GR-2-77
LIMNOLOGICAL RECONNAISSANCE OF SEMINOE RESERVOIR, WYOMING
by J.F. LaBounty J.J. Sartoris R.A. Roline
Applied Sciences Branch Division of General Research Engineering and Research Center Denver, Colorado
SI METRIC December 1976
UNITED STATES DEPARTMENT OF THE INTERIOR * BUREAU OF RECLAMATION ACKNOWLEDGMENTS
The Lower Missouri Region of the Bureau of Reclamation provided the funding and support for this project. Research was performed under the supervision of N. E. Otto, Head, Environmental Sciences Section, and L. 0. Timblin, Jr., Chief, Applied Sciences Branch.
This report is based on a study requested by the Bureau of Reclamation's
Lower Missouri Region as part of their Seminoe Dam Modification Studies.
The Physical Sciences and Chemical Engineering Section performed the chemical analyses under the supervision of T. E. Backstrom. Final edit- ing and preparation of the manuscript for publication was performed by
W. F. Arris of the Technical Services and Publications Branch.
The information in this report regard- ing commercial products or firms may not be used for advertising or promo- tional purposes, and is not to be con- strued as an endorsement of any product or firm by the Bureau of Reclamation. CONTENTS
Page
Abbreviations ...... vi
Introduction ...... 1
Application ...... 5
Summary ...... 6
Recommendations ...... 8
Methods and materials ...... 9
Physical-chemical factors ...... 12
Chlorophyll analysis for productivity ...... 12
Benthic analysis ...... 13
Zooplankton ...... 13
Results ...... 14
Physical-chemical factors ...... 14
Water chemistry ...... 21
Heavy metals ...... 26
P-N nutrients ...... 26
Light penetration and chlorophyll concentrations ...... 28
Benthic fauna ...... 33 1 I CONTENTS - Continued I Page I Zooplankton 38 I Bibliography 43 I I I I I I I 1 I I I 1 11 I TABLES
Table Page
1 Chemical analyses of water collected from
Seminoe Reservoir and its inflows ...... 22
2 Secchi disk readings, light extinction coeffic-
ients, and Zed (1 percent light euphotic
depths) ...... 29
3 Comparison of light extinction coefficients ...... 30
4 Chlorophyll a concentrations ...... 31
5 Results of benthic studies ...... 35
6 Comparison, in order of abundance, of benthic
fauna, excluding mollusks ...... 36
7 Concentration of zooplankton ...... 39
8 Relationship between cladoceran and copepod
abundance ...... 40
:III FIGURES
Figure Page
1 Area-capacity data, Seminoe Reservoir ...... 3
2 Map of Seminoe Reservoir, Wyoming, with 1976
sampling stations ...... 10
3 Seminoe Reservoir, Wyoming
a. In the Red Hills area, facing southeast ...... 11
b. In the Medicine Bow arm area, facing
north ...... 11
4 Temperature and dissolved oxygen, profiles ...... 15
5 Conductivity and hydrogen-ion concentration
(pH) profiles ...... 16
6 Oxidation-reduction potential, profiles ...... 17
7 Histogram of data on TDS (total dissolved
solids), Ca (calcium), and SO4 (sulfate)
concentrations at the sampling stations ...... 23
8 Profiles of calcium, magnesium, and sodium
concentrations ...... 24
9 Profiles of bicarbonate, sulfate, and chloride
concentrations ...... 25
10 Profiles of iron, manganese, and zinc
concentrations ...... 27
IV I
I FIGURES - Continued I Page I 11 Profiles of chlorophyll a concentrations ...... 32
I 12 Histogram of abundance and biomass of the I benthic fauna ...... 37 13 Relative abundance of zooplankton ...... 42 I I I I I I I I I 1 I I V ABBREVIATIONS
Eh oxidation reduction (redox) potential ha hectare rn metre mg/individual (unit weight) milligram per individual mg/litre (concentration) milligram per litre mg/m2 (wet and dry
weight) milligram per square metre mg/m3 (concentration) milligram per cubic metre mm millimetre mV millivolt n/litre (concentration) number per litre (x 1000 = n/m 3) n/m (light extinc-
tion coeff.) number per metre n/m2 (abundance) number per square metre n/m 3 (concentration) number per litre 1000 = n/litre) pH hydrogen-ion concentration
percent
TDS total dissolved solids pmho/cm (conductivity) micromho per centimetre pS/cm (conductivity) microsiemen per centimetre
(pmho/cm = pS/cm)
Z euphotic depth (1 % light level) ed
VI ABBREVIATIONS - Continued
-2 CO 3 carbonate
HCO3-1 bicarbonate
ortho-phosphate
NH 3-N ammonia nitrogen
NO3-N nitrate-nitrogen
VII
INTRODUCTION
Seminoe Reservoir is a mainstream North Platte River reservoir located in Carbon County (south central) Wyoming. It was formed by Seminoe
Dam which was built in 1939 by the Bureau of Reclamation and is the uppermost of six major storage facilities on the North Platte River.
Figure 1 shows area-capacity data for Seminoe Reservoir. The reser- voir has a capacity of 1 246 800 000 m3 (1 011 000 acre-ft), at water surface elevation 1938 m (6357 ft). The average annual volume is between 555 000 000 and 617 000 000 m3 (450 000 and 500 000 acre- ft), with a surface of about 4050 ha (10 000 acres).
Seminoe is one of the major fisheries of Wyoming (Wesche and Skinner
[311 1), and accounts for 1.4 percent of the total annual fishing for the state. Game fishes in Seminoe include, in order of abundance [31]:
walleye (Stizostedion vitreum vitreum Mitchell),
brown trout (Salmi trutta Linnaeus),
rainbow trout (Salm° gairdneri Richardson), and
brook trout (Salvelinus fOntinalis Mitchell).
1 Numbers in brackets refer to literature cited in the bibliography.
(hec
AREA CAPACITY CAPACITY CUBIC I ACRES METRES ACRE FEET acres xI03 acre-ft 1 0 0 0 19 e 0 0 0 1 5 4 19 44 328 266 84 658 533 19 : 123 1 309 1,06!
19 : 130 1 388 1,125 254 3 634 2,946 19 472 8113 6,577 664 I 5 1 20 12,258 1 ) 1,009 25 441 20,625 19 1,445 39 066 31 ,671 1,494 40 878 33,140 19
ELEVATION— metres - 2,199 63 1 60 51,204 2,848 93 794 76,039 19 : 3,833 I 34 999 109,444
18 E 4,953 1 89 188 153,375 6,133 257 563 208,807 18 7,513 341 728 277,039 8,519 410 944 333,153 18 8,951 443 268 359,358 18 10,714 564 551 457,682 12,808 709 625 575,294 3 (acre-ft X10 15,265 882 768 715,661 18,150 I 088 856 882,737 6 3 017,297 ( m x10 20,291 I 254 835 1 1 21,233 I 331 643 1,079,565 261 1,189,511 UNITED STATES * 22,745 I 467 DEPARTMENT OF THE I NTERIOR Star LM REGION 24,259 I 1,307,020 &UREIC/ OF RECLAMATION atim 612 209 KENDRICK PROJECT - WYO. NOTE- The 24,941 I 672 897 1,356,220 AREA CAPACITY DATA Floo 26,275 I 767 065 1,432,562 SEMINOE RESERVOIR com INCLUDING SI METRIC 27,563 I 932 095 1,566,352 EQUIVALENTS (ORIGINAL DATA elevo FROM DWG. NO. 144 -700-103) 1 are I phote orfrivER,COLO 77 144 - 700 -10 to co, Figure 1. - Area-capacity data, Seminoe Reservoir.
Nongame species include:
white sucker (Catostomus commersoni Lacepede),
longnose sucker (Catostomus catostomus Forster),
carp (Cyprinus carpio Linnaeus),
creek chub (Semotilus atromaculatus Mitchell),
fathead minnow (Pimephales promelas Rafinesque),
northern plains minnow (Hybognathus placitus Girard),
bigmouth shiner (Notropis dorsalis Agassiz),
longnose dace (Rhinichthys cataractae Valenciennes), and
Iowa darter (Ftheostoma exile Girard).
APPLICATION
This report will be used by the Bureau's Lower Missouri Region planners who requested this reconnaissance as a part of their Seminoe Dam modi- fication study. This baseline information will also be critical to the environmental impact assessment of the North Platte hydroelectric study, and any future projects in the North Platte River basin. In addition, these data will be helpful in the development and management of the fishery of Seminoe Reservoir, and will be of interest to anyone involved in limnological studies. This study is also an example of a baseline limnological survey that could be easily adapted to reservoirs throughout the Bureau's area of operation.
5 1
SUMMARY
Data collected during this study will be used to assess the environ- mental impacts of proposed modifications of Seminoe Reservoir. The 1 reservoir becomes only weakly stratified at any station and is influ- enced very heavily by the North Platte and Medicine Bow Rivers. Based on observed data of residents in the area, data collected by Wesche 1 and Skinner [31], and some fragmentary records from USGS (U.S. Geo- logical Survey), reservoir turnover occurs twice a year, during April or May and again during October or November. Wind action probably has a great influence on conditions within the reservoir. An anaerobic con- dition probably is approached, but never quite reached within the water 1 column at any one location. This is due to (1) the lack of strong stratification for any period of time, (2) ambient air temperature,
(3) strong winds, and (4) influence of the North Platte and Medicine
Bow Rivers. These four factors are all interrelated.
According to Pennak [21], Seminoe Reservoir is a nonalkaline body of water2. Values of pH are probably always above 7.0 and generally during the summer they are above 8.0. Calcium is the major cation and bicarbonate and sulfate are the major anions. Station 3 (Medicine
Bow Arm) contains the highest concentration of major cations and anions,
2 Pennak [21] considers nonalkali lakes in the Rocky Mountain area as those having total residues of less than 500 mg/litre, and alkali lakes as those having residues in excess of this figure.
6 indicating the Medicine Bow River as being the probable major contrib- utor. This conclusion is further substantiated by data presented from a water sample collected from the Medicine Bow River. There is indi- cation of the presence of some heavy metals (copper, manganese, iron, and zinc), especially at lower depths. However, they probably are not biologically important since redox potentials, D.O. (dissolved oxygen), and pH values were too high for metals to be available in a dissolved form. Nevertheless, this is an area where the limnology of the lake should be studied to learn the source and extent of these metals.
Data on light penetration and chlorophyll concentrations indicate Sem- inoe Reservoir to be basically a mesotrophic body of water of moderate productivity. The presence of the blue-green algae, Aphanizomenon, in somewhat large quantities at this time of the year indicates this moderate productivity, and also the availability of sufficient nutri- ents to result in this productivity. The Medicine Bow arm is espe- cially productive and, to a slightly lesser extent, so is the North
Platte arm, indicating that the nutrient load of Seminoe Reservoir is mainly from the Medicine Bow and North Platte Rivers.
The benthic fauna of Seminoe Reservoir is similar to other mesotrophic bodies of water, being of moderate abundance and consisting of the larvae of nonbiting midges (chironomids) and aquatic earthworms
(oligochaetes). The least abundant benthic fauna was found in the two
7 1 riverine arms, while the greatest abundance was found near the dam in the deepest portion of the reservoir. This situation may reflect the more lotic conditions that are found in the two arms. 1 The zooplankton fauna is also similar to that of other mesotrophic lakes. It is chiefly made up of two groups of crustaceans, cladoc- erans and copepods. Copepods are the most abundant group of zooplank- ton, especially below the 10-m depth. Zooplankton were least abundant nearest the dam where phytoplankton abundance was also lowest, and high- est in the two arms where phytoplankton abundance was highest. This relationship reflects the input of nutrients from the two rivers; con- sequently, one would expect the fish population within the two arms to also be larger than that of the main body of the reservoir. However, fish population data were not available to check this possibility.
Seminoe Reservoir is, therefore, a dimictic, mesotrophic, riverine, high-plains reservoir of moderate primary and secondary productivity.
RECOMMENDATIONS
The following recommendations should be considered for inclusion in the continuing Seminoe Dam modification feasibility study, as well as other feasibility grade studies for the North Platte River Basin.
8 1. Future studies should include investigations into the cause
and extent of trace element accumulations within the reservoir.
2. A somewhat detailed investigation of the distribution of
fishes, especially in relation to the apparent abundance of nutri-
ent and food supply within the North Platte and Medicine Bow arms,
is needed.
3. Investigations of sources of nutrient loading should be under-
taken to determine the extent of internal (autochthonous) and
external (allochthonous) sources.
4. Reservoir preenlargement studies should describe the impacts
of the development on the stratification patterns as well as the
extent of impoundment of further enrichment sources.
METHODS AND MATERIALS
Field work for this project was performed during August 31 through
September 3, 1976. Figure 2 is a map of Seminoe Reservoir with the five sampling stations designated. Figure 3 is comprised of two photo- graphs of the area. Station 1 is near Seminoe Dam and station 2 is well up into the North Platte arm. Data were collected on August 31 at
9 SEMINOE DAM
RED IF HILLS SAYLOR CREEK BAY
SAYLOR
BOAT CLUB TIN A CREEK
COALGREE BAY MEDICINE BOW
MEDICINE BOW RIVER ARM
NORTH PLATTE ARM SEMINOE RESERVOIR
0 1976 Sampling Station Numbers 00.
Figure 2. - Map of Seminoe Reservoir, Wyoming, with 1976 sampling stations.
station 1 in the morning and at station 2 in the afternoon. Station 3
is about midway into the Medicine Bow arm near Austin Creek Bay and sta-
tion 4 is in the basin containing the confluence of the North Platte and
Medicine Bow arms. Data were collected on September 1 at station 4 in the morning and at station 3 in the afternoon. Station 5, located just outside Saylor Creek Bay toward the dam, was surveyed the morning of September 2. At each station data were collected in the same manner.
10 "r.--
a. - In the Red Hills area, facing southeast. Photo P634-D-77754
b. - In the Medicine Bow arm area, facing north. Photo P634-D-77755
Figure 3. - Seminoe Reservoir, Wyoming.
11 Physical-Chemical Factors
Temperature, dissolved oxygen, conductivity, hydrogen-ion concentra- tion, and oxidation-reduction potential data were collected with a
Hydrolab Corporation Surveyor' multiparameter probe. Surface and bottom samples of the water were collected with a standard Van Dorn water sampler. Samples for the metal analysis were preserved immediately after collection with 1 ml of nitric acid per pint. Samples for nutri- ent analysis were frozen immediately after their collection. All water samples were analyzed according to APHA (American Public Health Asso-
ciation) [1] procedures. Light penetration was measured using both a standard Secchi disk and a limnophotometer. Details of this instrument and a description on use of the limnophotometer are described by Otto and Enger [19] and Otto [18]. Light extinction coefficients were cal- culated from these data.
Chlorophyll Analysis for Productivity
Samples for chlorophyll analysis were collected from a range of depths
from each of the first four stations. Following their collection,
800-ml samples were filtered through millipore glass filter pads. Chlo- rophyll extraction and analyses were determined colorometrically by
methods outlined by Parsons and Strickland [20].
12 Benthic Analysis
Three samples of benthic muds were collected from each statibn using a Petersen dredge. These samples were each filtered through a U.S.
Standard Series No. 30 sieve size (openings = 0.589 mm) and then pre- served in a 10-percent formalin solution for laboratory analysis. All specimens were identified according to type, counted, and weighed
Both wet and dry weights were obtained following methods found in
API-IA [1].
Zooplankton
Zooplankton were collected by towing a metered Clarke-Bumpus plankton sampler having a No. 10 (mesh openings = 0.158 mm) silk net and bucket.
Tows were made in a zigzag fashion from surface to 10 m, 10 to 20 m below the surface, and from 20 m to the bottom (as limited by the depth at the station being sampled). Samples were preserved with a 2-percent formalin solution for laboratory analysis. Replicate subsamples from each collection were counted, using a Sedgwick-Rafter counting cell, and identified to genus. Total counts were found to be adequate for the scope of this study.
13 I I RESULTS I Physical-Chemical Factors I Figures 4 through 6 are profiles of: °C (temperature), D.O. (dissolved I oxygen), pH (hydrogen-ion concentration), pS/cm (conductivity), and Eh (oxidation-reduction potential) from each of the five stations surveyed. I
The temperature profiles plotted in figure 4 indicate the near-maximum 1 of Seminoe Reservoir stratification. Data collected in early September
1955 and reported by Peterson and Leik [22] are similar to those I reported here. Seminoe Reservoir was found to be weakly stratified, as I might be expected of a riverine reservoir at this elevation. Neverthe- less, a thermocline (metalimnion) is somewhat apparent from about 15 to I 25 m below the surface at all stations. There is very little difference in the temperature at any given depth from one station to another. The I temperature differences between stations at the surface and 1-m depths I reflect changes in the ambient temperature from morning to afternoon and from day to day. 1 I I I I 14 I =II MN 11111 MI MI MI MN MO MI IIIII
•ra STA. I 0— —0 •• STA. 2 •------• STA. 2 M— --- 0 STA. ------STA. 3 — 0 3 0-- -0 ft ST A. STA 4 • 4 • • 14 — STA. 5 A--— — —6 STA. 5 6— — — — —6 . L t 4 šI 1 0 • 1 0 • • 1 /
/I ;// / / . . _ -- • 0-- • ../
20 20 • • /' 'I / i
30 30 l I i I/ i :IT /1 I I ' / I1 40 40 4/ I i
f I i / i 1 , i
50 50 i 10 2 14 1 6 1 5 20 2 3 4 5 6 7 TEMPERATURE %) DISSOLVED OXYGEN (mg/litre)
Figure 4. - Temperature and dissolved oxygen, profiles. 0 I STA I la- 1 1 1 'I. f STA 2 , -- , STA 3 0 ------0 —STA . 4 •—• STA .5 6— — — — —6 , . ,,, i 10 1 0 . , ciR, , \ — STA. I 0— —0 ' b STA. 2 —• STA. 3 0------0 STA. 4 4,--. STA. 5 6-- ---6 20 20 •
X •
30 30 1: 11
40 40
I
I C
Cill s
50 50 70 80 90 250 300 350 400 450 500 HYDROGEN - I ON CONCENTRATION ( pH) CONDUCTIVITY ( ES/cm)
Figure 5. - Conductivity and hydrogen-ion concentration (pH) profiles.
I= MI I= I= IIIMI II•11 MI NM IMO In I= I= • O STA. 1 0- --0 ; STA. 2 11---- STA. 3 0------0 STA. 4 0-0 S TA 5 6-- - -6 1
10 1
20
1
30
4 i1 40
I 1IF I
50 100 200 300 400 1 600 700 REDOX POTENTIAL, Eh ( my)
Figure 6. - Oxidation-reduction potential, profiles.
17 Based on results of this survey and other information on the area
reported by Peterson-Leik [22] and Wesche-Skinner [31], Seminoe
Reservoir is a dimictic3 lake of the second order4.
The D.O. profiles (fig. 4) also indicate stratification. Surface values
are at or near saturation while in the hypolimnion; at stations 3 and
4, stagnation resulted in values of 3.6 and 1.9 mg/litre, respectively.
These values, especially at station 4, are too low for maintenance of
many cold-water game species such as rainbow trout. Seminoe Reservoir
was observed to be a very productive body of water. This was apparent
from the abundance of a species of Aphanizomenon, a blue-green algae.
This algae resulted in the reservoir having an appearance as though
grass clippings had been thrown into the water. The presence of this
species of algae (that is, its decomposition) is one reason for the
oxygen depletion of the hypolimnion. In addition, relatively wide fluc-
tuations in the D.O. values at and near the surface probably occur
because of the photosynthesis of algae. The profiles (fig. 4) probably
represent the typical situation in late summer as stratification reaches
its peak.
3 Dimictic - a lake that turns over twice a year (Seminoe cycle: one in the spring following ice breakup and one in the fall, following summer stratification.) 4 Second order - a dimictic lake where marked thermo stratification occurs. The bottom water is somewhat or greatly above 4°C in summer, and there are one or two full circulating periods per year [34].
18 The pH profiles (fig. 5) show expected values for this type reservoir.
Values are highest at the surface nearest the inflows and lowest at the bottom nearer the outflow. The high values in the two arms may reflect elevated productivity rates. The profiles, like those of D.O., reflect the temperature stratification. The higher values in the epilimnion near the surface are the result of the photosynthetic activity of algae which is most abundant in this area. Values of pH recorded during this survey ranged from 7.6 to 8.6, thus in the alkaline range. Since all measurements were made during daylight hours, they are higher at and near the surface than they would be at night when the aquatic plant life is respiring.
Profiles of conductivity values are shown in figure 5. The average conductivity value for Seminoe Reservoir at the time of this survey was about 420 pS/cm (420 pmho/cm). There was little difference between values in the epilimnion and hypolimnion. The drastic rise in conduc- tivity at the bottom of station 4 was recorded after stirring the bot- tom sediments with the probe. Values at station 1 (North Platte arm) were significantly lower than those from the other four sampling loca- tions and do not reflect the value obtained from the water sample col- lected from the North Platte River. These relatively low values may be due to: (1) improper functioning or use of equipment, or (2) a freshwater surface or ground water inflow at the point that was being sampled. Most likely the readings were not accurate due to an air
19 bubble being trapped in the conductivity probe. Generally, the conduc- tivity values for Seminoe were found to be relatively high, reflecting the high productivity from the inflows.
Figure 6 presents profiles of the oxidation-reduction or Eh (redox potential) of Seminoe Reservoir. The Eh is proportional to the equiv- alent free energy change per mole of electrons associated with a given reduction, Wetzel [32]. The addition or removal of oxygen, changes in the content of hydrogen atoms (hydrogenation = reduction; oxygenation = oxidation), and gain or loss of electrons, are oxidation-reduction processes, Ruttner [27]. The values recorded at Seminoe Reservoir are all relatively high, or in the general category of "oxidation state."
An Eh of 200 mV is often considered the threshold of a strong "reduc- tion state," Mortimer [15]. Under strongly reducing conditions, heavy metals ionize and may become biologically important, either as toxi- cants or through their effect on nutrient cycles. Various metals ion- ize at different Eh, manganese and then iron being the first to dissolve.
A strong reducing state is initiated in the hypolimnion under condi- tions of complete oxygen depletion and low pH. These conditions are probably only approached in the hypolimnion of Seminoe Reservoir.
Reducing conditions generally exist within the bottom sediments of lakes; however, it was probably stirring these sediments with the probe that caused the 100 mV reading on the bottom at station 4.
20 Water Chemistry
The results are shown of chemical analysis of water (table 1) from all the Seminoe Reservoir sampling stations plus the inflows of the North
Platte and Medicine Bow Rivers. Figure 7 is a graphic display of TDS
(total dissolved solids), Ca (calcium), and SO4 (sulfate), in mg/litre.
Calcium and sulfate were chosen because they are the most abundant cation and anion, respectively. Data in this figure indicate the dif- ference in input between the North Platte and Medicine Bow Rivers. The
TDS, Ca, and SO4 at station 3 reflect amounts found in the North Platte
River, while the values from station 2 reflect those from the Medicine
Bow River. As with all major cations and anions, the levels found in the Medicine Bow River are highest. Values obtained from stations closer to the dam (downstream) result from mixing both inflows. The levels found at the bottom of the Medicine Bow arm seem to reflect those obtained from the Mecidine Bow River, which would indicate that the cooler river water flows to the bottom during the warm summer months. This would tend to recharge D.O. within the hypolimnion of this part of the reservoir. However, figure 4 indicates some oxygen depletion at station 2. This stagnation is further illustrated by a buildup of TDS near the bottom.
Profiles of the major cations and anions at each station are shown in figures 8 and 9, respectively. A buildup of ions near the bottom is indicated in almost every case, probably as a result of stratification.
21 Table 1. - Chemical analyses of water collected from Seminoe Reservoir and its inflows
Station 1 1 2 2 3 3 4 4 5 5 North Medicine Depth Surface 50 m Surface 9 m Surface 18 m Surface 35 m Surface 45 m Platte Bow River River
Conductivity 452 467 422 415 496 549 442 442 452 460 415 571 TDS 312 334 274 278 352 416 306 322 322 354 272 414 Ca 47.4 47.2 43.0 42.6 48.8 53.2 45.8 44.6 46.8 46.2 44.0 58.2 Mg 12.7 14.4 12.2 12.9 15.1 17.8 12.7 13.7 12.8 14.4 11.1 23.7 Na 26.0 26.5 22.3 22.8 29.9 34.7 25.8 25.1 25.1 26.5 22.8 23.2 2.35 2.35 2.35 2.35 2.35 2.74 2.35 2.35 2.35 2.35 2.74 1.56 -2 INJ CO3 0 0 0 0 0 0 0 0 0 0 0 0 -1 HCO3 130 134 131 127 132 135 127 124 127 134 143 110 SO4 109.0 115.0 90.2 90.2 126.0 151.0 105.0 105.0 108.0 109.0 80.2 197.0 Cl 4.26 11.40 7.81 7.81 9.23 8.52 7.81 8.52 9.23 9.94 9.90 3.55 Cu .004 <.002 <.009 <.002 <.002 <.002 <.002 <.002 <.002 <.002 _ Pb <.002 <.002 <.002 <.002 <.002 <.002 <.002 <.002 <.002 <.002 Mn .006 .028 <.005 .010 <.005 .040 <.005 .060 <.005 .016 Fe .030 .250 .030 .050 .050 .700 .030 .370 <.010 .250 Zn .042 .010 .004 .008 .005 .005 .006 .005 .004 .003 PO -P <.025 <.025 <.025 <.025 <.025 <.025 <.025 <.025 <.025 <.025 4 NH 3-N <.025 <.025 <.025 <.025 <.025 <.025 <.025 <.025 <.025 <.025 - NO3-N <.40 <.40 <.40 <.40 <.40 <.40 <.40 <.40 <.40 <.40 - -
Note: All values in mg/litre except conductivity, which is in pS/cm.
MN • SIMI • • ION MI • MO • • IN • NIB Nil MI • NMI 1111111 • NM NMI OM IIIIII IIIIII IMO • • MIIII MI MI
NORTH MEDICINE BOW RIVER PLATTE 60 RIVER DOWNSTREAM
Nv.v■ 40
Ca (mg/ I ltre
20
200 A \ A■ A 4 5 STATION 400 NORTH MEDICINE BOW RIVER PLATTE RIVER
300 150
DOWNSTREAM_
SO4 TDS 200 1 00 ( mg/Htre) (mg/litre)
100 50
3 4 5 1 STATION
Figure 7. - Histogram of data on TDS (total dissolved solids), Ca (calcium), and SO4 (sulfate) concentrations at the sampling stations. — • IV VT • 1 . I .1 • \ \ b 20
$TA. I 0-- —0 STA. 2 8— —• STA 3 0— ••••0 30 STA 4 0---4, — STA. 5 6-- — —6,
41 4- NORTH PLATTE RIVER *MEDICINE BOW RIVER • 0
50 40 45 50 55 60 CALCIUM(mg/Mre)
4 • 1 C • I, . • • 1 • . I1 • I S . \ . I 1) It 20 STA I 0— —0 STA \I 2 STA . 3 0— ------0 I I , STA 4 *---• STA. 5 6— -- —6 30 + NORTH PLATTE RIVER II *MEDICINE BOW RIVER I 40 I I
50, 14 16 121 20 22 24 26 MAGNESIUM ( mg/IIIre) 1 1-t 'a 1 TI:.-1 • .. • N. .... •.. 1 0 1 \ .5 ••• \ 5. 1 \ ...0 20 STA I 0— —0 STA 2 STA 3 0------0 I $TA. 4 40---4 STA 5 6-- — — —6 ° 30
4 NORTH PLATTE RIVER *MEDICINE BOW RIVER 40 1 50 22 24 26 26 30 32 36 SODIUM ( mg/litre)
Figure 8. - Profiles of calcium, magnesium, and sodium concentrations.
24 'I 1 0 % % \ t 10 \ \ \ % \ \ 20 \ t
\\ STA . I \ I STA 2 30 — STA 3 o------0 \ STA 4 49--• $TA 5 Of-- — --6
1 • 0
* NORTH PLATTE RIVER
* MEDICINE BOW RIVER
50 I I 1 20 1 25 1 30 1 35 1 40 145 BICARBONATE (m9/ litre)
s, * 80 1 X 1 10 I X X I X 13 20 I
I
‘Ij 30 I \ STA I 1:7 . —0 _ STA 2 I , 4 II---w I \, STA STA 5 6-- — --6 — I , + NORTH PLATTE RIVER 1 \I * MEDICINE BOW RIVER
50 I I I 1 110 120 130 1 40 1 50 160 SULFATE ( mg/litre)
0 - VR \ -11" • 1 1 1 I 1 STA I ID— —13 i 1 I STA 2 el— —M_ \ STA 30- -0 X I I STA 4 2a--• STA 5 A-- --- —.5, i \ 20 + NORTH PLATTE RIVER • *MEDICINE BOW RIVER
\ 30 1 N 40
9 1 3 CHLORIDE (mg/ I ltre
Figure 9. - Profiles of bicarbonate, sulfate, and chloride concentrations.
25 Heavy Metals
Table 1 indicates the presence of at least some heavy metals. Heavy metals are defined in this report as any element heavier than manganese.
In this study they include Cu (copper), Pb (lead), Mn (manganese), Fe
(iron), and Zn (zinc). The presence of detectable amounts of these metals indicates conditions that could be detrimental to aquatic life.
However, only under certain conditions (for example, pH below 7.0,
D.O. near or at 0, Eh below 200 mV) will the presence of these metals become biologically important. Data in figure 10 indicate accumulation of heavy metals near the bottom of Seminoe Reservoir, especially at stations 1 and 4 (those nearest the dam). Samples for heavy metals analysis were collected and preserved without filtering; therefore, unknown amounts of the metals detected could be in the particulate form and thus biologically insignificant. This one aspect of the res- ervoir limnology needs further study. If a portion of the amounts detected are in the dissolved form (biologically important), some parts of the hypolimnion could be toxic to some forms of aquatic life.
P-N Nutrients
Table 1 presents the values for the amounts of ortho-phosphate, ammonia nitrogen, and nitrate nitrogen. In almost every case analyses showed values to be at or below detectable limits, indicating that at the time
26 0 ---.. ... \‘ \ ■ ......
10 \'
\\
20 TA I 0--—0 \ TA 2 IO- TA. 3 0, —0 STA 4 STA. 0---4
X\ 40 \\
\I 50 0010 01 02 03 04 05 06 07 IRON (NO/II re)
..„...... '• ... \ N...... , \ 10 ■ , \ ■ ■ _ - \ \ ..s. , s 20 \ , O \ \
\ \
\ \ 30 , STA. I 0— \ STA 2 MI- \ STA 3 0- - - --0 \ STA 4 0.----4. 40 \ ‘ STA. 5 \ \X
500005 001 002 0.03 004 005 0.015 MANGANESE (rng/Iltre)
. I )11 10 / t STA i 0— --0 STA _AL 1 6 2 20 STA 3 0- -0 I STA 4 111----11 I STA 5 .5— ------—6 I I 11 40 1 1 f / I
/ 0.01 002 003 004 Goo ZINC (rng/li re)
Figure 10. - Profiles of iron, manganese, and zinc concentrations.
27 of this survey there were very low amounts of available P-N (phosphate- nitrogen) nutrients. One of two possibilities exists: (1) only minor amounts of nutrients are ever available and thus the values obtained during this survey are typical, or (2) nearly all these nutrients were
tied up inorganically or in plant material at the time of this survey.
The second possibility seems more reasonable as indicated by the obvious
abundance of Aphanizomenon, Dugan [9]. If sampling were done during
winter or spring, perhaps nutrients would be found in much more abun- dance. The data presented here could mean that the amount of aquatic
biomass found to be present during this survey was at or near the max-
imum possible, based on nutrient availability; however, this area needs
considerably more study.
Light Penetration and Chlorophyll Concentrations
Table 2 includes Secchi disk readings, light extinction coefficients,
and 1-percent light euphotic depths. The latter two are results of
limnophotometer readings. There is a direct correlation among all
three of these. Light penetration was greatest near the dam and low-
est in the Medicine Bow arm.
28 Table 2. - Secchi disk readings, light extinction coefficients, and Zed (1 percent light euphotic depths)
Station Location Secchi depth, Light extinction Zed, Time, No. m coefficient, n in hours m-1
1 near dam 5.0 0.55 8.37 1030 2 North Platte arm 2.0 1.04 4.43 1530 3 Medicine Bow arm 1.4 1.60 2.88 1330 4 confluence bay 2.6 0.76 6.06 0900 5 large bay near dam 3.6 0.69 6.67 1015
Table 3 compares light extinction coefficient values obtained during
this survey on Seminoe Reservoir with those from the literature cited
in the table. The higher the value the lower the light penetration.
The two arms of Seminoe Reservoir are toward the productive end, while the main reservoir stations are toward the less productive end. There
is a direct relationship between phytoplankton density and light pene- tration. This relationship can be seen in table 4 which contains the chlorophyll a concentration values in mg/m 3 at selected depths from stations 1, 2, 3, and 4, and contains light extinction coefficients.
Chlorophyll a concentration is a measure of the phytoplankton biomass or standing crop. Figure 11 is a graph of these chlorophyll a concen- trations. As reported in the previous section, based on nutrient avail- ability, these values for chlorophyll a may be maximum for this reser- voir. At all four sampling stations, the concentration of chlorophyll a drops significantly at the thermocline. This can be due to a reduc- tion in light availability and lower temperatures. According to the
29 Table 3. - Comparison of light extinction coefficients
Location Coefficient n Reference m-1 No.
Little Triste, Ariz. 12.9 1 Itasca, Minn. 4.3 1 Little Star, Wis. 3.9 2 Saguaro, Ariz. 3.3 1 Montezuma Well, Ariz. 2.3 1 SEMINOE RESERVOIR, WYO. MEDICINE BOW ARM ...... 1.60 Seneca, NY 1.6 1 Trout, Wis. 1.7 3 SEMINOE RESERVOIR, WYO. NORTH PLATTE ARM ...... 1.04 Trout, Wis. 0.375 2 Little John, Wis. 0.994 2 Mud, Wis. 0.944 2 Mendota, Wis. 0.88 3 Long, Minn. 0.83 1 Ruth, Wis. 0.81 2 SEMINOE RESERVOIR, WYO. CONFLUENCE BAY ...... 0.76 Allequash, Wis. 0.714 2 LARGE BAY NEAR DAM ...... 0.69 1 Upper Twin, Colo. 0.63 4 SEMINOE RESERVOIR, WYO. NEAR DAM ...... 0.55 Crystal, Wis. 1.2 1 Crystal, Wis. 0.27 3 Crystal, Wis. 0.192 2 1 Lower Twin, Colo. 0.47 + Muskellunge, Wis. 0.30 2 Tahoe, Calif.-Nev. 0.28 1
1 Adapted from Cole, [5] 2 Whitney, [33] 3 Ryan and Harleman, [28] 4 Sartoris, LaBounty, and Newkirk, [29]
30 Table 4. - Chlorophyll "a" concentrations
Station Location Depth, Chlorophyll a, Light extinction 3 mg/m coefficients- (n), m I
1 near dam 0 1.79 0.55 1 1.51 2 1.78 5 0.89 10 0.49 15 0.23 20 0.00 50 0.08
2 North 0 4.79 1.04 Platte 1 4.15 arm 5 1.60 9 0.87
3 Medicine 0 5.02 1.60 Bow arm 1 8.91 5 5.23 10 3.44
4 confluence 0 3.99 0.76 1 3.63 5 4.71 10 4.35 15 0.64 20 0.00 35 0.00
31 ,...,.. _.,...... Eru ---...0 )3 ...... -- • ......
{ 1 T ,K , ,/- 1 0 ..- # — 11 # STA. I 0— -0 i # # STA. 2 • --U # STA. 3 0- -0 STA. 4 0—* —
20
I I 1
30 L
I •
40
1 1 50 1 2 4 6 10 CHLOROPHYI I A ( mg/m 3 ) 1 Figure 11. - Profiles of chlorophyll a concentrations.
32 classification of lakes based on trophic status suggested by Leith and
Whittaker [13], the values for chlorophyll a and light extinction coefficient mean that Seminoe Reservoir is a mesotrophic body of water; that is, it is intermediate in amount of productivity when compared to other bodies of water in the world. This is especially significant when one considers that Seminoe is a high-plains reservoir in a rela- tively cool-weather environment. Any rise in average water temperature of the reservoir or any part of the reservoir and/or an addition of nutrients could lead to an increase in its productivity.
Benthic Fauna
Two types of benthic animals were found, chironomids and oligochaetes.
Chironomids, or the nonbiting midges (Family, Chironomidae - Tendipedae), are representatives of the order of flies, Diptera, and are best known as the predominant insect of lake sediments, Mundie [16]. They are sometimes present in great numbers and may be detritus, animal, or plant feeders, taking part in the exchange of substances within the sediments and between them and the outside water. Chironomids, as a larvae, are red and about 10 to 12 mm at maximum length. They are important to the food chain within lakes, providing food for suckers in particular, which in turn are forage for walleye in the case of Sem- inoe Reservoir. Oligochaetes (Family, Oligochaeta) are aquatic earth- worms that, like chironomids, burrow in the bottom sediments and take
33 part in the exchange of substances within the sediments, and between them and the outside water. In addition, they play a similar role to chironomids in the food chain of lakes.
Table 5 presents the results of benthic collections from Seminoe Res- ervoir. Information from this table is of limited value since benthic fauna exhibit cyclical patterns; it is not known if, during the sampling period, the maximum, minimum, or average abundance and biomass of the population were sampled. In addition, many more locations within the reservoir should be sampled before certain conclusions can be made.
Nevertheless, some generalizations can be made based on the samples collected. Table 6 shows the rank from the least to the most abundance of benthic fauna for locations found in the literature. According to this table, the faunas in the two arms of Seminoe Reservoir are some- what sparse, while those in the main body of the reservoir have inter- mediate abundancy. Figure 12 presents abundance and biomass (both wet and dry) graphically. The difference among the benthic faunas collected on this date shows that the richest fauna is nearest the dam, while the sparsest is in the riverine arms. Biomass data also show this trend.
Data on the average weight per individual indicates close similarity between locations. Some authors have attempted to correlate a certain abundance with oligotrophy, mesotrophy, and eutrophy. Generally, oligotrophic lakes have fewer larvae represented in their benthic faunas than do eutrophic lakes, Brinkhurst [3]. Northcote and Larkin [17] considered benthic faunas sparse (oligotrophic) when the number of
34 organisms averaged 189/m2 or less, and abundant (eutrophic) when over
473/m2. Based on this classification the two riverine arms contain
somewhat sparse faunas, while two of the three locations sampled within
the reservoir contained relatively abundant faunas. The third location
fell into the midrange. The average abundance for the five locations
sampled is 406 plus or minus 352/m2. The average falls between the
sparse and abundant categories according to Northcote and Larkin's
classification. Therefore, based on these sparse data, Seminoe Res-
ervoir is tentatively classified as mesotrophic or intermediate in
benthic biomass compared to other lakes in the world.
Table S. - RESULTS of BENTHIC STUDIES
Station Abundance, Wet Dry Unit wet Unit dry No. number/m2 weight, weight, weight, weight, mg/m2 mg/m2 mg/individual mg/individual
1 961 2.0801 0.3192 0.002 16 0.000 33
2 129 0.2473 0.0376 0.001 96 0.000 29
3 129 0.3441 0.0538 0.002 67 0.000 42
4 537 1.7473 0.2204 0.003 25 0.000 41
5 274 0.7366 0.0968 0.002 69 0.000 35
35 Table 6. - Comparison, in order of abundance, of benthic fauna, excluding mollusks
Location Abundance, Reference number/m2
Twin Lakes (upper), Colo. 0-200 LaBounty, et al., [29] SEMINOE RESERVOIR, WYO. (North Platte & Medicine Bow Arms) ...... 129 Lake Shaswap, Canada 214 Ricker, [24] SEMINOE RESERVOIR, WYO. (Large bay near dam) .... 274 Apache Lake, Ariz. 144-488 Rinne, [25] Lake Okanagan, Canada 364 Rawson, [23] Lake Okanagan, Canada 342 Ricker, [24] Waterton Lake, Canada 370 Rawson, [23] Roosevelt Lake, Ariz. 210-999 Rinne, [25] Canyon Lake, Ariz. (Feb. avg.) 43-1025 Rinne, [25] SEMINOE RESERVOIR, WYO. (Confluence bay) ...... 537 Bow Lake, Canada 706 Rawson, [23] Saguaro Lake, Ariz. (Feb. avg.) 0-1471 Rinne, [25] Lake Maligne, Canada 805 Rawson, [23] SEMINOE RESERVOIR, WYO. (Near dam) ...... 961 Lake Cultus, Canada 1087 Ricker, [24] Lake Minnewanka, Canada 1141 Rawson, [23] Lake Paul, Canada 1353 Rawson, [23] Lake Paul, Canada 829 Ricker, [24] Boomer Lake, Okla. 520-1850 Craven, [7] Lake Itasca, Minn. 1617 (sublit.) Cole 4 Underhill, [6] 1484 (prof.) Great Slave Lake, Canada 1603 Rawson, [23] Queechy Lake, Conn. 1640 Deevey, [8] Loch Levan, Scotland 2027 (sand area) Maitland, et al., [14] Twin Lakes (lower), Colo. 1300-3800 LaBounty & Sartoris, [12] Lake Francis Case, S. Dak. 564-5929 Benson & Hudson, [2] Mississippi River, Iowa 2924 Carlson, [4] Gulf of Maine 4000 Rowe, et al., [26] Volcanic Lakes, S. Australia 2018-7922 Timms, [30] Candlewood Lake, Conn. 5500 Deevey, [8] Lake Cayuga, NY 6000 Henson, [11] Mt. Tom Pond, Conn. 9380 Deevey, [8] Jobs Pond, Conn. 12320 Deevey, [8] Kempton Park E. Res., UK 5565-36 000 Mundie, [16] Third Sister Lake, Mich. 2000-70 000 (prof.) Eggleton, [10]
36 1 000
900
800 1 5
700
600
t.0 (mg/m2) c.) 500 1 0 0
D 400
300 WET WEIGHT
200
1 00
3 4 5 3 4 5 STATION STATION
) 3 2
m 0 003 Wet Weight
2 c.7 0.002 LTJ
DRY WEIGHT (mg/ Dry Weight
0005
3 4 5 3 4 5 STATION STATION
Figure 12. - Histogram of abundance and biomass of the benthic fauna.
37 Zooplankton
Table 7 presents results of zooplankton sampling by station and depth.
The three major groups of zooplankton were found: rotifers, copepods, and cladocerans. Cladocerans and copepods dominated. The values in table 7 are based on number of organisms collected per litre of water, sampled with the metered Clarke-Bumpus plankton net. The concentra- tions are in the range that is expected for a mesotrophic lake in early autumn at this approximate latitude. Table 8 presents these data as percentages of the total.
Zooplankton abundance was highest in the two riverine arms, especially the North Platte arm. The sparsest zooplankton concentrations were found at station 1 (nearest the dam). These data are somewhat contrary to those reported by Peterson and Leik [22], who found only a low abun- dance of both zooplankton and phytoplankton in the North Platte arm; however, they mention a heavy silt load in this arm. A heavy rain and resultant heavy inflow of the North Platte River prior to sampling would result in a low abundance. No storms of this magnitude occurred during or just before the survey reported here. Thus, the values herein reported for both zooplankton and phytoplankton abundances probably reflect more stable weather conditions.
38 I
I Table 7. - Concentration of zooplankton
I Station Depths Concentration number/litre l No. sampled, Cladocerans Copepods Total I m 1 0-10 5.50 5.00 10.50 10-20 0.90 1.30 2.20 I 20-50 0.15 0.65 0.90 I 2 0-10 24.25 20.00 44.25 3 0-10 13.10 15.60 28.70 I 10-16 4.30 4.35 8.65 4 0-10 12.60 17.60 30.20 10-20 3.50 8.10 11.60 I 20-30 0.65 2.50 3.20 5 0-10 17.65 24.45 42.10 10-20 1.30 5.05 6.35 I 20-40 0.25 1.15 1.40
I 1 To obtain results in number/m3 multiply by 1000. I I I I I I I I 39 Table 8. - Relationship between cladoceran and copepod abundance
Station Depth, Cladocerans, Copepods, % of total % of total
1 0-10 52.4 47.6 10-20 40.9 59.1 20-50 27.8 72.2
all depths' 1 48.2 51.8
2 0-10 54.8 45.2
3 0-10 45.6 54.4 10-16 49.7 50.3
all depths 46.7 53.3
4 0-10 41.7 58.3 10-20 30.2 69.8 20-30 20.3 79.7
all depths 37.2 62.8
5 0-10 41.9 58.1 10-20 20.5 79.5 20-40 17.9 82.1
all depths 39.3 60.7 all stations 0-10 46.9 53.1 10-20 34.7 63.3 20-bottom 19.6 80.4
all depths 44.3 55.7
1 Percentages obtained by using data in table 7 Example: ([5.50 + 0.90 + 0.15]/[10.50 + 2.20 + 0.90] = 48.2%)
40 At three of the five stations sampled, cladocerans were dominant in the area between the surface and 10 m below the surface. However, at all stations, copepods dominated the area below 10 m. The deeper the area sampled, the higher the percentage of copepods. Cladocerans, however, are noted for their diurnal migration habits; that is, they tend to migrate to the surface at night. All these samples were collected during full daylight; yet, there were more cladocerans per litre in the surface to 10-m area than there were below 10 m. The high abundance of the blue-green species of algae Aphanizomenon caused the light pene- tration to be low, so that cladocerans penetrated the upper layers in more abundance than they perhaps would have if the Aphenizomenon con- centrations were lower. Thus, the relative abundance of cladocerans and copepods expressed in tables 7 and 8 are what would be expected.
Figure 13 shows a graph of the distribution of zooplankton according to depth. At all stations, the area between the surface and 10 m con- tained higher concentrations of zooplankton, resulting from the pres- ence of light, food, and warmer temperatures. Since only one series of collections of zooplankton was made, the only reliable summarizing statement that can be made is that the zooplankton population of Semi- noe Reservoir is similar to other mesotrophic lakes.
41 STATION 1 4
10 10
20 20 --
0 0
30 30
40
50 50
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 20 M 0 10 20 20 10 0 M 20 10 0 10 20 M 10 20 10 0 10 TOTAL ZOOPLANKTON ( n / I itre )
Figure 13. - Relative abundance of zooplankton.
NO 11•11 ON NO NW INS ON NB ON ON ON NW MN SIN MI Nil NO MIN BIBLIOGRAPHY
[1] "Standard Methods for the Examination of Water and Waste Water,"
American Public Health Association, Inc., N.Y., 874 p., 1971.
1 [2] Benson, N. G., and Hudson, P. L., "Effects of a Reduced Fall
Drawdown on Benthos in Lake Francis Case," Transactions of the
American Fisheries Society, v. 104, no. 3, p. 526-528, 1975.
[3] Brinkhurst, R. O., "The Benthos of Lakes," St. Martin's Press,
N.Y., 190 p., 1974.
[4] Carlson, C. A., "Summer Bottom Fauna of the Mississippi River,
Above Dam 19, Keokuk, Iowa," Ecology, v. 49, no. 1, p. 162-169,
1968.
[5] Cole, G. A., "Textbook of Limnology," C. V. Mosby Co., St. Louis, a 283 p., 1975. [6] Cole, G. A., and Underhill, J. C., "The Summer Standing Crop of
Sublittoral and Profundal Benthos in Lake Itasca, Minnesota,"
Limnology and Oceanography, v. 10, no. 4, p. 591-597, 1965.
43 [7] Craven, R. E., "Benthic Macroinvertebrates and Physicochemical
Conditions of Boomer Lake, Payne County, Oklahoma," masters
thesis, Oklahoma State University, Stillwater, Okla., 62 p.,
1968.
[8] Deevey, E. S., "Limnological Studies in Connecticut. VI. The
Quantity and Composition of the Bottom Fauna of Thirty-six
Connecticut and New York Lakes," Ecological Monographs, v. 11,
no. 4, p. 414-455, 1941.
[9] Dugan, P. R., "Biochemical Ecology of Water Pollution," Plenum
Press, N.Y., 159 p., 1972.
[10] Eggleton, F. E., "A Limnological Study of the Profundal Bottom
Fauna of Certain Freshwater Lakes," Ecological Monographs,
v. 1, no. 3, p. 232-331, 1931.
[11] Henson, E. B., "The Profundal Bottom Fauna of Cayuga Lake,"
Ph.D. dissertation, Cornell University, Ithaca, N.Y., 1954.
[12] LaBounty, J. F., and Sartoris, J. J., "The Profundal Benthic
Environment of Twin Lakes, Colorado," in J. F. LaBounty,
"Studies of the Benthic Environment of Twin Lakes, Colorado,"
Bureau of Reclamation REC-ERC-76-12, in press, 1976.
44 [13] Lieth, H., and Whittaker, R. H. (editors), "Primary Productivity
of the Biosphere," Ecological Studies No. 14, Springer-Verlag,
N.Y., 339 p., 1975.
[14] Maitland, P. S., Charles, N. W., Morgan, N. C., East, K., and
Gray, M. C., "Preliminary Research on the Production of
Chronomidae in Loch Leven, Scotland," "Productivity Problems
of Freshwater Warszawa-Krakow, Poland," p. 795-812, 1972.
[15] Mortimer, C. H., "The Exchange of Dissolved Substances Between
Mud and Water in Lakes," Journal of Ecology, v. 29, P. 280-329 and v. 30, p. 147-201, 1941-1942.
[16] Mundi, J. H., "The Ecology of Chronomidae in Storage Reservoirs,"
Transactions of the Royal Entomological Society of London,
v. 198, no. 5, p. 149-232, 1957.
[17] Northcote, T. G., and Larkin, P. A., "Indices of Productivity
in British Columbia Lake," Journal of the Fisheries Research
Board of Canada, v. 13, no. 4, p. 515-540, 1956.
[18] Otto, N. E., "Survey of Irrigation Canal Ecological Parameters
Influencing Aquatic Weed Growth," Bureau of Reclamation
REC-ERC-75-9, 54 p., 1975.
45 [19] Otto, N. E., and Enger, P. "F.," "Some Effects of Suspended
Sediment on Growth of Submersed Pondweeds," Bureau of
Reclamation GEN-27, 1960.
[20] Parsons, T. R., and Strickland, J.D.H., "Discussion of
Spectrophotometric Determination of Marine-Plant Pigments,
With Revised Equations for Ascertaining Chlorophylls and
Carotenoids," Journal of Marine Research, v. 21, no. 3,
p. 155-163, 1963.
[21] Pennak, R. W., "Rocky Mountain States," in Frey, D. G., (editor)
"Limnology in North America," University of Wisconsin Press,
Madison, Wis., p. 349-369, 1963.
[22] Peterson, L. W., and Leik, T. H., "North Platte River Investiga-
tions," Fisheries Technical Report No. 3, Wyoming Game and Fish
Commission, Cheyenne, Wyo., 19 p., 1956 and 1955.
[23] Rawson, D. S., "A Comparison of Some Large Alpine Lakes in
Western Canada," Ecology, v. 23, no. 2, p. 143-161, 1942.
[24] Ricker, W. E., "The Benthos of Cultus Lake," Journal of the
Fisheries Research Board of Canada, v. 9, no. 4, p. 204-212,
1952.
46 [25] Rinne, J. N., "A Limnological Study of Central Arizona Reservoirs
With Reference to Horizontal Fish Distribution," Ph.D. disser-
tation, Arizona State University, Tempe, Ariz., 350 p., 1973.
[26] Rowe, G. T., Polloni, P. T., and Haedrich, R. L., "Quantitative
Biological Assessment of the Benthic Fauna in Deep Basins of
The Gulf of Maine," Journal of the Fisheries Research Board
of Canada, v. 32, p. 1805-1812, 1975.
[27] Ruttner, F., "Fundamentals of Limnology," University of Toronto
Press, Ontario, Canada, 295 p., 1952.
[28] Ryan, P. J., and Harleman, D.R.F., "Prediction of the Annual
Cycle of Temperature Changes in a Stratified Lake or Reservoir:
Mathematical Model and User's Manual," Report No. 137, School
of Engineering, Massachusetts Institute of Technology, Cambridge,
Mass., 132 p., 1971.
[29] Sartoris, J. J., LaBounty, J. F., and Newkirk, H. D., "Historical,
Physical, and Chemical Limnology of Twin Lakes, Colorado,"
Bureau of Reclamation REC-ERC, in preparation, 1976.
[30] Timms, B. V., "Aspects of the Limnology of Lake Tali Karng,
Victoria," Australian Journal of Marine and Freshwater Research,
v. 25, p. 273-279, 1974.
47 [31] Wesche, T. A., and Skinner, Q. P., "An Environmental Inventory
of Present Conditions Coincident with the Enlargement of
Seminoe Dam and Reservoir," Water Resources Research Institute,
University of Wyoming, Laramie, Wyo., 1973.
[32] Wetzel, R. G., "Limnology," W. B. Saunders Co., Philadelphia, Pa.,
743 p., 1975.
[33] Whitney, L. V., "Transmission of Solar Energy and the Scattering
Produced by Suspensoids in Lake Waters," Wisconsin Academy of
Sciences, Arts, and Letters, v. 31, p. 201-221, 1938.
[34] Hutchinson, G. E., "A Treatise On Limnology, Volume One," John
Wiley & Sons, Inc., New York, N.Y., 1015 p., 1957.
48 GPO 840-224