LAND USE AND WATER RESOURCES IN THE MINNESOTA NORTH SHORE DRAINAGE BASIN
Carol A. Johnston, Brian Allen, John Bonde, Jim Sal6s, and Paul Meysembourg
Natural Resources GIS Laboratory (NRGIS)
NRRI Technical Report NRRI/TR-91/07 July 1991
Research funded by the Legislative Commission on Minnesota Resources INTRODUCTION
Rivers and streams are an important feature of the Minnesota North Shore. A
dozen state parks and waysides lie at the mouths of rivers that cascade down the steep
slopes of Minnesota’s northern highlands into Lake Superior,-carving beautiful waterfalls
out the basalt bedrock. But the rivers that drain the 5778 km2 North Shore drainage basin
provide more than scenic beauty, delivering nutrients and other materials to Lake
Superior. Lake Superior’s tributaries provide about half of its annual water input (Bennett
1978), more than 90% of its total dissolved solids, and 68% of its phosphorus (Upper
Lakes Reference Group 1977). Moreover, the water from these tributaries is delivered to
the nearshore zone, in which Lake Superior’s biological communities are concentrated
(Rao 1978, Munawar and Munawar 1978, Watson and Wilson 1978). Since these
communities of bacteria, algae, and zooplankton form the basis of the food web, the
productivity and integrity of Lake Superior’s waters are heavily dependent on water
supplied by the North Shore drainage basin.
While some of the materials delivered by rivers and streams are essential to
aquatic life, excessive inputs of sediment and nutrients can cause nonpoint source
pollution, the flow of pollutants from land to water in stormwater runoff or from seepage through the soil. In the Great Lakes, nonpoint source pollution is highest from lands that are urbanized or intensively farmed (Gregor and Johnson 1980). Such intensive land
uses are uncommon in the Lake Superior drainage basin, which is 91% forested
(Environment Canada et al. 1987). Even under current low-intensity land uses, however, nonpoint source inputs to Lake Superior are not negligable. The majority of Lake
Superior’s phosphorus inputs come from nonpoint sources, due to the relative lack of
1 point sources (e.g., sewage treatment plants, industrial outfalls) and the size of the lake’s drainage basin (127,700 km2), that funnels water and materials from an area 1.6 times the surface area of the lake itself. Therefore, even a small nonpoint source pollution yield per unit area of drainage basin can result in a large cumulative total delivered to the lake.
Inputs of nitrogen and phosphorus from Lake Superior’s tributaries contribute 34x the nitrogen and 12x the phosphorus of municipal and industrial inputs combined (Table 1).
When land uses intensify, nonpoint source inputs can increase, potentially affecting the streams that deliver water into Lake Superior as well as portions of the lake itself.
The major land use change currently occurring in the Lake Superior drainage basin is the increase in deforestation resulting from demand for wood and paper products, which is projected to increase total harvest by 50% between 1988 and 1995 (Minnesota DNR
1989). We know that the extensive pre-settlement logging of the Great Lakes drainage basin affected water quality, as indicated by sediment evidence of increased phosphorus concentrations (Kemp et al. 1972) and diatom production (Stoermer et al. 1985; Schelske et al. 1988), and model predictions of increased phosphorus loading (Chapra 1977).
However, we don’t know the magnitude of land affected by more recent clearcutting, nor its effects on water resources. The purpose of this report is to describe these land use changes and other characteristics of the Minnesota North Shore drainage basin that could potentially affect fluxes of sediment and nutrients into Lake Superior.
2 Table 1. Drainage basin inputs of nitrogen and phosphorus (as total N and P) to the Great Lakes, metric tons/yr (Upper Lakes Reference Group 1977).
Source Direct Direct Sampled Unsampled Total Municipal Industrial Tributaries Tributaries NITROGEN: Michigan 50 65 4050 1470 5640 Wisconsin 149 6 3060 3070 6290 Minnesota 50 39 7320 551 7870 Ontario 249 456 14700 2420 17800
TOTAL 498 566 29130 7511 37600
PHOSPHORUS: Michigan 22 6 206 63 297 Wisconsin. 60 2 485 456 1000 Minnesota 14 4 496 27 540 Ontario 36 88 920 178 1220
TOTAL 132 100 2107 724 3057
METHODS
Geographic Information Systems (GISs) were used to enter and analyze mapped information pertainent to forests and water quality of the North Shore drainage basin.
Data were summarized from existing databases obtained from the Minnesota Land
Management Information Center (LMIC) and the U.S. Geological Survey, as well as databases created at the Natural Resources Research Institute for this and previous projects (Table 2). Data were summarized for three different levels of geographic extent: the drainage basin as a whole, the coastal zone, and individual watersheds for the Lester and Gooseberry rivers.
Existing maps and databases were used for the drainage basin and coastal zone, but their level of spatial resolution and classification detail was inadequate for the individual watersheds. For example, when the data from the Minnesota Soil Atlas were
3 summarized for the Lester River watershed, it was found that a single patch of one soil landscape unit covered 82% of the watershed (11,000 ha). This is due to the course resolution of the original map, which is inappropriate for analysis of individual watersheds.
1. Detailed Watershed Studies
The boundaries of the Lester and Gooseberry River watersheds were mapped by determining the location of topographic divides on 1:24,000 USGS topographic maps with contour intervals of 10 or 20 feet. The location of water quality sample points used by co investigator Naomi Detenbeck were used to map subwatersheds, which were digitized using a Calcomp digitizing table and a PC-ARC/INFO GIS.
Several county, state, and federal agencies maintain detailed land use maps for portions of the study site watersheds, but there are differences among them in classification, and none of the agencies maps private lands. The Minnesota Land
Management Information System (MLMIS100) includes a land cover map as of 1969, but its age and generality (40 acre minimum mapping unit and a classification system does not distinguish forest types nor sylvicultural practices) limit its use in this region. Updated land cover maps being prepared by The International Coalition with LCMR funding are not completed in northeastern Minnesota. Therefore, it was decided to prepare new land use maps for the study site watersheds.
Detailed land use/land cover maps (1:24,000) were prepared by stereoscopic interpretation of 9" x 9" black and white infrared aerial photos of the Lester River watershed (1989 photos) and Gooseberry River watershed (1990 photos). Mapping units as small as 1 ha were classified into one of 30 land use/land cover types and 4 silvicultural practices. Boundaries of land use classes were transferred from the aerial
4 photos to a 1:24,000 USGS topographic map base using a Bausch and Lomb Stereo
Zoom Transferscope. The maps were digitized, and PC-ARC/INFO was used to
determine the number and area of land use patches by cover type within each of the
study site watersheds.
Topography was digitized from 1:24,000 topo maps for the Lester watershed and a
portion of the Gooseberry watershed using PG-ERDAS (a total of 39,927 elevation points
were digitized), but was rendered unusable by a bug in the GIS software. Stream
information was obtained from USGS 1:100,000 Digital Line Graph (DLG) files, converted
to ARC/INFO format (James and Dulaney 1989), edge-matched, and summarized by
watershed to determine stream lengths.
2. Coastal Zone
Maps of land use, soil series, and surficial geology were analyzed for the
Minnesota coastal zone (Table 2). The land use and soil series digital databases were
purchased from LMIC (Minnesota State Planning Agency 1978), and the surficial geology
map was digitized from "Environmental Geology of the North Shore" (Green et al. 1977)
under a project previously conducted by Johnston and Bonde (1990a). Statistical
summaries were prepared for each of the maps. The surficial geology maps were also
used with previously measured erosion rates (Johnston et al. 1990b) and soil phosphorus data (Bahnick 1977) to calculate the mass of material and associated phosphorus eroded into Lake Superior from clay bluffs along the Minnesota North Shore.
3. Drainage Basin
The extent of the Minnesota Lake Superior drainage basin was determined using
Minnesota Land Management Information System (MLMIS100) files for St; Louis, Lake,
5 and Cook counties (Table 2). The MLMIS major watershed file was used to identify the outer extent of the North Shore drainage basin, and was used to define the limits of analysis for the remainder of the MLMIS databases: minor watersheds, proximity to water, public ownership, forest cover, soil geomorphic units, soil landscape units, elevation, and slope. The watersheds for each river or stream draining to Lake Superior was determined by aggregating subwatersheds in the MLMIS minor watershed file. All MLMIS files were analyzed using an EPPL7 GIS.
A portion of the map of Minnesota pre-settlement forest cover prepared by F.J.
Marshner was scanned using an Eikonix camera, and intersected with the MLMIS major watershed file to determine forest characteristics-of the North Shore drainage basin prior to European settlement. Data were summarized and compared with data from the MLMIS
"Major forest types, 1977" to determine changes in cumulative forest cover as a result of post-settlement logging.
6 Table 2. GIS data files used and created by this project. USGS = U.S. Geological Survey, LMIC = Minnesota Land Management Information Center.
DATABASE DATABASE ORIGINAL MAP SOURCE ORIGINAL DATABASE SOURCE SCALE RESOLUTION
STUDY SITE WATERSHEDS: Land use/land cover this study 1989 & 1990 air photos 1:15,840 1:24,000 Subwatersheds this study USGS topographic maps 1:24,000 1:24,000 Topography this study USGS topographic maps 1:24,000 1:24,000 Streams USGS DLGs USGS topographic maps 1:24,000 1:100,000
COASTAL ZONE: Land use LMIC LMIC 1:24,000 1 ha cells Soils LMIC Soil Conservation Serv. 1:15,840 1 ha cells Surficial geology previous study Environmental Geology 1:24,000 1:24,000 of the North Shore
DRAINAGE BASIN:
Pre-settlement forest this study Marshner (1930) map 1:500,000 — Major forest types MLM1S100 U.S. Forest Service 1:24,000 40 acre cells Proximity to water MLMIS100 USGS topographic maps 1:24,000 40 acre cells Major watersheds MLMIS100 USGS hydrologic units 1:24,000-1:62,500 40 acre cells Minor watersheds MLMIS100 DNR watershed maps 1:24,000-1:62,500 40 acre cells Public ownership MLMIS100 several sources various 40 acre cells Elevation MLMIS100 Defense Mapping Agency 1:250,000, 50-100’ contours 40 acre cells Slope MLMIS100 Defense Mapping Agency 1:250,000, 50-100’ contours 40 acre cells Soil geomorphic units MLMIS100 Minnesota Soil Atlas 1:250,000 40 acre cells Soil landscape units MLMIS100 Minnesota Soil Atlas 1:250,000 40 acre cells
7 RESULTS
1. Detailed Watershed Studies
Lester River Watershed. The 135 km2 Lester River watershed lies just east of
Duluth in St. Louis County. The Lester River is a third orderstream for 16 km upstream of Lake Superior (Fig. 1). It is joined near its mouth by the Amity River, which drains the southwestern portion of the watershed. There are 19 km of second order streams in the watershed as a whole, and 70 km of headwater streams (Table 3). Eagle Lake and Mud
Lake are the watershed’s only two named lakes (Fig. 1).
Table 3. Lengths of streams in the Lester and Gooseberry River watersheds, by stream order.
Stream Lester Watershed Gooseberry Watershed Order Stream Lenath (km) Stream Lenath (km)
1 69.8 88.3 2 18.7 36.5 3 16.5 23.7 4 4.1
TOTAL 105.0 152.6
Air photo mapping of the watershed showed that the U.S.G.S. topographic maps used to derive Figure 1 were conservative in depicting small water bodies and wetlands.
In addition to the two lakes, there are 37 small ponds (primarily beaver ponds) scattered throughout the watershed (Fig. 2). Wetland extent is also much greater than shown on the topographic map: wooded wetlands cover 11% of the watershed area, while marshes and open water cover 2% (Fig. 2, Table 4). Bog vegetation (muskeg) occurs in large patches (average area = 10.6 ha) in the northern half of the watershed. Lowland brush
(i.e., alder) is the most extensive individual wetland type (5% of watershed area: Table 4)
8 FIGURE 1 :srR RIVER WATERSHED Stream Order Classification I7VI 1st Order Stream I7S71 2nd Order Stream IA/I 3rd Order Stream I7\7l Watershed ■ Open Water Wetland R Sample Point
Work funded by Legislative Commission on Minnesota Resources Figure 2 on following page tfSTER RIVER WATERSHED Land Use Classifications Forest Wetlands 3 kl£S □ Coniferous ■ Open Water ■ Mixed P Non-forested Deciduous EH Forested Plantation Other Harvested □ Agricultura I I Residential ■ Rock Outcrop
Work funded by Legislative Commission on Minnesota Resour Table 4. Land use/land cover In the Lester and Gooseberry River watersheds.
------lestei1 RIVER—------GOOSEBE RRY RIVER------Area (ha) Percent of No. of Mean Patch Area (ha) Percent of No. of Mean Patch Watershed Patches Size (ha) Watershed Patches Size (ha) WETLANDS & WATER: Swamp hardwoods 338 2.5% 73 4.6 709 3.7% 135 5.3 Swamp conifers 464 3.4% 83 5.6 955 5.0% 191 5.0 Lowland brush 616 4.6% 132 4.7 887 4.6% 236 3.8 Muskeg 117 0.9% 11 10.6 32 0.2% 13 2.5 Marsh 153 1.1% 47 3.3 .268 1.4% 137 2.0 Open water 139 1.0% 39 3.6 213 1.1% 90 2.4
SUBTOTAL 1827 13.5% 385 3064 15.9% 802
AGRICULTURE: Permanent meadow 692 5.1% 81 8.5 27 0.1% 5 5.3 Pasture 130 1.0% 28 4.6 0 0.0% 1 0.5 Orchard/nursery 25 0.2% 6 4.1 0 0.0% 0 - Row crops 33 0.2% 4 8.2 0 0.0% 0 ~ Feedlot 5 0.0% 2 2.4 0 0.0% 0 ~ Abandoned meadow 310 2.3% 52 6.0 8 0.0% 4 1.9
SUBTOTAL 1195 8.8% 173 35 0.2% 10
URBAN: Residential 656 4.8% 92 7.1 7 • 0.0% 8 0.8 Commercial/industrial 32 0.2% 9 3.5 4 0.0% 4 1.1 Gravel pits 89 0.7% 18 4.9 25 0.1% 10 2.5 Other open land 35 0.3% 7 5.0 3 0.0% 3 1.1 Golf courses 8 0.1% 1 7.7 0 0.0% 0 - Utility rights-of-way 33 0.2% 10 3.3 0 0.0% 0 -
SUBTOTAL 853 6.3% 137 39 0.2% 25
FORESTED UPLAND: Rock outcrop 24 0.2% 8 3.0 1 0.0% 2 0.5 Northern hardwoods 155 1.1% 17 9.1 191 1.0% 18 10.6 Aspen/birch 2686 19.9% 44 61.0 3542 18.4% 153 23.1 Upland brush with aspen 447 3.3% 60 7.5 236 1.2% 54 4.4 Upland brush 290 2.1% 51 5.7 83 0.4% 28 3.0 Mixed decid./conifer 4650 34.4% 81 57.4 9043 46.9% 119 76.0 Red & white pine 141 1.0% 28 5.0 121 0.6% 40 3.0 Jack pine/upland spruce 3 0.0% 1 3.4 0 0.0% 0 - Balsam fir/spruce 773 5.7% 93 8.3 1340 6.9% 208 6.4 Pine plantation 74 0.5% 37 2.0 1 0.0% 2 0.5 Jack pine plantation 14 0.1% 1 14.4 0 0.0% 0
SUBTOTAL 9258 68.5% 421 14557 75.5% 624
RECENTLY LOGGED: Aspen/birch, clearcut 331 2.5% 15 22.1 478 2.5% 18 26.6 Aspen/birch, partial 0 0.0% 0 103 0.5% 4 25.8 Mixed, clearcut 0 0.0% 0 — 121 0.6% 11 11.0 Mixed, partial cut 60 0.4% 5 12.0 886 4.6% 48 18.5 Mixed, clearcut & plant 0 0.0% 0 - 3 0.0% 1 2.7 Fir/spruce, partial cut 0 0.0% 0 5 0.0% 1 4.9
SUBTOTAL 391 2.9% 20 1596 8.3% 83
TOTAL 13524 1136 19291 1544
11 Agriculture constitutes 9% of land use (Table 4), and is scattered throughout the watershed (Fig. 2). Most of the agricultural land is pasture or permanent meadow, which yield little nonpoint source pollution because the soil is not tilled and nutrient additions
(e.g. manure) are minimal. Only 38 ha of land is in intensive-agricultural uses such as row crops and feed lots that could contribute more nonpoint source pollution.
Urban lands make up only 6% of the watershed area, and are primarily low-density residential. Most of the urban lands drain to Amity Creek in the southwestern portion of the watershed near Duluth. The Lester River golf course occupies only 8 ha of the watershed, but is a potential source of nonpoint source pollution due to high fertilizer inputs, soil erosion during course expansion in 1988-89, its proximity to the Lester River, and its downstream location near the mouth of the Lester.
Forest is the major land cover in the Lester River watershed (Table 4).
Aspen/birch stands occupy 20% of the watershed (2686 ha), while mixed deciduous/conferous stands occupy 34% (4650 ha). These stands occur in large patches averaging about 60 ha in size (Table 4). Upland conifer stands (pine, spruce, and fir) cover 7% of the watershed (1006 ha), and tend to be in much smaller, scattered patches
(Fig. 2, Table 4). Forested wetlands and uplands constitute three-fourths of total watershed area.
Recent logging is a relatively minor land use in the Lester River watershed in terms of total watershed area (3%; 392 ha). However, a single 166 ha clearcut is the largest contiguous patch of disturbed land in the watershed, larger than any of the agricultural or residential patches. This clearcut constitutes 42% of the total area logged. Most of the area logged was clearcut, which is the standard silvicultural practice for aspen.
12 Gooseberry River Watershed. The Gooseberry River is best known for its spectacular series of falls over which the water drops 240 feet to Lake Superior. The headwaters of the river mainstem lie in the northernmost portion of the watershed, and are joined by several unnamed and named tributaries (Little Gooseberry R., Dago Cr.) before its confluence with Skunk Creek, a third-order stream. Tributaries to Skunk Creek include Stony Creek and Mink Creek. The Gooseberry River is a fourth order stream from the mouth of Skunk Creek to Lake Superior, a distance of 4 km (Fig. 3, Table 3).
Headwater streams constitute 58% of total stream length in the watershed.
The Gooseberry River stream network is longer (153 km) than the Lester River network (Table 3). However, since the watershed of the Gooseberry River (193 km2) is larger than that of the Lester, both watersheds have the same stream length per unit area
(0.8 km/km2). Both watersheds also have only 1%.surface water (Table 4).
There are six named lakes in the Gooseberry River watershed (Amberger L.,
Christianson L., Highland L., Long L., and Twin Lakes) and all of them are at the furthest extreme of the watershed away from Lake Superior (Fig. 3). There are 85 small ponds
(Table 4) scattered throughout the drainage basin, however, many of which are too small to be visible on the land use/land cover map (Fig. 4). The total area of lakes and ponds is 213 ha.
Wetlands cover 15% of the Gooseberry River watershed (2851 ha). Swamp conifers and swamp hardwoods cover 5% and 4% of watershed area, respectively, while lowland brush covers an additional 5%. There are 712 patches of wetland and open water in the watershed, but average patch size is 5 ha or less for all wetland types.
13 FIGURE 3
Work funded by Legislative Commission on Minnesota Resources 0 1st, Order Stream N\ 2nd Order Stream |7\7] 3rd Order Stream W\ 4th Order Stream W\ Watershed ■ Open ■ Water ® Wetland fi~l Sample Point f1! Additional Sample Point Figure 4 on following page Work funded by Legislative Commission on Minnesota Resources t=d s C ass icat ions n io t a i c i f s s a CI Use d n a L h HI HI H Plantation Plantation H oet Wetlands Forest Mixed H F . Coniferous ■ Open Water Water Open ■ . Coniferous Harvested Deciduous D H Forested Forested H Non—forested H Other Rc Outcrop Rock l Residential i ; Agricultural ; Agricultural SUPERIOR LAKE Unlike the Lester River watershed, there is virtually no agriculture nor urban land use, each of which constitutes only 0.2% of the watershed area (Table 4). Upland and wetland forests cover the vast majority of the watershed (84%); Mixed deciduous/ coniferous stands are the predominant forest type (47% of watershed area), followed by aspen/birch (18%) and spruce/fir (7%). Pines remain as small stands (average area = 3 ha) covering only 121 ha (Table 4).
Recent logging has affected 8% of the land area in the watershed (Table 4).
Several silvicultural techniques have been employed, and partial cuts are more common than clearcuts. While logged areas are scattered throughout the watershed, three large clear cuts (211, 189, and 156 ha) constitute 35% of the logged area. The two largest logged areas are adjacent to Skunk and Mink Creeks in the southeast portion of the watershed.
2. Drainage Basin and Coastal Zone
Water Resources. Rivers are an important feature of the 5,778 km2 area that drains the Minnesota North Shore; 29% of all 40 acre parcels ajoin permanent or intermittent rivers (Table 5). Watersheds for 54 named streams terminate at Lake
Superior (Fig. 5). The largest of these is the 1646 km2 Pigeon River watershed, which is split between Minnesota and Ontario. Other major watersheds (> 200 km2) include the
Brule, Cascade, Poplar, Temperance, Cross, Manitou, Baptism, Beaver, and Knife Rivers.
Lakes cover only 0.4% of the drainage basin due to its well-developed stream networks, but lakeshore 40 acre parcels constitute 13% of the drainage basin, indicating a large perimeter-to-area ratio caused by the long, narrow shapes of most lakes in the drainage basin (Table 5).
16 1 Chester Cr 19 Beaver R 37 Cascade R 2 Tischer Cr 20 Palisade Cr + 38 Good Harbor (Cut Face) Cr + 3 Lester R 21 Baptism R 39 Rosebush Cr 4 Talmadge R 22 Crystal Cr + 40 Devils Track R 5 French R 23 Manitou R 41 Durfee Cr + 6 Schmidt Cr + 24 Little Manitou R + 42 Kimbal R 7 Sucker R 25 Caribou R 43 Stone Cr + 8 Little Sucker R + 26 Sugarloaf Cr + 44 Kadunce R 9 Knife R 27 Two Island R 45 Colville Cr E + 10 Stewart R 28 Cross R 46 Brule R 11 Pete's Cr + 29 Temperance R 47 Myhr Cr + 12 Silver R 30 Carlton Cr + 48 Flute Reed R 13 Encampment R 31 Onion R 49 Carlson Cr 14 Crow R 32 Rollins Cr + 50 Farquahr Cr + 15 Castle Danger Cr + 33 Poplar R 51 Reservation R 16 Gooseberry R 34 Alfred & Jonvick Crs + 52 Hollow Rock R 17 Stream No. 30 + 35 Spruce (Deer Yard) Cr 53 Grand Portage Cr + 18 Split Rock R 36 Indian Camp Cr + 54 Pigeon R (Minn, portion)
Figure 5. Major watersheds of the North Shore drainage basin (+ indicates areas containing drainage directly to the shore as well as to named creek). Table 5. Proximity to water of 40-acre parcels in the North Shore drainage basin.
Water Orientation Area (km2) Percent Island shoreline 13.4 0.2% Lake shoreline 773.1 13.4% Permanent river 1381.8 23.9% Intermittent river 268.3 4.6% Drainage ditches 4.7 0.1% SUBTOTAL 2441.3 42.2%
Water surface 23.1 0.4% Inland areas 3313.6 57.4% TOTAL 5778.0 100.0%
Topography. The North Shore drainage basin contains both the highest (230T) and the lowest elevations (602’) in Minnesota (Fig. 6a, Table 6). Both of these elevations occur in the Cascade River watershed, giving it the maximum relief of any watershed in the state. The land surface rises steeply from lake level (602’), and levels off at about
900’ in the southern portion of the drainage basin and 1500’ in the northern portion. Two- thirds of the drainage basin area lies between elevations 1350’ and 1950’.
Table 6. Elevation of the North Shore drainage basin.
Elevation (ft) Area (km2) Percent 600-749 209 3.6% 750-899 184 3.2% 900-1049 331 5.7% 1050-1199 357 6.2% 1200-1349 535 9.3% 1350-1499 860 14.9% 1500-1649 885 15.3% 1650-1799 1173 20.3% 1800-1949 935 16.2% 1950-2099 285 4.9% 2100-2301 24 0.4%
1 8 Figure 6. Topographic characteristics of the North Shore drainage basin. (A) Elevation (B) Slope, Although slopes are generalized by the coarse resolution of the source data
(1:250,000 maps, 50-100’ contours, 40 acre cells), it is still apparent that this is a region of rugged topography (Fig. 6b, Table 7). Slopes are steep along Lake Superior and adjacent Sawtooth Mountain range (ie., the Highland Flutes geomorphic region: Fig. 7a), and in the Boundary Waters Canoe Area along the northern edge of the drainage basin
(Fig. 6b). Slopes are more gradual in the Highland Moraine and the Nernadji-Duluth
Lacustrine Plain geomorphic regions (Fig. 7a). Two-thirds of the drainage basin has slopes of 0-3% (Table 7).
Table 7. Slope of the North Shore drainage basin.
Slooe (%) Area (km2) Percent 0 1048 18.2% 1 1243 21.5% 2 924 16.0% 3 644 11.1% 4 498 8.6% 5 398 6.9% 6 274 4.8% 7-8 340 5.9% 9-10 182 3.2% 11-13 124 2.1% 14-16 50 0.9% 17-20 28 0.5% >20 25 0.4%
Geomorpholoqy. The drainage basin is about evenly divided among three geomorphic provinces: the Tower-Ely Glacial Drift and Bedrock Complex, the Highland
Flutes, and the Highland Moraine (Fig. 7a, Table 8). Other major geomorphic provinces are the Vermillion Range and the Nernadji-Duluth Lacustrine plain (Fig. 7a). Minor areas of the Toimi Drumlin area and the Brimson Outwash Plain also extend into the North
Shore drainage basin (Table 8).
20 Tower - Ely Glacial Drift
Highland Flutes A
HHHH ■ RCWL
LLWL ■ LLPL
*! SSWL W ■ NPNP
PEAT SLWL
Figure 7. Geomorphic characteristics of the North Shore drainage basin. (A) Major Geomorphic Regions (B) Soil Landscape Units. Map codes are described in Table 10. Table 8. Geomorphlc regions of the Minnesota North Shore drainage basin.
Geomorohic Reaion Area Percent {k n fl Tower-Ely Glacial Drift and Bedrock Complex 1601 27.7 Highland Flutes, Rocky, and Strongly Sloping 1438 24.9 Highland Moraine, Loamy, Rolling to Hilly 1865 32.3 Toimi Drumlin Area, Loamy 8 0.1 Nemadji-Duluth Lacustrine Plain, Clayey 436 7.6 Vermillion Range (Moraine) 420 7.3 Brimson Outwash Plain, Sandy 10 0.2
Minnesota’s shoreline is often portrayed as rocky, and bedrock is the major
surficial geologic type (Table 9). However, more than half of the coastal zone is
composed of erodible glacial and post-glacial deposits in the form of glacial till, sand and
gravel deposits (e.g., outwash, alluvium), and glaciolacustrine clays and silts (Table 11).
Bedrock and clay & silt deposits have the largest cumulative areas (8311 and 6138 ha,
respectively) and average area per patch (54 and 68 ha, respectively), while glacial till,
organic deposits, and fill occur in only a few, small patches (Table 9). Sand and gravel
deposits are intermediate in extent (3938 ha) and average patch size (38 ha).
Clay and silt deposits are high in phosphorus (Bahnick 1977), so erosion of clay
bluffs along the Minnesota shoreline contributes both sediment and nutrients to Lake
Superior. Based on average erosion measurements made under previous funding, we
estimate that bluff erosion contributes 7 x 104 metric tons of sediment and 2.1 metric tons
of P04 per year to Lake Superior (Johnston in press).
Soils. The Minnesota Soil Atlas (Soil Science Department 1977, 1981) depicts four
major soil landscape units along the Lake Superior drainage basin (Table 10): deep loamy well-drained (LLWL: 37%), loamy over bedrock well-drained (RLWL: 31%), deep clayey
22 Table 9. Surficial geology ofthe North Shore coastal zone.
Type Area Percent No. of Mean Patch (ha) Patches Area (ha)
Bedrock 8311 41.8% 153 54.3 Clay & silt deposits 6138 30.9% 90 '68.2 Fill 168 0.8% 11 15.3 Glacial till 444 2.2% 25 17.8 Organic deposits 81 0.4% 12 6.8 Sand & gravel 3938 19.8% 102 38.6
Urban 813 4.1% — —
TOTAL 19892 393 well-drained (CCWL: 12%), and deep sandy well-drained (SSWL: 9%). The LLWL soils are the most extensive, occurring along the entire length of the drainage basin (Fig. 7b).
Well-drained loamy soils over bedrock (RLWL) predominate in the Tower-Ely geomorphic region, deep sandy soils (SSWL) predominate in the Vermillion Range region, and clayey soils (CCWL, RCWL) predominate in the Nemadji-Duluth Lacustrine Plain (Fig. 7, Table
10). Organic soils (NPNP, PEAT) occupy about 5% of the drainage basin.
A detailed soil survey was done by the Soil Conservation Service (1977) for the
Lake Superior coastal zone. This survey provides more spatial and classification detail than the Minnesota Soil Atlas, but covers only a fraction of the drainage basin. Clayey soils (Bergland, Ontonagon, and Hibbing) are common from Duluth to Beaver Bay, shallow to bedrock loams (Quetico, Barto, and Mesaba) predominate from Beaver Bay to
Grand Marais, while sand and gravel deposits (Amasa soils) occur primarily north of
Grand Marais. There are few wetlands in the coastal zone because of its steep topography, and therefore a relatively small percentage of muck soil (1.7%: Table 11).
Some soils are more abundant at the shoreline than they are in the coastal zone
23 as a whole: Amasa, Barto-Mesaba, and Quetico soils (Table 11). Other soil types occupy a portion of the shoreline comparable to or less than their abundance in the coastal zone, and several (Ahmeek, Bergland, Duluth, Seelyeville) do not occur at the shoreline at all.
Table 10. Soil landscape units of the Minnesota North Shore drainage basin.
Soil Landscape Unit Code Area (km2) Percent Clayey over bedrock, well-drained, light colored RCWL 19 0.3 Clayey over clayey, well-drained, light colored CCWL 688 11.9 Loamy over bedrock, well-drained, light colored RLWL 1779 30.8 Loamy over loamy, poorly-drained, light colored LLPL 41 0.7 Loamy over loamy, well-drained, light colored LLWL 2109 36.5 Loamy over sandy, well-drained, light colored SLWL 11 0.2 Sandy over sandy, well-drained, light colored SSWL 535 9.3 Peat NPNP.PEAT 308 5.4 Shallow to bedrock ROCK 264 4.6 Water HHHH 23 0.4
Table 11. Soils of the North Shore coastal zone.
Soil Series Area Percent Lenqth of Percent of M l shore (km) shore Ahmeek fine sandy loam 177 0.4% 0.0 0.0% Amasa gravelly fine sandy loam 2142 4.7% 33.8 10.8% Barto-Mesaba gravelly silt loam 14433 31.4% 132.8 42.3% Bergland silty clay 90 0.2% 0.0 0.0% Duluth very fine sandy loam 897 2.0% 0.0 0.0% Hibbing silt loam 7401 16.1% 19.6 6.2% Mesaba gravelly silt loam 2106 4.6% 16.6 5.3% Ontonogan silt loam 6710 14.6% 31.0 9.9% Quetico-rock outcrop complex 7390 16.1% 65.6 20.9% Seelyeville muck 210 0.5% 0.0 0.0% Suamico muck 558 1.2% 4.5 1.4% Tailings basin 116 0.3% 3.2 1.0% Fluvaquents 376 0.8% 0.4 0.1% Udorthents 3339 7.3% 6.5 2.1%
45945 314.0
24 Land Use. Like the rest of the Lake Superior drainage basin, the Minnesota coastal zone is predominantly (91%) forested (Table 12). Year round and seasonal residential areas constitute 3% of the coastal zone, while agriculture constitutes only 2%.
Although 43% of the drainage basin is in public ownership (Table 13), only 4% of the coastal zone is public land, mostly in State Parks (Table 12). Commercial and manufacturing areas are minor in extent (0.4%).
Ownership. The U.S. Forest Service is the North Shore’s largest land-holder, overseeing 2451 km2 in the Superior National Forest and Boundary Waters Canoe Area
Wilderness, primarily in Cook County (Table 13). Private landowners own a surprisingly large portion of the drainage basin (1735 km2), 30% of its total area. State and county land holdings constitute only 16% and 11% of drainage basin area, respectively.
25 Table 12. Land use of the North Shore coastal zone.
Land Use Area Percent M i FOREST & SILVICULTURE 77493 90.7%
AGRICULTURE 1773 2.1%
COMMERCIAL & MANUFACTURING: Mineral extraction, active 20 0.0% Mineral extraction, inactive 38 0.0% Manufacturing 11 0.0% Commercial, retail 80 0.1% Commercial, service 23 0.0% Dwelling w/ attached commercial 130 0.2%
SUBTOTAL 302 0.4% RESIDENTIAL: Residential, year round 1651 1.9% Residential, seasonal 683 0.8% Mobile homes, year round 101 0.1% Mobile homes, seasonal 30 0.0% Abandoned buildings 58 0.1%
SUBTOTAL 2523 3.0% PUBLIC & RECREATIONAL: Public land 33 0.0% Semi-public land 13 0.0% Wayside 25 0.0% Campground 13 0.0% Picnic ground 1 0.0% Public access 7 0.0% State Park 3283 3.8% Camping trailer facility 2 0.0% Boat docking area 2 0.0%
SUBTOTAL 3379 4.0%
TOTAL 85470
26 Table 13. Ownership of lands in the Minnesota North Shore drainage basin.
Ownership Area (km2) Percent FEDERAL LANDS: Boundary Waters Canoe Area 615.3 10.7% National Forests 1835.5 31.8% BLM 1.7 -0.0% National Park Service 8.6 0.2% U.S. Army Corps of Engineers 0.6 0.0% Other Federal Lands 1.8 0.0% Both Federal & State 14.9 0.3% Both Federal & County 6.6 0.1%
FEDERAL SUBTOTAL 2484.9 43.0% STATE LANDS: DNR State Forest 523.6 9.1% DNR Forest (not state forest) 220.8 3.8% DNR Other 0.7 0.0% DNR Wildlife Management Area 2.7 0.1% DNR Fisheries 61.8 1.1% DNR Enforcement 0.3 0.0% DNR Parks & Recreation 63.9 1.1% DNR Trails 0.3 0.0% Multiple State Agencies 7.1 0.1% DOT Rest Areas 2.0 0.0% DOT Adjacent to Lakes & Streams 5.2 0.1% DOT Gravel Pits 4.0 0.1% DOT Other 0.5 . 0.0% Military Affairs 0.2 0.0% University of Minnesota 3.6 0.1%
STATE SUBTOTAL 896.8 15.5% COUNTY LANDS: County Forests (Tax-Forfeit) 223.8 3.9% Other County (Tax-Forfeit) 437.5 7.6%
COUNTY SUBTOTAL 661.3 11.4%
PRIVATE LANDS 1735.0 30.0% TOTAL 5778.0
27 Forest Cover. Prior to European settlement, the North Shore drainage basin was
dominated by aspen/birch (52% of drainage basin area) and pine stands (37% of
drainage basin area), with smaller amounts of spruce/fir and maple/basswood (Fig. 8a,
Table 14). As of 1977, aspen-birch still covered a comparable area of the drainage basin
(3056 km2), but in different locations. The pine forests in the southern half of the drainage
basin were converted to aspen/birch forests by post-settlement logging, while many areas
of pre-settlement aspen/birch succeeded to spruce-fir. Pine forests now constitute only
5% of drainage basin area, and are primarily located in Superior National Forest. Maple-
basswood forests are still uncommon (6%: Table 14).
Table 14. Major forest types of the Minnesota North Shore drainage basin.
Forest Tvoe Area (km2) Percent MAJOR FOREST TYPES, 1800s: Aspen-birch 3002 51.7% Pine 2130 36.7% Spruce-fir 499 8.6% Maple-basswood 177 3.1%
TOTAL 5808
MAJOR FOREST TYPES, 1977: Aspen-birch 3056 52.9% Spruce-fir 1858 32.2% Maple-basswood 348 6.0% Pine 267 4.6% Non-forest land 232 4.0% Unproductive land 14 0.2% Swamp hardwoods 3 0.0%
TOTAL 5778
28 Pine
Spruce - Fir
Maple - Basswood
Aspen - Birch
Spruce - Fir
Maple - Basswood
Aspen - Birch
Wetlands
Non-Forested Land
Figure 8. Major forest types of the North Shore drainage basin. (A) Presettlement (B) 1977. LITERATURE CITED
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