainages. Alaska Dept. of Fish and Game. Fed. Aidin Fish Res- toration. Annu. Prog.Rept. 1971-1972, Proj. F-9-4, l3:1-30.

Hynes, H. B. N. 1972. The Ecologyof Running Waters. University of Toronto Press,Toronto, Canada. 555pp.

Nie, N. H., C. H. Hull, J. G. Jenkins, K. Steinbrenner,,and 0. H. Bent. 1975. Statistical Package forthe Social Sciences. Second Edition. McGraw-Hill,Inc. 675 pp.

Stalnaker, C. E., and J. L. Arnette(eds.) 1976. Methodologiesfor the Determinationof Stream Resource Flow Requirements: An Assessment.Utah St. Univ.,Logan, Utah. 199 pp.

Woodward-Clyde Consultants. 1976. PreliminaryReport - Gravel Removal Studiesin Selected Arctic andSub-Arctic Streams in Alaska. U. S. Fish and WildlifeService. FWS/OBS 76/21. Wash. D. C. 127 pp.

Zar, J. H. 1974. BiostaticalAnalysis. Prentis-Hal I, Inc.Englewood Cliffs, N. J. 620 pp.

214 EFFECTS OF GRAVEL REMOVAL ON TERRESTRIAL BIOTA M. R. Joyce

INTRODUCTION

The ecologicalimportance of floodplain and riparianterrestrial habi- tatsin temperate regions has been well documented in the ecological Iitera- ture. These habitats,particularly the riparian zones,have highprimary and secondarybiological productivity and typicallysupport a diverse andabun- dantflora andfauna. These biotictones frequently provide temporary and permanentrefuge for many ofour rare andendangered species. The signif i- canceof these floodplain and riparianhabitats has recently been recogn i zed andincorporated into the management plansof several Federal agencies (Johnson and Jones 1977; U.S.Army Corpsof Engineers 1979).

Arctic and subarcticfloodplain and riparianhabitats are no less significantin their importance and ecologicalvalue. The riparian zones develop dense shrubthickets dominated by willows and alderin all four studyregions. Overstory forest dominated by white spruce andpaper birch alsofrequently inhabit the riparian tones of the Northern andSouthern Interiorregions. (Scientific nommenclature for terrestrial flora andfauna is presentedin Appendix A.) Highprimary productivity in these zones pro- videsoptimum feeding, nesting, and coverhabitat for a diversefauna usually dominatedby small mammals and passerines.These riparian habitats in interiorAlaska frequently support over 100 birdsper 40 haduring the nestingseason (Spindler andKessel 1979). Some birds,such as theyellow warbler and northernwaterthrush, very seldom nest in habitats other than riparianshrub thickets. Thesezones also arepreferred habitats for tundra voles and singingvoles. The moredense riparianshrub thickets provide criticalfeeding andcover habitats for moose and ptarmiganduring winter.

215 The unvegetatedand sparsely vegetated areas within arctic andsub- arcticfloodplains provide equally valuable habitat for a different segment offauna. Many ofthe major floodplains provide key migratory corridors for large numbers ofwaterfowl, shorebirds, and caribou moving to andfrom wintering zonesand summer nesting and calvingterritories. Unvegetated areas of largerfloodplains are used as primenesting and feeding habitat by numerous shorebirds,gulls, terns, and waterfowl. The deltaareas of larger riversalso are prime juvenal rearing habitats for shorebirds andwaterfowl. Alongcoastal regions, these river deltas also are key nesting sanctuaries for geese, brant, swans, gulls,terns, and shorebirds,and during late summer and earlyfall they provide protected habitat for large concentra- tionsof molting waterfowl. Due tothe high secondary productivity of these areas,predators including bears, wolves, eagles and jaegersalso frequently concentratetheir feeding activities along floodplains.

Unfortunately,from a biologicalviewpoint, floodplains also provide easilyaccessible gravels that are available in large quantities andfre- quentlyclose to development sites. As previouslynoted, arctic andsub- arcticconditions, primarily associated with the presence of permafrost, placelarge demands upongravel resources by all development projects.

Duringthe construction of the Trans-Alaska Pipeline System, over 3,300 ha ofunvegetated floodplain habitat and approximately 1,000 ha ofriparian habitatwere affected by gravel removal operations (Pamplin 1979). The proposedconstruction of a gas pipelinethrough Alaska, depending upon final routeselection andthe degree of use of existing construction facilities, couldrequire similar gravel suppliej. Other development projects are expectedto increase the future demand upongravel resources.

Previousto this study, natural resource managershad littleindepth knowledge, relativeto arctic and subarcticterrestrial floodplain ecosystems,of how tobest mitigate the use of floodplains as gravel removal sites. The short-termeffects of gravelremoval operations were believed to beassociated with reduction of habitat, probable decrease in local fauna populationsites, and potentialindirect effects through reduced habitat qualityin adjacent anddownstream habitats. However, thevariations in the

216 levels of influence and thedurations of influence between differing gravel removalsites and methodsof operation were not completely known. Also, therewere no data on long-termeffects in the arctic or subarctic. Factors such as thesize and location of thesite, andthe characteristics of the stream and floodplainwere believed to be influencingparameters, but their relationshipsto short-term andlong-term detrimental effects were not understood.

To help answer thesequestions, a terrestrialstudy was incorporated into this project. The study was designed to be compatiblewith the hydrologyand aquaticbiology programs and organizedto provide answers on: (1) thedegree of flora andfauna change resultingfrom gravel removal operations; (2)the rate of habitat recovery at disturbedsites respective to the characteristicsof the gravel removal operation and thecharacteristics of theriver and floodplain system;and (3) how thedetrimental affects of gravelremoval operations could best be mitigated.

217 METHODS OF DATA COLLECTION

As previouslydescribed in APPROACH AND METHODOLOGY, terrestrialdata werecollected at all 25 studysites, with individual site visits occur- ringeither during the summer of 1976, 1977, or 1978. Standardprocedures wereused tocollect field data on flora, soils, birds, and mammals.

Sitelocat ionsare identified on Figure I. Sitesoccurred on the Seward Peninsula,North S lope (inboth the coastal plain and Arcticfoothills), NorthernInterior (betweenthe Brooks Mountain Range andYukon River), and SouthernInterior (betweenthe Alaska Mountain Range and the Yukon River). One studysite, se lectedas being most representative with respect to river typeand biological conditions in each regional study area, was sampled during a 5-day visit. We attemptedto coincide this visit with the peak of theavian nesting season. All othersites were surveyed during a 3-day visit.Within eachregion, the 3-day visits werespaced throughout the spring, summer, and fallto measureseasonal fluctuat i ons inspecies composition andabundance.

The selectedapproach to meet the objectives of t his project was to document thepresence and establish the habitat relati onshipsof the flora andfauna of thedisturbed area and comparethese topredisturbance flora andfauna populations and habitat affinities. A controlarea which was most representativewith respect to physical site characteristics (i.e., inside oroutside meander) and habitat characteristics (i.e., dense riparian shrub thickets,or unvegetated floodplain) was selectedto establish pre-gravel removalbiological conditions and flora-faunarelationships. In addition, surveyswere conducted in floristic seral stages representative of the disturbedarea during the time of thefield visit, and inseral stages representativeof anticipated future disturbed-area vegetative development.

218 Theseareas were surveyed toidentify flora-fauna re lationshipsduring varioussite recovery stages.

The MajorVariable Matrix Table (Table I) ident ifiesthe variety of sitesstudied. Study sites varied from large braided rivers to small , single-channelstreams located in four major geographical regions of A I aska Selectedsites were studied from 2 to 20 yearsafter disturbance, al lowing datagathering on short-term andlong-term response and recovery by the terrestrialbiota. Characteristics of gravel removal areas included: scrapingoperations of surface gravels within and adjacentto active channels; scrapingin areas separated from the active channels; and pitexcavations separatedfrom active channels. This range of sites allowed comparison of theeffects of d.ifferent techniques and sitelocations on terrestrialbiota.

219 METHODS OF DATA ANALYSIS

Dataanalysis initially resulted in the identification of the degree of change in measuredparameters at each study site. A numericalrating ranging from 0 to IO was assignedto indicate an increase(ratings IO through 61, no change (rating of 5) or a decrease(ratings 4 through 0). These ratings indicatethe degree of change atthe time of the site visit betweenthe pre-gravelremoval conditions (i.e., extent of shrub thicket cover, or number of passerinespresent) and the post-gravel removal conditions. Each numericalunit increase (6 through IO) ordecrease (4 through 0) approxi- mates an alterationsimilar to a 20 percentlevel of change in that param- e ter.

Each site was analyzed to determine how measuredparameters (vegetation,soils, birds, and mammals) interacted, and how theyresponded as a whole tothe Physical Site Characteristics (such as riversize and configuration) and Gravel Removal AreaCharacteristics (such as type and location of gravelremoval). After individual site analysis, all sites were compared toevaluate similarities and differencesin the degrees of change in biolog- icalparameters.

Fauna directlyrespond to the presence (and type) or absence of vegetative development,consequently, the degree of change and the rate of re- coveryat the gravel removal sites received major emphasis in the vegetative dataanalysis. Factors that influence vegetative recovery (e.g., soil conditions and aufeisdevelopment), also werethoroughly reviewed.

Selectedbiological data were subjected to a computerizedhierarchical clusteringroutine to identify similar responses in a measured biological

220 parameterbetween rivers. This analysis grouped similar sites and similar responses(increase or decrease)by biological parameters,

All datawere thoroughly reviewed to identify any correlationsbetween PhysicalSite Characteristics, Gravel Removal AreaCharacteristics, degree of changeby the terrestrialbiota, and short-term andlong-term recovery rates. The followingsections include the results of data collection and analysis.

22 I RESULTS AND DISCUSSION

Changes inselected terrestrial parameters that were induced by gravel removalare identified in Table 28. Thesechanges were based upon measured levelsof variation in eachparameter at each site. In general, the degree ofboth short-term and long-term changes in local faunal communities strongly reflectedthe extent of disturbance to floodplain and riparianvegetative communities.

VEGETATIVECOMMUNITIES OF STUDY AREA FLOODPLAINS

Vegetativecommunities of floodplain and riparian zones atthe study sites weretypical of those occurring throughout arctic and subarctic regions.In general, the Seward Peninsularivers and thesmaller North Slope riversusually were meandering or sinuous in configuration with well-defined (incised)outside meander banks(Figure 61). Thisconfiguration and profile created a relativelynarrow floodplain (30 to 60 m) andallowed extensive developmentof mature shrub thickets adjacent to single channel rivers. These shrubthickets usually were dominated by Salix alaxensis. On inside meanders (pointbars) and in more activeportions of floodplains (lateral and mid-channelbars) herbaceous, woody pioneer and earlywillow communities occurredadjacent to unvegetated gravels bordering the river.

Meanderingand sinuous rivers of the Northern and Southern Interior weresimilar in pattern andwere characterized by extensive shrub thic5ets with densestands of advanced and mature successional stage boreal forest communitiesat the edges of active floodplains (Figure 62). Whitespruce usuallydominated these stands, but paper birch andbalsam poplar also were common, Similarpioneer and early shrub successional stage communities occupiedpoint bars and edgesof lateral andmid-channel gravel bars.

222 Tabla 28. Qusntltstlve Changes In Selected Terrestrial Blologlcal Paraeters at Gravel RemDval Study Sltas'

L VI u1 X 3 0 .-> a ! ! a a a f t b X 3 - x X X I a f 1. w b I X > X X c: c & - > 2. + s' a t CI P 5 X X - 0 e x a n C - I H 0 > 0 C 4 0 5 b' 4 m X L t I- I-

V.g.t.tlon """" hU.tWy fWe6t """ 551514 14035 YVrO thickets SI1114 41511554133313 147t5 Lff I). dxed rhrub-hwb-s 9 6 7 3 7 4 54573554 337433 36735

Soll. Taxture 7797'16 54557556757587 16775 Ilutrtants 551563 556\53555 545555 55555

31It#J 51531553 131411 15135 536495 58566554 6'16595 95595 3t3s15 53531354 114413 11635

155373 57551557351500 47575 577575 65595556 65555555555 3I33L5 535311541144513 14634 Figure 61. Penny Riverundisturbed floodplain showing typi- calNorth Slope andSeward Peninsulafloodplain characteristics of sinuouschannel bordered with dense shrub thick- etswith incised outside meanderbank, and narrow gravel pointbar on inside meander.

Figure 62. West Fork Tolovana Rivershowing typical South- ern and NorthernInterior medium riverfloodplain characteristics with shrub thickets and whitespruce-paper birch standsalong the riparian zone.

224 The largerrivers within all fourregions typically flowed in braided or split channelconfigurations. These floodplains weremore hydraulically dynamic, with much wideractive areas, and contained advanced seral stage vegetativecomunities only along floodplain borders andon isolatedmid- channelislands. Much of thefloodplain in these large, braided rivers containedexpansive areas of unvegetated gravels or were sparsely vegetated withherbaceous and woody pioneeror early shrub thicket communities.

Thisvery briefly describes in general terms the normal vegetative patternsof floodplains in the area of study, For a more detaileddescrip- tionof normalpatterns, refer to the "Preliminary Report Gravel Removal Studiesin Selected Arctic andSub-Arctic Streams inAlaska" (Woodward-Clyde Consultants 1976) and for a detaileddescription of the vegetative structure whichoccurred at eachstudy site refer to the Project Data Base.

VEGETATIVE COMMUNITY CHANGES ATGRAVEL REMOVAL SITES

The observedchanges invegetative communities of the study sites variedfrom no significant change to long-term loss ofhabitat. Habitat loss and alteration(both short-term andlong-term) repeatedly resulted in signif- icantsecondary changes within the bird and mammal populationsthat inhab- itedstudy area floodplains. Thesefaunal responses are discussed in a fol lowing section.

Significantareas of existing floodplain vegetative cover were removed at 18 ofthe 25 sites(Table 28). Lostvegetative habitats usually consisted ofmature shrub thickets on the Seward Peninsula and North Slope sites, and a mixture of shrubthickets andadvanced successional stages of boreal forestfloodplain communities in Northern and Southern Interior regions. At all sitesthese habitats supported a diverse andabundant fauna dominated by passerines and small mammals priorto clearing andgravel removal activities.Refer to the Project Data Base for a completelisting of recorded flora andfauna at eachstudy site.

Vegetativehabitat removed atthese 18 sitesaveraged IO haand ranged fromapproximately I ha at Gold Run Creek to 35 ha atDietrich River- Upstream(Table 28).

225 Ingeneral, sites separated'from the active floodplain frequently disturbedthe most vegetative habitat as a percentageof the total disturbed area. For example,Table 28 identifies seven sitesthat were entirely (lorn) vegetatedprior to gravel removal and all wereseparated from theactive floodplain. At all seven sitesvegetative cover and associatedorganic overburdenwere completely cleared prior to gravel removal.

Lona-Term Loss ofVeaetative Habitats

Long-term loss of terrestrialhabitat occurred at those sites where: (1) thegravel extraction method (eitherpit excavation or deep scraping) removedgravel to depths that resulted in permanent flooding; or (2) the specificsite location and materialsite characteristics resulted in river hydraulic changeswhich annually affected the site.

PermanentlyFlooded Material Sites. Eight of thestudy sites were excavatedpits, either totally or in part (Figure 63). Pits variedfrom an

Figure 63. West Fork TolovanaRiver showing permanently floodedpit excavated adjacent to theactive floodplain with a downstreamconnection.

226 averageof 1.5-m indepth at the Penny Riverto over 7 m deep atthe Dietrich River-Upstream, West ForkTolovana River, andTanana River- Downstream sites. The pits wereeither connected or unconnected to adjacent activeriver channels, however, in all casesthey were permanently filled with pondedwater (Figure 63). Surfaceareas ranged from 7.5 ha at Tanana River-Upstream to 0.1 ha atUgnuravik River. Six of the eight sites were separatedfrom the active floodplain andwere completely vegetated with maturewhite spruce-paper birch and/or willow and aldershrub thickets prior toexcavation. At thesesites the depth andsubsequent floodingcreated aquatichabitats that led to long-term loss ofterrestrial habitats. At the twoother pit sites, the excavations occurred in unvegetated point bars (UgnuravikRiver) andunvegetated lateral bars (Kavik River). Thus, no vegetatedhabitat disturbance occurred.

Excavationof deep pits, however, was notthe only gravel removal methodthat led to development of permanentlyponded water and consequently thelong-term loss ofterrestrial habitats. The combinedgravel removal and sitelocation characteristics at the Jim River and Dietrich River-Downstream sitesalso led to permanentponding.

At the Jim River,gravel was scrapedfrom within and immediatelyadja- centto a high-waterchannel. The resultingprofile at the completion of the scrapingoperation resulted in an almostcircular depression in the middle of theworked area. The high-waterchannel traversed this depression. Since thischannel carries summer flow, it consequentlyhad formed an annually pondedarea of approximately 4.5 haover thiscentrally depressed portion of the II ha site.Before clearing andgravel removal, with the exception of theapproximately IO-m widehigh-water channel, this site contained a di- versecomplex of mature and intermediate-agedwhite spruce-paper birch standswith scattered willow and alderthickets.

The Dietrich River-Downstream site was scrapedto an averagedepth of I to 1.5 m in a rectangularshaped 7.5 ha. The area was separatedfrom the activefloodplain by approximately 150 m priorto the activity. However, the depthof excavation was theprobable cause of a permanentchannel change by a majorside channel of the Dietrich River. This channel entered the pre-

227 v i ous I y dry siteduring the second spring breakup following the activity. Th i s channe I changecaused flooding of approximately 90 percentof the materialsi te.This condition will remainas long as this side channel flows throughthe site.

Thus, atboth the Jim River and DietrichRiver-Downstream sites, mining depthand sitelocation characteristi csalso created permanently ponded aquatichabitats which will leadto I ong-term loss ofterrestrial habitats.

AnnualHydraulic Stress. In addi tionto the creation of permanently pondedsites, long-term loss and alterationof habitat occurred at sites wherethe gravel removal operation resulted in significant changes in river hydraulics. Examplesof such changes include shifted channels, annually floodedsites, and aufeisdevelopment within the material site.

On the SewardPeninsula, the Penny River and Oregon and Washington Creeksare small rivers with relatively narrow, densely vegetated floodplains. Penny River andWashington Creek flowed in a sinuousconfiguration, while OregonCreek flowed in a straightconfiguration. The portionof the totaldisturbed area which was vegetatedby dense, matureshrub thickets priorto disturbance at each site was extensive(Oregon Creek 65 percent; Penny River 80 percent;and Washington Creek 85 percent) (Table 28). At all threesites, the working area (which was scraped to a levelequal to or slightlybelow normal water levels) extended across the entire floodplain and at Washingtonand Oregon Creeks the disturbed area extended approximately 9 to 15 m beyondthe floodplain banks and intothe adjacent shrub- tussocktundra. The resultingeffect of these scraping operations created: anunvegetated, flatfloodplain which was 2 to 3 timeswider than upstream ordownstream reaches; a floodplainthat wasequal to, or only slightly higherin elevation (IO to 20 cm onthe average) than normal summer flows; and a widerchannel with increased braiding, straighter configuration and shallowerflow (Figure 64).

The effectsof these induced hydraulic changes created direct impediments tovegetative recovery andthus they also resulted in long-term alterationof the habitat structure of the disturbed reach in these floodplains.

228 Figure 64. A viewof Oregon Creek looking downstream throughthe mined area showing site conditions that remain I3 yearsafter gravel removal.

The specificchanges that retarded vegetative recovery anddevelopment at thesesites were related to induced aufeis development - and increasedannual high-waterstresses.

At Washingtonand Oregon Creeks, extensive aufeis fields annually developedwithin the material sites. This ice, which is known tolast until late Junethroughout the d-isturbed areas, severely impeded vegetative recov- eryat these sites. No significantvegetative communities had developed withinthe disturbed areas of either site during the 13 yearsfollowing the gravelremoval operations.

There is noevidence of aufeis development at the Penny Riversite. However, thearea was scrapedin an irregularsurface pattern over 15 ha to a depthequal toor slightly below normal summer flowlevels (Figure 65). The site was v isited II yearsafter gravel was removed. As a result of the d eP th of scrap ing, much ofthe site contained either small pools ofponded

229 Figure 65. Penny Rivermined area looking upstream. Note theflooded conditions within the disturbed area, and theoverburden piles in the center of the site (circled on photograph).

water or watersaturated sa ils. A sma II 0.6 ha, 1.5 m deep pit was dug in thesoutheast corner of the site. The hydraulicanalysis shows thatthe Penny Riversite is flooded forshort durationsduring higher flows on an annual and possibly semiannualbasis. Flowsof only approximately 150 percent of mean annual flowbegin to flood the material site.

Duringthe II growingseasons following the disturbance, only sparse, scatteredpioneer and earlywillow floodplain communities haddeveloped withinthe scraped portions of the Penny Riversite. These early succes- sionalhabitats werenot present in the undisturbed floodplain reach which, as previouslystated, consisted almost entirely of mature shrub thickets. Thus, thestructure of the vegetative community withinthe mined site changed forthe long-term from one dominatedby dense matureshrub thicket habitatsto one dominatedby scattered and low-densityimmature herbaceous and woody speciesthat are adapted to wet soilconditions. Repeated stress fromannual or semiannual high water, combined with the continuously

230 water-saturatedsoils over much ofthe Penny Riversite, were probably the keyfactors impeding vegetative recovery (especially by woody species).

Anotherexample of gravel removal and site location characteristics whichresulted in known short-term(the site was visited 3 yearsafter disturbance),and probably long-term annual hydraulic stress occurred at the SagavanirktokRiver study site. At this site 20 ha of a complexmixture of matureand advanced, seral-stage shrub thickets was removedand the under- lyinggravels excavated to anaverage depth of 1.5 m. Thisarea was located between a high-waterchannel and the main river channel. The Sagavanirktok River was a largeriver with moderate channel slope that flowed’ in a sinuous configuration.

Thisgravel removal operation resulted in a permanent shift of much of themain channel through the material site. Hydraulic analysis at this site shows thatextensive flooding is expectedto occur on anannual basis withwater potentially influencing the site for up to 70 dayseach year.

The site was visitedduring the third growing season after disturbance, andno vegetative recovery had occurred. As longas the river continues to flowthrough and annuallyflood the material site, it isnot expected that significantvegetative recovery will occurin the long-term.

Short-TermAlteration of Vegetative Habitat Structure

Short-termalterations, in the typesof vegetative habitats present withindisturbed areas, occurred at those sites where vegetation was removed, butwhere some naturalvegetative recovery began within I or 2 years post-miningand continued thereafter unimpeded. At noinstance did an entire disturbedarea naturally revegetate over the short-term, However, inpor- tionsof 13 sitespioneering communities became wellestablished within I or 2 years(Table 291. Thisdevelopment most frequently occurred in those portionsof the disturbed areas which: were not influenced by normal or high waterflows; had a plentiful seedsource or contained root stocks and other woody slash;and/or consisted of well drained but moist soils with high silt

23 I Site age at L oc at ion of first of ionLocat Comnun i t y initiationof S ite vegetative recovery characteristics vegetative recovery vegetative characteristics recovery vegetative Site I years 1

Go1 d Run Creek Overburden pi les Herbaceousshrubs)(few Unknown SinukRiver Overburden pi les Herbaceous with woody Unknown shrubs Wash ingt on Creek Overburden piI es Herbaceous with woody shrubs Penny River Overburden pi les Herbaceous with woody shrubs Aufeis C reek Broadcastslash and debris Herbaceous with woody Iu at edge of floodplain shrubs Crr I’ SkeetercakeCreek Jnside meander of abandoned shrubs)Herbaceous (few 2 channel MF KoyukukRiver-Downstream Broadcastslash and debris Herbaceous w i th woody I at edge offloodplain shrubs Jim River Slopingbanks above ponded Herbaceous with woody water shrubsand trees ProspectCreek Slopingbanks above ponded Herbaceous with woody water shrubs and trees West Fork TolovanaRiver Slopingbanks above ponded Herbaceous with woody wa t er shrubsand trees McManus Creek Overburden pi I es Herbaceous with woody shrubs TananaRiver-Downstream Overburdenpiles surround i ng Woody shrubs pondedwater TananaRiver-Upstream Overburden pi les surround i ng Herbaceous with woody 2 pondedwater shrubs andsand content. The resultsof soil sampleanalysis indicated soil nutri- entswere not limiting factors influencing vegetative recovery at any of the 25 studysites.

The initialrecolonization of these disturbed areas most frequently occurred byseed development; at several locations, however, willows had reinvadedthrough development of adventitious stems and rootsfrom old woody slash and rootstocks. Adventitious stem development occurred most often in overburdenpiles where woody slash was placed. All overburdenpiles occurred insites developed before 1971. Morerecent regulation of gravelremoval activitiesrequire overburden and woody coverto be removedcompletely from floodplainsites.

Ingeneral, herbaceous species dominated in those pioneer communities whichwere developing from seed. However, Salix alaxensis was a frequent member ofthese communities in all four geographic regions, and seedling

Betulapapyrifera andPopulus balsamifera commonly occurredin pioneer communitiesat several Northern Interior sites. Taxa that most oftenwere dominant inthese invading communities included Epilobium latifolium, Salix alaxensis,Salix spp., Equisetumvariegatum, Stellaria spp., Hedysarum Mackenzii,Astragalus spp., Oxytropis spp.,Juncus spp., Carex spp., Eriopho- -rumspp., Calamagrostis spp., and -Poa spp. Insoi Is thatwere less moist and morecoarse, Artemisia spp., Crepis nana, Aster sibiricus, and Erigeron spp. frequentlyoccurred as initial invaders.

Overburden was piledeither within the disturbed area or at its edge at many ofthe older sites. At the Penny River andWashington and McManus Creeksthese overburden piles contained many organicsand woody slash,root stocks,and debris. At Penny River,three piles of material were located withinthe 15-ha site(Figure 65). At WashingtonCreek, one pile was p4aced inthe middle of the 3-ha site andone on its edge,and at McManus Creekthe organicoverburden was all piled onthe edge of the 4-ha disturbedarea. These pilesaveraged I to 2 m inheight, however, a fewwere 5 to 7 m (Figure 66).

At allthree sites, herbaceous and woody vegetationwere well established onthe overburden piles within I yearafter disturbance. Development

233 Figure 66. Close-upview of an overburdenpile in the Penny Rivermined area. Note the development of herbaceous and woody vegetationduring the II yearsfollowing gravel remova I

onthese piles preceded other disturbed area revegetation at Penny River and McManus Creek by approximately 6 to 7 years. At WashingtonCreek, which was visited 13 yearsafter disturbance, the only significant revegetation of the siteoccurred on overburden piles (Figure 67). At all sites,the initial

Figure 67. WashingtonCreek mined area showing vegetative recoveryonly present on theoverburden pile 13 years aftergravel removal.

234 shrubdevelopment was throughadventitious stems (Figure 68 1 , Willows, primarily -S. alaxensis, most frequently developed from o Id s lash and root stocks.

a. View of broadcastslash and 2-year-old stems.

b. View of old rootstock with new stem.

Figure 68. Woody revegetationoccurring through development of adventitiousstems.

235 Similarrapid developmentof woody shrubsthrough adventitious stem developmentoccurred in I- to 2-ha area3at both Middle Fork Koyukuk River- Downstreamand Aufeis Creek studysites. However, at thesesites the slash and woody debris were notpiled, but werespread over the ground at the edge of thedisturbed areas (Figure 69).

Figure 49. Distribution of woody slashdebris and other organicsover the ground on the edge ofthe gravel removal areaat Aufeis Creek.

At the Tanana River-Downstream site overburdenfrom the 5-ha pit was placed--incontoured banks surrounding the flooded pit. These overburden piles wereapproximately 2 to 3 m deep inverselypiled (top material covered by bottommaterial), and consequentlycontained no organics or woody remains nearthe surface. However, an earlyshrub communitydominated by Populus balsamifera, -S. alaxensis, and -Ainus crispa, with a density of 230 stems per 0.004 ha, was presentduring the fourth growing season following gravel removal.This shrub community developedfrom seed and invaded in mass during thefirst growing season. The shrubsoccurred in uniform density over approximately 60 percent of thegently-sloped, 20 to 25 m wideoverburden banks surround ing the' p i t .

Rapidnatural recolonization of disturbed areas was notalways limited to overburdenpiles. At the Jim River, West Fork TolovanaRiver, and Prospect Creek, pioneercommunities were well developed at the end ofthe

236 first full growing season followingdisturbance. At thesesites the communities weredeveloping on thecontoured side slopes of the permanently ponded areas. An average of 13 species,with a range of 7 to 21 species, occurredin 0.0004-hasample plotslocated in these habitats during the second (Jim River and ProspectCreek) and third (West ForkTolovana River) growingseasons following disturbance. Willows, alders, birch, and spruce occurredwith the herbaceous taxa in these habitats at all three sites. Althoughthese sites have not been inspectedsince 1978, thepioneer com- munitieswill probably develop unimpededand quicklylead to early and advanced seralstage shrub communities.

The Tanana River-Upstream site was very similar to the West Fork TolovanaRiver site with respect to Physical Site Characteristics and Gravel Removal Areadharacteristics. The mined site was IO yearsold during site inspection, and 13 yearsold at the time of datacollection (sumner 1978). Shrub thickets dominated by -Salixarbusculoides and Alnustenuifolia had developedsurrounding much of the pit andon spits and islandswhich remained above thewater level of the upper pit (Figure 70). These comnunities had

Figure 70. View ofthe upper pit at Tanana River-Upstream showing diversity of shorelineconfiguration'and development of woody and herbaceousvegetation 13 yearsafter gravelremoval.

237 reachedan advanced shrub stage with densities as high as 990 stemsper 0.004 haby the 13th year. Thickets averaged 2 to 3 m inheight. During site inspectionthese thickets most likely wereequally as dense and practically as tal I.

At mostabove mentioned sites, following rapid invasion anddevelopment ofpioneer communities (both by seed and adventitious stems), early shrub communitiesusually were well established in 3 to 5 years. The majorityof theseareas were small (0.5 to 2 ha) andwere usually scattered throughout thescraped sites or surrounding the flooded sites. Usually only one to threeisolated patches of early shrub communities occurred in the scraped sites, Those sitesthat were of sufficient age (including Penny River, OregonCreek, Washington Creek, Sinuk River, McManus Creek,and Tanana River-Upstream)began toprovide sufficient cover for nesting andfeeding passerines and summer and wintercover for small mammals about IO years afterinitial disturbance.

Thus, atsites that provide areas (of various sizes) for revegetative growthwithout severe stresses from flooding or aufeis scour, -habitats that providedfood and cover for passerines and small mammals (primaryshrub thicketoccupants) were naturally replaced about IO yearsafter completion of gravelremoval activities.

No Sianificant Chanae inVeaetative Habitats

Contrastedto long-term loss ofhabitat and short-termalteration of habitatstructure are gravel removal operations that resulted in no measur- ablechange inthe vegetative structure of the study areas.

Gravelmining did not affect vegetation at 5 of the 25 studysites, eitherbecause of the disturbance location, or thefloodplain characteristics,or both (Table 28). At twoadditional sites, the Nome River and KavikRiver, only slight reductions in vegetative cover were observed.

Threeof the five sites with no vegetative disturbance were large flood- plainswith large- andmedium-width channels flowing in braided patterns. At

238 allthree sites large quantities of gravelwere removed by shallow scraping surfacelayers over a broadarea. Specifics on these sites are:

Study site Scraped sur face area Quantityof gravel removed

3 lvishakRiver 40 ha 120,000 m 3 KuparukRiver 14 ha 42,000 m 3 PhelanCreek 70 ha 575,000 m

Although Phe IanCreek was a wide(approximately 1,000 m) unvegetated floodplain, and t he lvishak andKuparuk Riversalso hadextensive unvegetatedgravel bars, the latter two sites also contained numerous islandswith denselyvegetated shrub thicket stands (Figure 71). At thelvishak River and

Figure 71. View of thelvishak River floodplain looking downstreamshowing typicalbraided channel characteristics withextensive gravel bars,and isolated, vegetated islands.

KuparukRiver sites, operators conformed the configuration of their gravel removalareas to avoid the vegetated islands. At thePhelan Creek site, gravel was scrapedfrom a uniformlyshaped and contiguous area, because the floodplain was entirelyunvegetated within the work area.

239 The best example of avoidingdisturbance to vegetated areas on a meandering or sinuousriver occurred at the Shaviovik River study site (Figure 72). Thisriver flowed in a medium width,single channel and in a sinuous

Figure 72. View ofboth undisturbed (background) and mined (foreground)reaches of theShaviovik River. Note that gravelremoval maintained natural point bar contours and shapes and didnot disturb riparian vegetative zones.

configuration.With these characteristics the floodplain consisted of broad (averagingapproximately 40 to 50 m inwidth) unvegetated point bars at everyinside bendand numerous unvegetatedlateral bars located between pointbats. Gravel removal consisted of shallowscraping on everypoint bar and lateralbar over a distanceof several river kilometers. Small quan- 3 tities were takenfrom each location, however, a total of 116,000 m was removed,

The actualscraping of unvegetated gravel deposits throughout most of theShaviovik River site was conducted in a manner that causedminimal, or no biologicaldisturbance. Gravel bars were scraped only in their unvege- tatedportions and riparianshrub thickets werenot disturbed. Also, the miningoperation maintained natural contours andshapes on gravelbars and

240 didnot mine adjacent to the river. Thus, theShaviovik River has maintained itsnatural channel and configuration.

FACTORSAFFECTING VEGETATIVE RECOVERY RATE

Severalfactors found to be influencing vegetative recovery already havebeen discussed. The compositionof faunal communities using disturbed areas was directlyrelated to the habitat, types available, thus, anunder- standingof how factorsat the study sites influenced the rate of natural vegetativerecovery warrants further discussion. Overburden piles, woody slash, and debris, an abundantseed source, and displaced organic mats enhanced recoveryrate, Hydraulic stress such as aufeis development, permanentponding, actual channel shifts, and increasedflooding impeded development. Soilconditions andgrowing season, depending upon sitespecific characteristics,either enhanced or impeded vegetativerecovery.

Impediments

Among thefactors believed to be impedingvegetative recovery, hydrau- licstress influenced most sites andhad the strongest and most long-term effect. These stressesresulted from changes induced by gravel removal infloodplain elevations, dimensions, and configurations. They included:

0 Permanent or annualflooding, Increasedfrequency and duration of temporaryflooding, a Long-termchannel changes (increased braiding and channel width and decreasedchannel stability), and New orincreased aufeis development.

The specific knowncauses forthese induced hydraulic changes are presentedin detail in EFFECTS OF GRAVELREMOVAL ON RIVER HYDROLOGYAND HYDRAULICS. Ingeneral, they most frequently resulted because sites were excavatedtoo deeply (excluding pit sites) without maintaining buffers or stablechannel banks, or because the gravel removal method and characteristics werenot correct for the chosen location.

24 I At 13 sitesthe gravel removal method led to significant hydraulic changes thatsecondarily impeded thevegetative recovery rate (Table 30). Permanentlyponded water and aufeis -development caused the most significant impediment.Permanently ponded water occurred at thosesites wherethe miningplan called for excavated pits, but also at sites wheredepressions werescraped below summer waterlevels. The latteroccurred at sites that were directlyconnected to an activechannel (Jim River); at sites that were notdirectly connected to an activechannel (Penny River); and atsites that wereoriginally not connected, but where gravel extraction caused an active channel toreroute through the deep depression(Dietrich River-Downstream).

Aufeis impeded vegetativerecovery at foursites (Washington Creek, OregonCreek, MiddleFork KoyukukRiver-Downstream, and Jim River), all of whichwere directly connected to active channels. Aufeis development is believedto occur annually at all sites, and affectsthe entire disturbed areaat Washington Creek andOregon Creek and most likelyaffects much of thedisturbed areas at JimRiver and MiddleFork KoyukukRiver-Downstream.

Two additionalfactors were impediments to vegetative recovery under certainconditions: soil condition andlength of growing season. Vegetative recovery was occurringto some degreeunder a widevariety of soil type, texture,nutrient, and moisturelevels. Differences in the degree of developmentand thespecies composition reflected the wide range of xeric andmesic soilconditions. Soil nutrients were not found to be limiting factors at any siteregardless of its age, originalcondition, or final condition. However, vegetativeinvasion was restricted by verycompacted surface layers at severalof the more recent sites. Theseareas most frequently were associatedwith access routes over gravel surfaces leading to andfrom the mined sites. At Dietrich River-Downstream,heavy equipment compacted the floodplaingravels approximately 25 cm adjacentto the gravel removal area (Figure 73). This site was visited 3 yearsafter completion and vegetation hadnot invaded this access road although the unflooded banks of thematerial site weresupporting pioneer communities.

Anothersoil condition which restricted vegetative development 13 years after site work,occurred at Oregon Creek. Inorganic materials were scraped

242 Table 30. Quantif icat ion of Change inSelected Hydrology Parame ters Which Were Impeding VegetativeRecovery at Study Sitesa

Hydrologyparameter Study iite - Age Channe I F 1 Pondedooded Aufeis in years potentia area areawidth Braiding I

SinukRiver - t0 9 8

Washington Creek - I3 IO IO

OregonCreek - 13 9 8

Penny River - 11 10 IO

Nome River - 20 10 7

10 P UgnuravikCreek 7 IO 8 w - Aufeis Creek - 5 IO IO

Skeetercake Creek - II 8 IO

SagavanirktokRiver - 3 IO 8 IO - -

Dietrich River-Downstream - 3 - - 7 7 -

MiddleFork Koyukuk R.-Upstream - 4 IO 7 9 8 -

MiddleFork KoyukukR.-Downstream - 2 8 9 IO 7 8

Jim River - 2 - IO 10 8 8

a Refer to EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND HYDRAULICS for explanation of parameters and quantification of changevalues. Figure 73. Compacted surfacegravels in an accessroad leadingto the Dietr chRiver-Downstream site.

fromthe site and placedin pilesalong the northern boundary of themined area(Figure 74). Pilesof hismaterial supported no growth, while adjacent

Figure 74. Inorganicoverburden piled on the edge of theOregon Creek sitewhich supported no vegetation 13 yearsafter grave I removal.

244 piles of organics, silts and sandssupported advanced seralstage shrub thickets. The undesirablematerial was of unknown substance,but appeared to be a mica-like material.

The averagegrowing season varies from approximately 130 to 150 days in thoSouther Interior, from 100 to 120 days on the Seward Peninsula, and from 75 to 95 dayson the North Slope (Mitchel personal communication). This factor was believedto be stronglyinfluencing the rate.of vegetative recov- eryat the twomost northernstudy sites (Ugnuravik and Kuparuk Rivers). Bothsites were only 6 km inlandfrom the Arctic Ocean and at both sites vegetativerecovery in nonflooded areas was progressingvery slowly even when compared to similarly aged NorthSlope sites (7 and 9 years)located 80 to 90 km inland.

Enhancements

Severalfactors were found to enhance vegetativerecovery, the most significantof which appeared to be the presence of organic soil with woody slash and debris.This material was most effective when placed in piles that werehigher than frequent flood levels, or broadcast in those portions of thedisturbed site where-it would not get washed downstream orfrequently flooded by highwater.

Overburden pilesoccurred at II ofthe 25 studysites, however, onlyat thosesites where this overburdencontained organics with fine textured soils (silts and sands) and woody slash and debris, was vegetativerecovery mostenhanced. Insteadof being placed in piles, this material was broadcast overthe surface at two additional sites (Aufeis Creekand MiddleFork KoyukukRiver-Downstream). At bothsites, this material was placedin areas where it was notstressed by highwater levels. At bothsites these 2- to 4-ha areaswere the firstto begin natural revegetation and supportedthe most diverse andmost developedcommunities. Revegetation began the first growing season followingcompletion of gravel removal at both sites. Develop- ment of adventitious stems was theprime method of revegetationby willow (Figure 75).

245 Figure 75. Close-up of denseand diversevegetative development in an areaof surface broadcast of woody slash andorganics. Note the willow advent'itious stem development.

Otherfactors that enhancedvegetative recovery were' the presence of siltdeposits, an abundantseed source, and the deposition or grounding oy displacedorganic vegetative mats.

At severalsites (including Kavik River, Skeetercake Creek, Kuparuk River,Sagavanirktok River, and Dietrich River-Downstream) the deposition of pockets of silt in lowdepressions within the disturbed areas quickly led to thedevelopment of a pioneercommunity dominated by wetlandplants adapted to wetand silty soils. Theseareas frequently were dominated by Carex spp., Juncusspp., Eriophorum spp., Equisetum spp., and Salix spp. (Figures 76 and 77). Theirsire was highlyvariable anddependen.t upon rivercharacteristics (suspendedload) and sitecharacteristics (disturbed area profiles and shapes 1.

At several of thepermanently ponded sites (Jim River,Prospect Creek and West ForkTolovana River) the development of herbaceous and woody plants was foundto be frequentlymost concentrated at old andrecent high water

246 Figure 76. Distantview of a large siltdepositional area atthe Sagavanirktok River study site.

Figure 77. A siltdepositional area of theKavik River supporting a well-developedpioneer vegetative community.

247 lines(Figure 78). These waterbodies concentrated available seeds on their surfaces and thendeposited them al'ongthe shoreline.

Figure 78. Close-up of .a concentrationof willow seedlings atthe shoreline of the Jim River ponded area.

The erosion, downstream transport, and subsequent depositionof large, intactvegetated organic mats also was found toinitiate vegetative recovery. ofgravel mined sites (Figure 79). However, thisprocess was notoverall significant because it most oftenoccurred on a smallscale and was not widespread. It most frequentlyoccurred in the larger moredynamic rivers. Most observationsof this occurrencewere of-mats that were believed to have been deposited I or 2 yearsprior to site visits. In the type of river where they most frequentlyoccurred, they were vulnerable to continued downstream movement duringfloods. However, in a few locationsthe root systems of woody specieshad penetrated the underlying gravels and thesemats appeared to be firmly establ ished.

FAUNAL COMMUNITY CHANGES AT GRAVELREMOVAL SITES

Terrestrial fauna eitherdisplayed no response to gravel removal opera- tionsor displayed one offour different reactions depending upon fauna

248 F i gure 79. Vegetatedorganic mats that were washed downstream and grounded duringhigh water on ToolikRiver f loodp laingravel bars.

type,habitat preferences, and home range size. Most responseswere directly relatedto the removalof floodplain vegetation. A response was recordedat 19 of the 25 studysites (Table 28). In all caseswhere no differencesin populations(particularly birds and small mammals) wererecorded, vegetation was eithernot removed(Kuparuk, Ivishak, and ShaviovikRivers and Phelan Creek)or only very sparse vegetative cover was removed(Ugnuravik River and MiddleFork KoyukukRiver-Downstream).

At those sites where significantquantities of floodplain Vegetation were removed, faunalresponses basically consisted of four different reactions:

e PopulationReductions - passerines and smallmamals responded to the loss ofvegetative habitats.

0 PopulationIncreases - waterbirds and groundsquirrels responded to theremoval of heavy vegetative cover, and, inthe case of ground squirrels, also tothe presence of overburden piles.

249 a AlteredD.istribution - overwintering moose and ptarmiganmost likely respondedto the reduction of food andcover habitat provided by floodplainthickets, by eitherincreasing their winter reliance upon adjacentundisturbed thickets, or by shifting their local winter distribution and movement patterns.

No ApparentResponse - large mammals (such as caribou,bears, and wolves) showedno significantresponse to floodplain alterations createdby gravel removal operations.

PoDulationReductions

At 18 of the 25 studysites significant areas of vegetated habitat were removed priorto gravel mining. These habitatsusually were of advancedor maturevegetative stages andwere dominated by a diverse andabundant passerine and small mammal community in all fourregions. In Southern and Northern Interiorregions red squirrels also were dominant members ofthese communitiesat sites that contained stands of mature spruce, or mixedspruce and birch.

On theNorth Slope andSeward Peninsula, the passerine'populations inhabitingriparian shrub thickets most frequentlywere dominated by yellow warblers,Wilson's warblers, orange-crowned warblers, white-crowned sparrows,fox sparrows, tree sparrows, gray-cheeked thrush, American robins, common redpolls, andyellow tails.Although population sizes werenot est,imated,at sites with ex tensivedevelopment of riparian shrub thickets as many as 50 individualbirds of 13 specieswere present in an areaof approximately 3.5 ha(Penny River) . In Southernand Northern Interior sit.es, many ofthe abovepasserines werejoined by yellow-rymped warblers, gray jays, black-cappedchickadees , dark-eyedjuncos, and alder flycatchers.

At many sitessmall mammals also were common to abundant inheavily vegetatedhabitats. Tundra voles were the most frequently captured species, andwere recorded in all four regions. Theywere captured in a widevariety of vegetatedhabitats andappeared to bemore tolerantthan other small mammals ofthe low-lying habitats which frequently contained water saturated

250 soils.Singing voles andred-backed voles also were commonly capturedin all regions.Most singing voles were captured in habitats that were more removed fromthe active portions of the floodplains, while red-backed voles were mostabundant inthe mature spruce-birch forest of theInterior sites.

Themost importantaspect of clearing advanced andmature shrub thickets and spruce-birchstands was theloss of feeding, nesting, and cover habitatsfor passeri.nes and small mammals. No small mammals wereobserved or capturedin unvegetated or sparsely vegetated portions of di'sturbed areas at any ofthe 25 studysites. Also, passerinesdisplayed no direct association withthese areas, and only were observed on a fewoccasions. feeding or drinkingin these habitats. As identifiedin previous sections, characteristics of thegravel removal operation5 and subsequent hydraulic changes most frequentlyresulted in long-term loss of terrestrial habitats. Thus, the local passerine and small mammal populations,primarily at the larger sites, most likelywere significantly reduced as a result of lost habitat.

PopulationIncreases

At some sitesthe gravel removal operation created habitats that were more desirableto some speciesthan predisturbance habitat conditions. Populationlevels of waterbirds (including waterfowl, shorebirds, gulls, and terns)increased within the disturbed area at 12 sites(Table 28). These sitesincluded those where mining resulted in permanently ponded areas (such as Jim River, West ForkTolovana River, or Tanana River-Upstream)and where miningremoved dense vegetation creating ponded water or backwater areas and/or mud flat and gravelbar habitats (PennyRiver and Aufeis Creek). These habitatsprovided the preferred feeding and nestingareas for these birds.

Many ofthe most significant increases occurred at sites where the adjacentupstream and downstream floodplain was heavilyvegetated, and the gravelexcavation provided habitats that were not readily available in the immediatefloodplain vicinity (Penny River, West ForkTolovana River, and Tanana River-Upstream).Birds that were most frequently associated with gravel and mud flathabitats in material sites included semipalmated

25 I plovers,Arctic terns, western sandpipers, ruddy turnstones, spotted sandpipers,glaucous gulls, northern phalaropes, and semipalmated sandpipers. At sitesthat provided desirable conditions, primarily abundant food supplies, thedisturbed areas supported abundant shorebird populations. At the Penny River,56 individuals of 8 speciesof water birds were using the 15-ha mined siteduring the nesting season, whileat Aufeis Creek 100 individuals of I3 species of waterbirds were present within the site during the post-nesting period. At bothstudy sites, these numberswere a severalfactor increase overthe numbers ofindividuals and speciespresent in the undisturbed reachesof these floodplains.

Floodedpits provided feeding and/or nesting habitat for waterfowl (mostfrequently green-winged teal, mallard, red-breasted merganser, pin- tail,bufflehead, and Barrow'sgoldeneye). Tree, violet-green, and bank swallows,Arctic terns, mew gulls, and herringgulls also were frequently observedfeeding in these pits.

At seven sitesground squirrels were found to bemore abundant within thedisturbed areas than within adjacent undisturbed zones (Table 28). At sixof the seven sites this response was directlyrelated to the presence of overburdenpiles located within or at the edge ofthe material sites. These pilesprovided denning sites, convenient observation posts, and thefirst availablefood source (through vegetative development) within the mined s-ite. At severalsites (Washington Creek, Penny River,and Skeetercake Creek)the only ground squirrels observed were in the mined site.

Inaddition, at West ForkTolovana River, TananaRiver-Downstream, and TananaRiver-Upstream, beaver were actively using the ponded waters in these pits.Muskrat also were encountered at the TananaRiver-Upstream pit.

AI tered Distribution

Moose and ptarmiganconcentrate many of theirwinter activities in dense floodplainthickets. Evidence of their past presence was recordedat most sites and inall four regions. Theseanimals normally move throughout largeareas, hence the localized removal of vegetated habitat was not be-

252 Iievedto have significantlyaffected their population levels. However, at sites wherelarge areas of vegetati'on were removed (including Dietrich River-Upstream,Sinuk River, Sagavanirktok River, Penny River, andJim River)the 105s ofhabitat may influencethe winter distribution and movement patternsof these animals.

No ApparentResponse

Mammals thathave large home ranges(including bears, caribou, wolves, and foxes)generally displayed no apparent attraction to or avoidance of the disturbedfloodplain areas. Hence, theonly apparent effects of gravel removalon these animals would be those associated with reducing their cover andfood supplies (vegetation, sm'all mammals, passerines,and fish) or increasingtheir cover andfood supplies (water birds, ground squirrels, and fish).

An exceptionto this pattern was recordedat a few ofthe sites located alongthe Trans-Alaska Pipeline corridor. At thesesites (Jim River, Dietrich River-Upstream, West ForkTolovana River, and Middle Fork Koyukuk River-Downstream)individual bears and wolves have become attractedto these areasby associating them withdiscarded food and garbage.

FACTORSAFFECTING RECOVERY RATE OFFAUNAL COMMUNITIES

Forspecies whose populationswere reduced as a resultof gravel mining,specifically passerines and small mammals, therate at which they began torecolonize disturbed areas was directlyrelated to redevelopment of vege- tativehabitats. Vegetative recovery was most directlyinfluenced by hydraulic parametersas discussed in previous sections.

At sitesthat were of sufficient ageand containedsufficient vegetativerecovery, passerines did not begin to again usethe disturbed areas as nesting and feedinghabitat until shrub thickets of an intermediatestage withdensities approaching 200 to 300 stemsper 0.004 haand 1.0 to 1.5 m in heightwere present. In addition, small mammals didnot begin to usevege- tatedareas as primary habitats until the ground cover developed to a multi- layeredcover with densities of at least 60 to 70 percentsurface coverage.

253 As statedin discussions of vegetative recovery, some sites began to providehabitat of this level in portions of the disturbed areas approximately IO yearsafter disturbance. Most frequently this occurred in overburdenpiles. At foursites (Sinuk River, Washington Creek, Penny River, and KavikRiver), the only significant use of the disturbed area bypasserines and small mammals occurredat the overburden piles even though these sites averagedover IO yearsin age.Thus, atsites wheregravel removal created a sitesubject to frequent hydraulic stresses, overburden piles not only providedareas for rapid vegetative recovery, but frequently provided the firstuseable nesting, feeding, and coverhabitat for passerines andsmall mammals. All vegetatedoverburden piles were found to be of sufficient sizeto support at least one pairof nesting passerines andone resident small mammal. The smallestOverburden pile sampled was approximately 9 m x 15 m, whilethe largest was approximately 15 m x 100 m. As was anticipated, thelarger piles supported the larger populations

PERMANENTLYPONDED SITES

Many gravelremoval operations resulted in 5 I gnificantlong-term loss and reductionsin vegetative habitats and associatedpasserine and small mammal populations. However,one gravelremoval method frequently led to an increasein local habitat diversity, even though it resultedin a permanent changefrom original habitat conditions. This increased habitat diversity alsofrequently led to increased fauna diversity. This method created perman- entaquatic habitat either by excavating a pitseparated from the active floodplainor byscraping a deep depressionadjacent to an activechannel. Eightsites provided this lacustrine habitat. (Note: the Kavik River and UgnuravikRiver pits were not considered in this evaluation; the Kavik River pit had filled in prior to the site visit and theUgnuravik pit was very sma I I (IO to 15 m indiameter) and primarilycovered with main channel flow.)

Severalparameters at pit sites were qualitatively evaluated (Table 31 1 Increasedfauna use was associatedwith those ponded waters that had hig bordercover, irregular pit shape, vegetatedor graveled islands, high foodavailability, and a diversityof water depths. Also, pitsize apparently was a limitingfactor, because both Penny River andProspect Creek

254 Tabte 31. QualitatlveEvaluatlon of HabitatQuallty andFauna Use at Permanently Ponded Gravel Removal Sites

Rank by Detrital habitat valp Pit Border Pit IsI ands Mater Food organics Fauna Site Idiversity) Age sire tower shape present depth avai labi I i ty present use

Tanana River-Upstrean I 13 yrs 7.5 ha High L Very VegetatedDiverse Abundant L Migh Very high dtverseIrregu-grave1 diverse & di verse lar & diverse

Dletr ich Rlvw-Downstream 4 3 yrs 6.5 h8 Low Irregu- None Sbal low Abundant High Medium I arbirds water benthos

W%sl Fwk TolovnnaRiver 2 3 yrs 4.5 ha hdlm & Irregu- GravelDiverse Abundant & HighHigh & div e rse tar diverse diverse diverse tar diverse

Tanana River-Downstrean 8 4 yrs 4.25 ha Medium Regular Mone Very Low VeryVery low but Low deep laW quality

Jim River 3 2 yrs 4.1 ha Medium & Irregu- None Shal Iwv Abundant L HIgh High diverse l8r birds water d i verse

Dietrlch River-Upstream 7 2 yrs I .8 ha LaW Regu bar None Deep Very low Very Very Iow lovl

Prorpec t Creek 6 2 yrs 1.0 ha Medium L Regular None Shsl low Abimdant & High Lovr d iverse diverse

Penny River 5 It yrs 0.6 ha cow Regu I ar None Shallow Abundant & High Low d I verse

"A subjectiveevaluation and relatlve ranki.ng of ovdrall habitat quality based upon habitatparameters of bordercover, pit shape, presence of waterdepth, food avai labi I I ty, andpresence of detrital organics. appeared toprovide adequate habitat with sufficient food supplies but both received lowfauna use. They were both 1.0 ha or lessin size.

The TananaRiver-Upstream pit,which was 13 yearsold, provided the most desirablelacustrine habitat. This 7.5-ha pit had a veryirregular shoreline with heavyvegetative cover; contained numerous shrub-thicket vegetatedislands in its southernhalf (upper pit) and graveledislands in itsnorthern half (lower pit); had anabundant food supply dominated by fish and macroinvertebrates; andhad a varietyof deep and shallowwater zones (Figure 80). Duringthe site visit 147 individualbirds of 39 specieswere

Figure 80. TananaRiver-Upstream showing shoreline diversity and vegatativedevelopment in the upper pit.

recordedin the entire study area and fourindividual beaver, at least two muskrats, and three moose wereobserved using the pits. The avifaunaobserv- ed we identifiedin Table 32.

The West ForkTolovana River pit was smaller(4.5 ha) and not as old (3 years)but otherwise was similarto the TananaRiver-Upstream pit.Avifauna observedat this site are identified in Table 33. Due tothe young age and sparsevegetative cover, the avifauna in the disturbed area included few

256 Table 32. Bird Observations by Mabitat Type Withln the Control and Oisturbed &eas at Tanan& River-Upstream 3-7 June, 1978. -era lndlcate Yinllaun lndlviduals Knm to Occur in Each Habitat Type.

Control Disturbedarea rarmval Gravel Mature spruce Intwmdiate-aged 0.Clduoua w~np lntermdlate-aged Car.x wetland Bare gravell Early ui I lavl Ponded water in pits rn I xed & 1 dwur mi xed dec 1 duous mud flat herbaceous

Gray Jar t31 Ye1 ic)r wb4.r 151 Narthem waterthrush t2) Yellow warbler (4) Rusty blackblrd HerringgulI 161 Wh I t e-crwned Tree watlar 4101 121 sparrar (21 Ya 1 l0w-r mped Oark-eyed junco 121 Beltad ktngfiahw III Gray-cheeked Spotted sand- Ilm gulI 14) hericanrobin (11 Bsrrorr's goldeneye 101 warbler 131 thrush 121 piper (21 Alder flycatcher 131 Fox sparrw 121 Ye1 lar-rmped Lesser ye I I OYI legs Arctictern 121 Savannah sparrwHerrlng gull 181 Oart-eyed Junco 121 Gray-&@eked thrush warbler IIL 1Il Semipalmated 1 I1 Bank swal Low (81 C-n raven I I1 tL1 -n fl Icker m I t @"owned plover 12) Spotted sand- Violet-green swallw (61 Black-cspped (I1 sparrow (1) Spot tad ssnd- piper 111 Bufflehead 45) ch Ickadea I I1 Dark-eyod Junco Savannah sparrcrr piper 12) Mew gull 141 kwrican robln LII tl1 tII lesser ye1 larlegs Lesser yet lowlegs 13) Ptarmigan (11 Ptardgan I I I Cararrn snip. 111 (11 Canada goose (21 Baid oagla tI1 Rebbreasted merganser 121 Amr i can go I den Arctlctern I21 plover t I I Smipalmotedplover (21 tlorthernphalarope 12) Spottedsandpiper (21 6reewingedteal (21 AmtKIcan goldenplover (1) Bald eagle II) Westernsandpiper I I1 Beltedkingfisher II) Pinta4 1 1 I I Greaterscaup I I1 bllard II I

Totals 5 1191 7 1131 2 13) 6 1101 6 181 8 1211 4 151 22 175) Table 33. BirdObservations by Habitat Type Within the Control and DlsturbedStations at West ForkTolovana River 9-11 June, 1976. Humbers Indicate Total lndlviduatsXnwn to Occur in Each Habitat Type.

Control area Gravel removal

M atu re spruce/ Riparian shrub/ Intermediate-agedshrub/ Riparian spruce/ Mature Rlvershore- Baregravel F I ooded area Inc i sed bank dec 1 duous backwater slough dec iduous I Ine 80d islands and of pit ot pit water surface spits

Gray jay 441 Spottedsandpiper L41 Dark-eyed junco t31 Spotted sand- Bufflehead I131 Buff lehead ( 141 Bank swal low piper 121 151 Dark-eyed junco (41 Northernwater- Wilson’s warbler Canada geese Spotted sand- Bank swal Iw thrush I41 (31 (21 piper. (4) (51 8 I ack-capped Fox sparrow 131 6 lack-capped Red-breastedSemipalmated 8onapart’s gul I chickadee 131 ch i ckadee ( 3 I merganser t 1 I toverp (21 I31 Alder Ilycatcher (3) Rusty blackbird (3) Alder f tycatchw Green-winged Mew gul I 131 (21 teal 12) td 111 Hermitthrush 121 Yellaulegs (21 Wh it e-crowned Mal lard (21 Canada geese L21 OD sparrow (21 Variedthrush 121 Yetlcur warbler [II American robin 121 Canada geese 121 Mal tard 12) American robin (21 Yettcur warbler lib Mew gull (21 Green-winged teal(21 C-n ravin (21 Hermitthrush 11) Comnon go1 den- Cmngo I den- eye [ I I eye I I I Cmnf I icker 12) Red-breasted Red-breasted American kestrel (11 merganser 1 1 merganser t I I

Totals IO (25) 6 It71 8 1171 3 [St 9 1291 9 -1351 I 15) passerines. However, vegetativerecovery had become wellestablished onthe gravelislands and shoreline and it isbelieved this site will soonprovide the same quality of habitat as the TananaRiver-Upstream. One colonyof beaver also wereusing the West ForkTolovana River pit.

Permanentlyponded material sites of sufficient size (at least larger than I to 2 ha) will provide a highquality habitat if they have:

a A diversityof shore1 ine configuration andwater depth,

0 Dense bordercover,

a Islandsor peninsulas or both, and

An abundant fish and macroinvertebratefood supply.

SIMILARITIES OF RESPONSE BETWEEN BIOTIC AND STUDY SITE PARAMETERS

A computeranalysis for similarities in responsebetween terrestrial bioticparameters andstudy site characteristics was conducted(TabI-e 34). Ten bioticparameters were selected for analysis. The analysisdemonstrated thatresponses of bioticparameters could be categorizedinto three groups. Eachparameter within eachgroup displayed a simi.Iarreaction to specific gravelremoval operations. When comparingthe responses of the biotic param- etergroups for all 25 sites, 5 siteresponse combinations were found (Table 34). Afterthese analyses, the material site characteristics were compared foreach site response group.

BioticParameters

The bioticparameters reacted in three groups of similarresponse to gravelremoval induced changes, Group I includedpasserines, shrub thicke moose habitat, andptarmigan habitat; Group I I includedsoil nutrients, groundsquirrels, early shrub communities, and small mammals; andGroup I includedsoil texture and water birds. Table 34. Two Way CoincidenceTable Displaying a HierarchisalClusterlng of SimilarSites and SimilarBiotic Parameters

Bioticparameters Group I Group I I Group I I I

Shaviovik R Pheian Ck Ugnursv i k R Kuparuk R lvishak R A M.F. Koyukuk R-DS Nome R Dietrich R-OS

Kavik R * + - McManus Ck + B M.F. KOyUkUk R-OS -L ++ + Tanana R-DS += + +

Oregon -Ck + Dietrlch R-US "" " +

W.F. Tolovana R = = = = I +* C Sagavanirktok R * - * - " ++ Jim R ===x -= ** Prospect Ck "-= " +

Aufeis Ck "PI + * Tanana R-US "=- -+ ++ 0 Penny R *"a= +++ +*

Gold Run Ck "" *a + Washington Ck "== ++- * E Sinuk R ===x + +- Skeetercake Ck "" *+

Symbolsused for cmputor analysis wereadaptod from quantification of change ratings(Table T-I) qs follows: I0.L) equals =; (2.31 equals -; 14,5,61 equals b; (7,81 equals +; and (9,tO) equals *. Note: all b's (norosponse OT wonk rosponrel were eliminatod from this table to rmve clutter.

Responcroa by group woro: A - essentially no responcre. B - minor decreases in biotic parameter Group I; minorincreases in bioticpermetor Groups II and 111. C - significant decrease in biotic Group I; minordecrease in biotic Group II; lncreasoin biotic Group 111. 0 - significant decrease in biotic Group I; increasein biotic Group II; significantincrease in biotic Group 111. E - decrease In biotic Group I; increasein blotic Groups II and 111.

2w Ingeneral, Group I parameterseither; showedno response, or displayed a significantdecrease resulting from gravel removal induced changes. This was directlyrelated to clearing of significant quantities of vegetation whichpasserines, moose, andptarmigan used as primary habitat.

Group II parametersdisplayed no response at sites where vegetative habitatswere not disturbed. However, allparameters except soil nutrients decreasedat sites that were subjected to permanent orfrequent hydraulic stresses(aufeis, ponding, and flooding) and didnot contain overburden piles. At sitesthat were subjected to hydraulic stress but which contained overburdenpiles, small mammals, groundsquirrels, and early shrubs increased. Soilnutrients basically displayed no response.

Group Ill parameterseither displayed no response at sites where the floodplaincharacter was notsignificantly disturbed, or they increased. Bothparameter responses were once again directly related to removal of extensivevegetative cover. Water birds increased in response to the increasein aquatic, gravel bar, and mud flathabitats, while soil texture increaseddue to the removal of organic, silt, andsand overburdens and the exposureand deposition of coarse gravels and cobbles.

PhysicalSite Characteristics

The PhysicalSite Characteristics that were analyzed are those ident i- fiedin the Major Variable Matrix Table (Table I). They included:drainage basinsize, channel width, channel configuration, channel slope, and stream origin.

Responses of bioticparameter groups at the 25 studysites displayed fivebasic combinations. Theseare labeled Site ResponseGroup A through E onTable 34. Eightsites occurred in Group A, whereno signlficantresponses weremeasured in any ofthe biotic parameter groups. These sites were mostly of medium tolarge channel widths, of braidedor sinuous configuration, and ofmountain or foothillorigin. However,these sitecharacteristics were not consideredto have significantly contributed to the minimal disturbance at thesesites. Of greatestsignificance was theminlmal vegetative disturbance whichoccurred during the gravel removal operations.

26 I Site ResponseGroups B through E didnot display any apparentsimilar PhysicalSite Characteristics. Thus, it was judgedthat drainage basin size, channelwidth, channel configuration, channel slope, or stream origin were notsignificant factors in governing the responses of terrestrial biota.

Gravel Removal AreaCharacteristics

The most significantsimilarities in Gravel Removal AreaCharacter- istics werethose that led to permanent or frequenthydraulic influence withinthe disturbed area. This annual stress led to a significant and often long-termimpediment of sitevegetative recovery. Two similarGravel Removal AreaCharacteristics were observed that produced this result. Theywere: scrapingwithin the active channel at any locationalong the river coarse; and scrapingadjacent to an activechannel primarily on an inside bend,and without anadequate buffer along the channel.

ScrapingWithin the Active Channel. Wherever gravel was scrapedfrom withinthe active channel, the scraping also extended beyond the original channel toadjacent gravel bars. In these areas gravel was scrapedto depths equalto or slightly below normal water levels. This characteristic produced a long-termdecrease in Biotic Group I (primarilyshrub thickets andpasser- ines). The hydraulicchanges that occurred in these areas were the prime factorfound to be influencingsite vegetative recovery. Thesechanges are discussedin further detail in EFFECTS OFGRAVEL REMOVAL ON RIVER HYDROLOGY AND HYDRAULICS.

ScrapingAdjoining the Active Channelon an Inside Bend. At seven sites gravelremoval occurred on a pointbar or inside meander butdid not extend intothe adjacent active channels. All siteswere of sinuous or meandering configuration and werescraped on sharp inside bends. At fiveof these sites (PennyRiver, Ugnuravik River, Skeetercake Creek, Middle Fork Koyukuk River- Upstream,and Middle Fork Koyukuk River-Downstream) the scraping occurred to withinor below the water level, Except at Middle Fork Koyukuk River- Upstream,no buffer was maintainedbetween the scraped area a nd themain riverchannel. At the M iddleFork KoyukukRiver-Upstream site a 30-m wide vegetated buffer was ma intained. However, within a fewyears therivers had formedcut-off channels throughthe scraped areas at allfive sites.

262 Thus, scrapedsites located on sharpinside bends ledto the formation ofcut-off channels unless extensive vegetated buffers (Jim River)or naturally contouredchannel slopes (Shaviovik River) were maintained during the gravelremoval operation. These cut-offchannels subjected the mined areas tofrequent or permanentponding and flood ingwhich impeded vegetative recovery .

AdditionalSimilarities. Overburden piles, as previouslydiscussed, were a positiveaddition at sitesannually subjected to ponding, flooding, and aufeisdevelopment. At sites where pilesoccurred, Biotic Group II (primarilysmall mammals, ground squirrels, and earlyshrub communities) increased(Site ResponseGroup E, D, and E, Table 34). However, at sites whereoverburden pilesdid not occur, but the site received annual hydraulic stressof flooding, permanent ponding, or aufeis development, Biotic Group I1decreased (Site ResponseGroup C).

Overburden pilesoccurred in a varietyof shapes and sizes and were placedin various locations within the material site. From a revegetative viewpointthe most effective pile compositions were thosewith a mixtureof silts,organics, woody slash,root stocks, and debris. These pilesonly occurredat the older sites and all were atleast I to 1.5 m above normal waterlevels. Itis not known ifadditional piles of lowerheight originally occurred andhad been eroded andremoved by floodwaters. Also, all piles that were withinthe central portions of the mined areas were eithernot directlyin the path of maincurrents or were placed in windrows oriented parallelto the current. Overburden piles that remained in the middle of largescraped sites were judged to be of more overallbenefit than those placed on the edge ofthe disturbed areas. These pilesprovided imnediate denninghabitat for ground squirrels and, withinseveral years, began to providecover and nestinghabitat for small mammals and passerineswithin the central portionsof large mined areas.

The ef fectivenessof natural buffers was relatedto their location and dimensions in relation to river site and conf iguration.Twelve of the 25 studysites included some useof buffers. Two typeswere employed:

26 3 Undisturbedgravel bars separating scraped sites in active flood- plainsfrom active channels, and

a Incisedbanks and associated riparian zones separating scraped and pitsites located in inactive floodplains and terracesfrom active floodplains.

The levelof understanding that was obtainedregarding the effective- nessof these buffers does not allow conclusions to bedrawn. Accurate data describingoriginal buffer characteristics (such aswidth, height, veget- ativestructure, and soilcomposition) were not available for many sites, however,several trends were observed.

At smallerrivers of sinuousand meandering configuration, buffers (primarilyincised banks and associatedriparian zones) of widths in the range of IO to 15 m wereeffective in containing active channels at sites thatwere 5 to 16 yearsold (Figure 81).

Figure 81. Undisturbedbuffer along the original stream channel at AufeisCreek (downstream disturbed area only).

264 Inlarger rivers, most naturalbuffers that were maintained to protect scrapedsites in active floodplains failed within a coupleyears. At Middle ForkKoyukuk River-Upstream a 30-m wide, I- to 1.5-m highheavily vegetated bufferprotecting an inside meander site was breachedin I year;at Sagavan- irktokRiver, a 30-m wide, 0.5-m highgravel buffer protecting a mid-channel site was breachedin I year;and at Dietrich River-Downstreamma 504 wide and 0.5- to I-m highgravel and sparselyvegetated buffer protecting a site onthe edge of the active floodplain of a braidedriver was breachedin 2 years.These buffer failures have all created permanent channel changes throughthe mined areas of these sites.

At pitsites located in inactive floodplains andterraces, buffers composed ofincised banks and heavily vegetated riparian zones rangingfrom 50 to 90 m inwidth were sufficient in protecting the pits from active channeldiversion at sites up to 13 yearsold. However,most ofthese sites (threeof five) are located onsmaller rivers with relatibely stable channels and areon the inactive side of the floodplain. On theother hand, at theoldest pit site (TananaRiver-Downstream) a 50-m widebuffer separated thepit from an erosionalzone of a side-channelof this braided river. During 1977 and 1978 thisbuffer was beingactively eroded. It is not known how widethe buffer was atthe completion of the mining activity.

One miningmethod (pits) andone sitelocation (separated from the activefloodplain) frequently led to the creation of high quality habitat thatresulted in an increaseof water birds (Biotic Group Ill). As previouslydiscussed, this method created a habitattype that frequently was not readilyavailable in adjacent floodplain reaches. The qualityof this habitat was related to its size,shoreline diversity (configuration), water depthdiversity, shoreline cover, presence of islands, and food availability.

Othercharacteristics occurred that were not directly related to the locationor operation of the material site but that reduced detrimental i mpac tsto the terrestrial biota. At those s ites whereaccess tothe floodplain had to passan incised bank, gravel fiII ramps (Figure 82) reducedthe over a II impact. At sites whereincised banks werecut for access severe

26 5 Figure 82. Gravel fill rampused toprotect the incised bank atthe Sagavanfrktok River study site.

erosionfrequently resulted. In permafrost areas both thermal and hydraulic erosioninduced by surfacetravel on unprotectedbanks can, and atthe UgnuravikRiver site did, create uncontrollable problems (Figure 83). At sitesseparated from active channels by buffers, a heavylayer of rip rap on thebuffers significantly increased their effectiveness (Figure 84).

266 Figure 83. Thermal and hydraulicerosion of permafrost induced by multiplepasses of a trackedvehicle across an unprotectedincised floodplain bankand adjacenttundra.

Figure 84. Armored bank protecting the West ForkTolovana Riverpit from a channeldiversion intothe mined site.

26 7 SUMMARY AND CONCLUSIONS

Overall,gravel removal from floodplains frequently had a detrimental long-termeffect upon localterrestrial biota. Specific site locations coupledwith the depth of scrapingproved to be the most influencingfac- tors.

VEGETATIVE REMOVAL

At 18 ofthe 25 studysites gravel removal operations cleared significantquantities of riparian vegetated habitat. This loss most significantly affectedpasserines and small mammals whichrely upon theseriparian tones forprimary feeding, nesting and coverhabitats. At most ofthese sites this habitatreduction led to long-term changes in fauna utilization and.com- munt ty structure.

At 4 of the 25 sites,gravel removal operations did not alter existing vegetativecomnunities, and consequentlydid not lead to changes in local faunalcommunities. Three of these sites were located in floodplains with large and medium widthchannels that flowed in a braidedpattern. At all threesites large quantities of gravel wereremoved by shallowscraping of surfacelayers over a broadarea. The fourthoccurred on a sinuous to meanderingriver. At this site a largequantity of gravel also was removedby shallowscraping unvegetated portions of lateral bars and pointbars. This scrapingmainTBined.naturaI point bar profiles and subsequentlydid not induce any channel changes.

MlNiNG DEPTH AND LOCATION

Gravelremoval operations that scraped to within or slightly below the watertable and thatoccurred at inside bends orimmediately adjacent to, or

268 withinthe active channel also produced a long-termnegative response (decreasein numbers)from terrestrialbiota. At I3 of the 25 studysites gravelremoval operations with these characteristics caused hydraulic changes (such as permanent channel shifts,aufeis development, or increased flooding)that impeded subsequentvegetative recovery of the disturbed areas. However, atthose sites wheregravel removal' created,permanently ponded areas,or extensive gravel and mud flathabitats with pockets of ponded wateror backwater areas, water birds (including waterfowl, shorebirds,gulls, and terns)frequently increased utilization of the area.

OVERBURDEN

Overburden pilescontaining'silts, organics, and woody slash and debris facilitated rapid and continued vegetative recovery within the mined site. These areasprovided islands of useablopasserine and small mamnal habitat within a relativelyshort-term period. At many sitesoverburden piles were providingvegetated habitats that werebeing used by thesespecies within IO yearsafter gravel removal. Ground squirrelpopulatione frequently showed immediateresponse toavailable denning habitat provided by overburden piles. At most sites where pilesoccurred these animals were significantly moreabundant withinthe mined sitethan in adjacent floodplain reaches.

When this overburdenmaterial was broadcastover the ground in areas where it wouldnot be washed downstream it was equallyeffective in facil- itatingrapid vegetative recovery and development.

PERMANENTLY PONDED HABITATS

At eightsites the gravel removaloperation (primarily through pit excavation)created permanently ponded habitats.Although this operation led to a long-term change fromnatural terrestrial conditions, at several sites thismining result led to the development of a diversehabitat that provided highquality feeding, nesting, and coverareas for passerines, small mammals,water birds, and furbearers.Factors that were found to influencethe faunaresponse to theseareas were: shoreline configuration, shoreline vegetativecover, water depth profiles, presence of islands,pit sire,

269 availabilityof food, and connectionto an activechannel. Fauna utilization ofthe area significantly increased at several sites with a highdiversity ofthese factors.

RECOMMENDATIONS

Gravelremoval operations in floodplains shouldat tempt toincorporate thefollowing recommendations into site selec tion and s it@operation de- cisions inorder to minimize long-term disturbance to terrestrialflora and fauna :

I. Whenever possible,avoid vegetated habitats.

2. When scrapingin active or inactivefloodplains, maintain buffers that will containactive channels to their original locations and configurations.

3 3. When sma II quantities arerequired (approximately 50,000 m I select s itesthat wil I scrapeonly unvegetated gravel depos ts.

4. When I arge quan t i t i es arerequired (approximately in excess of 50,000 m3 1, selectlarge rivers containing sufficient grave in unvegetatedareas, or select terrace locations on the inact ve s de ofthe floodplain andmine by pitexcavation.

5. If pit mining,design a configurationwith high shoreline and wa er depth diversity and provideislands.

6. Ifmining in vegeta t edareas, save alloverburden and vegetative slash and debristo useduring site rehabilitation to facilitate vegetative recovery Thismaterial should be piled or broadcast in a manner so it will notbe washed downstream.

Detailedelaboration andexpansions of these recommendations are presentedin the Guidelines Manual.

270 REFERENCES

Johnson, R. R., and D. A. Jones, (tech.coord.) 1977. Importance, preservation and management ofriparian habitat: A symposium. Tucson,Arizona. July 9, 1977. USDA F,or.Serv. Gen. Tech. Rep. RM-43, 217 pp.

Pamplin, W. L., Jr. 1979. Construction-relatedImpacts of the Trans- AlaskaPipeline System on Terrestrial Wildlife Habitats. Joint State/FederalFish and WildlifeAdvisory Team. SpecialReport No. 24. 132 pp.

Spindler, M. A., and B. Kessel. 1979. Forty-secondbreeding bird census:Census 167. AmericanBirds 33(1):99-100.

UnitedStates Army., Corpsof Engineers. 1979. WetlandValues: Con- ceptsand Methods for Wetlands Evaluation. Research Report 79-RI. 109 pp.

Woodward-Clyde-Consultants. 1976, PreliminaryReport - Gravel Removal Studiesin Selected Arctic andSub-Arctic Streams in Alaska. U. S. Fish and WildlifeService.. FWS/OBS 76/21. Wash., D.C. 127 pp.

27 I' EFFECTS OF GRAVEL REMOVAL ON WATER QUALITY L.L. Moulton

INTRODUCTION

Water qualityparameters were measured in conjunction with the aquatic biologicalstudies at the 25 gravelremoval sites. Since the sites were visit- edfrom 2 to 20 yearsafter gravel removal had been completed, the results of themonitoring program reflect only long-term effects onwater quality conditions. The sitesselected for study represented a broadrange of Physical SiteCharacteristics andGravel Removal AreaCharacteristics, which are describedin the Major Variable Matrix (Table I). Instrumentsand procedures usedare described in APPROACH ANDMETHODOLOGY. Changes inwater quality duringgravel extraction were not measured because active gravel removal sites werenot available for study. A review of availableinformation on this aspect was includedin an earlierreport (Woodward-Clyde Consultants 1976). Table 35. SelectedAlaska Water Quality Standards

Beneficialuse Par am8 t er suppWater I y AquaticRecreationlife

Dissolvedoxygen >75% saturation >7 mg/R >5 mg/a (rng/f!.) or >5 mg/R

Temper at ure <1B0C over (2.2 Oc over (OC) natural,no changes ifnaturally <18OC

Dissolved solidschronic Avoid <500 mg/a (mg/R or pmhos/crn) ( ~800pmhos/cm) toxicity specificconductance)

Turbidity (5 JTU (25 JTU except (25 JTU except (JTU) when natura I when natural d egra dation degradationdegradation

Suspended solids 80 mg/aa (mg/R)

a Notan Alaska Standard, but 80 mg/k is consideredpotentially hazardous; 25-80 mg/R alsohas potentially detrimental effect onaquatic life (National Academy ofSciences 1973).

274 Table 36. Water QualityParameters Measured at Gravel Removal Sites Which ExceededAlaska Water Quality Standards (Values arethe Average of Two toEight Measurements)

Specific Suspended conductanceTurbidity sol ids Studysite Area (JTU)(pmhoslcm) (mg/k)

b Dietrich-Upstream Ups t r eam 275 "- 56.0 8 July 1978 Mined 365 "* I .2b Downstream 342 "- 56.0

Dietrich-Downstream Ups t r eam 324 "- I I *Ob I I July 1978 Mined 340 "- 29.0 Downstream 3 30 "- 18.0

MF Koyukuk-Downstream Ups t r earn 320 6.30: "- 20 August 1976 Mined 300 5.20 "- Downstream 300 2.60 "-

Phelan Ck Upstream 77 -" 154.0: 21 August 1978 Mined 79 "- 270. Oa Downstream 56 "- 186.0 a Valueexceeds Alaska waterquality standard for adefined beneficial use(see Table 35). bMay have some effect onaquatic life (see Table 35).

275 RESULTS AND DISCUSSION

POST-MININGEFFECTS OFGRAVEL REMOVAL OPERATIONS

GeneralWater QualityConditions

Temperature,dissolved oxygen, specific conductance, turbidity, suspended solids,oxidation-reduction potential (ORP), and pH weremeasured upstream,downstream, and withinthe gravel removal area at most sites. Measurementswere taken inconjunction with the aquatic biological surveys. Temperature, specificconductance, turbidity, andsuspended solidsvalues variedsubstantially among thedifferent sites. However, dissolvedoxygen, ORP, and pH valueswere relatively similar at all sites. The parameter valuesmeasured at eachstudy site were compared tothe Alaska Water Quality Standards(Table 35). The waterquality standards were established to pro- tectvarious beneficial uses of receiving waters. The mostimportant beneficial uses associatedwith arctic and subarcticstreams include water supply,,aquatic life, and recreation. At the 25 studysites, aquatic life was themost common beneficialuse being supported. Alaska does not have a waterquality standard for suspended solids,but a valueof approximately 80 mg/R suspended solids is usuallyconsidered potentially hazardous for aquaticlife. Waters containing 25-80 mg/R suspended solids havebeen shown to have a loweryield of fishthan water with less than 25 mg/R (National Academy ofSciences 1973 1.

Water qualitystand ardswere exceeded for turbidity, andsuspended solidsat a few riversites (Table 36) whiletemperature, dissolved oxygen, specific conductance,and pH criteria werenot exceeded. The highsuspended solidsvalue at PhelanCreek was due tothe glacial origin of thecreek; the

276 sample site was approximately 9 km downstream fromthe foot of the glacier. Otherhigh suspended solids and turbidity values wererecorded at the Dietrich and MiddleFork Koyukuk Riversites.

Turbidity measurements recordedat the Middle Fork Koyukuk River- Downstream site exceededwater qualitycriteria for water supply. The only otherbeneficial usestandard exceeded was theaquatic I ifestandard for turbidity at Phelan Creek. Thisparameter was exceededby approximately 340 percentduring August. Phelan Creek watershould still be considered con- sumable, dependingon other (unmeasured) parameters. Most valuesexceeding theAlaska Water Quality Standards reflected a natural situation with only suspended solids at Dietrich River-Downstream possiblyinduced by gravel remova I .

'The pH and ORP values measured at all sites reflected a basiccondition that was neitheroxidizing nor reducing, The ORP valueswere relatively high becauseof the high dissolved oxygen concentrations. The pH and ORP values showed thatthere were very little organics in the monitored waters and that most of the heavy metalswould be insoluble. Some of the pH valueswere slightlyhigh (i.e., at Tanana River-Upstream, pH = 8.5-9.0 inthe two pits) and may beassociated with some heavy metal solubilities.

Water Quality Changes atGravel Removal Sites. Most ofthe water quality changes observed as thereceiving waters passedthrough the abandoned gravel r.emovaI sites canbe associatedwith physical changes inthe -stream. A major change was reducedwater velocity within the mined area promotingsedimentation, warming of thewater, and stratification. At other sitesphysical changes affectingwater quality conditions include a steep- eningof the bottom gradient through the mined site, which would increase thevelocity of the water and increasethe scour of the bottom sediments.

Turbidity and suspended solids changeswere observed between the upstream andmined, mined anddownstream, and upstream anddownstream study areas at 19 of thesites (Table 37). The changesare expressed as the percentage change occurringfrom the upstream samples to the downstream

277 Table 37. Changes in Twbldity andSuspended Solids Between Sample Areas at Selected Study Sites

Percent change inturbldlty Percent change in suspended sol ids Site characteristics Upstram Mined Upstram Upstrem Mined Upstrem Years Channel Volume to to dam- io darn- to to dwn- to down- slopesince reyved Study site mined strean stream mined stream stream mining Imlkml 1m 1

Sward Peninsula

Go1 d Run. Ck 42 " II 6.8 7,740

Slnuk 8 I4 I IO 2. I i74,oOo Wash I ngton Ck 233 -33 I3 12.4 20,503

Oregon Ck June " 620 13 11.8 20,500

August " -67 13 11.8 20,500 September -- 25 I3 I 1.a 20,500

Penny R June " 5900 !I 4.5 50,700 August 70 0 II 4.5 50,700 September IO a0 II 4.5 :50,700 NomaR -63 t7 202 2.6 unknown

Math Slope

Ugnuravik R " -48 I92 52 7 23,000 Aufeis Ck July 42 0 0 0 5 3.0 288,000

August " -25 -03 -87 4 2013,ow Kuparuk R - 260 0 260 9 dl ,3# Skeetercake Ck -25 0 0 0 II 2.0 38 ,ooo

Sagavanirktok R I -32 93 32 3 43 I ,000 Ivishak R -24 -85 275 -43 3 2. I I19,ooo

Cont I nued. Table 37. ~Concludadl

Percent change inturbidity Percent change in suspended sol Ids Site characteristics Upstrem Mined Upstrerm Ups t r em Mined Upstrem Years Channel Volume to to davn- to down- to to down- to dmn- reyvedslope since Study site nrlned strean strean mined strem miningstream Imlkm) Im 1

Shavi ov i k R -5 -5 -10 -75 IO0 -50 5 2.8 Il6,Ooo Kavik July 3 -7 -5 29 II 43 5 7.0 247,000 early August 41 -40 -15 29 II 43 5 7.0 247.000 late August -8 4 -4 0 -12 -12 5 1.0 241,000 h) Nathern Interior 4 W Dletrich-Dwnstrerm " " - 3 I 28,600

MF Koyukuk-Upstream -- " " 4 I35,OiK) MF Koyukuk-Downstram -17 -50 -59 2 I.3 215,000

Southern Inter Icr

&Manus Ck June 0 3 3 42 -4 I -17 16 22.4 75,000 July -24 34 3 -25 33 25 16 22.4 75,000 September 0 3 3 -I2 37 56 16 22.4 75 ,ooo

Phelan Ck - - -- 75 -3 1 21 3 " 575,000 samples.Negative values signify a decreasein the parameter while a posi- tivevalue indicates an increase. The column entitled"upstream to downstream"for each parameter indicates the net affect of the mined site on the waterquality during the site visit. There was significantseasonal variation, as indicatedby the results from OregonCreek, Penny River,Kavik River, and McManus Creek,which makes completeanalysis of the data of questionablevalue. There appeared to be some sedimentationassociated with remnantinstream depressions and this sediment was subjectto scour during highflow.

Changes inother parameters were observed with temperature and dissolvedoxygen showing the greatest frequency of change (Table 38). The tem'peratureand dissolved oxygen changes resulted from the reduction of velocity and spreadingof flow over the mined area, a situationwhich occurred at many ofthe study sites. The ORP valuesdid not change significantly, indicatingthe absenceof heavy organic loading. Conductivity values changed inthe mined area at several study sites, possibly indicating the exposure of a spring. The differences,judging by the age ofthe mined areas (i.e., 2 to II years),were probably not caused by the dissolving or precipitation of substancesin the mined area. Spring sources were identified at Penny River and DietrichRiver- Upstream, bothof which showed alteredconductivity. A springsource may be indicatedat the Aufeis Creekand Skeetercake Creek minedareas, but the conductivity change at McManus Creek may havebeen a metermalfunction because the change was notobserved during the other two site visits.

The waterquality parameters in inundated pits were generally quite differentfrom those in the associated river (Table 39). Summer temperatures werenormally higher and dissolvedoxygen levels lower in the pits. An exception was theDietrich River-Upstream pit where spring flow kept the water temperature low throughoutthe summer. Thermaland oxygen stratification wereevident at the West ForkTolovana River and Tanana River-Upstream pits.

280 1 Table 38. Relative Change of WaterQuality Parameters Between Upstream andDownstream Sample Areas at SelectedStudy Sites (%no Change, 0-&Decrease in DownstreamParameter, 6-l0=lncreasein Downstream Parameter

Study Dissolved Suspended Oxidation-reduction site oxygenTemperature Conductivity Turbidity sol potentids i a I

Seward -Pen i nsu I a

Gold Run Ck 8 4 5 6 Sinuk R 7 6 5 5 - Wash i ng ton Ck 5 3 5 IO 9 tQ Oregon Ck June I 8 5 7 IO CD- August 2 IO 7 5 2 Sept . 6 5 6 4 6 Penny R June 9 3 3 10 IO August 3 9 6 9 4 Sep t . 4 9 3 5 4 Nome R 5 5 6 3 6

North S I ope

Ugnuravik R 7 5 Aufeis Ck July 3 IO August 7 IO Kuparuk R 4 5 Skeetercake Ck 2 10 Sagavan ik tok R 5 5

Cont inued Table 38. (Concluded)

Study Di sso 1 ved Suspended Oxidation-reduction site oxygen Temperature Conductivity Turbidity solpoten-t ids i I I

lvishak R a 1 Shaviovik R 3 6 Kavik R July 6 5 August 8 5 Sept . 7 2

Northern Interior

Oietrich R-Upstream 9 0 I 5 Oietrich R-Downstream 3 IO 0 6 MF Koyukuk R-Upstream 4 7 7 4 MF Koyukuk R-Downstream - 7 5 2 -

Southern Inter iw

McManus Ck June 5 5 5 4 - July 6 IO 5 6 5 Sept . 5 5 5 7 5 Phelan Ck 5 4 - 6 4 Table 39. Average Measured VOlUO8 Of Selected WotW Quality PlrUnetefSat Study Sitos wlth Inundoted Pttr'

Act i vo Parameter channel lunits l IupstremlStudy lit0 lunitsl

Penny R T ('CIb 2.0 4.0 8 June 1917 00 lnyl/&l' 12.6 12.0 Cond lpmho~/cml I40 S5

8 AUgU8t 1977 t lot) 12. I 10.6 DO ImgILI 9.8 I I ,6 Cond (pmhor/cmI 510 250

Dietrich-Up8trean T r°Cl 4.5 14. I 8-1 I July 1978 Do tmQ/r, 10.6 8.5 Cond (umhos/unl 400 274

Jim Rlvr f IOCI 13.2 9. I 3-5 July 1977 w Img/ll 9.8 10.2 Cond lphoslcml 64 45 Prospect Ck T 1"CI 16.7 11.4 7 JuI,y I977 w Img/&) 8.4 11.9 Cond t 70 45

WF Tolevma R T IOC) 17.8 7.5 8-12 Juno 1978 00 IfqILl - 11.4 Cand Iwnhoa/cm) 320 225 t l°CI 10.4 8.0 w (mglll 9.3 10.2 Cond Iymhoslm~I I85 235

Tanana R-Damstram T IO0 13.0 7.0 9-10 Sept. 1976 .Do (q1111 10.2 12.7 Cond lpmhoslcml 200 85 Tanana R-Upmtram T I0Cl 17.2 - 4 Junq 1978 DO Img/Ll 10.7 - Cond I~mhos/cinI asa I

18 August 1978 f l°Cl 15.2 c 00 tmqlkl 9.4 I

18 mt. 1978 t (%I 9.0 I 00 rrngtri 10.0 I Cond I~mhoslcml 280 I

'S*nple mlrea nnd vwtinc. .atImtos anttted to simplify Table. bT - trmperoturo. 'DO dlasolved oxygen. dCond - conduct v it y .

283 SUMMARY AND CONCLUSIONS

Few changes inwater quality parameters were measured that could be attributed to gravelremoval; most of the observed changes were within the rangeof that expected by naturalvariation. The majorreason for a lack ofmeasurable effects was the age of thesites, asmost were visitedseveral yearsafter mining had ceased. The fewchanges thatwere observed were relatedto physical changes inthe rivers, generally due to a reductionin velocity and spreading of flow.

284 REFERENCES

National Academy of Sciences.1973. Water Quality Criteria 1972. Environ- mentalStudies Board, National Academy ofEngineering, Wash. 0. C. 594 pp.

Woodward-Clyde Consultants.1976. Preliminary Report - Gravel Removal Studiesin Selected Arctic andSub-Arctic Streams inAlaska. U. S. Fish and WildlifeServices. FWS/OBS 76/21. Wash. D. C. 127 pp.

285 EFFECTS OF GRAVEL REMOVAL ON AESTHETICS D. K. Hardingera

INTRODUCTION

Aestheticspertains to manmade modificationsof natural landscapefeatures to a degreethat public concern may beexpressed. Aesthetic concerns of State and Federal government includemaintenance of visualresource values byminimizing undesirable modifications to natural landscapes.

Visual resourcevalues of natural landscapes are the particular physical cmponents of an areathat havebeen identified as havinghigh value based on any number of measurable criteria, These couldinclude unique cultural, historical,recreational, geological, or biological significance,,TypicaIly the management objectives of an agency havingstatutory powers formaintaining visualresource values are toprotect land areas identified as having high aesthetic values. The agencies maydo this by diverting proposedconstruction toless valued locations, modifying the construction plan, or requiringthe application of mitigating measureswhere construction-related visual impact provesunavoidable.

Maintenanceof visual resource values has become increasinglyimportant tothe Americanpeople. Federal legislation has recognized this concern by establishingthe visual resource asan integral and coequalresource under themultiple-use concept of land management. At the sane time,there is an increasing demand forother resource developments that may not be compatible

a Thissection was reviewed and input was provided by 6. Sharky of Land Design North.

287 withthe management ofvisual resources. In order to resolve potential con- flicts, it has become necessaryto develop a systemthan can identify visual resources and providemeasurable management standardsthat are practical to implement.

Numeroussystems foridentifying visual resource values and evaluating visualimpact have been developed. The systemsvary considerably both in proceduresfollowed and criteriaapplied. On Federallands there are two principalvisual resource management (VRM) systemsin use today. One was developedby the U.S. ForestService and theother by the U.S. Bureauof Land Management (BLM). Bothsystems have the capability to:

a ldenti fyareas of significantvisual resource value;

rn Establ ishland units with each unithaving measurable, homogeneous qual ities; and

0 Prioritizethe land units through establishment of unitsof low visual quality, hence requiringminimal management protection, and units havinghigh visual quality requiring maximum management protection.

The majorcomponents of each systeminvolve a systematicfield inventory including (I) scenicquality or visual variety, (2)visual sensitivity, and (3) degreeof visibility. Generally, the field inventories are conducted from an on-the-groundperspective. Visibility from the air is generally not consideredexcept under specialized circumstances.

Definitionsof the three key VRM inventorycomponents of scenic quality, visualsensitivity, anddegree of visibilityfollow. Inventoried systemat- icallyusing the BLM system,these components yield a landunit rating system dividedinto five classes. Eachcla,ss provides various degrees of resource management controlover prospective resource development proposals, including gravelremoval operations from arctic and subarcticfloodplains.

288 SCENIC QUALITY

Establishing a scenicquality rating begins byusing physiographic prov- incesto distinguish landscape character units having common visualqualities and toprovide a regionalcontext for the specific area being evaluated. Within eachmajor landscape unit there may beareas having significant visual differences.These differences might include variations of typical landforms thatwould be classified as characterrating units. Each ratingunit is fur- therclassified according to the degree of scenicquality or variety as being distinctive, common, orminimal. Generally anylandscape has recognizable partsthat can be describedin terms of form, line, color, and texture.These basicvisual elements exert various degrees of influence and theircomposition will determinethe scenic quality of a givenlandscape unit. The premise isthat landscapes with the most variety or diversity have the greatest potentialfor high scenic value.

Severalkey factors are inventoried in determining the scenic quality ofthe landscape and are used to delineate VRM land classes.

0 Landform.

0 Vegetation.

0 Water.

0 Color.

0 The influenceof adjacent scenery,

0 Scarcity(distinctive features) or uniqueness.

V I SUAL SENS I T 1.V I TY

Visualsensitivity levels measurethe public concern for the scenic quality of thelandscape and for the changes that may alterthe existing landscapecharacter. The degreeof sensitivity is determined byuser attitude and use demand (volume).User attitude can be measured by a surveyof private citizens and publicofficials, or indirectlyby public documentssuch as recreationplans, trail systems, scenic highways, and otheritems. These documents indicateareas of generalconcern. Use volume identifiesareas of pedestrian and motorizedvehicular use and rates them high, medium, or low

289 based upon frequency and durationof use. User attitude and use demand are frequently combined in a matrixto determine final sensitivity levels.

DEGREE OF VISIBILITY

A distance zone isthe area that canbe seen from a sensitivity area, and is described as foreground,middleground, background, or seldom seen. Distance zones aredelineated on thepremise that the ability to perceive change or deta II inthe landscape is a functionof distance.

Specificsite information (Scenic Quality, Visual Sensitlvity, and Degree of v isibility) is initiallydisplayed onseparate topographic maps. A hier- archyof importance isestablished and the maps are combined. The resulting classifications are the basis for defining minimum management objectives and thedegree of acceptable alteration for each landscape classification. The determfnationof the degree of acceptablealteration for each landscape unit is defined utilizing a numericalrating system that enables a decision maker to see exactly what feature(landform, water, vegetation, structures) is beingaffected and to what extent.This method allows some flexibility in determining appropriate mitigation measures. APPROACH

The aestheticanalysis of gravel removal from the 25 projectstudy sites utilized the premises and criteria of the VRM systemdeveloped by theBureau of Land Management. However, an actual VRM inventory and classification was conducted on a site by site basis rather than on a regionalbasis as would normallyoccur. Each project study site was rrnalyredfor scenic quality, visualsensitivity, and degree of visibil'ity.Project aerial and on-site groundphotography, USGS togography maps, and project site descriptions were theprimary data source- for thescenic quality and degree of visibility analysis.Visual sensitivity data sources are limited in Alaska;therefore, user attitude and use volumewere interpretedfrom the public documents cited in thebibliography and by communications withpersons familiar with the locations understudy. After the sites Tn each generalregion were inventoried for existingvisual resources, a contrastevaluation was conducted, The contrast evaluationoutlines specific visual effects of gravel removal accwding to BLM definitions.

29 I THE VISUAL RESOURCES OF THE STUDY REGIONS

Characteristiclandscape descriptio n s are needed inorder to assess thedegree of change or contrast that is createdby floodplain gravel removal. The followingsection describes the phys cal characteristicsof each region orsite location in terms of the basic v sua1elements of form, I ine,color, and texture.Although site specific phys caldescriptions are found else- wherein this text, the purpose here is to create an overallimpression of thelandscape quality in the vicinity of the study sites. When available, informationdocumenting public concern anduse (orvisual sensitivity) in eachregion is also included in this section.

SEWARD PENINSULA

Scenic Quality

Seward Peninsulasites include Gold Run Creek,Sinuk River, Washington Creek,Oregon Creek, Penny River, and Nome River. The typicallandform in thevicinity of all sites is characterized by broad,smooth textured, rolling hillswith moderate to gentle slopes (Figure 85). The hillsare separated by sharp V-shaped valleysnear stream headwateps; these valleys become wider nearthe coast, All studysites onthe Seward Peninsula are located in narrow valleysor at the point where a narrowvalley opens into a broadvalley. The panorama atthese sites includes both gentle andmoderately steep slopes. Angular,rugged mountains are visible in the distance from all Seward Penin- sulasites, but do notsignificantly influence or enhance thelocal scenic qual i ty.

The studysite rivers onthe Seward Peninsula usually flow in sinuous configurationwith moderate to swift currents. The SinukRiver is thelargest

292 Figure 85. Typical Seward Peninsulalandform at Penny River.

river and it flowsin braided pattern through the study reach. The other rivers have a singlewell-defined active channel with occasional side channels orislands. The presenceof occasional reaches of steeplyeroded river bankdo notcreate strong, visibly apparent vertical lines. Some river edges we of coarsetexture with cobbles and boulders. All river systemsenhance the scenic quality of theimmediate surroundings, but they are not the most dominant elementin the large scale landscape.

Inthe Seward Peninsula,riparian vegetation grows in various densities andheights. In most cases low-growing shrubs (1-2 ml areinterspersed with otherground cover species (herbaceous and woody). Islands frequegtly are vegetatedwith similar vegetative communities. The Fenny Riverin particular hasextensive, wide bands of tall (2 to 3 m) riparianwillow. The greener shrubthicket vegetation also extends up adjacentvalleys providing a sharp color and texturecontrast with the matted browntundra on the surrounding hillsides. Dense shrubthickets also are a common featurealong old diversion ditches, seeps,and otherwater sources; these create contrasting bands and clumpsof dense green color across the brown hillsides.

293 The predominant summer colors ofthe region are provided by the vegetativepatterns. Common patternsinclude: bright green near water sources and dull green or brownon thehillsides. During fall the floodplains turn bright yellow,while red and goldenyellow colors dominate the hillsides. Ridges ofnearby hi I Is arebarren and appear gray in color withoccasional dark brown rock outcrops.

Culturalmodifications are visible from every site in the Seward Penin- sula. The Nome-Teller Highway intersectsand/or parallels five of the region's studysites, and theNme-Taylor Highway parallelsthe Nome Rivernear tho sixth study site in this region. The roadwaysare the most visible cultural modifications,but the lines they create generally blend into the lines of surroundinglandscape. Several streams are crossed by bridges of varied design. These bridgescreate vertical and horizontallines that are not fre- quentlyfound in theselandscapes. Access roads frequently lead from main highways toriver floodplains. Drainage ditches constructed during early gold miningperiods frequently canbe seen asthey follow the contours of adjacent hillsides. These ditches wereconstructed to collect and providewater at uplandgold mining sites. Several trails traverse the local terrain and are visuallydisruptive. Some cabinsare situated within sight of roadways, but none arenot ceablefrom within the study sites. There also is evidenceof othergravel removal and goldmining sites throughout the region.

VisualSensi ivity andDegree of Visibility

The Seward Peninsulastudy sites arelocated within immediateor fore- groundview of the Nome-Teller and Nome-Taylor Highways.There areonly three establishedhighways for vehicletravel onthe Seward Peninsula and all radi- atefrom Nome, thelargest population center on the peninsula. AI'I ofthe study sites are within a 40 km:radiusof Nome. There is an established ELM campground about 24 km north of the Nome Riverstudy site. This campgroundand thohistorical gold mining districts near Noma attractadditional summer touristtravel along these routes. Commercial toursof the peninsula usually beginin Nome and branchout along these roadways. Any changes oralterations ofthe landscape that occur in the foreground along these roadways would be

294 highlyvisible, However, loweruse volume than inother parts of the State, and less resource agency concernfor the quality of this landscape (nowild- life refuges, wild and scenicrivers, etc.), give the study areas only a moderatevisual sensitivity.

NORTH SLOPE

Scenic Quality

NorthSlope study sites include the Ugnuravik River, Aufeis Creek, Kuparuk River,Skeetercake Creek, SagavanirktokRiver, Ivishak River, ShaviovikRiver, and theKavik River. The Kuparuk River and theUgnuravik Riversites are located on theArctic Coastal Plain which is characteristically flat to slightly rolling. The steeplyincised river banks accentuate thestrong horizontal line of thecoastal plain and also providevertical relief (Figure 86). The remainingsites are located in the Arctic Foothills

Figure 86. Typical view of an ArcticCoastal Plain floodplain.

which is a transitionarea between thecoastal plain and theBrooks Mountain Range. Gentle,undulating slopes with occasional isolated, round and rolling

295 hillscharacterize the landform of 'the foothills (refer to Figures 4 and 5 in DESCRIPTION OF STUDY RIVERS). Incisedriver banks or terrace banks establish horizontallines that contrast with the characteristic undulating terrain. The landformfeatures appear to be smooth with few surface rock outcrops.

Rivers,tributaries, lakes, and ponds are common featuresof the North Slopelandscape. On thecoastal plain the abundance ofthese water features compriseapproximately 75 percentof the land's surface. However,no single landformor water feature stands out or is visually significant. The braided river systems withtheir islands create variations in line, texture, and colorthat contrast with the surrounding homogeneous landscape. The rivers offoothill region study sites are more visuallysignificant elements in the landscape due tothe diminishing frequency of other water features and their prominent,focal location traversing foothill valley floors.

The vegetationof the North Slope study sites is relatively rich in color and texture.Riparian vegetation usually consists of low-growing com- munitiesof dense willowthicket interspersed with herbaceous and woody ground coverspecies. These riparian communities develop irregular outlines created by irregularchannel patterns anduneven texture. Occasionally there are concentratedstands of taller, moremature willow that become a visualfocus due tothe contrast in height with surrounding low-growing vegetation.

The colorvariation of the North Slope landscape is varied particularly inthe fall. The most significantcolor contrast exists between the greens ofthe riparian shrub thickets and thetans andbrowns of unvegetated floodplains.

Some formof cultural modification is evident near al.1 NorthSlope sites. Mostmodifications are the result of oil andgas exploration.Several gravel accessroads parallel and intersectthe floodplains near many ofthe study sites.Gravel drill pads, camp pads,and airstripsare adjacent to several sites. These surfacematerials with various buildings sharply contrast the form,line, color, and textureof the surrounding undisturbed landscape.

296 Inaddition, the Trans-Alaska Pipeline and.Haul Road arewithin II km and 1.5 km, respectively,of the lvishak andSagavanirktok River sites. these featuresare visible from the floodplain banks at both sites. Thedominant visualfeature of elevatedsections of the Trans-Alaska Pipeline consists of thevertical pipe supports and thehorizontal pipe. The rigidlines of both elementscontrast sharply with surrounding undulating landscape.

The NorthSlope scenery is unusualand intriguing. This vast landscape with its subtlevariety provides a sustainingviewer interest and, therefore, yields a fairlyhigh scenic quality rating.

VisualSensitivity and Degree of Visibility

At thepresent time, there is little visitor or public use near the North Slope studyareas. However, several sites are located within or adjacent toareas identified byvarious groups as lands of national interest. The lvishakRiver, for instance, has been recommendedas a wild andscenic river. Thesedesignations do notguarantee increased public use, butthey are an expressionof public concern for preservation of scenic quality. Increased usecould result if and when theHaul Road is opened forpublic access. Mater- ialsites within view of the Haul Road wouldhave increased degree of visibility and thereforehigher visual sensitivity.

NORTHERN INTERIOR

Scenic Quality

The landscape of theNorthern Interior is among themost spectacular sceneryin Alaska. It includesthe Dietrich River (two study sites), Middle Fork Koyukuk River(two study sites), Jim River, and ProspectCreek. The siteson the Dietrich River andMiddle Fork Koyukuk River-Upstream are located inflat glaciated valleys surrounded by steep, rugged mountainous terrain (Figure 87). The steepangular mountain walls areoften crested with massive lightcolored rock outcrop and cutby jagged ravines. Near theMiddle Fork KoyukukRiver-Downstream site and theJim River andProspect Creek sites

297 Figure 87. DietrichRiver valley.

the valley widthsfluctuate andmountainous features diminish in visual domi- nance(Figure 88). The slopes are moregentle and thesurrounding mountains are morerounded in form.

Figure 88. Lower MiddleFork Koyukuk Riverval ley.

298 Riversystems of theNorthern Interior exert varying degrees of influence onoverall scenic quality. The large,active floodplain of theDietrich River coversnearly one half of the valley floor. This river flows in braided pat- ternover much of its length, Numerous lightcolored unvegetated gravel bars inthe active floodplain sharply contrast with the remaining vegetated valley floor and valleywalls. The MiddleFork Koyukuk River varies from a large, sinuoussingle channel to a braidedsystem with a largemain channel. Through- out,there are many abandonedchannels, vegetated islands, and terraces. Both JimRiver and Prospect Creek are smaller, slnuous to meanderingand less dominant inlocal scenic quality than the Dietrich and MiddleFork Koyukuk Rivers. All NorthernInterior study sites are in an enclosedlandscape where therivers become a focalpoint.given their prominent and centrallocation.

The vegetationalong the floodplains and hillsides is a diversemixture ofconiferous anddeciduous trees of varying ages and dens'ities. Dark-green whitespruce trees contrast with the rounded, lighter green deciduous trees and willowthickets. High-water andabandoned riverchannels have created brokenpatterns in the vegetation throughout the floodplain. A rich,complex visualtexture has developed because of thevariable heights and colors of the vegetativecommunities.

Colorvariety is further enhancedby the gravel deposits in the floodplains,local patterns of vegetation,and in some areasextensive rock outcrops.During fall, vegetativechanges introduce another dimension of color varietywith the seasonal colors of red, orange, andye1 low added tothe landscape.

Themost noticeablecultural modifications in the Northern Interior are thoseassociated with the Trans-Alaska Pipeline System. Facilities adjacent to thestudy sites include construction andmaintenance camps, airstrips, material and disposalsites, and elevatedand buried pipeline. Spur dikeshave been builtinto the floodplain in severa I locationsalong the Dietrich and MiddleFork Koyukuk Rivers. The lightco loredgravel materials used to con- structthe pipeline work pad,Haul Road, and camp facilitiessharply contras t

299 withthe rich natural color variety of this region. The pipeline andHaul Road oftencreate contrasting lines in the natural landscape.

The scenicquality of the Dietrich and MiddleFork Koyukuk Rivers can be characterizedas a regionof high diversity. This diversity is a result of 8 rich andcomplex texture of color, landform, and contrasts. Thedegree ofdiversity provides the region with a somewhat uniquecapability of accom- modatinglimited manmade encroachmentsin comparison with the North Slope landscapewhere manmade structureswould produce highly visible results.

Althoughthe scenic quality is notas distinctive, Jim River andProspect Creekhave greater recreation potential than the Dietrich and MiddleFork KoyukukRivers. This recreationpotential may have an overridinginfluence onthe final outcomeof the visual analysis.

VisualSensitivity andDegree of Visibility

The NorthernInterior (at the time of this evaluat ion) is access ible tothe recreation and touristoriented public only by a ir orby foot; hence, publicuse is limited at the present time. The Bureauof Land Management has severalproposals that would affect the use patterns in this region if the Haul Road is opened tothe public. Most development would be restricted to presentlydisturbed areas with anemphasis on maintainingscenic quality. Not all studysites are easily visible from the Haul Road becauseof screening qualities of thenatural vegetation. However, current andproposed river recreationuse would increasethe amount ofvisible area. In addition, lands ofnational ahd Stateinterest are adjacent to the Trans-Alaska Pipeline System UtilityCorridor (proposed IId-2” lands). Hence, thereis strong public interestin maintaining the scenic quality of this region.

SOUTHERN INTERIOR

ScenicQuality

Moststudy sites of this region (WestFork Tolovana River, McManus Creek, andTanana River)have some similarlandform characteristics. Rounded foot-

300 hillswith moderately steep slopes surround the flat-bottomed West Fork TolovanaRiver valley and thenarrow McManus Creek valley(Figure 89). Lower, gently rolling hills border one sideof the Tanana River,while the opposite

Figure 89. McManus Creek valley.

sideconsists of a broad, flatplain. Rock outcrops and barrensoil are usually confinedto the tops of the higher foothills surrounding these sites.

PhelanCreek, however, is locatedin a mountainousriver valley (Figure 90). The valley walls aresteep and angularwith rugged ridges of rock outcrop.Mountain glaciers provide added visualinterest to the surrounding landscape.

The Tanana River and PhelanCreek flow inbraided configuration. The Tanana Riverhas numerous gravel bars and vegetated islands in the active floodplainthat contrast with eachother in visual appearance. On theother hand, PhelanCreek has a gravelfloodplain with little contrasting vegetation. The contiguousgray-white color sharply defines the Phelan Creek valley floor.

30 I Figure 90. PhelanCreek valley.

The West ForkTolovana River and McManus Creekflow in sinuous configuration throughheavily vegetated, more narrow floodplains and do notstrongly dominatethe surrounding landscape.

The vegetation at mostSouthern Interior locations is a diversemixture ofdeciduous-coniferous forest and riparianshrub thickets. The roundeddecid- uousshrubs and trees contrast with the dark, slender white spruce. The West ForkTolovana River and fananaRiver floodplains have a particularlylush understorythat increases the variety of texturepatterns. The valleywalls nearmost Southern Interior sites are less obviously patterned with a more sparseunderstory except near drainages. However, contrastingpatches of dark and lightgreen can still be seen in mostlocations.

The colorvariety near the Southern Interior sites includes a complex mixture of greens,browns, grays, and tans with fallvegetative foliage adding reds,oranges, and yellows.

302 The SouthernInterior sites are in the vicinity of manymanmade modif I- cations. The Trans-AlaskaPipeline System is nearthe West ForkTolovana R iver andPhelan Creek sites, with State highways, rural communities, and recrea- tionalfacilities present in the vicinity of all SouthernInterior sites. These facilities,with their modifications of landformand vegetation patterns,detract from the overall scenic quality of thesurrounding natural landscape.

SouthernInterior sites, with the exception of Phelan Creek,have minimum or common scenicqualities because landforms are not unique and thereare a relativelyhigh number of culturalintrusions. Phelan Creek has more landform variety and in some sections is highlydistinctive.

VisualSensitivity andDegree of Visibility

The SouthernInterior sites are located in the vicinity of some ofthe mostheavily used recreation, tourist, and scenicareas in Alaska. In addition, most sitesare close to major Alaskan highways connecting the largest populationcenters in the state. Increasing recreational use of rivers(leadingto increased view area) is facilitated byconvenient road access. Nearby campgroundsand waysides increase the viewing time in the landscape. All ofthese factors contribute to high visual sensitivity in the Southern Interior.

303 EFFECTS OF GRAVELREMOVAL ON VISUAL RESOURCES

Gravelremoval activities caused alterations in the landscape that in many caseswere not visually harmonious with the surrounding landscapes. These alterationsare discussed in this section in terms of contrast. Contrast isdetermined by the change inthe form, line, color, and textureof characteristic landscapefeatures such as landform,water, vegetation, and structures. Thedegree of contrast can vary widely; however, the significance of each contrast will dependupon thescenic quality and visualsensitivity of the characteristiclandscape. The contrastspresented in the following sections generallydenote a negativeeffect unless otherwise stated. Similar contrasts frequentlyexist at separate study sites in eachregion, hence discussions havebeen grouped by regionwi,th exceptions noted.

SEWARD PENINSULA

Gravelremoval activitiesin the Seward Peninsulacreated the most significantcontrasts in local landform andwater features of all study areas. Theuneven texture or angular lines, or both, of gravel stockpiles andover- burdenpiles present at mostSeward Peninsulasites, visually disrupt the existing smooth linesof the surrounding homogeneous landscape.

Scrapingand pit excavation have left contrasting rigid, rectangular linesat several site locations. The presence of waterlocated throughout much ofthe gravel removal areas in unnatural shapes and configurations ac- centuatesthis contrast. The constructionof access roads hasintroduced anadditional contrasting form and linein this landscape.These features are particularlydisruptive if there are several at one site (Nome River,Oregon Creek).Landform contrasts are more evident in this region because the vegetation is relatively lowgrowing and cannot effectively screen gravel removal

304 activities. The overallcolor contrast has beenincreased at all sites by removingriparian vegetation. However, gravelremoval has not created signif- icantoverall contrasts with the form, line, and textureof the existing vegetationpatterns except at Penny Riverwhere the vegetation is much taller. Rigidblocks of vegetation now define some bordersof the gravel removal area at Penny River,thus producing a contrastwith the existing random pattern and heightvariations of the natural vegetation.

NORTH SLOPE

Veryfew significantcontrasts are visible onthe braided rivers of theNorth Slope. The riversare large enough tovisually absorb the changes in channeland island configuration, The banks,however, are a strongvisual focusin many places and are more visuallysensitive to change.The height of inciseabanks necessitated the use of gravel fill ramps in many locations. Some rampswere partially removed aftermining was completedand the remnants are still visible.In either case,the ramps produce a moderatecontrast withthe form and lineof the river bank. The KavikRiver is an exampleof strongcontrast in the form and lineof the landform-water feature. Large portionsof the bankwere alteredat this site. In addition, a largerectangu- larscraped area adjoins the river. These linesare not unlike those of the nearbyairstrip, but in this case they disrupt the visual linear flow of theriver's edge. The removalof vegetation andoverburden in this area has produced a colorcontrast that accentuates the unnatural rectangular lines ofthe disturbed area.

Gravelremoval created stronger contrasts along the smaller and/or single channel riversin the North Slope region. The creationof additional wafer channelsand/or ponds at the Aufeis Creek and Skeetercake Creek has signifi- cantlydisrupted the natural lines of each system. Removal of vegetatedover- burdenand stockpiling of gravelcreated additional contrasts in color and texture. The resultingbroken textures and configurationsat these sites contrastsharply with the existing natural landform and vegetationpatterns.

305 NORTHERN INTERIOR

The NorthernInterior sites are generally located in areas where patterns of manmade activityalready exist and arevisibly apparent. Gravel removal sitesin vegetated floodplains developed the most significantvisual contrasts.Rectangular excavation boundaries contrast with the curvilinear shape ofnaturally vegetated floodplains.

Theremoval of vegetation and overburden created color contrast at the DietrichRiver-Upstream, Middle Fork KoyukukRiver-Upstream, Jim River, and ProspectCreek. This contrast distinguishes the rectangular lines of the disturbedareas from the surroundings. Color contrast would not be as signif- icantat these sites if the disturbed area boundaries were developed in config- urationto reflect surrounding landform and vegetativepatterns.

Sitesthat have filled with water (Prospect Creek,Jim River, Dietrich River-Upstream,and Dietrich River-Downstream) have produced line and form contrastsbecause ponding is not a common element inthe floodplains of this region.Angular diversion channels at Dietrich River-Upstream were equally contrastingwith natural channel patterns. The abrupt and block-like shape of existinggravel stockpiles at Dietrich River-Upstream sharply contrasted with theflat terrain of Northern Interior river valleys.

SOUTHERN INTERIOR

The presenceof tall white spruce-paper birch stands associated with specificsite locations make thestudy sites of this region less visible frompublic roadways than sites studied in other regions. However, the SouthernInterior is a highrecreational use area and naturalscreens between roads and gravelremoval areas are ,not iotally sufficient to keepthe disturbedareas from public view.

Landformcontrast is themost obvious change in visual quality resulting fromgravel mining at the Southern Interior sites. The West ForkTolovana River, TananaRiver-Upstream, and Tanana River-Downstream sites haverectan-

306 gular,flooded pits with steeply sloped banks. The angleof bank slope and pit shapecontrast with the natural flat floodplain form and thecurvilinear lines ofthe river systems. Where gravelstockpiles remain within the visible portionsof the study site (such as at PhelanCreek) they create a contrasting unnaturalform.

307 SUMMARY

Afterstudying the effects of gravel removal on visualresources at specificsites, some overal.1generalizations can be made. Certainlandscape featuresor conditions will besimilarly effected bygravel renioval in all regions. The decidingfactor in determining total impact will bethe relative publicsensitivity to the specific landscape. The same impact in twodifferent areas may bejudged differently depending upon publicpriority. Theoretically, thelandscapes that are highly visible and highlyregarded by the public will bemore seriouslyaffected than landscapes of lesserpriority. The following summarizesthe effect of gravel removal on generalized landscape features and brieflydiscusses public priority.

Small, singlechannel rivers bordered with low-growing vegetation experi- encedthe most dramatic visual impact. The locationof gravel deposits on theserivers usually requires the removal of riparian vegetation andover- burdenalong incised banks. Along meandering and sinuous systems this pro- cedurefrequently results in significantly altered river configuration. The vegetationremoval causes a colorchange that clearly brings attention to thedisturbed area. The remaininglow-growing shrub vegetation is notof sufficientheight to screen the disturbed area.

Braidedrivers with or without vegetated islands usually can visually absorbmining induced changes ifthe gravel removal occurs between the floodplain banks. Any changes tothe banks create noticeable visual contrasts. The mostfrequently observed contrast to river banks result from access roads andfill-ramps, cut banks, andmined banks.

Tall, dense vegetationbuffers surrounding the work area often screen many miningsites from public view at ground level. However, theremoval of

308 vegetationfrom buffer areas at most study sites has caused unnatural line and colorcontrasts that draw attentionto the disturbed areas. Color con- trastsare more visiblefrom an elevatedposition where a vieweris looking down ontothe site.

Rectangular,water-filled excavation pits, due totheir unnatural shape, generallycreate significant contrasts in all floodplain landscapes. The contrast is accentuated when thevegetation bordering the pit is tall and conformsto the rectangular shape.

Sitesthat can be viewed from above,where the viewer is ableto look down onto a site,generally results in high visibility potential particularly inareas of sparse or low-growing vegetation.

Accessroads also have resulted in significant contrasts in many study sites.Access roads frequently create a highdegree of visual prominence and contrastwhere they traverse perpendicularly across existing slope contours.This contrast is more disruptivein regions of rolling or steep terrain,having sparse or low-growing vegetation, as exists onthe Seward Penin- sula and NorthSlope. The presenceof more than one access road can produce a multiplyingeffect with respect to increasing visual prominence.

The presenceof stockpiled gravel andoverburden piles often increase visualprominence to a site.Often due totheir height or linear shape, or both,the piled material tends to attractthe viewer's attention to a site eventhough the site itself may notbe clearly visible. Large stockpiles are detractivein mostlandscapes although less noticeable in broad floodplains surroundedby tall, highly patterned, mixed stands of vegetation. Tall vegetation and terrainfeatures can provide a visualscreening effect particularly wherethe viewing location is atground level.

Areashaving more or less homogeneous vegetation and terraingenerally are more highlyvisible than those areas that are morediverse. The diverse landscapecharacter types generally can accommodate gravelremoval partic- ularlyat locations where the potential viewer is at a substantialdistance

30 9 f rom thesite or is at a similarelevation (ground level with respect tothe site).

Visualprominence of a sitetends to increase where vege tative c lear i ng occursalong straight, long lines. This pattern is generally true in regions ofboth high andlow landscape character diversity. Less visual contrast results whereirregular clearing patterns have beenaccomplished. Site visi- bilityis further reduced wherenatural vegetative recovery has occurred on sitescleared on irregular patterns.

Fourdifferent regions of Alaskawere included in this study andeach regionevokes a differentpublic response to visual resources. The regions thatappear to bethe most publicly sensitive to changeare the Northern andSouthern Interior regions because of exceptionalscenic quality or inten- sivepublic use.The visualeffect of gravelmining activities is expected to bemore scrutinizedby the public in those areas. Visual standards for gravelremoval areas should recognize this public sensitivity.

310 GEOTECHNICAL ENGINEERING CONSIDERATIONS OF GRAVEL REMOVAL H. P. Thomas and R. G. Tart, Jr.

INTRODUCTION

The initialgeotechnical effort onthe project consisted of a literaturereview and evaluationof questionnaires sent to highway departments aroundthe United States. Results of this effort were presented in a preliminaryreport (Woodward-Clyde Consultants 1976). Thissection presents the findings of a geotechnicalreview that consisted of an officeevaluation of thelimited data from the 25 studysites made availableto the project geotechnicalengineers. This section identifies general geotechnical consid- erationsthat should be considered in gravel removal projects. The major datasources were: the mining plans that varied greatly in detail from site to site (for some sites nomining plans are available); aerial photography thatvaried from site to site in scale, coverage (both historical and areal), and quality; and sitephotographs collected during biological and hydrologicalfield inspections. This section is, in many cases, generic and generalin its treatment because of the limitations of the available data.

The objectivesof this evaluation were to identify:

I) Engineeringtechniques that led to efficient development andopera- t ionof gravel removal areas;

2 1 Eng i neer ingtechniques that mitigated environmental disturbance; and

3 1 Eng i neer ingtechniques that could have been used in various cond I- tionsthat would have led to more efficient operation with less environmentaldisturbance.

31 I Volumes ofgravel removed from each site ranged from approximately 3 8,000 m3 to 630,000 m , withthe largest volumes removed from Dietrich River-Upstream,‘Phelan Creek, Aufeis Creek, and Sagavanirktok River. Refer toTable 4. Scraping was themost common removalmethod used, but four sites wereoperated as pits andanother four sites were operated as combinations ofscrapes and pits.Nine of thesites were developed in connection with constructionof the Trans-Alaska Pipeline System.Most North Slope sites wereopened inconnection with oil exploration and drilling activities, while all Seward Peninsula andmost Southern Interior sites were developed inconnection with local highway projects. More detailed information on site use ispresented in DESCRIPTION OF STUDY RIVERS.

Permafrostcondi,tions at most of the study sites are unknown. There normallyis a thawbulb associated with rivers in permafrost areas. In continuouspermafrost, the thaw bulb may be a transitoryfeature present onlyduring summer flows. However, indiscontinuous permafrost and forlarge riversin continuous permafrost, the thaw bulbpersists year-round although it may shrinkconsiderably in winter. A 1969 studyon the Sagavanirktok River II km southof Prudhoe Bay (Sherman1973) showed thatin summer the thawbulb associated with the main channel was 12 m deep andhad a cross- 2 2 sectionalarea of 762 m . Inwinter, this thaw bulb shrank to 167 m with a maximum 7 m depth.Depending especially on whetherunderflow occurs, thaw bulbs may or may not bepresent outside the main channel.

A majorgravel use in arctic and subarcticAlaska is directly related tothe need toprovide a graveloverlay sufficient to carry traffic and to preventpermafrost degradation (progressive thawing). The minimum overlay thicknessto prevent thawing can be calculated as a functionof the local thawingindex. The thicknessis 1.5 m at Prudhoe Bay and increases as one moves southward(e.g., it is 2.1 m atGalbraith Lake and inFairbanks it wouldapproach 6 m). A 1.5 m graveloverlay has generally been used for roads,drillpads, airstrips, and otherpermanent facilities at Prudhoe Bay. However, it hasbeen shown that a 60-cm thickgravel overlay with 5 to 10cm ofpolystyrene insulation is thermally equivalent to 1.5 to2.1 m ofgravel. Thisrepresents a 60 percentreduction in gravel thickness and a 64percent reductionin gravel quantity, considering a typicalgravel pad with I&:I side slopes and a crestwidth of IO m. Gravelneeds during construction of theTrans-Alaska Pipeline System were reduced by using this solution for 110 km of thepipeline workpad on the North Slope. Depending upon relative costs of gravel and insulation,synthetically-insulated embankments may or may notbe less cosllythan their all-gravel counterparts (Wellman et al. 1976)

313 APPROACH

Themain factors considered in the geotechnical evaluation were site selection,access, operation, and rehabilitation.Primary information reviewedfor each siteincluded mining plan information from permitting agencies,aerial photographs, ground photographs, and field notes taken by theproject hydrologists.

Earlyin the review effort, a geotechnicalfact sheet and evaluation formwere developed and filled out for each site. The purposeof these forms was to assemblerelevant information, to draw out observations of projectpersonnel who had visitedthe sites, and togenerally focus the revieweffort. Although the geotechnical data base was verylimited at a number of thestudy sites, it was believedto be sufficientoverall to allowcertain meaningful judgments to be drawn,

The follwingsections contain geotechnical discussions related to gravelremoval during principal stages in the life of a materialsite.

314 SITE SELECTION AND INVESTIGATION

Selectionof a gravelremoval site often begins with a comparison of candidatefloodplain and/or upland sites in the immediate use area. Uplandsites are beyond the scope of this report and will notbe further considered. The siteselection process includes preliminary selection, site investigation,final selection, and miningplan preparation.

PRELIMINARY SITE SELECTION

Preliminaryselection of one or morecandidate sites results from assemblingand reviewing available information fallowed by implementation of an appropriateselection procedure.

Sources of Information

Primarysources of information used in preliminary site selection aretopographic maps, surficialgeologic maps, and aerialphotographs.

Topographic maps of 1:250,000and 1:63,360 scaleare available from the U.S. GeologicalSurvey (USGS). Similartopographic maps are also available for Canadian arctic and subarcticregions. Fromthese maps, onecan obtain a generalimpression of thesize and typeof river, potential gravel availability,desirable access routes, and proximityto the usearea.

The onlycurrently available surficial geologic map ofAlaska is the 1964 USGSmap entitled "Surficial Geology of Alaska". With a scaleof 1:1,584,000, this map does not show much detail. However, USGS recently published a potentiallyuseful set of maps whichcover the Trans-Alaska Pipelineroute from'Prudhoe Bay to Valdez.

315 Aerialphotographs frequently are the most useful sources of information.Stereo pairs are needed to show relief (e.g., heightof banks) and a scaleof not more than 1:12,000 ispreferred. Color photographs are available for some areasof the State, and black and whitephotography is availablefor mostareas of the State, For some areas,pre-existing aerial photo coveragecan be purchased from local aer i a I survey companies.However, it is frequentlyworthwhile to have the area in question flown andphotographed in orderto obtain the neededcoverage. From adequate aerialphotographs, one can normallydistinguish such features as thephys icalcharacteristics of the floodplain(e.g., channel configurations, flow regime,gravel avai labi I ity,vegetation patterns) andcan selectpotent ial accessroutes and f ac ilitylocations.

PreliminarvSelection Procedure

The procedurefor selecting a gravelremoval site usually involves identifying two or threealternative sources that appear to have sufficient quantitiesof gravel. These alternatesare then compared eitherin an in- formalbasis (usually minJ-mizing haul distance) or in a moreformal pro- cedureinvolving establishing criteria, evaluating significant factors, and rankingsites. The criteriawould be specificto the situation, however, factorsthat may be consideredinclude physical properties of the material available,haul distance, material site size and configuration needed to producedesired quantities, equipment available andequipment needed, re- quiredsite preparation (e.g.,ramps, berms, dikes,overburden), river hydraulics, and floodplainaccess from nearest point. At thisstage the anticipatedlife-span of the material site also should be considered. If it isdesired to usethe site for several consecutive years, or for two or more periodsseparated by inactive periods, the potential bed-load replenishment rateshould be incorporated into site selection. It is generally assumed lSee EFFECTS OF GRAVEL REMOVAL ON RIVER HYDROLOGY AND HYDRAULICS) that riversof glacial and mountainorigin, particularly near the ir headwaters, havegreater potential for gravel replenishment than streams of foothi I I or coastalplain origin. Non-engineering aspects of siteselect ionare discussedin other sections of this rep.ort.

316 SITE INVESTIGATION

The importanceof anadequate on-the-ground siteinvestigation cannot beoveremphasized. At theUgnuravik River site, the investigation stopped with an interpretationof aerial photographs. Subsequent siteoperations discoveredthat the gravel was merely a veneerand not present in 'sufficient quantitiesto meet project needs. Incontrast, before construction of the Trans-AlaskaPipeline System rather extensive site investigations were conductedwhich significantly increased the knowledge of site gravel quantity and quality.

Typesof Data

Severaldifferent types of data need to be obtained in a material siteinvestigation.

AerialExtent andDepth of Deposit.Estimating the volume of material available dependson establishment of the aerial extent and depth of the depositin question. If this volume is lessthan the neededvolume, the site will beinadequate to satisfy the material needs. Hence, this is oneof the mostimportant types of data to be obtained.

Thicknessand Aerial Extent of Overburden.Gravel sites frequently have a coveringof silt ororganic material, over all or part of the site, which mustbe removed inorder to expose underlying gravel. Mining may notbe economical if morethan about I m of overburden ispresent over most of the site.

Homogeneityof Deposit. A depositwhich appears suitable on the surface may beunsuitable at depth. This change in deposit quality frequently is a resultof fluvial processes involving channel shifting, alternating erosion and deposition, andoverbank flows associated with periodic flooding. Test pitsor borings from several locations within the site should be analyzed to determine deposit qual i ty.

317 GroundwaterTable. It is importantto establish the depth to the groundwatertable together with spatial andtemporal variations in this parameter. Groundwaterconditions may varywidely throughout the year in response tochanging river levels, thus, several measurementsare preferable. The dateof measurements should be carefully recorded.

Extentof Permafrost. Although permafrost occurrence in the vicinity of rivers and streamscan be highly erratic, it shouldbe anticipated in arctic and subarcticregions. The presenceor absence of permafrost can be an importantfactor in developing a gravelremoval site.

Field Techniques

Bothborings and test pits canbe used for geotechn icalexp lorat ion. Testpits are generally preferred in granular soils because of the diffi- culties of drilling andsampling in small-diameter borings. However, borings canprovide a good indicationof overburden thickness, water table, perma- frostconditions, andpresence and extent of unacceptable (e.g., silty) materials. These boringsor test pits should extend to the depth of the anticipatedgravel removal. The number ofpits or borings would dependupon thesize and variability of the site.

Laboratorv Test ina

The requiredlaboratory testing effort varies. Sieve analyses are needed,as a minimum, toclassify the material and establish its suitability for its intended use.For these tests, rather large (50 to 100 kg)bulk samplesare desirable. Other tests that may beneeded include hydrometer tests(if frost-susceptibility is a concern)and compaction tests ifthe gravel will beused tosupport structures.

FINALSITE SELECTION

The finalsite selection is basedupon the criteriaanalysis of the alternativesites. This analysis comparesthe characteristics of the ma-

318 terialsfound at the available sites to the needs of the project. A major portionof this analysis is thecost-benefit trade off ofthe options developedduring the site investigation process. Sites further from where the material is needed may havegravel that requires less processing; the re- ducedprocessing cost may lowertotal costs despite the added costof transport and roadconstruction. In another case a more distant site may havean existingaccess road which would, on a costbasis, justify use of the more distantsite rather than a closersite. In some instances,such as pipeline beddingand padding, rounded well-graded gravel might be preferable. Spe- cificgradation requirements may be necessaryfor subsurface drains. Uni- formlygraded angular gravel may be a requirementfor asphalt pavement aggregate.In final site selection the engineer makes tradeoffs to choose thesite that will providethe required material at the least cost.

Thisengineering analysis is then reviewed and biological resources, hydraulicfactors, and aestheticconcerns are considered before the final site selection.

MINING PLAN PREPARATION

The agency havingjurisdiction will generallyrequire preparation and submittalof a miningplan. Minimum elements of the mining plan are:

e Planneduse of gravel,

0 Basisfor determination of material quality and quantity(e.g., borings,test pits, laboratory tests.)

0 Siteconfiguration anddepth,

0 Quantity limits,

0 Projectschedules,

0 Overburdenpresence, Access to site,

0 Bufferlocations,

0 Operationplan, and

0 Rehabilitationplan.

319 Specifically,thi mining plans should include at least the follawing information:

0 A sitesketch drawn toscale showing: projectlocation cross-sectionsof borrow areas, gravelsource locations, existingor planned haul road locations, testpit or boring locations (if an Y);

0 An estimateof the volume of material thatis needed; e An estimateof the volume of material that is anticipatedat the avai lable sites; e An estimateof the properties of the materialrequired; e An estimateof the properties of the in-situmaterials; An estimateof the type andamount of processingthat will berequired;

0 Projectschedules for all majoractivities; Preliminarydesign features of any requiredsupport structures, such asaccess roads, processing plants, culverts, and bridges; and e Descriptionof operational and rehabilitation31aspects of site use.

Plansprepared as describedabove should provide sufficient information toevaluate the appropriateness of the planned development of thegravel sources.

Miningplans were prepared and submitted to the appropriate government agencyfor most ofthe 25 studysites. However, nomining plan information was foundfor the Washington Creek, Nome River,or Skeetercake Creek sites. The mining was apparently a trespassaction at the upstream Aufeis Creek site and for initialgravel removal at the Kavik River site. Only results of a verylimited site investigation were found for the Penny Riversite; only some correspondence was foundfor the Ugnuravik River site; and only a right-of-waypermit was foundfor the McManus Creek site.Mining plan infor- mationreviewed ranged from sketchy (for the Seward Peninsulasites) to quitedetailed (in the case of the Trans-Alaska Pipeline System sites).

320 SITE PREPARATION

Havingselected and gained approval to de,velop a gravelremoval site, sitepreparation activities can begin. These activities may include COnStrUC- tionof access roads, removal of overburden, and construction of channel diversions and settling ponds.

ACCESS

As a partof most floodplain gravel removal operations, haul roads must bebuilt to connect the site to the use location or existing roads. This constructionposes no special engineering problems in non-permafrost areas orin areas where the permafrost is thaw-stable. However, inareas of ice- richpermafrost, protection of the tundra is of vitalimportance. From an engineeringstandpoint, tundra-insulated permafrost, as long as it remains frozen, is an excellentbase or foundation for structures whether they be drill pads,roadways, pipelines, or other structures. When thepermafrost beginsto thaw two crit.icaI things happen. First,there is a tremendous loss instrength, andsecond, thethawing process is very difficult to stop. Thus, afterthe tundra is disturbed enough toallow the permafrost to begin thisprogressive thawing, the same areathat formerly was an excellentbase forstructures becomes a verydifficult, if not impossible, foundation problemfor any engineeringpurpose. Drainage and other related problems also beginto develop and thesecan have significant adverse impacts on engineeredstructures.

Access roads traversedice-rich permafrost at several of the study siteswith varying degrees of success. In general, where a? least 0.5 m of graveldepth was used, permafrostintegrlty was maintained. However, at severalsites (Ugnuravik Rlver, Aufeis Creek, Skeetercake Creek, and Kuparuk

32 I River)the access roads were less than 0.5 m indepth andsubsidence frequent ly occurred.

Accessroads to a givensite should be limitedin number and confined toprepared surfaces. Both season of operation and long-termeffects need to beconsidered in planning. Access to most of the study sites seemed to be appropriate and usuallyconsisted of shortgravel ramps and haul roads, sometimesincluding gravel bars within the river floodplain.

The practice of constructingtemporary gravel ramps, as at the Kuparuk, Sagavanirktok,Ivishak, and Shaviovik Rivers sites to provide access over incisedpermafro.st river banks,reduces bank disturbance (Figure 91). How-

Figure 91. Gravelramp atShaviovik River site providing accessover a permafrostriver bank.

ever,cutting into permafrost banks, as was done atthe Kavik River, can leadto severe thermal erosion and is not recommended.

32 2 Winter-OnlvAccess

Winteraccess to a floodplainsite is generally easier than summer accessbecause the surrounding terrain is frozen and riverlevels are low. However, even frozenorganic mats need to be protectedfrom mechanical crushing and rippingcreated from multiple passes over an unprotectedaccess roadwhile building snow orice roads.

The UgnuravikRlver site provides an example of adverselong-term effects: access to the site was via a temporary winter trai I acrossthe frozenNorth Slope tundra. As far as is known, thetrail was usedonly duringthe last week of March 1969. However, as was commonly done, the tussocks may havebeen bladedoff to provide a smoother ridingsurface.

Erosion was continuing, and a permanentscar had been createdon the landscape (Figure 92; alsorefer to Figure 83). Basedon thecurrent state of

Figure 92. Thermal erosionnear Ugnuravik River resulting fromcompaction and destructionof the vegetative mat overlyingice-rich,permafrost soils.

323 knowledge, a bettersolution would have been to construct a snow orice road (Adam 1978).

Year-RoundAccess

A substantialgravel 41-3 m thickness)overlay is requiredwhere year- roundaccess to a site is needed over ice-richpermafrost. However, placementof insulation beneath the gravel would reduce the thickness of overlay required.Year-round access roads must also be above flood stage of the river,which may requireplacement of culverts at high-water channels crossedby the road.

OVERBURDENREMOVAL

The strippingof overburden involves the removal of any materialcover- ingthe gravel deposit. The overburdenmaterial, usually topsoil and organics,is normally removedfrom the site and either stockpiled for later use insite rehabilitation or hauledto approved disposal sites. Stripping is normal ly done withgraders, scrapers, or dozers. Overburden depths were notrecorded at all of thestudy sites. However,where information was available,the depths ranged from a thinveneer (at six of thesites) to 0.9 m .(atone of the sites) andthe, average was 0.3 m.

CHANNEL DIVERSION

Forefficient gravel removal at some floodplainsites, it may bedesir- able todivert river flows, especially those associated with subchannels, away fromthe area from which gravel is to be removed. Thisdiversion is normally doneby constructingearthen dikes or levees upstream from the site.Armoring of the upstream face and outer end ofthese structures may be necessary toprovide erosion resistance. Erosion prevention is discussed further in EFFECTS OF GRAVELREMOVAL ON RIVER HYDROLOGYAND HYDRAULICS.

324 SETTLING PONDS

It is necessaryto wash gravelif the mined material has an appreciable siltcontent. When gravelis washed, it isessential that settling ponds be providedto allow silt to settle out before the wash waterre-enters the river. Theseponds should be of sufficientcapacity to handle the daily volume of wash wateror stream flow, or both, considering the settling velocity of theentrained silt particles. Design considerations for settling pondscan be foundin Appendix F ofthe Guidelines Manual.

325 SITE OPERATION

The basicelements of a gravelremoval operation are excavation, transportation, and materialprocessing, The detailsof equipment selection, scheduling,and operation procedures are dependent on the composition of the gravel,the season of operation, the topography, the haul distance, and the environmentalcharacteristics of the site.

EXCAVATION

The two basicgravel removal techniques used at the 25 studysites were scrapingand pit excavation. Table I identifiesthe technique used at the respective sites.

Rippingand Blasting

Frequently,site operators prefer removing gravel in winter because waterlevels are lowand access is easier. However, wintermining means excavatinggravel in a frozen,possibly ice-saturated condition. At the studysites, if the gravel deposits were well above waterlevels andwere low infrozen moisture, excavation by scraper was normallynot difficult. Rippingfrozen gravel was requiredat at least three of the sit Middle ForkKoyukuk River-Upstream, Prospect Creek, and Phelan Creek). It is not known ifblasting was utilized to removegravel at any of the s i tes

Scrap i ng

Scrapingat larger sites is usually done withbelly-dump scrapers. At smal ler sites or remotesites, or both, D-9 or mal ler caterpi I lar tractors

326 arefrequently used.Scraped sitesare usually dry when worked,however, caterpillartractors can work in shallow water (possibly up to 0.5 m).

Pit Excavation

Pit excavation is generally done withdraglines or backhoes. Dewatering may or may not benecessary. At thestudy sites some of the moreshallow pits weredewatered, but deeper pits, e.g., DietrichRiver-Upstream, West ForkTolovana River', andTanana River-Downstream were excavated underwater.

Comparisonof Techniques

Some engineeringand economic advantages and disadvantages of removing gravelvia pits versus scraping are listed below. Advantagesof Pits Versus Scraping

0 Greaterquantity from smal lerarea.

0 Can work withinconfined property limits (if necessary).

0 Lessclearing required. e Less strippingrequired.

0 Can providesilt trap.

Disadvantagesof Pits Versus Scraping

0 Dewateringor underwater excavation required.

0 May provideless gravel per unit time than scraper operation. Cannotbe restoredas closely to original condition.

TRANSPORTATIONAND STOCKPILING

Transportationof gravel from the material site to the stockpile or processingplant may bedone withscrapers or front-end loaders and dump trucks.Stockpiling gravel removal operations greatly reduces scheduling problems. It ispossible to load trucks directly for long-haultransport to ultimate-useareas without stockpiling, but a greatdeal of coordinationis

32 7 requiredbetween the excavating and transporting activities. It is advan- tageous tomaintain a stockpileof at least moderate sire to serve as a bufferbetween excavating and transporting, Gravel stockpiles remained on or immediatelyadjacent to nine of the study sites, however, onlyDietrich River-Upstream, Jim River, andPhelan Creek stockpiles were still being used.

PROCESS I NG

Gravelprocessing can involve screening, washing, crushing, mixing, or combinationsof these. Materials of the study sites frequently were fairly uniform,subrounded to well-rounded, hard gravels with varying amounts of sandand cobbles. Such materialsare suitable for road embankments with littleor noprocessing. However, siltcontent should be limited to approximately IO percentto minimize frost susceptibility. Processing apparently was onlyconducted at those study sites used for construction of the Trans- AlaskaPipeline Systemwhere screening and some crushingwere done topro- ducebedding and padding material for the below-ground pipeline.

328 SITE REHABILITATION

Engineeringconcerns contribute to rehabilitation mainly if futuresite development(e.g., erecting of structures)is planned. In this situation, long-termintegrity of structures is the primary concern of siterehabilitation.Otherwise, the primary purpose of siterehabilitation is erosion control. The mainfunction of erosioncontrol is to prevent degradation of disturbed andadjacent areas.

Some rehabilitation was done atall study sites worked since 1972. There was noevidence of rehabilitationhaving beendone at any ofthe older sites. Where finalsite grading was conducted, it typicallyincluded sloping or flattening of stockpiles andoverburden piles to blend with the terrain, contouringthe site to a maximum 2:lslope, andremoval of gravel ramps (not done atthe lvishak and ShaviovikRivers).

329 REFERENCES

Adam, K. M. 1978. Winter Road ConstructionTechniques, pp.429-440. In Proceedingsof ASCE Conferenceon App I iedTechniques for Cold Environ- ments. Vol. I. Anchorage,Alaska.

Sherman, R. G. 1973. A GroundwaterSupply for an Oil Camp nearPrudhoe Bay, ArcticAlaska, pp.469-472. InProceedings of the Second Inter- nationalConference on PermafrostrYakutsk, USSR.

Wellman, J. H., Clarke, E. S., and Condo, A. C. 1976. Designand Construc- tion of SyntheticallyInsulated Gravel Pads inthe Alaskan Arctic, pp. 62-85. InProceedings of Second International Symposiumon ColdRegions Engineezng.Fairbanks, Alaska.

Woodward-Clyde Consultants. 1976. PreliminaryReport - Gravel Removal Studiesin Selected Arctic and Sub-ArcticStreams in Alaska. U. S. Fish and WildlifeService, FWS/OBS 76/21. Wash. D. C. 127 pp.

330 INTERDISCIPLINARY OVERVIEW OF GRAVEL REMOVAL E. H. Follrnanna

INTRODUCTION

Thischapter presents a generaloverview of the effects of gravel removalin contrast to the preceding disciplinary chapters that rely more heavilyon analytical treatments of data collected at the 25 studysites. Each ofthe Major Variables identified in the Matrix (Table I) is discussed relativeto its influence onthe effects of a gravelremoval operation. These characteristicsdirected the early phases of thestudy, including the siteinvestigations, andform, forthe most part,the framework of the gravelremoval guidelines. The disciplinarychapters on gravelremoval effects did notnecessarily treat each of thesecharacteristics because some were notrelevant or theydid not influencethe evaluations or syntheses suf f icientlyto warrant individua I attention. Thus, thisoverview chapter cons titutesthe functional bridge betweenthe Guidelines Manual and the Techn i ca I Report .

Few problemswere encountered in the discussion of the Physical Site Characteristics and theirinteraction with gravel removal projects because thecategories are mutually discrete, i.e., a rivercannot be both meandering and straightwithin the study reach. Tho categoriesunder each of the Gravel Removal AreaCharacteristics, however, arenot mutually exclusive and,thus, cause difficultyin the developmentof that discussion. The sites selected encompassed atleast several individual locat-ions from which gravel

3 E. H. Follmann is presentlyassociated with the Institute of Arctic Biologyof the University of Alaska.

33 I was removed. Sitessuch as Aufeis Creek on the North Slope andPenny River onthe Seward Peninsulaeach included 8 ofthe 12 specificsite locations thatwere possible (Table I). Thiscomplexity made it difficultto identify any specificfloodplain changes withspecific gravel removal locations. For thesesites, the overall effect onthe floodplain resulted from the total gravelremoval operation and specificeffects were masked. The problemof siteswith multiple Gravel Removal AreaCharacteristics was unavoidable becausealmost allof the over 500 sitesoriginally considered reflected the same situation. The majorresult is that, in some cases,generalities are discussedwith little or noreference to specific material sites. If none of thesites clearly exhibited the relationship being discussed, nonewere cited as examples.However, the generalitiesdiscussed are considered accurate becauseof the analyses and conclusionsreached in the preceding disciplinarychapters.

332 PHYSICAL SITE CHARACTERISTICS

The PhysicalSite Characteristics considered in this project were: drainagebasin size, channel width, channel configuration, channel slope, and streamorigin (Table I). Followingstudy of the 25 materialsites and analysesof data, it was establishedthat channel configuration was themost importantfloodplain characteristic affecting environmental change when combinedwith gravel removal activities. Drainage basin size (channel width) was foundto be less significant, andchannel slope and stream origin were found to have littleinfluence onthe effects of gravel removal. The followingdiscussion is subdividedaccording to these categories.

CHANNEL CONFIGURATION

The channelconfiguration or pattern of a riveris the shape ofthe riverchannel(s) as seenfrom the air, Thechannel configurations considered inthis study were braided, split, meandering, sinuous, and straight.

Braided

A river with a braidedchannel pattern typically contains twoor more interconnectingchannels separated by unvegetatedgravel bars, sparsely vegetatedislands and, occasionally,heavily vegetated islands. Its floodplain istypically wide and sparselyvegetated and contains numerous h igh-water channels. The lateralstability of these systems is quite low within the boundariesof the active floodplain.

Fourbraided systems used for material sites were studied. lvishak River on theNorth Slope, Dietrich River in the Northern Interior, and Tanana River and PhelanCreek inthe Southern Interior. Thesesystems usu-

333 allycontain large quantities of gravel and, therefore,are often utilized asgravel sources (Figure 93). Thebed load carrying capacity of these rivers is large,thus facilitating the replenishment of extracted gravels aftersite closure,

Braidedriver systems are dynamic and lateralshifting of channels from year-to-year is common, therefore, anychannel shiftingresulting from lower- ingbars through gravel removal would be similar to the natural processes. Forexample, any diversion,of a channelthrough an areathat was loweredby theremoval of gravelpossibly would have occurred naturally sbmetime in the future.Material sites in these areas typically are scraped because required quantities of gravelusually can be obtained over large areal extents and it is more efficient to work a site abovethe existing water level. Due tothe bedload carrying capacity of these systems, the typical shallow scraped sitesare subject to sedimentation rates similar to natural depressions occurringin these floodplains. Therefore, the minded sites can return relativelyquickly to near natural conditions. This recovery is particularly trueif the site is located near the active channel. An example ofrapid recoveryis the lvishak River site, which was shallowscraped over a large areaof unvegetated gravel bars. After several years the only evidence of gravelmining is the presence of access roads and fill ramps thatconnected thematerial site with an airstrip and drill pad.

Long-termeffects of gravelremoval on water quality were not evident atthe four sites located in braided systems. Due tothe relative instability of channelsin a braidedriver system,any channels routed through an abandoned materialsite probably would be affected in a manner similarto a channelbeing rerouted due tonatural hydraulic processes. An exception wouldbe where an aliquotof a material site was usedas a settling pond during a gravelremoval operation, The accumulatedfines could be suspended duringsubsequent high flows ifthis material was notarmored and was left inthe depression during site closure. None ofthese situations wasen- counteredat the study sites, however,the possibility would exist in similarsite conditions.

3 34 Sp I,i t

Meander i ng

Sinuous

Straight

Figure 93. Configurations of study rivers.

335 The aquaticorganisms in braided systems are adapted to the seasonal dynamicsof the channels and, therefore, anychannel changes resultingfrom gravelremoval operations provide situations for which the organisms are alreadyadapted. An exceptionto this generalization occurs where a pit is separatedfrom the active channel (Tanana River-Downstream) or is within the floodplain(Dietrich River-Upstream) andconnected to an activechannel. In thesecases, organisms that are more adapted to lentic environments become established.Also, certain fish species may usethe calmer waters of these pitsfor spawning,rearing, and feedingareas. These pitsites are the exception,because scraping is the usual procedure selected to excavate sites in braidedsystems. Excavating aspects are discussed further in the following section onTypes of Gravel Removal.

Terrestrialspecies that utilize braided river systems similarly are littleaffected bythe usual scraping operation. Since non-vegetated bars arefavored gravel removal sites, few small mammals orpasserines are affected. The water-associatedbirds that use the various channels andback- watersfor feeding are also little affected bythe material sites because theusual result of these operations is to providehabitats already present.

Due tothe dependence ofsmall mammals and passerines on vegetated islands,gravel bars, andbanks present in braided systems, any removal of vegetationto expose a graveldeposit would totally displace birds and eliminatesmall mammals fromthe disturbed site. Similarly, these areas, whichoften have associated dense shrub thickets, are used by moose and ptarmigan,especially during winter. Loss ofthis habitat would cause lo- calizeddisplacement of theseanimals.

Maintenanceof the scenic quality of an areacan be achieved by de- signing a materialsite to complement thenatural setting. Material sites in braidedsystems did not detract from the visual quality of the floodplain wheregravel removal was restrictedto unvegetated gravel bars. The ex- pansivefloodplains typical of these systems are somewhat uniformin appearance,yet the numerous channels and gravel bars endow theseareas with a complexitythat permits material sites to belocated with little effect.

336 The usualmining technique for these sites is toscrape unvegetated gravel barsrather than to excavate deeply, thus, any rearrangementof channels through anabandoned sitewould closely resemble the natural annual processesof lateral channel migration.

In summary, braidedriver floodplains can be desirable locations for extractinggravels (Table 40). Theabundance ofwell graded materials and thepotentially small effecton the physical, biological, and aestheticchar- acteristicssuggest the desirability of theseareas for materialsites. = conclusion assumes thatthe procedures of shallow scraping of unvegetated gravelbars with minimal disturbance to active channels, banks, andvege- tatedareas, andcomplete rehabilitationof sites during site closure, are adheredto.

Sol it Channel

A river with a sp lit channelpa tternhas numerous islandsdividing theflow into twochannels. The islands andbanks are usually heavily vegetated and stable(Figure 93). The channelstend to be narrowerand deeper andthe floodplain narrower than in a braidedsystem. Four split channel riverswere included in this study: theKavik, Kuparuk, and Sagavanirktok Rivers onthe North S lopeand the S inuk R iveron the Seward Peninsula.

A I though the bed load carrying capac ityof split channel riversis lessthan for braided systems,they of tenhave a greatercarrying capacity thanequivalently sized meandering or sinuous rivers. The narrowerflood- plains and lackof numerous gravelbars restrict the extent of potential gravelremoval areas. Channels, islands, and banks are often used for extraction, as was thecase at the four sites studied. Islands andbanks typically arevegetated and relatively stable, consequently, there is a directeffect onsmall mammals, passerines,ptarmigan, and moose utilizingthese areas. The long-termterrestrial disturbance is directlyrelated to the extent of vegetationremoval and therehabilitation practices used during site closure.

337 Table 40. InterdisclplinaryRating of CumuIativeEffect of Scraping, Using VariousIndices of Change, on Selected StudySites VIsited from 1976 to 197e'

Hydraulic effects Aqua€ i c effectsTerrestrial effects M acro inver- Index of Index Macroinver- Degreetebrate of Fish Water Environ- Increased hybsul ICmental birdRiparianstanding habitat R lver type Study type Rlver site LOCQtiOtl braidingvegetationalterationdiversityhabitatcrop change

Bralded tvishak A Nath Slope 6 6 5 8 5 I .8 Diefr 1 ch R-US Wortherntnterlor 5 5 0 5 6 1.3 Dietrlch R-DS NorthernInterla 6 6 7 3 8 1.8 Phelan Ck Southern lnterla 5 5 5 5 5 0.0

Spl It Sinuk R Sward Pen I nsu Is 6 7 2 5 6 1.8 Kuparuk R North Slope 6 6 2 I 5 1.5 0 W Sagavanlrktdc R North Slope 0 7 9 0 3.2 W Kavik R North Slope 0 3 1.8 aD 7 3 6

kQn- Aufeis Ck North Stope 9 8 1 5 I 7 2.8 der Ing Skeetercake CK North Slope 7 a 4 5 I 6 1.8

s inuous Gold Run Ck Seward Peninsula 5 6 5 5 3 5 0.5 Washington Ck Sward Peninsula IO 9 0 2 I 6 3.7 Penny R Sward Peninsula IO IO 2 4 I 9 3.7 Nome R Sward Peninsula IO 8 4 e 4 5 2.2 Ugnuravik R North Slope 7 7 5 IO 4 5 I .-I Shaviovlk R North Slope 5 6 5 5 5 5 0.2 M.F. Koyukuk R-US Northern.tnterior 9 7 9 2 3 7 2.6 B.F. Koyukuk R-DS NorthernInterlor 7 7 4 9 3 6 2.0 MflaIlUtr Ck Southerntnterlor 5 7 5 5 4 5 0.5

Straight Oregon Ck Sward Peninsula 10 8 0 3 I 6 3.3

'15 = no change, 0-4 = decrease in parameter, 6-10 = increase in parmeter) bindex of environmental change IIEC) = E Ixi-5t here xi = rating valuesof disciplinaryindices; IEC rangesfrom 0-5. i=I -6 Loweringislands andbanks by removing gravel, even ifmaintained abovethe existing water level, can result in reduced stability of channels duringhigh water. Material sites will thenbe inundated at least temporarily.Spreading water over a broaderarea reduces its velocity, causing depositionof suspended and bed load materials. Some ofthis reduced Vel- ocity may functionto replenish materials in the abandoned materialsite but thisprocess would probably require a longerperiod than would be expected in a braidedsystem.

Spreadingof water and reductionof velocity is conduciveto changing watertemperatures during the open water season. Altered water temperatures may influencethe abundanceand diversityof aquatic biota by altering the amount ofusable habitatfor particular species.

The reduced stability of thechannels that could occurafter site closurecould be detrimental tothe establishment of permanent biotic populations,in part icular,benth ic organisms.In addition, entrapment of fish inpockets and poolsin the d isturbed site may occuras water recedes into theactive channels following high-waterconditions.

The increased depos i t i on of bothsuspended and bed load materials couldbe detrimental to the establishment of benthic communities. Fine materialswould likely be deposited in these areas, thus changes in the structure of benthiccommunities could be expected, These changes would be fromorganisms adapted to coarse substrate to those able to exist on finer lessstable substrate.

Changingchannel configuration by removing islands, removing gravel depositsfrom banks, and locally widening the active floodplain will affect thescenic quality of anarea. This aesthetic effect was quitenoticeable at theSinuk and Kavik River sites where care was nottaken to preserve natural contours andchannel configurations. In addition, stockpiles andremnants of diversion bermswere leftin place. The neteffect of these conditions was to form a majorcontrast with the natural conditions occurring both upstream anddownstream of the site.

339 In summary, thesplit channel system is one thatcontains a relatively largequantity of gravel material, but its narrow floodplain with stable islands andbanks restrictsthe areal extent where gravel can be easily obtained. Use ofvegetated areas will directlyaffect terrestrial organisms by eithercomplete removal or displacement to undisturbed areas. Similarly, thetendency for localized widening of the floodplain will reducelateral stabilityof channels, facilitate the possible formation of a braided channelpattern, decrease water velocity, increase sedimentation rates and, perhaps,increase water temperature. These changes will affectaquatic organismsby increasing secondary productivity, by changingbenthic com- munitystructure, by providingrearing areas for some species of fish, and perhapsby affording situations conducive to fish entrapment (Table 40).

Meandering

A meandering riverwinds backand forthwithin the floodplain. The meanderingchannel shiftsdownvalley by a regularpattern of erosion and deposition. Few islandsare found in this type of river and graveldeposits typicallyare found onthe point bars at the insides of meanders (Figure 93). Sedimenttransport in meandering systems is usually less than forbraided and split-channelriver systems of equivalent size.

The sizeof individual gravel deposits in a meandering river depends on thesize of the river. On a largeriver, point bars can be quite ex- tensivewhile on smaller rivers the point bars are characteristically smaller. The arealextent of these gravel bars determines, to a largeextent, thedegree of change which gravel extraction has on a meanderingsystem. For example, if a largepoint bar is used tosupply gravel for B smallproject, theoperation of a materialsite may cause little change tothe river system. However, when projectswith large gravel requirements are situated closeto a smallmeandering river or where the gravel requirements exceed thatavailable on a largepoint bar, potential effects to the river system increasegreatly. The alternativemining procedures are to completely remove thepoint bar, use several point bars, or removevegetated deposits back fromthe channel. In al I cases,varying degrees of impact can be expected, butall will dependon the manner inwhich the gravel is extracted.

340 Fourmaterial sites onmeandering systems were studied on this project (Table I). Two weredug as pits andtwo were scraped,

Pit Sites. The materialsites at Prospect Creekand West ForkTolovana Riverwere dug in abandonedchannels. In neither case was there a change in thelateral stability of theactive channel. There was loss ofterrestrial vegetationand associated fauna because the material sites were located back fromthe active channels. Aquatic fauna in the active channel apparently did not change. Change, if any, was due tothe presence of an adjacent floodedpit. Similarly, water quality did not change inthe active river channels but, as expected,water quality in the pit was differentfrom that in the activechannel. These differences andchanges are discussedin the section on Type ofGravel Removal becausethey were not unique to meandering sys- t ems.

Formationof a permanentlyflooded pit within a floodplain,that other- wisecontains fewponds orlakes, changes the appearance of the area by in- creasingthe diversity of physical features. These pitsare quite visible when seenfrom the air or from a highterrestrial vantage point. Tall vege- tationin the areas of these two materialsites contributed greatly to blockingview of the sites.

Many meandering riverfloodplains contain a multitudeof oxbow lakes thatare formed by channel cutoffs. In these cases, a pitcould blend e,asily intothe natural landscape, thus greatly reducing the visual effect of gravelremoval operations. However, most pits are dug withangular perim- eterswhich create a visualcontrast in the floodplain. This contrast is a genericproblem and will bediscussed further under Type ofGravel Removal.

ScrapedSites. The materialsites on Aufeis Creekand Skeetercake Creek werescraped. The environmentalchanges were quite different at the two sitesresulting principally from differences in their locations relative to thechannel (Table 40). The gravelat Aufeis Creek was scrapedfrom across the entire channel,which changed the channel from a singleto a brai ded conf igurat ion. The short-terminfluence was so severethat surface f low was

34 I nonexistentthe year following site closure but, over 3 yearssurface flow was re-established.Although the site was notstudied when surfaceflow was absent,the effect on fish would have been to prohibit passage. Epibenthic communitieswould have been reduced due to the lack of surface water. Fol- lowingre-establishment of surface f I ow, benthiccommunities characteristic of riffle zoneswould be most common due tochannel spread andreduced water depth.

Thechange from a single channe I to a braidedchannel can significantly affectthe local distribution of aquatic organisms. The alteredcommunity wouldbe similar to thattypically found in a naturallybraided system. Reducedwater velocity enhances sediment deposition and can alter water temperatures.During the study, changes in water temperature were noted betweenthe upstream and disturbedsample areas, but a differencein suspended solids was notfound.

Theimpact on the terrestrial environment frequently entails removal of vegetation and otherhabitats along the bank. Little change tothe terrestrialenvironment would be expected when gravel is minedonly on unvegetatedgravel bars, unless the hydraulic characteristics of the channel are changed significantlyfollowing site closure. Also, little changewould be expectedin the scenic quality of anarea as a resultof gravel removal, unlessvegetation is removed. At AufeisCreek, changes in both the terrestrialenvironment andscenic quality resulted from the gravel removal operationbecause of the area disturbed, the site location, and operating proceduresthat were used, none of which complemented the floodplain characteristics.

At SkeetercakeCreek the hydraulic changes were somewhat different. Theexposed gravel deposits were limited because this was a smallriver. Thus, gravel was minedfrom vegetated areas in the floodplain, with concom- itanteffects on theterrestrial fauna. The gravelremoval activity affected channel stability by facilitating a channelcutoff, however, the channel did notbraid due, atleast in part, to the restricted floodplain. The cutoff formed an oxbow lakein the abandoned site. The floodplainin this reach of

342 the river hadfew oxbow cutoffs,consequently, mining changed the appearance ofthe area, However, thepresence of overburden and gravel stockpiles detractedfar morethan the altered channel.

Aquatichabitat changes atSkeetercake Creek were not as greatas would beexpected if the channelhad become braided. The narrownessof the natural channelimparted a greatersignificance to the value of bank vegetation. Loss ofthis cover can change the distribution of fishes. Thechange from an incisedchannel to a shallowriffle area through the abandoned site caused thewater temperature, during the study, to behigher in the disturbed area thanupstream. However,changes in suspended solidswere not noted.

Summary. Scrapingpoint bars can have little environmental effect assumingthat the operation is conductedin a manner thatminimizes changes

t.0 thehydraulic characteristics of the channel and adjacentvegetated areas. If change isminimized, the effects on aquatic and terrestrialbiota, and waterand scenic quality are greatly minimized.

Meandering riversprovide usab ledeposits of gravelfrom point bars, in i nac tivefloodplains, and terraces. The potentialeffects onsuch a system vary dependingon whether only poin t barsare used orwhether the adjacent inactive f I oodplain and terracealso are mined. Sites in inactive flood-

plains and terracesoften are dug as pits while PO intbars in active floodplainsare scraped.

Pit s i tesremote from the active channel have caused some prob lems duringspring breakup at sites visited during site selection,but not studiedas primary sites in this project (unpublished data). When channels areblocked with ice, melt water must flow over the ice and may overflowthe bankand spread across the entire floodplain. Pit5 locatedin these floodplainsare then subject to filling which can facilitate diversion of flow throughthe site. This diversion is particularlypossible where pits are dug withinthe inside of a meander.Depending on thesize and inherentstability of theundisturbed buffer between the pit andchannel, the flow may cut

343 throughthe buffer zoneand permanently divert flow. Ultimately, the meander will becut off through sediment deposition and form anoxbow lake.

Othereffects can be anticipated when pitsare dug inthe floodplain of meanderingsystems, however,they are characteristic of pit mining.There- fore,these aspects arediscussed under Type of Gravel Removal.

Sinuous

Sinuouschannels are similar to meandering channels except that the windingpattern is less pronounced. The channel may containsmaller point bars andhave less tendency for downvalley shifting. Also, thechannels are more stablewith respect to lateral shifting.

Ten of thesites studied on this project were onsinuous rivers (Figure 93). Theirsimilarity to meandering channels suggests that the effects from gravelextraction are also similar,with the majoi. influencedetermined primarily bythe site location and theremoval method. Due to this simi- larityonly a few characteristicsof mining gravel at sinuous channels are discussed.

The smallerpoint bars in sinuous rivers, as compared to meandering rivers, limit thequantity of exposedgravel that is locallyavailable for removal.This limitation can magnify the need for using multiple point bars orvegetated areas back from the channel to fulfill the gravel requirements of largerprojects.

Floodplainareas adjacent to the channel contain gravel deposits that aretypically overgrown with vegetation. Floodplain width usually is roughly equivalentto the meander beltwidth, thus, the floodplain of a sinuous rivertends to benarrower than in a meanderingsystem. Therefore, the area inthe floodplain that is availablefor gravel extraction is more limited. Thisplaces restrictions on theareal extent of potential gravel resources, and may requirethat a greaterlength of floodplainbe used to extract grave I b

344 The potentialeff ectsof removing gravel from sinuous channel rivers areincreased because ofthese limitations. If point bars are scraped too deeply, or ifincised banks and theadjacent floodplains are disturbed, the potentialfor decreasi ngchannel stabilityis greatly enhanced. The initial disturbancefrom site clearing, and thechanges resultingfrom a poorly located and operatedsite, will have multipleeffects.

The decreasedchannel stability and tendency forbraiding will affect bothbenthos and f'ish by alteringaquatic habitats. Benthic communities adapted to riffles, fine sedimentbottoms, and a relativelyunstable bottom, will become established. Loss of bank cover and potentiallyreduced current inthe disturbed site will affect fish distribution and perhapsspecies composition.In addition, reducing water depth and-velocity could change watertemperatures and affectthe level of dissolved oxygen. Fishcould become trappedin the disturbed site when waterrecedes following high flows.

Terrestrialvegetated habitat will be destroyed when thefloodplain adjacentto the channel is used as a materialsite. This destruction of vegetation will cause eitherelimination or displacement of terrestrial fauna. If thestream banks are affected the decreased hydraulic stability in the areacould reduce the potential for re-establishment of vegetative com- mun i ties,thus creating a long-term rehabilitation problem.

Gravelremoval from a sinuousriver will have effects on thescenic qua I ity similarto those discussed for a meanderingsystem. The degreeof effectis fully dependenton thediversity of landforms in the area of the site and the amount ofdisturbance. Single channel river systems are scen- ically more sensitivethan multiple channel systems particularly those single channel riverslocated in areas with low growingvegetation, such as on theNorth Slope.

In summary, the amount of environmental change that canbe anticipated in a sinuousriver system is largely dependenton thelocation of the material site and themethods of operation. Anticipated effects are similar to

34 5 thosefor a meanderingsystem but, because floodplain; generally are more narrowand contain smaller point bars, the potential for permanent alteration is generallygreater (Table 40). Properplacement of the material site and operationalproce.dures can minimize permanent change and theseshould be selectedto prevent or minimizechanges to the hydraulic characteristics of thechannel.

Straight

Straightchannel patterns are less common thanother types. The thalweg of a straightriver typically winds backand forthwithin the channel. Gravelbars form opposite where the thalweg approaches the side of the channel(Figure 93). Thesegravel bars may notbe exposed during high flow. Banks of straightsystems typically are stable and floodplainsare usually narrow.These river systemsare considered to be an unusualconfiguration in transitionto Some otherconfiguration. Only the material site studied at OregonCreek was situatedon a straightchannel system.

As withother types of singlechannel systems the major potential effectfrom scraping floodplain gravels is decreasedstability of the channel and a tendency todevelop a braidedconfiguration. Theseare probable occurrencesbecause of thetypically narrow floodplains and thelimited number of exposedbars available. Often the adjacent floodplain will have to bedisturbed, or even the channel itself, because of thelimited area available. The OregonCreek sitetypified the extensive long-term changes that canoccur when gravel is removedfrom withinthe channel and theadjacent floodplain(Table 40). Thechannel stability was greatlyreduced and the channelhad become braidedwithin the confines of the abandoned site. These conditionsexist 13 yearsafter the site was closedand probably wi I I remain inthat condition for many moreyears.

Thechange from a single to a braidedchannel alters water qual i ty parametersand aquatic biota as discussed in previous sections on sinuous andmeandering systems. These alterations include the potential for changing watertemperature and increasingsedimentation in the disturbed site where

346 , thewater fans out andbecomes sha.lIowerand slower in velocity. Dissolved oxygenand conductivity levels can also be altered. Benthic communities may changefrom a communityassociated with the relatively stable channel of a straightriver to one that is betteradapted to the less stablesubstrate characteristicof braided areas. Removal oralteration of vegetated banks andchanges in pool:riffle ratios canalter the distribution of fish within theimmediate vicinity of thedisturbance. Fish passage is obstructed if the spreadingof water sufficiently reduce its depth.

The disturbancesat the Oregon Creek site provided a situation conduciveto the formation of aufeis. Aufeis could have direct effects on fish " byeliminating or greatly reducing the flow downstreamfrom the ice field, thusthreatening overwintering areas andspawning beds. Similarly, during breakup,delayed thawing of the ice field could obstruct fish passage. Benthiccommunities would be later in establishing at the disturbed site due tothe delayed melt of the ice field.

The terrestrialenvironment will almostalways be subject to disturbance for any sitesituated on a straightchannel river. This vulnerability is due tothe rarity of large exposed gravel bars in the channel which necessitatesmining the adjacent vegetated floodplain banks or terrace. At the OregonCreek sitethe vegetated overburden was removedand placed in a rowat the edge ofthe terrace. The gravel was removedfrom the exposed area andfrom within the channel causing extensive spreading of theflow through theexposed floodplain. Inundation of this area during high flow and the build-upof an aufeis field greatly minimized the potential for stabilization and revegetationof the disturbed area. This stabilization andrevege- tation hadnot occurred after 13 years,thus the likelihood of the site revegetatingin the near future is remote.

Theappearance of the floodplain was greatlyaffected at the Oregon Creek site.This altered appearance will exist for a longtime and will only diminish when thechannel begins to narrow and when adjacentareas revegetate. The potentialfor major changes in the appearance of a straight chan- nelfloodplain, that is mined, is great because of the limited availability

3147 ofexposed gravels, which necessitates the disturbance of adjacent vegetated areas. The magnitude of effectincreases with a decreasein river sire.

Ingeneral, the rarity of 5traight channel rivers probably is fortunate fromthe standpoint of gravel requirements . The relatively fewexposed graveldeposits and thenarrow floodplains suggestthe major problems that canresult from gravel removal operations inthese systems. Major distur- bancesprobably wi I I occurin any river of thistype unless precautions are taken to protectthe area. When miningis restricted to exposed gravel deposits a majorlength of floodplain will be disturbedif gravel require- mentsare large. The latterproblem can be prevented by restricting mining tothe adjacent vegetated floodplain. Straight channel systems should be avoidedwhere it is possibleto select alternate areas to mine.

DRAINAGEBASIN SIZE (CHANNEL WIDTH)

Drainagebasin size andchannel width are closely related from a hydrologicalstandpoint and analysisof only the former would be sufficient forassessing change from gravel removal activities. However, channelwidth was includedin the Major Variable Matrix (Table I) because it is a measurement easilyobtainable in the field while drainage basin must oftenbe estimatedfrom topographical maps. Becauseof the close relationship between thesetwo parameters, the following discussion applies to both.

Drainagebasin sire (channel widtti) was consideredto bethe second mostimportant Physical Site Characteristic influencing the amount ofchange in a floodplainfrom gravel removal activities. In general, the effects of miningwere considerably greater on small rivers than on large ones. The determiningfactor isthe amount ofexposed gravel material available within thefloodplain. In I arger systems,gravel deposits can be numerous and any givendeposit usua I ly con tains a largequantity of material. The situation isthe opposite in a mal I river - the fewexposed deposits generally do not contain much mater ial.

348 Inlarge rivers, a given amount ofgravel can be removed from exposed depositswith relatively less effect on the floodplain than at a small river.If gravel requirements are very large, the alternatives are to use multiplegravel deposits along the channel, or to expandthe areal extent of one siteto include adjacent vegetated areas. In a smallriver system,there areno real options. Gravel has to be removedfrom adjacent vegetated areas, or from theactive channel, or both.This solution was thecase for Seven of the small riversstudied. The Gold Run Creek siteexhibited less changethan theother small river systems (except for the site at Phelan Creekwhere vegetation was notremoved). At Gold Run Creekthe gravel removal operation was restrictedprincipally to gravel bars andan islandin the channel. A bank was removedbut the degree of floodplaindisturbance was lessthan for thesites onWashington, Oregon, and McManus Creeks,and Penny River. At theselatter sites, extensive adjacent floodplain disturbances tended to eithergreatly expand thechannel width or divert the channel.

PhelanCreek is a braidedsystem andhas a smalldrainage basin above thematerial site. Although the site is situatednear the headwaters, the channel is of medium widthbecause of flowcarried in the summer during glacialmelt. In this case the large exposed gravel deposits were scraped andthe material site included neither vegetated areas nor channels carrying flow. Eventhough thisis a smallriver system, the long-term effects are minimalbecause of otheroverriding factors. Minimal effects are usually not the case,however, on small rivers.

Location of thematerial site is most critical onsmall river systems becauseof the limited availability of exposed gravel deposits and therela- tivelynarrow floodplain. Extensive damage canoccur to the entire flood- plainreach being mined in these systems, while on large rivers the effects arenot as great because the material sites cover a smallerproportion of thefloodplain. Location of sites and potentialeffects are discussed in a subsequentsection.

349 CHANNELSLOPE AND STREAM ORIGIN

Neitherof these Physical Site Characteristics was foundto greatly influencethe effects of gravel removal in floodplain environments. Both channelslope and streamorigin are closely related to such factors as drainagebasin size and channelconfiguration, therefore, their influence on theeffects of gravel removal are dependent on these factors, The Physical SiteCharacteristics are discussed separately because of specific impli- cationsinvolved.

ChannelSlope. Removal ofgravel from a channel will affectthe channel slopewithin the site and, perhaps,immediately upstream anddownstream. Usuallythis effect entails increasing the slope, which can have localized effects onthe floodplain. The maineffect is to increasewater velocity.

Localizedchanges that can be expected due tothe relationship of increasedvelocity and increasedslope are scour and alterationsof aquatic communities.Increased scour in a disturbedsite can increase downstream depositionof bed load materials where the water slows to the velocity characteristicof the undisturbed channel. The greaterscour potential in thedisturbed site decreases the stability of bed materialsthus affecting habitatfor benthic organisms.

Increasedwater velocity can directly affect benthic organisms by displacingthose not adapted to higher velocities and favoringthose adapted tothese conditions. Similarly, fish may become redistributed locally becauseof water velocity changes. Those fish species or age groups preferring lowervelocities may displaceto areas upstream or downstream.

Alteredvelocity is not expected to changethe terrestrial environment orthe scenic quality of anarea. Indirectly, an effectmight occur to water- associatedbirds that are dependent on benthic organisms as a foodsource, Any alterationsto benthic communities could alter feeding sites for these birds.

350 Significantchanges in slope most oftenreflect changes in channel length. If a channel isshortened bymining then the slope is increased; if thechannel is lengthened,the slope is decreased. At allstudy sites the slope was either unchangedor it increased. The I ikel i hoodof decreasing channelslope by lengthening the channel is slight becausewater tends to flowdownvalley over the shortest distance. However, if channellengthening shouldoccur by diversion through a site,then the effects would reflect reducedvelocities.

StreamOrigin. The originof the stream was foundto have little or no relationshipto the effects of gravel removal activities. Origin can influence,at least in part, other characteristics of 3 river sy.stem,e.g., channelconfiguration andshape. Therefore, the preceding discussions are indirectly related to this characteristic. The origin of a streamdetermines greatlythe quality and quantityof gravel materials available in downstream areas.

The originalpurpose for including stream origin in the study was to maximizediversification of the types of sites to bestudied. The origins ofstreams included were mountain, foothill, coastal plain, and glacial.

Twelveof the sites studied were of mountainorigin, 9I wereof footh ill origin, and only 4 wereof glacial or coastal plain or igin.

The availabilityof gravels in streams of coastal plain origin is generally low and thematerials are finer in texture than those found in othersystems. Within the geographical limits ofour study, only the Seward Peninsula and NorthSlope have coastal plains. The coastalplain of the Seward Peninsula is so narrow it precludesthe existence of such river systems. On theNorth Slope material sites were located on the Sakonowyak, Putuligayuk, and UgnuravikRivers, but only the latter was studied. Gener- ally,these sites are not favored and areonly used if alternativeSites are notavailable. The lackof rock in the headwaters and thelow mean annual dischargesare thereasons that gravel materials are only minimally avail- ablein coasta I plainstreams. If these sites are utilized, the potential for rep I acemen t ofgravel sources is very loweven over extended time

35 I periods. The minimalareal extent of exposedgravel bars also generally leads toextensive damage to the river system either by use ofextended lengthsof river channel or by disturbingvegetated floodplains.

Glacialorigin streams are not common inthe area of study;only three sites situated on this type of river werestudied. These wereon Phelan Creek and the Tanana River. Because thesesystems are of mountain origin, theavailability of weathered parent materials is not limiting and usually largequantities are available. The Phelan Creek site was situated nearthe glacier and gravel was abundantacross a widearea. The proximityof the siteto the glacier strongly influenced the seasonal fluctuationsin discharge.During winter, water flow fromthe glacier is greatlyreduced and is supplementedby thatfrom associated springs. This reduced flow exposes vast expanses of gravelfor extraction.

The Tanana River sites are wel I downstream from the river origin, therefore,water flows throughout the year because of the numerous spring- and groundwater-fed tributariesentering the river. Affects include those associatedwith braided channels that flow in winter. In these systems,however, icecover on channels is more of a factorthan on a system likePhelan Creek,near itsorigin.

The availabilityof gravels in glacial origin rivers makes them a viablesource of materials even when needed inlarge quantities. This is basicallytrue for systemsof all sites although on smallerrivers the localized deposits are more restricted.

Most riversin northern and interiorAlaska are of mountain or foothill origin. The weatheredparent material in the headwaters prov.ides large quantitiesof gravels, particularly in the mountain systems. These rivers arefed by springs,melt water, and runoff and, therefore,discharge fluc- tuatesseasonally. Spring-fed systems can be expected to have at least intergravelflow in winter. Moderate to steep channel slopes are normal inthe headwaters but these s lopesare influenced by thelength of the r i ver and thetopography through wh ich it flows. Bed load movements are usua I lY

352 higherthan in rivers with mild slopes. These riversgenerally have large quantities of gravelavailable even nearthe mouth. The sizeof the system and otherhydrological and hydraulicfactors also influence availability of gravel. The abundance ofmountain and foothill origin rivers and thefre- quent availability of suitablegravel materials generally combine tofavor thelocation of material sites in these systems. The geographicallocation ofthese rivers, and thetopography through which they flaw, directly affect

353 GRAVELREMOVAL AREA CHARACTERISTICS

Inthe preceding section on Physical Site Characteristics it was apparentthat not al I characteristicswere important in evaluating the po- tentialfloodplain changecaused by gravel removal activities. In contrast, allof the factors discussed in this section were found to greatly influence the amount ofchange to a river system. The threemain features discussed aretype. of gravelremoval (pit orscrape), location of the material site relative to theactive channel(s), and theoccurrence of dikes and stockpiles.Singularly and incombination these factors caused varying degrees of change atthe 25 studysites, in some cases,irrespective of thespecific physicalsite characteristics.

TYPE OF GRAVELREMOVAL

Thereare two basic types of materia I sites:pits andscrapes. Pits are dug deeply,usually with drag linesor backhoes, and areflooded year- roundafter site closure. In many cases pitsare flooded during gravel extractionunless water is pumped outto keepthe site relatively dry. Eight pit sites werestudied and they represented two types, those connected to an activechannel and thosecompletely separated from an activechannel by a buffer zone. Pits usuallyare situated away from an activechannel.

In a scrapingoperation, gravel deposits are removed with bulldozers orscrapers in active and inactivefloodplains and terraces.Gravel is extracted bysuccessive removal of thin layers, and scrapingdepths usually aresufficiently.shallow to minimizethe occurrence of surface water. At certainstudy sites, gravel was extractedbelow the water table, thus water ponded inthe site. This situation is not conducive to a scrapingoperation and, therefore,is usually avoided unless it isrequired for other reasons.

3 54 Pitsare usually excavated away from an activechannel and cause little orno change to the natural hydraulic processes of the channel. Where pits areconnected to a channe1,'eitheryear-round or seasonally,, some change to thehydraulics of a rivercan occur. The mostobvious alteration occurs when springbreakup or other high water flows spread throughout the floodplain; much ofthe water can flow out of the channel because it is oftenfilled withice. A pitin the floodplain probably would fill during high flows and then,through erosional processes at the upper and lower ends, functionas a channel, The inlets or outlets(or both) connecting the pit to the channel couldenlarge significantly and rerouteflow through the excavated pit. Dependingon siteconditions this could be only temporary, for example, where a pit is adjacentto a relativelystraight reach of channel. In this case,following high breakup flows, the water would again flow down the originalchannel because the downvalley distance is shorter than if the waterflowed through the channel formed by the pit.

A permanentalteration to flow is more likelyto occur where a pit is locatedon the inside bend of a meanderingstream. Even with undisturbed bufferzones separating the pit from the channel, spring breakup flows can overflowthe pit and exitinto the downstream reach of the meander surround- ingthe pit. If the stability of the buffer zone is low, erosioncan breach thebuffer zone,thus, connecting the pit to the active channel. The downvalleydistance is shorter through the pit, consequently, there would be a tendencyfor permanent redirection of flow through the pit and eventualcut offof the meandering channel.

Excavationof a pitseparate from the channel does notaffect the water qualityof the active channel. As wouldbe expected, however, the water qual- ityis different in a floodedpit than in the channel. In comparisonto channelwaters, pitwaters typically have higher temperatures during ice freecon.ditions, the dissolved oxygen levels are lower, andsometimes there is stratificationof both temperature and dissolvedoxygen. Differences in waterquality parameters could be less in situations where channel flow is

355 through a pit. Thisdifference dependson the size of the pit and the amount ofmixing. A pitcould facilitate deposition of suspendedand bed load ma- terialsif f lowsare through a pit and velocityis decreased.

The aquaticbiota of pits differ depending onwhether there is an opportunityfor exchangebetween the pit and theactive channel. Those pits thatare separated (e.g., TananaRiver-Downstream) or have littlepotential for exchange (DietrichRiver-Upstream) typically are unproductive. The TananaRiver-Downstream pitis situated in the middle of an island and is completelysurrounded by a broadundisturbed (except for an accessroad) timberedbuffer zone. The likelihoodfor injection of nutrients andorgan- isms intothis pit is remote,except during high flows. The aquaticsurveys reflectedthis. The occurrenceof a few fishsuggests that overflow may occurat irregular intervals. The DietrichRiver-Upstream pit, on the other hand, is connectedby itsoutlet to the channel. 4 spring,exposed during excavation,floods the pit and exitsthrough a channel. The pit systemhas beenused by overwintering fish but the pit itself is relativelyunpro- duct ive.

All otherpits studied were highly productive andthe diversity of the fish community was usuallyincreased over that in the river channel. All of thesepits were connected to the river channel through either inlets or outlets and thusexchange was possiblebetween the two systems. The still watersin the pit, whichare warmer thanthe river water, provided conditions more suitablefor primary andsecondary productivity. Fish such 85 Arcticgrayling entered presumably to utilize the pit as a feedingarea. Thissituation is particularly good forfeeding by fishof younger age classesbecause of the greater suppl y offood available and thelack of a current.

Fish well suitedto a still wat erenvironment, such as northern pike andburbot, also didwell in some of thesepits and, beingpiscivorous, had anabundance of youngage classes of otherfish to feed upon as theyentered thepits to feed and rear.Northern pike also utilized twoof the pits as spawningareas. The potentialfor the pits to provide a more diversified

356 fish community inthe river also existsbecause of the connection between the twosystems. This increased community diversit,y may berestricted to the area of thechannel in the immediate vicinity of the pit.

Pit depthsare important to fish utilization, Obstructions to movement arenot a factorduring openwater periods ifeither an inletor outlet are availablefor fish movement betweenthe river and the pit. A potentialfor fishentrapment exists, however, during winter when ,icecover is present on theriver, the pit, and theinterconnecting channel. In the latter situation thepit mustbe sufficiently deep so it doesnot freeze to the bottom and decompositionof aquatic vegetation does not decrease the oxygen content of thewater below that necessary for fish survival.

The creationof a pit in a floodplaincons'titutes a majorchange tothe localterrestrial environment. Pits are usually situated onvegetated floodplains,consequently, terrestrial habitat is almostalways destroyed. The depthof excavation and thepermanent inundation that results also greatly retardsor prevents on thelong-term, the re-establishment of predisturbance conditions. What most frequentlyoccurs, however, is thecreation of a more diversehabitat with concomitant changes in faunal communities.

The creationof a pit in meandering riverfloodplains, that contain oxbow lakes,merely adds tothe habitat diversity in a localizedarea. Where pitsare located in floodplains lacking natural lakes andponds, the effect isagain principally local, but has implications thaf affect 8 much larger system.In these cases, the newly formed body of water can attract migrant waterfowl and shorebirdsand perhaps even provide habitat suitable for nesting and rearingthat did not previously exist. The higheraquatic productivity of many ofthese ponds could afford a significantfood source for thosespecies adapted to feeding in pond and lake environments.

The effectof creation of a pit, onthe scenic quatity of anarea, is totally dependenton the diversity of the floodplain environment. A pit will haveless effect where lakes and ponds occur naturaHy than where thesetypes of aquatic systems do notoccur. Where lakes andponds do not

357 occurlocation should be selected so thatview of the site is blocked from vantagepoints. For example, the Tanana River-Downstream pit,which is large andcontains very clear water, is in a floodplainwhere the river channels arehighly turbid, thus, offering a dramaticvisual contrast. However, the site is situated on an islandcompletely surrounded by a heavily wooded buffer zonewhich blocks'view of the site from the Richardson Highway.The pit is visibleonly from the air.

Pits areoften excavated with angular perimeters that ignore natural landcontour. Since angularity is not characteristic of naturally formed aquaticsystems the usual pit site offers some contrasteven in areas where lakes andponds occur naturally. Excavating these sites with perimeters that blendwith natural land contours, such a$ in abandoned riverchannels, de- creasesthe visual diversity that will resultfrom development of pitsites. The West ForkTolovana River and Tanana River-Upstream sites are excellent examplesof this management technique(refer to Figures 63 and 70).

Pit sitesrequire considerably less area to obtain a given amount of gravelthan do areasthat are surface scraped. Because of the depths nor- mallyrequired, subsurface waters are exposed, usually filling the pit duringsite operation. This water poses problems for the efficient extrac- tionof materials but, since draglines or backhoes are usually used for excavation,the presence of water does not prevent the removal of gravels. Pumping is theonly method used to eliminate the water but even this is impossiblein some systemsbecause of thevolume of subsurfaceflow through floodplaingravels. During mining, the water in a pit is usuallyhighly turbid andshould not be pumped intoadjacent channels.

In summary, there is little doubtthat the excavation of a pitmateri- alsite creates significant change in a floodplainenvironment (Table 41). If situated andoperated properly, the hydraulics of the river system are little affected whereassignificant changesoccur to the terrestrial system andthe scenic quality of the area. Differences in water quality andaquatic biota can be expectedbetween a pit and theadjacent channel regardless of whetherthey are connected. The increasein both aquatic and terrestrial

358 Table 41. lnterdiscipllnaryRating of Effects of Pits on AssociatedFloodplains at Selected StudySites Visited from 1976 to 1978 Using Various Indices of Change*

Potentialfor f lcru diversion Aquat lo habitatTerrestrial habitat Partial Ful I Fish DbsturbanceBenthos Water Pit (relativeblpotential habitat standiag to riparianbirdsuitabi 1 ity R iver type Study siteStudytype River Locat I on frequency 1 diversitybufferllfelcvegetation crop habitat index

%rai ded Dietrlch RdS Nw thorn Inter lor 3 4 2 2 3.2 Tanana R-OS Southern Interior 9 8 3 I 4.7 Tanana R-US tlarrerl Southern Inter tor IO 6 5 4 7.8 Tanans R-US lupperl Southern lnterior IO e IO 9 5.7

Split Hone studied u u mean- Prospect Ck Northern Interior 4 9 7 10 6.5 der I ng W.F. Tolovana R Southern Interior 6 IO IO 4 6.8

S 1 nuous Penny R Sward Peni nsu I a I 4 5 3 3.5 Ugnursvlk R Nwth Slope 0 0 0 2 I .EI Jim R Northern Interim 0 3 3 IO 4.3

Straight None studied

“LUnless otherwise deflned below, .5 = no change, 0-4 = decrease in pwmeter, 5-10 = increase in parmter.1 bEstimtedfrequency of sollls flowbeing dlverted through rite rangesfrom 0 = frequent tI or metimes per year) to IO = infrequent (5-10 years . ‘Estimated potentiallength of time before buffer becomas ineffectlveranging From I =within a decade to IO = greaterthan 3 decades. dRelstive to pits studled. *Man of the six ratlngs at a particular pit, potentlal range = 0-10. fScrapedside channel acquired some characteristics of a pit f0,ilawing rehabilitation. habitatdiversity is reflected in a morediverse faunal community. Pit sites are a viablealternative for material extraction in areas where changes to theriver hydraulics can be avoidedor greatly minimized. When majorhydraulic changesoccur the effects on the environment can be damaging from many standpoints.

ScraDed Si tes

Scraped sites canoccur essentially anywhere in a floodplainfrom withinthe active channel to vegetated areas in the inactive floodplain and terrace.Location of the site greatly affects the potential impacts that can beexpected from a scrapedsite. Although scraping implies that material sitesare operated byshallow removal of gravel, certain sites studied on thisproject were excavated below the water table and thusresulted in permanentflooding. These sites, however, were worked with scrapers or bulldozers andnot draglines or backhoes as might be implied by depth of excavation.

Scrapedsites have several operational advantages; usually the sites aredry, providing better working conditions andmore efficientgravel extraction.Additionally, excavated materials require less handling when usingscrapers to remove the gravel becaus e onlyone machine is norma I I y used toexcavate, transport, and deposit a t theconstruction si te.This is notfeasible using a bulldozeron a scrape or when diggingpits withdrag- I inesor backhoes.

Giventhe same gravelrequirement, the scraped site will generally disturb a largerarea than a pit site becausethe excavation is moreshallow. Inthe study sites, the large area affected was oftenthe greatest problemof scrape-mining because there were few restrictions regarding avoidanceof channels and areas adjacent to channels. Locations of extrac- tionsites are discussed in the subsequent section.

Scrapesare generally situated in active floodplains adjacent to active orhigh-water channels. Lowering these areas spreads water flow, at least

360 d ur ng highflows, and in some casesforms a braidedconfi gurationthrough the disturbedsite. When thisoccurs onunvegetated gravel barsin braided ems, theeffect on the floodplain is relatively minor becausethe ef- f ec s aresimilar to naturalhydraulic processes. After si te closure, unless stockpilesor dikes are present, the disturbed site can return to a rather naturalconfiguration within a maximum of a fewyears. This, however, isnot thecase where lateral bars are excavated to include removal of adjacent banks. Bank removal isdiscussed in the subsequent section.

The potentialfor causing braiding from scraping operations within the activefloodplain, is usually insignificant in a riversystem that already has a braidedchannel configuration. However, insplit channeland single channelsystems braiding constitutes a significant change tothe aquatic environment and altersthe aquatic biota; species which benefit are those betteradapted to riffle areas, to lessstable substrates and,perhaps, to substratesless granular than those found in the natural system. These habitat changes primarilyaffect the distribution of organisms. This study generallyfound a localdecreased diversity of the fish community as a result of braiding.There is a potential of blockageto fish passage, at leastduring low flowconditions, as occurred at the Aufeis Creek site becausethe water flows over a widerarea than in the undisturbed channel. Blockage is mostsevere ifthe entire active floodplain is disturbed, not justthe lateral bars. Entrapment of fish, in depressions created by scraping, isalso possible during periods when wateris receding from high flows.

Effects on theterrestrial environment depend greatlyon the river type involvedand on the location of the work area within the floodplain. In braidedsystems mined in the active floodplain, there essentially is no effect. However,on split and singlechannel systems, braiding caused by gravelmining can provide feeding habitat for shorebirds that utilize benthicorganisms. Destruction of banks with associated vegetation removes habitatused by terrestrial fauna; the effects are the same asremoval of vegetationfor pit sites.

36 I The potentialfor re-establishment of natural configurations and flow patternsafter site closure are totally dependent on the degree of change tothe hydraulic processes characteristic of the river system. Long-term effectscan be expected where major changes to the stability of channels occur. The majorterrestrial effect of scraping resulted where deep scrapes occurredin areas immediately adjacent to the channel. Channel flow often divertedthrough these depressions andcaused year-round ponding which retardedthe re-establishment of vegetation. These deep scrapesusually were inadequate as quadityhabitat for waterfowl and shorebirds and unsuitable forfish. To minimizeshort- andlong-term effects, scraped sites should not beexcavated beyond certain depth limits. These restrictionsare discussed inthe Guidelines Manual.

The effects of scrapingoperations on the scenic quality of a braided floodplaincan beminimal ifthe material sites are rest-ricted to the active floodplain. Where banksand vegetated areas are altered, significant effects canbe anticipated, In split and singlechannel systems the establishment of a braidedconfiguration in the disturbed area produces an unnaturalcondi- tionin the floodplain, thus affording a visualcontrast. Properly located scrapingoperations that avoided or minimized disturbances to the hydraulic characteristicsof a river,minimized long-term environmental change. How- ever,where sites were poorly located and caused significant changes to the channelhydraulics, major long-term effects were evident on the scenic qualityof the area.

In summary, scrapingoperations typically occurred in both active and inactivefloodplains. Both vegetated and unvegetated areas were used but thefewest long-term disturbances occurred where only exposed gravel depositswere scraped. The potentialfor broadening or diverting channel flow insplit and singlechannel systems is great if depths of excavation are excessive and locationsof sites are poor. The potentialfor braiding in thesesituations was increasedwith concomitant changes in aquatic biota. Terrestrialeffects were greatest when thedepth of excavation was excessive and ledto permanentponding which retarded recovery to predisturbance

362 conditions.Visual effects of scraping operations depend greatlyon the type ofriver system,the location of the site, and theareal'extent of the site withinthe floodplain.

LOCATION OF GRAVEL REMOVAL

Locationof a gravelremoval operation in relation to the channel of a river was found to bethe most important aspect influencing long-term change to a floodplainenvironment. Whether a pitor scrape, in general, the location of thesite was a moreimportant consideration than the type of site. Sitelocation in this section is discussedwith minimal reference to the type of sitealthough the latter is a factorinfluencing the extent of change.

In-ChannelLocations

As used inthis project, in-channel gravel removal includes areas in theactive channel, high-water channels, and abandoned channels. Fourteen of thesites studied on this project were situated in high-water channels and 7 of the 8 siteslocated in the active channel also included areas in high- waterchannels. From hydraulic and hydrological standpoints, material sites inactive andhigh-water channels caused the greatest long-term change to thefloodplain environment.

ActiveChannel. Gravel removal operations in the bed of an active channelcause a seriesof changes all basically related to changes in the depthand location of thethalweg. The degreeof change depends on the type ofchannel configuration, principally whether it is a braidedor a single channel.In a braidedsystem the channels generally shift throughout the activefloodplain on an annualbasis. This is due tothe lateral instability of theindividual channels. In these systems removal of gravelhas the effectof perhaps causing greater instability in the area of the disturbance.Changes occurringin a singlechannel river caused by removing bed materialare unknownbecause all seven siteswith this mining location had substantialalteration to adjacent deposits or banks.

363 Removing gravelfrom within.the channel is accomplishedeither by dredging or byscraping the bed after flow has been diverted. Either method can resultin a deepeningof the thalweg and, ifthe edgesof adjacent gravelbars or banksare removed, a wideningof the channel. Depending on thelocation of thematerial site, this operation could alter the pool: riffle ratio in the river.

Where thechannel is dredged, turbidity in anddownstream of thesite willincrease greatly during mining. Turbidity should reduce quickly after theoperation has ceased. Ifthe channel is diverted during mining, the effectson water quality entail suspension of the fines exposed during mining when water is diverted back throughthe site. This suspension will resultin a temporaryincrease in turbidity.

Reductionin the velocity of water entering the excavated hole will causesedimentation of bothbed load and suspended materials. This will aid inrapid replenishment of the gravel materials removedfrom the site. Being inthe active channel, the replenishment rate IS consideredhigh compared to other areas inthe floodplain.

Excavationof the channel bed can remove spawning areas. During a dredgingoperation fish probably will redistributeto less turbid waters. Benthicorganisms adapted tosilt-laden areas will establishfollowing excavation andremain untilthe natural gravel bed becomes established.

Assuming thatthe disturbances resulting from gravel removal are restrictedto the channel, and do notinclude the banks or edgesof gravel bars, little long-termeffect on theterrestrial environment is expected. Changes couldoccur ifhydraulic changes inthe channel affect adjacent banks,

Aesthetically,the in-channel material site has little or noeffect. Hydraulicchanges resulting from in-channel disturbance that affects banks cancause some effect.

364 High-WaterChannel. High-water channels flow only during high-water periods. The hydrauliceffects of removing gravel from high-water channels arenot as great as they are in the active channel where the disturbed area issubjected to flow throughout !he year. The changesthat can be expected aresimilar to those described for the active channel although they occur onlyduring the period when thesite is subjectedto flow.

Effects on waterquality are only evident during the high-flow period. Localizedwidening or deepening of the high-water channel would slow the watervelocity andthus facilitate deposition of both bedload and suspended materials.Depending on thedegree of change to the channel this deposition wouldreduce the time required to re-establish near-natural conditions in thearea. Also, any finesexposed during mining would be available for suspensionduring high flows.

Removing gravelfrom a high-waterchannel could trap fish and benthic organismsin the depressions of the disturbed areas as flowrecedes. Many benthicorganisms that are adapted to a riffle communityand most fish specieswould not be able to survive in such a habitat.

Sincehigh-water channels are subjected to less flowthan active channels,they tend to be more stable and areusually bordered by established terrestrialvegetation. Any disturbanceto these channels causing lateral instabilityduring high flows could facilitate erosion of adjacent banks and thusserve to reduce the areal extent of vegetated areas. Loss ofhabitat wouldcause localized elimination of small mammals anddisplacement of birds and larger mammals. Havingwater pooled in the high-water channel during low-flowperiods could attract shorebirds, particularly where a benthic faunahas become establishedto serve as a potentialfood source.

The mostserious effect from a gravelremoval operation in a high-water channel is bank destructionwhich often occurs with this type of operation. Thisaspect is discussed in a subsequentsection on removing gravel from banks.

365 The effectof mining gravel from a high-waterchannel on thescenic qualityof an areais minimal if the disturbance is restricted to the channel.If banks are destroyed the effect would bemore significant.Since the high-waterchannel isactive only part of the year re-establishment of pre-existingconditions wilt require a longertime. Formation of pits in high-waterchannels would have effects similar to those described in the section onType ofGravel Removal.

AbandonedChannel. Abandoned channels carry water only during major floodevents. NormalIy, these channels are considered to be dry during most years.Since they represent old riverchannels they usually contain reason- ablylarge quantities of gravel, depending on the type of river with which theyare associated. Only two of thesites studied were located on an abandonedchannel, Prospect Creek and West ForkTolovana River, both in meanderingsystems. Abandoned channelsare common inthis type of floodplain becauseof the formation of cutoffs that result from the fluvial processes ofmeandering channels.

Locationof material sites in abandonedchannels causes littleproblem withregard to changes inriver hydrology and hydraulicsbecause the sites areseparated from active flow. Where pitsare dug in abandonedchannels and areconnected to the active channel, flow can be diverted through the site duringhigh flows. The magnitudeand duration of this change is dependent on thenature of the connection between the material site and thechannel and theintegrity of theundisturbed buffer zoneseparating the site from the activechannel. Where the once-abandonedchannel carrieswater annua I lY duringhigh-flow stages, theeffects to the floodplain would be similarto thosedescribed for sites inhigh-water channels.

Where an abandonedchannel is scrapedand the water tab le is not reached,water quality does not become a problem. Where p its become flooded, thewater quality would be differentthan that occurring in theactive channel,as isdiscussed in the section on pits.

366 Aquaticbiota will notbe affected in a scrapeoperation located in an abandonedchannel, however, if a pit is dug, aquaticbiota could become established.In these cases the effect depends on whether the gravel removal operationalters the site sufficiently to cause it to besubjected to annual highflow or whether it is connectedto the active channel. In the former case,there is potential.for entrapment of fish during high flow as was discussedfor high-water channels. In the case of a siteconnected to a channel,the effects are those discussed in the section on pits.

The effects of removinggravel on the terrestrial environment can be greaterin an abandonedchannel than inother in-channel locations. Aban- donedchannels are rarely subjected to hydraulic forces, consequently, vegetationusually is established, and thestage of succession is dependent onthe time since the channel ceased to carry flow. Thus, vegetationmust be removedfrom these sites to expose gravel deposits. Removal of thishabitat resultsin a loss offeeding, nesting, andcover habitat for those small mammals and passerinesthat utilize riparian shrub thickets. Larger mammals, beingmore mobile, are displaced to adjoining areas.

Ifthe abandonedchannel is scrapedabove the water table , the disturbedsite will initiateprimary plant succession following s ite c losure. The timerequired to reach the predisturbance stage of vegetat i ona I succession is dependenton the geographical region and the vegetative characteristicsof the area. This process is the same asoccurs in other recently abandonedhigh-water channels and entails the same vegetationaland faunal communi t i es. Ifthe site is a pitthat is permanently flooded, the site wouldno t returnto a terrestrialenvironment in a relativelyshort time. However, overallhabitat diversity is increased. Further discussion of these aspects i s includedin the section on pits.

The effects of siting a gravelremoval operation in an abandonedchannel,on the scenic quality of an area, reflect the changes occurring to the terrestrialvegetation. The short-termeffect is to expose an areathat was previouslyvegetated. The long-termeffect in a scrapedsite dependson the rate of revegetationof the disturbed area. Where a pit is dug thealtera-

367 tionis long-term but, in fact, could blend more withthe interspersion of cutoffs and lakesoccurring naturally in the floodplain.

Adjoining ChannelLocations

The MajorVariable Matrix (Table I) includesfour subdivisions under adjoiningchannel locations. These are: point bar, lateral bar, mid-channel bar,and bank. To thoroughlycharacterize the 25 studysites it was necessaryto utilize all ofthese subdivisions but the gravel removal effects are similarfor some. Therefore,the following discussion combines the three bar locations and discussesbanks separately. Remember, at a givenmaterial site thesebars andbanks are associated with one of thethree channel types discussedin the previous section.

Point,Lateral, andMid-channel Bars. Thisdiscussion only considers removinggravel from unvegetated bars with exposed gravel deposits. All threegravel bars are usually numerous in braided systems but, in single channelsystems, usually only point and lateralbars are found.

The effectof removing gravel from a bar isto lowerthe elevation of thebar thus allowing flow to inundate an areathat was previously above thelow-flow water line. These sites are usually scraped. Maintenance of the integrity and conformationof the bar will cause little permanentchange to channelhydraulics and will facilitatereplenishment of thegravel during subsequenthigh flows. Changes inthe active channels can and probably will occurwhere bar integrity is notmaintained. In a braidedriver system this change will besimilar to the natural processes and thelong-term effects will beminimal. In a single-channelsystem redistributing flow by removing barscan have long-term effects by changing the local hydraulics of the channel.This hydraulic change could either decrease the lateral stability ofthe channel or widen or deepen the flow because the cross-sectional area islarger. Where thebanks are stable, the river eventually will equilibrate itself byreforming gravel bars as upstreambed load materials become avail- ableduring subsequent high flows. Where banksare less stable it is pos-

368 siblethat subsequent high flows will causeerosion due tothe hydraulic forcesacting on the once protected banks. This could significantly alter thelocal reach of a river.

Thiseffect is less likely to occur in straight andperhaps sinuous river systemsbecause the flow isrelatively unidirectional down thefloodplain and directhydraulic forces onthe banks would be less than in a meanderingsystem. The effect on a meandering rivercould be to facilitate the formationof cutoffs by increasing thehydraulic force onthe inside bank atthe upstream end of a meander.

Removal orlowering of gravel bars will facilitatethe spreading of riverflow when waterlevels are higher than during the gravel removal operation.This flow spread has the effect of reducing the depth and velocityof thewater and will increasesedimentation rates of both bed load and suspended materials.Additionally, water temperature and dissolved oxygen contents could change. Benthiccommunities would develop that are adapted to riffles and less stablesubstrate. Fish would become redistributedwith younger age classesperhaps being attracted to thedisturbed site where currents would beless.

The effectsto the terrestrial environment, of removing gravel from a bar,are minimal if theintegrity of the bar is basically maintained. The only changes thatcould be expected are if the hydraulic regime of the river channel isaltered, thus, causing changes in adjacent vegetated areas. The spreadingof flow between the banks when barsare removed might attract shorebirdsfor purposes of feeding.These effects would only be expected in s i ng I e-channe I systems.

Removing gravelfrom isolated material sites using accepted mining techniquesfrom bars in braided river systems would have little or no effect onthe scenic quality of a floodplain. The lateralinstability of the chan- nelsthat characterize these systems would cause anychanges resultingfrom gravelremoval to blend in with natural processes. Removal of barsin a singlechannel system will locallyaffect the appearance of the river sys-

369 tern, themagpitude of effect depending completely on the degree to which the bar was disthrbed. Any significant changes tothe hydraulic geometry of the reachcausinb subsequent disturbance to adjacent vegetated areas wi I I lo- callyalter the appearance of the floodplain.

-Banks. hobably the most consistent long-term changes to a floodplain occurred when bankswere destroyed or greatly modified during a gravel removaloperCtion. In these cases significant changes to the hydraulic geometryof {he river occurred. Banks typically are stable and functionto restrictthe flow of the river to the channel except during high flows. When theseare rerhoved ordisturbed the river is nolonger contained and it begins to waider and erode the adjacent f loodp lain. This wandering resu I ts fromthe hydflaulic forces of theriver impinging onnewly exposed bank ma- l terial. Wherd banksare made ofstable materials the degree of erosion shouldnot b4 greater on the newly exposed bank than what occurred naturally beforethe site disturbance. Where thenewly exposed bank materials are not stableerosidn wi II occurat a ratefaster than occurred previously. Also, if the newly!exposed bank issituated at an angleto the flow different than whatoccurred naturally in that reach of the river, erosion could be aggra- vatedbecausd of theincreased hydraulic force onthe bank.

Generallly,channel width increases with bank destruction.Previous discussionidentified that increased channel width can result in reduced watervelocifly, reduced water depth, changes in water temperature, and dissolvedox gen,and increasedsedimentation. Aquatic biota would reflect these altere 1 habitatconditions by changes in benthic communities to those thatare adapted to riff le areas with unstable substrate andchanges in distributionof fish in the reach affected bythe disturbance. endercut and vegetatedbanks are heavily utilized by fish ascover and removal of this habitatcan greatly reduce the local abundance of certainspecies.

The effects onthe terrestrial environment include destruction of riparianhabitat during site clearing with resultant effects on faunal distribution. The decreasedlateral stability of the channel can cause more destructionafter site closure if hydraulicforces erode newly exposed

370 areas.In addition, even if the newlyexposed banks are stable the hydraulic forcesoccurring over the disturbed. site would retard the re-establishment ofterrestrial floodplain habitat.

The effect onthe scenic quality of thearea will reflectthe changes occurringto the terrestrial environment and tothe hydraulic geometry of theriver channel. Major changes to these aspects will greatlyalter the appearanceof the floodplain in the affected reach.

LocationsSeparated From Active Channel

The fivespecific site locations identified in the Major Variables Matrix(Table I) thatare separated from the active channel are not mutually discretelocations. That is, a site canexhibit a combinationof these locations by for example, beinglocated near the channel on the outside of a meander.Hence it is more difficultto assess thepotential impact for these locationsthan for those previously discussed. The followingdiscussion has beenseparated into two sections: inside and outside of meanders, and islands.These then are discussed from the standpoint of whether a material site is nearor distant from the active channel.

The essentialfactor with sites in all of these locations is whether diversionof the water out of the active channel andthrough the site is possible. The distancebetween the material site and theactive channel is ofmajor concern, but the height of the intervening bank certainly would be a necessaryconsideration in this evaluation.

Inside and Outsideof Meanders. The locationof a site onthe outside of a meander is possibleon any sizedriver system regardless of theareal extentof the material site. This, however, is notthe case on the inside of meanders. Insmall river systems the areal extent of the floodplain or terracecircumscribed by the meandercan be quitesmall. In cases where thesewere used for material sites, the surrounding areas, includingthe channel,were often disturbed by the gravel removal operation. Therefore, to

37 I limit activities t o the insideof a meanderand maintainundisturbed buffers thesite mustbe I oca tedon atleast a medium sitedriver.

Any activity inside a meander, thatwould reduce the integrity of the banksor weaken the cross-sectionalarea, could lead to premature cut off of the meander. In many Alaskanrivers during breakup, water often flows over theice in the channel and, ifsufficiently high, over the banks and down thefloodplain. A depressionresulting from a materialsite located near the channelon the inside of the meander would aid in channeling the water throughthe site. Depending on theerodability of the soil separating the materialsite from the channel, a channelcould erode at both the upst;eam anddownstream portionof the mea,nder and thuseventually establish a cutoff. The erodabilityof the soil would govern the length of time required forthis natural event to occur. When a pitmaterial site is connected to theactive channel, the probability of a cutoffoccurring could be enhanced greatly,even in a veryshort time. Such an eventoccurred at Skeetercake Creekon the North Slope. The insideof a meander ofthis small river was minedfor gravel and when thesite was studied II yearsafter site closure, a cutoffhad occurred. The timerequired for this event to occur is unknown.

A pitvisited during site selection, but not studied in this project, that showed a potentialfor channel diversion, was locatedat Hess Creek in theSouthern Interior region. The bufferstrip was breachedduring the firstspring breakup following site opening while the site was being operated. The initialbreach was temporaryand the water remained in the activechannel when the flow receded.

Thekey pointof concern when miningin the inside of a meander is ma intenanceof a sufficientlywide undisturbed buffer zone between the ac tive channeland the perimeter of the material site. The size will depend greatlyon factors such as the discharge of the river, fl oodfrequency, and soilerodability andmust, therefore, be determined on a site-specific basis.In order to maintain the integrity of the channel overthe long-term it may benecessary to dig deeper toobtain neededgravel volumes, rather thandecrease the buffer width.

372 Buffer zonesare similarly important to separate the active channel frommaterial sites located onthe outside of meanders. A breachoccurring inthis situation would lengthen the meander. Thisbreach probably would be a temporaryevent during high flow periods and theriver would maintain its main f lowthrough the active channel during lower water levels because of theshorter downvalley distance. Periodic andaggravated damage tothe area betweenthe material site and theactive channel and perhapsthe creation of a backwaterarea in the material site, would occur from an outside meander breach.

It is obviousthat the closer a materialsite is to the activechannel thegreater the probability of a permanentbreach occurr ingin a shorttime.

Placementof a materialsite either onthe inside or outside of a meanderhas no effecton water quality, regardless of the distance separatingthe site from the channel. However, if wateris pondedthe water in thepit would differ from that in the channel, as describedin the section onpits. Changes inwater qua Iitycould result if a breachoccurs. These alsoare discussed in the sec tionon pits.

Change will notoccur to aquaticbiota when materialsites are located away fromthe active channel. However, ifhigh flow conditions reach a materialsite, andcause eithertemporary or permanent ponding, fish could become trappedin the site when thewater recedes. Effects similar to those describedfor connected pits could occur where the buffer is breached and a pit site becomes connected tothe active channe I

Ingeneral, locating material sites backfrom the active channe I will necessarilyentail destruction of vegeta tive habitat, This wi I I resu It in localized loss ofsmall mammals and disp lacementof birds and larger mam- rnals. Ifthe area is scraped anddoes not become floodedduring high water thesite eventually will returnto the predisturbance condition through processesof primary and secondary plant succession. The lengthof time required will dependon theregional characteristics. If the site is flooded

373 because it was dugas a pit,or because depressions are at least temporarily flooded,vegetative re-establishment will beretarded.

Becauseof the soil binding characteristics of vegetation, maintenance ofthe vegetation on the buffer zone between the material site and the activechannel is important. The widerthis zonethe less the likelihood of a breach. If a bufferbreaches, the progressive erosion of soils and loss of overlyingvegetation will resultin prolonged impact to the terrestrial environment.Concern for maintenance of the natural hydraulic geometry in thefloodplain while selecting a materialsite location, and whileoperating thesite, will limit terrestrial change tothe area of the disturbance.

The usualneed to removevegetation to operate a site away fromthe activechannel will affectthe scenic quality of thefloodplain environment. The magnitudeof effect will depend much onthe shape of the site, whether it conformsto natural land forms, andwhat the vegetative structure is in thearea. If thesite is not visible from a roador other accessible vantage point,the overall impact will occuronly from the air. The distanceof the sitefrom the active channel would not necessarily be related to the magnitudeof impact on the scenic quality but this would be det erminedon a site-specificbasis.

Islands.Material sites located on islandsrequire the removal of vegetation. The distancebetween the perimeter of the materi alsite and the activechannel is themajor consideration in the development of these sites. Islandsare situated in the active channel most ofthe time, thus, the maintenanceof buffer zone intregity is ofgreatest concern. If bufferzones areremoved or greatlydisturbed the net long-term effect could be the loss ofthe island, perhaps changing the hydtaul ic geometry significantly enough to causeother changes within the floodplain.

Sitesthat have been located on islands where the .banks were disturbed oreliminated have had greater effect on the floodpta'in t.han thosewhere thesite was developedtotally separate from the channel (e.g., Tanana River-Downstream).In the latter case there was nochange detectable to the

374 hydraulicregime of thechannel. In the other cases, induced erosion of the disturbedbanks has had more prolonged effects than where this erosion has notoccurred. Again, of prime concern with material sites on islands, as withother sites separated from the channel, is maintenance of the natural hydraulicgeometry of the river channel. If natural hydraulic forces erode islandsin a givenreach of a river,the presence of a materialkite, whether a pitor scrape, will weaken theintegrity of the island after natural bankerosion reaches the perimeter of the site.

Developmentof material sites on islands where the perimeters of the sitesare separated from the channel, will have little effect onwater quality and aquaticbiota. If thematerial site Is flooded because it was deeply dug, thecontained water will be differentthan the water in the activechannel, as discussedunder pitsites. If the site is floodedregu- larlyduring high-flow conditions there is a potentialfor fish entrapment as thewater recedes. The long-termeffect on aquatic biota depends on whetherthe site is permanentlyflooded and the depth of the water. If the site becomes connectedto the active channel by breaching of the buffer zone, theeffect may bedevelopment of a braidedsection with the accgm- panyingchanges. Flooding of depressions in the disturbed area could cause fishentrapment before the establishment of a braidedpattern.

Terrestrially,the loss ofvegetated habitat would result in loss of bothsmall mammals and perhaps some larger ones. Loss woulddepend on the sizerelationship of the material site to theisland, but would occur regu- larlywhere a largeproportion of the island is disturbed for thematerial site. The mortalitywould occur as a result of animalsnot being able to crossthe river channel(s1 to adjacent floodplain habitat.

The loss ofvegetation on an islandreduces the amount of birdnesting habitat.This could affect the total productivity of an areamore than if an equivalent amount ofvegetation were removed along the edges of the floodplain.This assumes that the islandprovides some protectionfrom mamma I ian predatorsunable to cross the interveningchannels. Otherwise, the mobi I ity

375 ofbirds allows them toredistribute in the floodplain just as large mammals do thatare dependent on floodplain habitat.

Materialsites onislands will affectthe scenic quality of the floodplain,but the type of vegetation characteristic of the area would determine thelong-term visibility of the site. Where stands of timberblock view of thesite except from the air, as withthe TananaRiver-Downstream site, little changewould occur. Where suchtimber is notpresent the material sitecould be quite conspicuous and affectthe appearance of the floodplain envir0 nment morethan if the site was locatedalong the edge of thefloodplain Ineither case, maintenance of an undisturbed buffer zone between the mater i alsite and theactive channel reduces the induced disturbances that cou Id furtherdetract from the natural appearance of thefloodplain.

Summary. The problemsassociated with material sites locatedseparate fromthe active channel are essentially dependent upon maintenance of the integrityof intervening buffer zones. Where thisis maintained, and the hydraulicgeometry of the river is notaffected, very little or no change wouldbe expected relative to hydrology-hydraulics, water quality, and aquaticbiota. The terrestrialsystem and scenicquality of the floodplain will be affectedbecause usually vegetation must be removed to expose under- lyinggravel deposits. Generally, sites located back from the channel are favoredfrom a practicalstandpoint because they can be operated in a dry conditionmaking for a more efficient and easieroperation. Excavating a pit would be an exceptionbecause the depths of excavation would normally be belowthe water table.

DIKES AND STOCKPILES

The locationof certain material sites and thegravel removal opera- tionsrequire the construction of a protectivestructure and/or the stock- pilingof overburden and gravel in or nearthe material site. Protective structuresprevent water from entering the material site and includechannel plugs and diversiondikes. Overburden piles consisting of brush,slash, groundcover,and organic soil are located either permanently or temporarily,

376 usuallyat the edgesof sites. Gravel stockpiles are considered to be temporary and arelocated within the material site. Dikes and stockpilesof unusedgravel were sometimes leftintact when thesite was abandoned, thus, contributingto the long-term effect of the gravel removal operation.

Any dikes or stockpiles deflecting or otherwisemodifying flow patterns couldaggravate the long-term hydraulic effects of the material site. Flow alterationscould significantly modify the hydraulic forces in the local reachof the affected floodplain andcause other damage. Alterationsto naturalflow patterns in the winter could induce or aggravateaufeis forma- t ion.

The waterquality of anarea could be affected by the location of these structuresin the floodplain. Any erosionof overburden piles by active flow couldintroduce large quantities of organic materials for suspension and eventualdownstream deposition. Also, any structures that would impound waters,after high flows have receded, would result in differences in the waterquality between the active channel andimpounded waters.

Aquaticbiota could be affectedby the presence of obstructions. Fish could become entrappedbehind any structuresthat impound water. Thesuspen- sionof fines in the water columnas a resultof erosion could cause redistribution of fish and reductionof riffle invertebrates.

Overburden pilesprovided a nucleusfor revegetation of abandoned materialsites. The organics, and particularlythe root stocks and slash, facilitatedre-establishment of vegetation in localized areas of the site. Overburdenpiles were used for denning by ground squirrels and, becausethey werevegetated, provided habitat for small mammals and nestingpasserine birds. Abandoned stockpilesof gravel were less prone to provide these conditions.

Inthe long-term, any alterations of flowpatterns that resulted from abandoned structuresprobably would be detrimental to vegetative recovery

377 onthe site. Revegetation in these cases would only occur on the area above thehigh flow levels.

Abandoned structuresin most cases furtherdetract from the already af- fectedscenic quality of a floodplain. Where thesite is hiddenfrom view exceptfrom the air abandoned structureswould not alter the overall impact. However, inplaces Characterized bytundra and low riparianvegetation, theseabandoned structures can attract attention to the floodplain site.

378 SUMMARY OF CONCLUSIONSAND RECOhWENDATlONS

SUMMARY

Not all of themajor variables used to characterize the 25 material siteswere significant determinants of gravel removal effects.

Amon,g thePhysical Site Characteristics, channel configuration was the mostimportant. Potential floodplain change is leastfor a braidedriver and greatest for a straightriver. Size of channel is a significantfactor, with theleast change to beexpected in a largesystem and the greatest in a smallsystem, This assumes equallysized material sites. Combining these two variables,(channel configuration and size)gravel removal operations can be expectedto have the least effect on large braided rivers and thegreatest effect onsmall straight rivers.

InfluencingPhysical Site Character,istics related to configuration and sizeare the availability and sizeof unvegetated gravel bars, floodplain width, and thedistance that can bemaintained between the mining site and activechannel. For example, in a small straightriver system the floodplain is narrawand gravel bars are neither plentiful nor large. Thus, toextract gravel,either a significantlength of active floodplain or the adjacent inactivefloodplain ana terrace mustbe disturbed. In the latter case the narrownessof the floodplain forces the operation to closely encroach upon theactive channel. In large river systems these problems can be less signif- icantbecause gravel bars are larger and, ifthe inactive floodplain or terraceare used, thewider floodplain allows maintenance of a broader undisturbedbuffer zonebetween the material site and activefloodplain.

379 Inthe present study, channel. slope andstream origin did not correlate withchanges resulting from gravel mining. However,channel slope influences thebed load carrying capacity of a stream -- steeperslopes indicate greatercarrying capacity. This relationship is usefulin evaluating po- tentialreplenishment rates in a disturbedsite after mining. Also, stream originhas an influencebecause rivers of mountain and glacial origin characteristically havelarger quantities of gravel available than do riversof coastalplain origin.

All ofthe Gravel RemovalArea Characteristicswere found to signifi- cantlyinfluence the effects of gravel mining. The locationof the material siterelative to the active channel is consideredto bethe most important factor. Whether a materialsite is scrapedor pit-excavated is important, butoften pits are located away from an activechannel, avoiding the types ofchanges that can be associated with scraping in active floodplains.

The majoreffects of pit sites located in inactive floodplains and terracesare the loss ofvegetated habitat, the possibility for fish entrapment, a change inthe appearance of the floodplain, andlong-term delay inthe re-establishment of predisturbance conditions. Where pitsites are situatedwell away fromactive channels they have little effect onthe activechannel and, thereis little chanceof contributing to channel diversion. When situatedclose to active channels, particularly onthe inside bends in meanderingsystems, the possibility exists for diversion of the channelthrough the pit, eventually forming a channelcutoff in the meander. Thisproblem highlights the importance of providing a bufferbetween the materialsite and theactive channel. Where pitsites are of suitable size, ofsufficient depth, andhave contoured perimeters, they can increase local habitatdiversity and provideconditions suitable for fish and various speciesof terrestrial fauna.

ScraDed materialsites in activeflood~lains haveminimal effects on thefloodplain environment when exposedgravel bars are only excavated above thewater level and slope and contoursare maintained resembling those of naturalbars. Removal ofvegetated areas or banks, which results in

380 decreasedlateral stability of active channels, or allows water to spread over a largearea, is not desirable. Decreased water depth and velocity increasessedimentation rates, alters water temperature, and alters dissolvedoxygen levels. These chan9es' in aquatic habitat usually affect the localdistribution andcommunity structureof benthos and fish.

The effectsof scraping in vegetated areas of inactive floodplains and terracescan be similar to those described for pits. However, long-term changes typicallyare minimalbecause the lack ofstand ingwater in the closed site wi I I faci Iitatere-establishment of pre-min ingvegetation con- dit ions.

In-channellocations thatare dredged have the potential for causing theleast change to channe I hydraulics,terrestrial biota, andaesthetics; however,they can have the greatesteffect onwater quality and aquatic biota.Gravel replenishmen t ratesare highest in this location. Mining exposedgravel bars in ac tivefloodplains potentially has the least effect onterrestrial systems. S itesin inactive floodplains and terracesaffect theterrestrial biota and scenicquality most, but potentially have no affect onthe aquatic sys tern. In general,the farther a materialsite is locatedfrom a channelthe greater the potential effect on the terrestrial biota and scenicquality and thesmaller the effect OR thechannel hydrology-hydraulics,aquatic biota, and water quality. This relationship constitutesthe major tradeoff consideration in locating material sites in floodplains.

If materialsites are located andoperated to prevent or greatlymini- mizeeffects on channelhydraulics, and to utilize only exposed gravel bars, theprobability of major localized changes to a floodplain is generally greatlyreduced. Where exposedgravel bars are not available or are inadequate, a tradeoffdecision between sites mustbe made thatweighs the potentialeffects of aquaticdisturbances against terrestrial disturbances. In thesecases, minimization of hydraulic change to active channels should be importantin the decision -- majorhydraulic changes can have a greater long-termeffect on terrestrial systems than the controlled disturbances

38 I associatedwith a sitelocated in a vegetatedinactive floodplain or terrace.

Dikes and stockpilesof gravel and/or overburden left in a material siteafter closure, have potential effects onthe floodplain. These struc- turescan alter channel hydraulics locally if they are subject to high flows.During high water the fines and organic debris may beintroduced intothe water and resultin downstreamsedimentation. Depending on their position and orientationrelative to flow, dikes and stockpilescan also cause fishentrapment. Where overburdenpiles are abovehigh-water levels, theycan facilitate the establishment of vegetation after site closure. This vegetationprovides habitat for small mammals and passerinebirds. In some cases,revegetation at a site was foundonly on such overburden piles. This observationsuggests that, as long as thepiles are situated where they are not subjectto inundation or hydraulicerosion, they can provide a source forrevegetation of thesite. Overburden piles may detractfrom the scenic quality of a floodplain.

RECOMMENDATIONS

The recommendationsdev elopedfor each of th le discipl i nes ar e generally in agreement, withseveral exceptions. All recommendationsare generally designedto minimize change to the floodplain and to enhance re- establishmentof predisturbance conditions.

I. Rivertypes that should be used in order of decreasing preference are: braided,split, meandering, sinuous, and straight. The majorconsideration inthis preference is theavailability of gravel from exposed bars. The largestvolumes are available from braided systems and theleast from straight systems. An additionalfactor is thedecreasing floodplain width of theconfiguration series identified above. Ifareas adjacent to the channel mustbe used for gravel mining, greater overall change w'i II resultin straightsystems.

382 2. Riversizes that should be used in order of decreasing preference are: large, medium, and small. The rationale is theavailability of gravels and widthof floodplain. Larger systems have more gravel. The proportionally smallerdisturbance in large systems will reducethe overall effect of gravelremoval.

5. Mininggravel from active channels should be avoided to reduce detrimen- taleffects on water quality, aquatic habitat, and biota. However, if hydraulic changescan be minimized, in-channel sites will replenish more rapidly than otherareas and effects on the terrestrial biota and scenic qualityof the floodplain will beavoided or greatly minimized.

4. Changes tochannel hydraulics should be avoided in all cases, es- peciallythe establishment of a braidedconfiguration in the disturbed s i te.

5. When possible,exposed gravel bars in large active floodplains should beconsidered for mining. A properlyoperated material site in these areas canminimize changes to channel hydraulics during low-flow periods, minimize changes towater quality andaquatic biota, minimize or eliminate affects on terrestrialbiota, and maintainthe scenic quality of thefloodplain. In addition,the probability of gravelreplenishment is increased.

6. Although pits reflect a majorchange from predisturbance conditions, theycan increase local habitat diversity if suitably located anddeveloped. They shouldbe located to minimizethe probability of channel diversion throughthe site. Adequate undisturbed buffers should be maintained between thematerial site and theactive channel.

7. Organicdebris andoverburden should be spread over or piled in the abandoned site to promoterevegetation and establishment of predisturbance conditions.This procedure must be conducted only in situations where there is a low likelihood of thismaterial being eroded into active channels.

383 RECOMMENDED FUTURE STUDIES

Duringthe present study a number ofsubject areas were identified that shouldbe investigated.

I. Evaluationof gravel mining from coastal and uplandsources; and, preparationof guidelines for users of these sources. These alternativesto floodplainsources have not been studied.

2. Evaluationof the effects of multiple sites on one river system. Suchan investigationshould be aimed at determining the critical, spatial, andtemporal relationships of multiple sites. Gravel replenishment rate predictionsshould be an integralpart of thisinvestigation.

3. Severalfloodplain gravel removal sites should be investigated before,during, and after mining to assess the adequacy of theGuidelines Manua I.

4. Severalspecific topics of theGuidelines Manual shouldbe studied indetail to assess their adequacy,i.e., buffers,pit design, and active channeldredging.

384 APPENDIX A

Scientific names of flora andfauna identified in the text are presented inTables A-I through A-5. Referencesare:

HerbaceousVegetation - Hulten, E. 1968. Flora ofAlaska and Neighboring Territories.Stanford Univ. Press. 1,008 pp.

Woody Vegetation - Viereck,L. A., and E. L. Little,Jr. 1972. AlaskaTrees andShrubs. U.S. Dept.Agric. Handbook 410. 265 pp.

Mammals - Hall, R. H., and K. R. Kelson. 1959. The Mammals ofNorth America. RonaldPress Co., New York. 2 vols.

Birds - AmericanOrnithologists' Union. 1957. Check-listof North American Birds.Port City Press, Inc., Baltimore, 691pp.

AmericanOrnithologists' Union. 1976. Thirty-thirdsupplement to the AOU check-listof North American Birds. Auk 93(4):875-879. -Fish - AlaskaDepartment of Fish and Game. 1978. Alaska'sFisheries At I as. Vel. I and II. AlaskaDept. Fish and Game, Juneau, Alaska. 83 pp. + maps.

Bailey, R. M., J. E. Fitch, E. S. Hera Id, E. A. Lachner, C. C. Lindsey, C. R. Robins,and W. B. Scott. 1970. Listof Common and Scientific Names ofFishes from the United States and Canada. Thirdedition. AmericanFisheries SOC. Spec. Publ. No . 6. 150 pp.

McPhaiI, J. D., and C. C. Lindsey. 1970. FreshwaterFishes of North- western Canada andAlaska. Fish. Res. Bd. Canada, Bull. No. 173. 381pp.

Morrow, J. E. 1974. FreshwaterFishes of Alaska.Alaska Northwest Publishing Co., Anchorage,Alaska. 78 pp.

385 Table A-I. VegetationIdentified in the Text

CommonName Scientific Name

Horsetai I Equisetumvariegatum Reed BentGrass Calamagrostisspp. Poa -Poa spp. CottonGrass Er i ophor um spp . Sedge -Carexspp. Rush Juncus spp.

BalsamPoplar Populus balsamifera FeltleafWillow -Salixalaxensis Littletree Willow -Salixarbusculoides PaperBirch Betulapapyrifera Amer i can Green A I der -Ainus crispa ThinleafAlder -Ainus tenuifolia Chickweed Stel laria spp. Mi Ik Vetch Astragalusspp. Oxytrope Oxytropis spp. Sweet Pea Hedysarum Mackenz i i Dwar f F ir eweed Epilobiumlatifolium SiberianAster -Astersibiricus F I eebane Er i geron spp. Wormood Artemisiaspp. Crep is nana Hawk’sBeard ”

386 Table A-2.Mammals Identifiedin the Text

Common Name Scientific Name

Arctic Ground Squirrel Spermophilusundulatus Red Squ irreI Tamiasciurushudsonicus Beaver -Castor canadensis Tundra Vo I e Microtus oeconomus S inging Vole Microtus miurus Microtus Vole Singing Muskrat Ondatra tibethicus Gray Wolf -Canislupus B I ack Bear -Ursus amer i canus Gr i zz ly Bear Ursus horr ibiI is AlcesAlces Moose " Car i bou Rangifertarandus

38 7 Table A-3. BirdsIdentified in the Text

Comm on Name Common Scientific Name Whistling Swan columbianus -Olor Trumpeter Swan buccinator -Olor Cana da Goose Canada canadensis Branta Blac k Brant Branta nigricans Branta Brant Black Mal lard -Anas platyrhynchos Pintai I Anas acuta " Gree n-winged Teal Anas Teal Green-winged inensis- carol G oldene ye Bucephala clangula BucephalaCommon Goldeneye Ba rrow's Goldeneye Bucephala islandica Bucephala Goldeneye Barrow's Bu fflehead Bucephala albeola Bucephala Bufflehead

Red-breastedMerganser Mergus serrator Se mipa lmated Plover Charadrius semiphalmatus Charadrius Plover Semipalmated Tu rns tone Arenaria interpres Arenaria tone Ruddy Turns Se mip alma ted Sandpiper Caldris pusillus Caldris SandpiperSemipalmated W estern Sandpiper Caldris mauri Caldris Sandpiper Western Sp otted Sandpiper Actitis macularia Actitis Sandpiper Spotted Northern Pha I arope Lobipes lobatus Glaucous Gut I hyperboreus Larus Herr i ng Gu I I Larusargentatus Mew Gul I Laruscanus " Arctic Tern Sternaparadisaea AlderFlycatcher Empidonaxalnorum Tree Swal low lridoprocnebicolor Violet-green Swallow Tachycinetathalassina

Bank Swal low Riparia riparia Gray Jay Perisoreuscanadensis Black-cappedChickadee Parus atricapi I Ius Amer i can Rob in Turdus migratorius

con t i nued

388 Table A-3. (Concluded)

C ommon Name Common Scientific Name

Gray-cheekedThrush Catharusminima Yellow Wagtail Motaci I la -f I ava Orange-crownedWarbler Verrnivoracelata - Yellow Warbler Dendroi eapetech i a Yellow-rumpedWarbler Dendroicacoronata NorthernWaterthrush Sei urus noveboracensi s

Wilson'sWarbler Wilsonia pusil la Common Redpol I Acanthis flamnea

Dark-eyedJunco "Juncohvemalis TreeSparrow Soizel la arborea White-crownedSparrow Zonotrichia IeucoDhrYs Fox Sparrow Passerel la iliaca

389 Table A-4. FishSpecies Reported and Caught orObserved in MajorGeographical Areas Represented by theTwenty-Five Sites

SewardPeninsula SlopeNorthernNorth InteriorSouthern Interior Common and - HistoricFlPresent - HistoricalPresent Historical Present Historical Present scient i f i c namesa recor dU studyL recordstudyrecord study record study

Arctic lamprey Lampterajaponica 4- + 24d Arctic cisco Coregonus autumnal is Beringcisco C. laurettae 4- -e 23 Broad-wh i tef i sh C. nasus + Humpback whitefish C. pidsch i an i 24 Least-c isco C. sardine1 la + + 24 Round-wh i tef ish Prosop i urn -cy I i ndr aceurn + + It + 15,16,17,18,20 + I nconnu Stenodusleuc - ich thys + + 17 + Pinksalmon Oncorhynchusgorbuscha + 2,5 + 9 Churn salmon 0. keta + + 18 24 " 2?5 + Coho sa 1 rnon 0. kisutch + 4,596 + SockeTe sa 1 mon 0. nerka + 5 Chi no& sa I rnon 0. tshawytscha + + 17,t8,19,20 23 Arctic char Satvetinusalpinus + I ,2,3,4,5,6 + lt,12,13,14 + 15 Laketrout -S. namaycush + +

Continued a

+++++ +

0 II II II II II 5 -Nn*(n NNNNN c m .- m m ??

+ +* +

+++ ++++ +

*+ + ++ ++ +

39 I Table A-5. AquaticMacroinvertebrates Caught at Study Sites During 1976-1978 FieldSampling

Taxon name Common

Nematoda round worms Oligochaeta earthworms Plecoptera stoneflies AI loper la Arcynop t er yx Caon i a

H~astaDer I a I soaenus I soDer I a Nemour a Par mer I a Ephemeroptera mayf I ies Ameletus Baet i nae Caen i s Callibaetis Centropt i lum Cinygmu I a

Eoeor~~ us Ephemere I I a Heptagenia Rh i throaena Siphlonurus Odona t a dragonflies and damselflies Ena I I agma I schnura Libellulidae Trichoptera caddisflies Apatania Arctopsyche Br achycen tr us Ecclisomvia Glossosoma Homophvlax Hydatophylax Lepidostoma Leptocella Limnephilus

Cont i nued

392 Table A-5. (Concluded)

Taxon name Common

Oecet is Onocosmoecus Phryganea P I atycentropus Po I ycen tropus Pseudostenophyl ax L Psychoglypha Rhyacophila Hemiptera water bugs Cor ixidae waterboatman Coleoptera beet. I es Dytiscidae divingbeetle Haiiplidae Diptera f I ies Athericidae Ceratopogonidae biting midge Chironomidae midge Ephididae Emp i d i dae Psychodidae Simuliidae blackfly Tipul idae cranefly Hydracar i na mites Mol I usca rno I I USCS Lymnaea snai I Physi dae snai I Pisidium fingernailclam P I anorb i dae snai I Va I vata snai I Amph i poda amphipods Gammar i dae

393 APPENDIX B

GLOSSARY abandonedchannel -- A channelthat was once an active orhigh-vyater channel,but currently flows only during infrequent floods. activechannel -- A channelthat contains flowing water during the ice-free season. act vefloodplain -- The portionof a floodplainthat is floodedfrequently; it containsflowing channels, high-water channels, and adjacent bars, usuallycontaining little or novegetation. aes hetics -- An enjoyablesensation or a pleasurablestate of mind, which hasbeen instigated by thestimulus of an outsideobject, or it may beviewed as including action which will achievethe state of mind desired.This concept has a basicpsychological element of individual learnedresponse and a basicsocial element of conditioned social attitudes.Also, there can be ecological conditioning experience because thephysical environment also affects the learning process of attitudes. algae -- Primitiveplants, one ormany-celled, usually aquatic andcapable ofelaborating the foodstuffs by photosynthesis. aliquot -- A portionof a grav-elremoval area that is workedindependently, oftensequentially, from the other portions of the area. alluvial river -- A riverwhich has formed its channelby the process of aggradation, and thesediment by which it carries(except for the wash load)is similar to that in the bed. arctic -- The northpolar region boundedon thesouth by the boreal forest. armor layer -- A layerof sediment that is coarserelative to the material underlying it and iserosion resistant to frequently occurring floods; it may formnaturally by the erosion of finer sediment, leaving coarser sediment inplace or it may beplaced by man toprevent erosion. aufeis -- An icefeature that is formedby water overflowing onto a surface, such as riverice or gravel deposits, and freezing,with subsequent layersformed by water overflowing onto the ice surface itself and freezing.

395 backwateranalysis -- A hydraulicanalysis, the purpose of which is to computethe water surface profile in a reach of channelwith varying bedslope or cross-sectional shape, orboth. bank -- A comparativelysteep side of a channelor floodplain formed by an erosionalprocess; its topis often vegetated. bank-fulldischarge -- Dischargecorresponding to the stage at which the overflowplain begins to be flooded. bar -- An alluvialdeposit or bankof sand, gravel, or other material, at themouth of a streamor at any pointin the stream flow. beadedstream -- A smallstream containing a seriesof deep poolsintercon- nectedby very small channels, located in areas underlain by permafrost. bed -- The bottomof a watercourse. bedload -- Sand, silt,gravel or soil and rockdetritus carried by a stream on, orimnediately above its bed. bedload material -- Thatpart of the sediment load of a sfreamwhich is composed ofparticle sires found in appreciable quantities in the shift- ingportions of the stream bed. bed,movable -- A streambed made up ofmateri3ls readily transportable by thestream flow. bed, stream -- The bottomof a streambelow the low summer flow. braidedriver -- A rivercontaining two or moreinterconnecting channels separatedby unvegetated gravel bars, sparsely vegetated islands, and, occasionally,heavily vegetated islands. Its floodplain is typically wide and sparselyvegetated, and contains numeroushigh-water channels. The lateralstability of these systems is quite low withinthe boundariesof the active floodplain. carryingcapacity, biological -- The maximum average number of a givenorgan- ism thatcan be maintained indefinitely, by the habitat, under a given regime(in this case, flow). carryingcapacity, discharge -- The maximum rateof flow that a channel is capableof passing. channel -- A naturalor artificial waterway of perceptib leextent which periodically or continuouslycontains moving water. It has a definite bedand banks which serve to confinethe water. configuration -- The patternof a riverchannel(s1 as it wouldappear by lookingvertically down atthe water. contour -- A lineof equal elevation above a specified datum.

396 cover,bank -- Areasassociated with or adjacent to a streamor river that provideresting shelter and protectionfrom predators - e.g., undercut banks,overhanging vegetation, accumulated debris, and others. cover,fish -- A more specifictype of instream cover, e.g., pools, boulders,water depths, surface turbulence, and others. cover,ins t ream -- Areasof shelter in a streamchannel that provide aquatic organ i sms protectionfrom predators or a placein which to rest, or both, andconserve energy due 'to a reductionin the force of the current . crosssect onarea -- The areaof a stream,channel, or waterway opening, usua I y takenperpendicular to the stream centerline. current -- The flowing of water,or other fluid. That portion of a stream of wa t erwhich is movingwith a velocity much greaterthan the average orin whichthe progress of the water is principallyconcentrated (not to be confusedwith a unitof measure,see velocity).

datum -- Any numericalor geometrical quantity or setof such quantities which may serveas a referenceor base for other quantities. An agreed standardpoint or plane of statedelevation, noted by permanent bench markson some solid immovable structure,from which elevations are measured,or to which they are referred. dewater -- The drainingor removal of water from an enclosureor channel. discharge -- The rateof flow, or volume of water flowing in a givenstream at a givenplace and within a givenperiod of time, expressed as cu f t per sec.

drainagearea -- The entirearea drained by a riveror system of connecting streamssuch that all stream flow originating in the area is discharged through a singleoutlet. dredge -- Any method of removinggravel from active channels.

drift,invertebrate -- The aquaticor terrestrial invertebrates which have been releasedfrom (behavioral drift), or have beenswept from (catas- trophicdrift) the substrate, or have fallen into the stream and move orfloat with the current. durationcurve -- A curvewhich expresses the relation of all the units of some itemsuch as head and flow, arranged in order of magnitudealong theordinate, and time, frequently expressed in percentage, along the abscissa; a graphicalrepresentation of the number oftimes given quantitiesare equaled or exceeded during a certainperiod of record. erosion,stream bed -- The scouringof material from the water channel and thecutting of the banks by running water. The cuttingof the banks is also knownas stream bank erosion.

397 fines -- The finer grained part clesof a mass ofsoil, sand, or gravel. The material, in hydraulic slu cing,that settles last to the bottom of a mass of water . flood -- Any fIow whichexceeds thebank-full capacity of a streamor chan- ne1and f I ows outon the f oodplain;greater than bank-full discharge. floodplain -- The relativelylevel land composed ofprimarily unconsolidated riverdeposits that is locatedadjacent to a river and is subjectto flooding; it contains an activefloodplain andsometimes contains an inactivefloodplain or terrace(s1, or both. floodprobability -- The probability of a flood of a givensize being equaledor exceeded in a givenperiod; a probabilityof I percentwould be a 100-year flood, a probabilityof IO percentwould be a I0-year flood. flow -- The movement of a streamof water or other mobile substances, or both,from place to place; discharge; total quantity carried by a stream. flow,base -- Thatportion of the stream discharge which is derived from naturalstorage - i.e.,groundwater outflow and the draining of large lakesand swamps orother sources outside the net rainfall which createsthe surface runoff; discharge sustained in a streamchannel, not a result of directrunoff andwithou? the effects of regulation, diversion,or other works of man. Alsocalled sustaining flow. flow,laminar -- Thattype of flow in a streamof water in which each particle moves in a directionparallel to every other particle. flow,low -- The lowestdischarge recorded over a specifiedperiod of time. flow,low summer -- The lowestflow during a typicalopen-water season. flow,uniform -- A flowin which the velocities are the same inboth magni- t ude and directionfrom point to point. Uniform flow is possible only in a channel of constantcross section. f low, var ed -- Flow occurringin streams having a var i ab le crosssection or s ope. When thedischarge is constant,the veloci ty changeswith each change ofcross section andslope. forkleng h -- The lengthof a fish measuredfrom thetip ofthe nose to the fork inthe tail. freezefront -- A surfacethat may be stationary,which has a temperature of O°C and is warmeron one si de of the surf aceand co I deron the other. frequencycurve -- A curveof the frequency of occurrenceof specific events. The eventthat occurs most frequently is termed the mode.

398 gage -- A devicefor indicating or registering magnitude or position in spe- cificunits, e.g., theelevation of a watersurface or the velocity offlowing water. A staffgraduated to indicate the elevation of a watersurface. geomorphology -- The studyof the. formand development of landscape features. habitat -- The placewhere a populationof animals lives and its surroundings,both living and nonliving;includes the provision of life requirementssuch as food and shelter. high-waterchannel -- A channelthat is drymost of the ice-free season, butcontains flowing water during floods. hydraulics -- The sciencedealing with the mechanical properties of fluids and theirapplication to engineering; river hydraulics deals with mechanicsof the conveyance of water in a naturalwatercourse. hydraulicdepth -- Theaverage depth of water in a streamchannel. It is equalto the cross-sectional area divided by the surface width. hydraulicgeometry -- Thosemeasures of channel configuration, including depth,width, velocity, discharge, slope, and others. hydraulicradius -- The cross-sectionalarea of a streamof water divided by thelength of that part of its peripheryin contact with its contain- ingchannel; the ratio of area to wetted perimeter. hydrograph -- A graphshowing, for a givenpoint on a stream,the discharge, stage,velocity, or another property of water with respect to time. hydrology -- The studyof the origin, distribution, and propertiesof water on ornear the surface of the earth.

ice-richmaterial -- Permafrostmaterial with a highwater content in the formof ice, often taking the shape of a vertical wedge or a horizontal I ens.

impervious -- A termapplied to a materialthrough which water cannot pass orthrough which water passes with great difficulty.

inactivefloodplain -- The portionof a floodplainthat is floodedinfre- quently; it may containhigh-water and abandoned channels and is usuallylightly to heavily vegetated.

island -- A heavilyvegetated sediment deposit located between two channels.

largeriver -- A river with a drainagearea greater than 1,000 km2 and a mean annualflow channel top width greater than 100 m.

lateralbar -- An unvegetatedor lightly vegetated sediment deposit located adjacent to a channelthat is notassociated with a meander.

399 Manning'sequation -- Incurrent usage, an empiricalformula for the calcula- tionof discharge in a channel. The formula is usuallywritten

I .49 s1/2 A. Q=-R 213 n mean flow -- Theaverage discharge at a givenstream location computed for theperiod of record by dividing the total volumeof flow by the number of days,months, oryears in the specified period. mean watervelocity -- The averagevelocity of water in a streamchannel, which is equal tothe discharge in cubic feet per second divided by thecross-sectional area in square feet, for a specificpoint location, it is thevelocity measured at 0.6 ofthe depth of the average of the velocities asmeasured at 0.2 and 0.8 ofthe depth. meanderwave length -- The averagedownvalley distance of two meanders. meandering river -- A riverwinding back and forthwithin the floodplain, The meandering channel shiftsdownvalley by a regularpattern of erosion anddepos tion. Few islandsare found in this type of river and grave I deos i t s typicallyare found onthe point bars at the insides of meanders. medium river -- verwith a drainagearea greater than 100 km2 butless than 1,000 Askm and a mean annualflow channel top width greater than 15 m but leSS than 100 m. microhabitat -- Localizedand more specialized areas within a community or habitattype, utilized byorganisms for specific purposes or events, or both.Expresses the more specific and functionalaspects of habitat and coverthat allows the effective use of larger areas (aquatic and terrestrial)in maximizing the productive capacity of the habitat. (See covertypes, habitat). mid-channelbar -- An unvegetated or lightlyvegetated sediment deposit lo- catedbetween two channels. parameter -- A variablein a mathematicalfunction which, for each of its particularvalues, defines other variables in the function. permafrost -- Perenniallyfrozen ground. pitexcavation -- A methodof removing gravel, frequently from below overburden, in a manner thatresults in a permanentlyflooded area. Gravels areusually extracted using draglines or backhoes. poi n t bar -- An unvegetatedsediment deposit located ad.jacent to the ins i de edgeof a channel in a meanderbend, poo I -- A body ofwater or portion of a streamthat is deepand quiet reI a- tiveto the main current.

400 pool,plunge -- A pool,basin, or hole scoured out by falling water at the base of a waterfall. profile -- In openchannel hydraulics, it isthe water or bed surface ele- vationgraphed aganist channel distance. reach -- A comparativelyshort length of a stream,channel, or shore. regionalanalysis -- A hydrologicanalysis, the purpose of which is toesti- matehydrologic. parameters of a river byuse of measured values of the same parametersat other rivers within a selectedregion. riffle -- A shallowrapids in anopen stream, where the water surface is brokeninto wavesby obstructionswholly or partly submerged. riparian -- Pertainingto anything connected with or adjacent to the banks of a streamor other body of water. riparianvegetation -- Vegetationbordering floodplains and occurring within floodplains. riprap - Largesediments or angular rock used as an artificial armorlayer. riverregime -- A stateof equilibrium attained by a riverin response to theaverage water and sediment loads it receives. run -- A stretchof relatively deep fastflowing water, w iththe surface essentiallynonturbulent. scour -- The removalof sediments by running water, usual ly associatedwith removalfrom the channel bed or floodplain surface. scrape - A methodof removing floodplain gravels from surface deposits using tractorsor scrapers. sedimentdischarge -- The volumetricrate of sediment transfer past a specific river cross section. sinuousriver -- Sinuouschannels are similar to meandering channels with a lesspronounced winding pattern. The channel may containsmaller pointbars andhave less tendency for downvalley shifting. The channels are more stablewith respect to lateral shifting. sinuousity -- A measure ofthe amount of windingof a river within its floodplain;expressed as a ratioof. the river channel length to the corres- pondingvalley length. slope -- The inclinationor gradient from the horizontal of a lineor surface. Thedegree of inclination is usuallyexpressed as a ratio,such as 1:25, indicatingone unit rise in 25 unitsof horizontal distance.

40 I smal I river - A river with a drainagearea less than 100 km2 and a mean annualflow channel top width of less than 15 m.

split river -- A riverhaving numerous islandsdividing the flow into two channels. The islands andbanks are usually heavily vegetated and stable. The channelstend to be narrower and deeper and the floodplain narrowerthan for a braidedsystem.

stage -- The elevationof a watersurface above or below an established datumor reference.

standingcrop -- Theabundance ortotal weight of organisms existing in an areaat a giventime.

straight river -- The thalwegof a straightriver typically winds backand forthwithin the channel. Gravel bars form opposite where the thalweg approachesthe side of the channel. These gravel bars may notbe ex- posedduring low flow.Banks of straight systems typically are stable andfloodplains are usually narrow. These river systems are considered to be an unusualconfiguration in transition to some otherconfiguration.

subarctic -- The borealforest region.

suspendedload -- The portionof stream load moving in suspension and made up ofparticles having such density of grain size as to permit movement far aboveand for a longdistance out of contact with the stream bed. The particlesare held in suspension by the upward components of turbu- lentcurrents or by colloidalsuspension.

talik -- A zone ofunfrozen material within an areaof permafrost.

terrace -- An abandoned floodplainformed as a resultof stream degradation and that is expectedto beinundated only by infrequent flood events.

thalweg -- The linefollowing the lowest part of a valley,whether under wateror not; also usually the line following the deepest part or middleof the bedor channel of a riveror stream.

thermokarst -- Landformsthat appear as depressions in the ground surface orcavities beneath the ground surface which result from the thaw of ice-richpermafrost material.

topwidth -- The width of the effective area of flowacross a stream channel.

velocity -- The timerate of motion; the distance traveled divided by the timerequired to travel that distance. wash load -- In a streamsystem, the relatively fine material in near-perman- entsuspension, which is transportedentirely through the system, withoutdeposition. That part pf the sediment load of a streamwhich is composed ofparticle sizes smaller than those found in appreciable quantitiesin the shifting portions of the stream bed.

402 waterquality -- A termused todescribe the chemical, physical, and biologicalcharacteristics of water in reference to its suitabilityfor a particular use. wettedperimeter -- The lengthof the wetted contact between the stream of flowingwater and itscontaining channel, measured in B planeat right anglesto the direction of flow. wildlife -- All livingthings that are neither human nordomesticated; most oftenrestricted to wildlife species other than fish and invertebrates.

403 IN ALASKA - TECHNICAL REPORT ~- I" Kuthor(s) WOODWARD-CLYDECONSULTANTS 1. OrganizationPerforming Name and Addms I 10. Pmlmct/Task/Work Unit No. Woodward-Clyde Consultants 4971 Buslness Park Blvd., Suite #l 11. Contmt(C) ot Qrant(Q) No. Anchorage, Alaska 99503 (c) FWS 14-16-0008-970

12. SponsoringOrgonlzationNamo wd Address 13. Typo of RopoR & Perlod Cowred F ina I Report U. S. Fish and Wild1 ife Serv ice 1975 1980 1011 East Tudor Road - Anchorage, Alaska 99503 I 14- LS. Suppiomontary Notos Thisreport is part of InteragencyEnergy - EnvironmentResearch and Development Program of the Off ice of Research and Development, U.S. EnvironmentalProtection Agency

16. Abstract (Limit: 200 words) A %year investigationof the effects of floodplbin gravel mining onthe physical and biological characteristics of river systems in arctic and subarcticAlaska is described.Twenty-five sites were studied within four geographic regions. The sites wereselected such'that within each of theregions the group of sites exhibited a widerange of river and mining characteristics. The field data collection program coveredthe major disciplines of hydrology/hydraulics,aquatic biology, water quality, and terrestrial biology. Inaddition, geotechnical engineering, andaesthetics site reviews wereconducted. A widerange of magnitude and type of physical and biological changeswere observed in response to mining activity. Little change was observed at some sites, whereasother sites exhibited changes In channelmorphology, hydraulics,sedimentation, ice regime, aquatic habitat, water quality, benthic macroinvertebrates,fish utilization, vegetation, soil characteristics, and bird and mammal usage.

Two majorproducts of the project are a TechnicalReport which synthesizes and evaluatesthe data collected at the sites, and a Guidelines Manual thataids the user indeveloping plans and operatingmaterial sites to minimize environmental ef fscts.

17. Docurnont AnaiyAr a. Deseripton Gravel Removal, Alaska,Arctic, Subarctic, Floodplains, Streams, Scraping, Pit Excavation,Environmental Impacts, Hydrology-Hydraulics, Aquatic Biology, Terrestrial Ecology, Water Quality,Aesthetics, Ceotechnical Engineering, Site Selection, Site Design.

b. idsntiflon/Open.Ended Terms

E. COZIATi Fioid/Qroup

L& AV8iiaMilty S8tMeTlt 19. Sacurlty Class (This Remrt) 21. No. d Pa08 Releaseunlimited Unclassified 403 20. Sreurlty Claw Uhis Pam) 22* price Unclassified ee ANSM39.18) Sea Inmtruetlonr on Rsvsrao 0mONAL rom 272 (4-7 (Formoriy NfiS35) Dopatmefit of commemo U v

REGIONAL OFFICE BIOLOGICAL SERVICES TEAMS

Reglon 1 Region 4 1 Team Leader Team Leader US. Flsh and Wildlife Service US. Flsh and Wlldllfe Service Lloyd 500 Bulldlng, Suite 1692 17 Executive Park Drive, N.W. 500 N.E. Multnomeh street P.O. Box 95067 Portland, Oregon97232 Atlanta, Georgia30347 FTS 4294154 FTS: 2574457 COMM: (503)2318154 COMM:(404)8814457

Reglon 2 Reglon 5 Team Leader Team Leader US. Fish and Wildlife Service U.S. Flsh and Wildlife Servlce P.O. BOX 1- CenterQateway One Albuquerque, New MexlCo87103 Suite700 FTS: 474-2971 Newton Corner, Massachusetts 02158 COMM: (505) 766-1914 FTS 829.9217 COMM: (617)9656100, Ext. 217 Region 3 Region 6 Team Leader Team Leader U.S. Flsh and Wlldllfe Servlce US. Flsh and Wildlife Service FedemlBulldlng, Fort Snelllng P.O. BOX 25488 TwlnCltlea, Mlnnesote 551 I1 DenverFederal Center 725-3593 Denver,FTS: 725-3593 Colorado 80225 COMM:(612)725-3510 FTS 2346586 COMM: (303)2346588 Alaska Area Offlce Team Leader US. Flsh and Wlldllfe Service 1011 E. Tudor Road Anchorage, Alaska99503 FTS: 399-0150ask for COMM: (907)276-3800 United States Department of the Interior

FISH AND wuuaSERVICE IN REPLY REFER TO: 101 1 E. TUDOR RD. ANCHORAGE, ALASKA 99503 (907) 276-3800 October 24, 1980

Dear Colleague :

Two FWS/OBS series reports have julst been released. They BFL: (1) the technical report Gravel Renaoval Studtes in &"ctic Subarcrik Flood- plains in Alaska mBS-80/08) * and (2TthQ companion manual, Gravel Remval~uidel.inetaManual "-in Arcttc and Subarctic Florjdplainr (FWS/OBS- 90/Q9). Thebe documents were deweloped br Woodward-Clyde Consultants