# -- 

# ~UURI RIVER

# AQUATIC ECOLOGYSTUDIES

TenYear 

# Suihmary 

# (1972

# -1982

# ) 

# n R



# by

# Morningside College, 

# SiouxCity, 

# Iowa -a 

# for 

# Iowa 

# Public Service Company, SiouxCity,

# IowaAQUATIC ECOLOGY STUDY OF 

### THE MISSOURI RIVER TEN YEAR SUMMARY 1972 TO 1982

FOR IOWA PUBLIC SERVICE COMPANY

ROD TONDREAU JANE HEY DR. EDWARD SWE MORNINGSIDE COLLEGE SIOUX CITY, IOWAABSTRACT

A ten year study of the channelized Missouri River near Sioux City and the operational effects of the George Neal generating units 1-4 are summarized inthis report. During this period (1972-1982) degradation of the river channel caused by channelization and above normal flow rates has resulted in the loss of much of the highly productive off-channel aquatic habitat

# - a loss that has severely impacted most river life forms. Water quality during the period was influenced by run-off from snow melt and rainfall and by input from point-source discharges in the Sioux City area. No effect from station operationwas observed on any of the chemical and physical parameters measured during the study. Plankton populations were characterized by low numbers and diversity. Diatoms were the dominant group. Macroinvertebrateshave become established on the rock rip-rap shoreline areas with channelizationnearly elbinating the benthic (botton dwelling) forms. Numbers were consistently gre.aLer in the plant outflow areas. Of 52 fish species collected inthe study area, only eight species (carp, carpsucker, gizzard shad, goldeye, shorthead redhorse, buffalo, channel catfish and flathead catfish) are present in significant numbers. Most other species have been unable to adapt to the harsh conditions resulting from channelization. Fish are attracted to the plant outflows especiallywhen river temperatures are colder. No adverse affects to the fish from this attraction have been observed. Fish impingement and entrainment by the plant intake structureswas found tobe minimal due to the low numbers of organisms affected. Thermal studies on the discharges from both plants found minimal areas of elevated temperatures which remain close to the shoreline allowing a substantial zone of passage for fish moving upstream. Some of the cooling water has been diverted into nearby oxbow lakes whose level and surface area have declined considerably due to channelization and degradation. This project :as improved the condition of these oxbows with no adverse affects on water quality and aquatic life.



# 3TABLE 

### OF CONTENTS
Page



# i Abstract Introduction Description of the Missouri River and StudyArea The George Neal StationUnits 1-4 Description of the Sample Sites Results Hydrology Water Quality Introduction StandardMethods Temperature PH TurbidityfSolids Dissolved Oxygen Chemical Oxygen Demand Nutrients: Ammonia and Nitrate Nitrogcr! and Phosphate Microbiological Studies Plankton Macroinvertebrates Fisheries Studies Introduction Adult Population Surveys Thermal Attraction Studies Larval Fish Studies Impingement/Entrainment Studies Thermal Plume Studies Brown's Lake Study Summary and Conclusions Hydrological Conditions Water Quality Plankton Macroinvertebrates Fisheries Impingement/Entrainment Studies Thermal Plume Studies Brown's Lake Study Conclusion Literature Cited Figures la Water Quality Sampling Sites from 1972-1976 lb Water Quality Sampling Sites from 1977-1982 

### IC Map of StudyArea 9 9 15 15 15 17 18 18 19 20 21 24 27 30 35 35 35 

### 44 47 57 60 65 67 67 67 68 68 69 69 70 70 70 71

5 6 7Table of Contents cont. Figures cont. Page Channel Depth Profiles Near Neal 1-3 2 3 4

5 6 7

8

'9

10 11 12 13 14 Mean Yearly Indicator Bacteria Levels 1973-1982 Comparison of Average Number of Organisms per Substrate for the Above Plume (-) and in Plume (--) Sites for the years 1972-77,1979 FisheriesMap 

## - backwater and shoreline areas Yearly Average Abundances for Selected Species Collected by ElectroshockingDuring 1974-1982 Comparisonof Electroshocking C.P.U.E.'s Between Wingdike and Traildike Habitats for the Years 1978 

## - 1982 Percentage of Fish Collected in the Plume Discharge Area (-) Versus Ambient River Temperatures (--) for each Sample Date (1974) Percentage of Fish Collected in the Plume Discharge Area (-) Versus Ambient River Temperatures (--) for each Sample Date (1980) Seasonal Distribution of all Larvae at the Port Neal Transects Water Temperatures ("C) for the Larval hish Sampling Seasons (1977 

# - 1979) Thermal Plume Maps of Neal 1-3 for July 20, 1977 and December 1, 1977 Neal 4 Plume Maps for July 9, 1980 and March 25, 1981 Brown's Lake Sampling Sites

I I Tables 1 General Specifications for the George Neal Electrical Generating Units 1-4 2 Upstream to Downstream Location of all Sampling Sites and Dates Sampled 1972

# - 1982 3 Missouri River Flow Data at Sioux City, Iowa 4 Yearly Precipitation (1972 

## - 1982) 5 State Water Quality Standards 6 List of Phytoplankton and ZooplanktonGenera Collected 1972

# - 1982 7 TotalNumbers of Macroinvertebrates Collected Above and Below the Thermal Outflow for the Years 1972-77, 1979 8 Total Numbers and Relative Abundances :f all Species Collected by Electroshocking 1974-1982 9 Yearly C.P.U.E. #/hr. 10 Fish Species List 11 Comparison of Total Numbers and Relative Abundances 

### (X) of all Larval Fish Collected in the Channel by Intercept Sampling Upstream from the Neal 4 Site (1977 

# - 1979) 14 26 34

38 40 41

45

46

50 51 63 64 66

3 8 12 13 23 29 32

39 41 42 49



# I I 

# 5Tables cont. Page 

# - 12 13

14

15 16 17 18



# 1 1

t Total Numbers and Abundance of All Types of Larval 52 Fish Collected During 1978 at each Sample Transect Total Numbers and Abundance of Larval Fish Collected 53 From the Main-Channel and Off-Channel Areas During 1980 Total Numbers and Abundance of Larval Fish Collected 54 From the Main-Channel and Off-Channel Areas During 1981 Total Numbers of Larval Fish Collected in 55 Off-Channel Habitats During 1980 Total Numbers and Densities of Larval Fish 56 Collected in Off-Channel Habitats During 1981 ImpingementData for Neal Units 1-2, 3 and 4 57 Thermal Plumes

# - Neal South

## - Unit 4 62INTRODUCTION

The channelized middle Missouri River had received very little study before 1970. During the late 1960's and early 1970's increased environmental awareness prompted Congress and agencies such as the Environmental ProtectionAgency to request studies of the nation's major waterways. In response, the Iowa Public Service Company has funded an ongoing study of the upper portion of the channelized Missouri River near Sioux City, Iowa. The study was initiated at Briar Cliff College in 1971 and transferred to Morningside College in 1977 where it is continuing. This report will briefly outline the results of many types of studies aimed at describing the Missouri River ecosystm and the interaction of the fossil-fueled electrical generating units, George Neal Units 1-4, with portions of that ecosystem. The data and discussion are the result of research conducted from 1972 through 1982. Description of the Missouri River and Study Area The main focus of the Iowa Public Service Missouri River Study is

a six mile stretch of river ranging from 

### R.M. 720.5 to 714.5 and located about twelve river miles downstream from Sioux City, Iowa. The river flowing through 

### the region 

### is part of the channelized system which extends downstream 752 miles to its confluence with the Mississippi River at St. Louis, Missouri. The river is managed by structuralmeasures and reservoir control to provide flood protection and a navigable channel. According to Slizeski et. al. 1982, stabilization structures include dikes to contract the channel to the desired width and revetment structures to protect the bankline or maintain channel alignment. These structures are composed primarily of limestone rock fill and some older wood pilings. Dikes are generally

-1-perpendicular to the river while revetments are parallel to river flow. The fivemainstream reservoirs are located inMontana, North Dakota and South Dakota. In downstream order they are Fort Peck, Garrison, Oahe, Big Bend, Fort Randall and Gavins Point Dams. These storage impoundments

are used topartially regulate stream flow and to generate power. The river in the study area flows past rock lined shores at a fairly high velocity (ave. 4.3 fps) and around wide uniform bends. A limited number of small backwaters exist adjacent to dikes on the shore on the non-channel side. Shoreline vegetation is found only inbackwaters. The river bottom is hard packed and scoured. River flows are regulated toprovide flood control protection and enhance navigation. Two distinct flow conditions prevail. During the eight month navigation season, flows average 30,000 cfs or more; during the winter months, low-flow conditions prevail with discharges averaging 17,000 cfs. At flows of 31,000 cfs, the Missouri is about 750 feetwide at the Neal Station (Units 1-3), river mile 718.43. The George Neal StationUnits 1-4 The Iowa Public Service George Neal Station's fossil-fueled electrical generating units are located on the east bank of the Missouri River midway inthe study area. Three of these units are at R.M. 718.4 and Unit 4 is about 1.8 miles downstream at R.M. 716.6 (Figure IC). Both upstream and downstream station sites are located on the outer or cutting bank of the river. The shoreline inthe vicinity and downstream is rock lined and subjected to the high velocity flow characteristics of main channel conditions. Neal 1 was completed in 1964 before Missouri River Aquatic Ecology Studies had been initiated. The other three units

# -- Unit 2 in 1972, Unit 3 in 1975 and Unit 4 in 1979

# -- have been completed within the time span -2-The total generating capacity of all four units included in this report. is 1538 megawatts. Table 1 contains general specifications including completion dates, electrical generating capacity, cooling water flow, condenser temperature rise and locationof all four units. 

# 1

J

d

I Table 1 General Specifications for the George Neal Electrical Generating Units 

### 1-4 Nameplate Design Cooling Condenser Commercial Rating Water Flow Temperat ure Unit No. Operation We) (cfs) Rise OF Location 1 May 1, 1964 138.7 167 18°F R.M. 718.43 2 May 8, 1972 320.6 291 25OF 718.43 3 Dec. 30, 1975 494.3 638 17.8"F 718.43 4 July 1, 1979 584.9 707 17°F 716.64

All four units use once-through circulating water systems. Water is withdrawn from the river through concrete intake structures which are located flush to the shoreline. Water entering the station passes between trash rack bars into intake bays. Each bay is fitted with a traveling screen constructed of 3/8" mesh openings. After the waste heat has been removed from the condensers,the water is discharged downstream through the concrete outflow structure. During the winter a portion of the discharge will be recirculated and discharged upstream to help prevent icing of the intake structures. Biocides

are not used to clean condenser tubes since the Missouri carries enough silt and sand to scour and clean condenser parts. Descriptionof the Sample Sites Study sites for water quality, plankton and invertebrateswere established at locations downstream and upstream as well as at the intake and outflow of the generating unit. These sites allowed comparisons and the development
-3-of a general picture of the ecology of the Missouri River. A descriptive listing of all sites, locations and dates sampled is given in Table 2. Site 8, the farthestupstream, served as a control or indicator of water quality coming fromupstream into the study area. The most frequently sampled sites designated as farthest downstreamwere site 1, 3000 feet downstream from the Neal North Station (Units 1-3); and site 

### B, 2000 feet downstream from Neal 4. (Figures la and lb). During the early studies (1972-1973) samples were taken at three points along a transect of the river at each site, to determine whether

or not water quality was uniform throughout the horizontal transect. In later study yearswater sampleswere collected matnly from the Iowa side, about 10 feet offshore at each site.



# J

-4­ 

# \aFigure la Water Quality Sampling Sites from 1972 

## - 1976 

# J J

-5-Public Service Neal 4



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# 1 

# 1 Table 2 Upstream to Downstream Location of all Sampling Sites and Dates Sampled 1972-1982 

# 1 Site Name and Location 1972 

## '73 '74 

## '75 '76 

## '77 '78 

## '79 

## '80 

## '81 

## '82 

# J 

# 1 

# 1 1 8 2000 feet upstream from X X X X X X X X 

### X X Units 1-3 7 1500 feet upstream from X X X X 

### X Units 1-3 

### I11 1380 feet upstream from Units 1-3 X X 6 200 feet upstream from Units 1-3 X X X X X X 

### X 5 Intake Units 1-2 X X X X Intake Unit 3 X X X



# 1 

# 1 4 Outflow Units 1-2 X X X X Outflow Unit 3 

## x X X 3 80 feet downstream from Units 1-3 

## x x x x x x IIA 350 feet downstream 

## x x from Units 1-2 2 700 feet downstream X X X X X X X 

### X from Units 1-3 l(I1) 3000 feet downstream from Units 1-3 X X X X X X X X X X X 

### F 2000 feet upstream from Unit 

### 4 Sr X X X X



### E 400 feet upstream from Neal 

### 4 X X X X

Intake Unit 

### 4 X X Outflow Unit 

### 4 X X D 

### 400 feet below Neal 

### 4 

# ** X X N4 600 feet downstream fromNeal 

### 4 X C 1000 feet downstream from Neal 4 X X X X 

### B 2000 feet downstream from Neal 

### 4 X X X X A(1) 5000 feet downstream from Unit 4(2 2/3 mile 

## x x X X X X X ' downstream from Units 1-3) -8- 

# * also sampled 7/77, 8/77 **sampled 6/77, 7/77, 8/77

## y-4

# 1 

# 1 I 

# 1 J 

# 1 

# 1 1 1 

# 1 

# 1 I 1 J 

# 1 

# 1 1 1 1 4 

# I 1 RESULTS Hydrology Mean Missouri River flows for the period 1972-82 were above normal for both the summer (April-November) and winter (December-March) flow periods (Table 3). Extremely high summer flow averages occurred during the years 1972, 1975 and 1978. Winter mean flows were greatest during 1972, 1973 and 1976. All of these events were due to above normal run-off into the upstream reservoirs during those years which necessitated significant increases inreservoir release rates to evacuate the stored run-off. This run-off generally consisted of mountain and plains snowmelt and/or significant rainfall events. Low flow years of 1977 and 1981were preceded by the dry years of 1976 and 1980whose yearly precipitation totals were 57%and 69%of normal (Table 4). Total precipitation was well above normal for the years 1972, 1977, 1979 and 1982 when greater than 30 inches of rain occurred during each year. Flow extremes for the 1972-82 period both occurred in 1975; 8000 cfs on January 10 and 65,000 cfs on August 26. Current velocities inthe study area are dependent on discharge (flow) rates, the cross-sectional positionwithin the channel, and the location within the channel alignment (i.e. at the beginning, middle or end of the river bend or at the channel crossover). Average main channel velocities for the years 1970-1979 ranged from 4.0 fps (at 30,000 cfs) to 5.3 fps (at 60,000 cfs) within the study area (Corps of Zitgineers, 1981). With reference to channel alignment, velocities tend tn be lowest at the channel

crossovers and increase with the decrease inbend radius. The main channel velocities for the river reach included in the study area are among the lowest observed inthe entire Missouri River from Sioux City, Iowa (R.M. 732)

-9-

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I to Rulo, Nebraska (R.M. 540). Velocities inthe main channel border and off-channel areas typically range from 0.5 to 3.0 fps. The phenomenon of river bed degradationhas been inevidence within the study area. The confining of the river channel to an average width of 700 feet inthe study area along with the corresponding increases in current velocities has resulted inthe eroding of the channel bed and a considerable lowering of water surface elevation. According to the recently released degradation study by the Corps of Engineers (1981) the extent of degradation inthe vicinity of Sioux City has been 7.2 feet since 1961. Of this amount 3 feet (42%of the total) of surface elevationwas lost inthe period 1969 to 1972. This severe loss of bed depth was attributed to sustained high flows during the period which accelerated til<degradation trend. The rate of degradation has slowed during more recent times with only an additional 0.8 feet lost for the period 1972 to 1980. The predicted additional amount of degradation inthe Sioux City area is 2 to 3 feet of additional bed loss by the year 2000. Inthe immediate Port Neal area, channel profiles conducted in 1975 and 1979 at a point 600 feet downstream from the Neal 1-3 discharge, do illustrate some change in surface elevation (Figure 2). At similar flow rates and allowing for differences inwater temperature,.a change inelevation of approximatel-y 1.5 feet is indicated by the differences inriver gage heights and measured channel depth. The profiles also indicate that the channel confiyurationremained relatively unchanged during the interim. The basic trapezzidal configuration is typical for this reach of the river and this skape has remained relatively constant during the past 15 years. Two severe impacts have occurred as a result of the degradatian problem. First is the severe reduction inthe amount of off-channel

-10­ 

## khabitat 

## - backwaters and side channels which have drained and filled in 

# I due to the lowering of mean river levels. These habitats are the primary spawning, nursery and feeding areas for many fish and wildlife species as well as habitat for the lower aquatic life 

### forms (algae, invertebrates and zooplankton) which contribute to the primary productivity 

### of the river

I ecosystem. These losses can only be described as staggering. The second impact is the loss of effective depth within water intake structures located along this reach of the river. The change in water surface elevation adjacent to such structures,which include the cooling water intakes for the 

### Neal Station Units 1-4, reduces the amount 

### of water entering these structureswhich has caused occasional unit shutdowns because of the lack of sufficient cooling water flow. This problem ic especially severe during low flow periods which generally occur during the winter months. 

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-12-

# 1 

# 1 

# I Table 4 YEARLY PRECIPITATION (1972-1982)* 

# 1

Year Total Precipitation (inches) Departure from normal 1972 33.72 +8.37 1973 27.89 +2.54 1974 17.96 -7.39 1975 26.31 +O. 96 1976 14.33 -11.02 1977 35.03 +9.68 1978 22.08 -3.27 1979 32.49 +7.14 1980 17.71 -7.64 1981 20.40 -4.95 1982 30.50 +5.15 Averages 25.31 -0.04

*As recorded at the Municipal Airport, Sioux City, Iowa

by the National Weather Service.

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# I i Water Quality Introduction The chemical and physical parameters monitored over the period from 1971 to 1982 include: 

### pH, temperature, turbidity, solids (filterable and nonfilterable, volatile and total), dissolved oxygen, ammonia nitrogen, nitrate nitrogen, chemical oxygen demand (COD), and phosphates (ortho and total). These are summarized and discussed individually in the latter part of this section. In all cases the methods employed were those recommended in Standard Methods (A.P.H.A.). One of the primary purposes of this project is to supply baseline data for many of the chemical parameters routinely monitored for surface waters. The U.S. Geological Survey reports water quality measurements for the major water basins in Iowa, including the Missouri River. Their station at South Sioux City, 

### NE, monitors: daily all year (discharge flows), daily for sixmonths of the year (conductance and temperature), monthly 

### (pH, turbidity, dissolved oxygen, chemical oxygen demand, hardness, calcium, magnesium, sodium, alkalinity, sulfate, chloride, fluoride, silica, solids, nitrogen, phosphorus and organic carbon), and quarterly (heavymetals and pesticides). Data from this fixed station is also reported by the Iowa Department of Environmental Quality. The chemical data collected for the Iowa Public Service Company complements nicely that collected by the Geological Survey since Morningside College's studymonitors the water quality downstream of Sioux City while the Geological Survey monitors the water quality upstream of Sioux City. A comparison of Geological Survey and Morningside College (site 8, background) water quality data for 1974 and 1979 shows very similar average

-15-yearly values for total phosphorus, COD, pH and turbidities. For both years the Morningside College data showed higher ammonia and nitrate nitrogen levels than the Geological Survey data. It is probable that input from tributary streams, located between the two stations, contributed to the increase inlevels of these nutrients observed at the downstream site.Table 5 summarizes the State of Iowa Water Quality Standards and lists typical background Missouri River values for the chemical and physical parameters. A review of the background river chemical parameters, as determined at site 8, over the ten-year period showed relatively constant year-to-year background levels for the chemical parameters monitored. Site 8 yearly averages for temperature, dissolved o;.I:-?en and pH were quite constant. Several of the chemical parameters were found tobe dependent upon climatic conditions, i.e., rainfall. For example, the 1979 yearly averages for the parameters COD, turbidity, solids, ammonia and nitrate nitrogen and phosphorus were found tobe significantlyhigher than for the other nine years. A closer evaluation of the 1979 data indicated, however, that the year's averages were biased on the high side by very heavy run-off due toheavy precipitationjust before or on several of the sampling dates. The total solids and turbidities were significantly increased by run-off. COD is increased by elevated organic load resulting from run-off. Nitrate and ammonia nitrogen and phosphates were significantly increased by run-off particularly during the spring fertilization period. On the whole the chemical and physical parameters were quite constant for the stretch of the river monitored. One exceptionwas the discharge at site 7 which was monitored between 1971 and 1978. Significant changes in

-16-ammonia nitrogen, nitrate nitrogen, phosphates, dissolved oxygen, pH and COD were routinely observed at this sampling site. Substantial improvements

were observed, however, in the last two years that this site was sampled. Without exception the Neal Units 1-3 and Neal Unit 4 were found to have no effect on the chemical and physical parameters studied, and in

no cases did outflows from these plants exceed water quality standards. Temperature Background river temperatures ranged from lows near O°C in the winter months to highs around 25OC in the summer months. Studies between 1972 and 1975 indicated that the Neal 1-3 Unit outflow averaged about 11 to 13OC above the inflow temperature. At a site 700 feet downstream of the outflow the temperature of the river on the Iowa side had dropped to within about l0C 

### of ambient river temperatures. Studies between 1976 and 1978 indicated that the Neal 1-3 Unit outflowwas about 8OC warmer than the inflow temperatures, but the temperature had returned to within about 1.5"C of ambient river temperature at a site 700 feet downstream. Studies of the Neal 

### 4 Unit outflow between 1979 and 1980 showed it to average about 8OC above the inflow temperature. At a site 1000 feet downstream 

### of the outflow the temperature had returned to within about 3OC of the ambient river temperature. The warm water from the Neal Units does not mix horizontally in the river but hugs the Iowa shore, so the temperature increases noted represent the 'worst cases', i.e., they are taken along 

### the Iowa shore. Thermal attraction (electric shocking) studies in 1974 and 1979 showed that fish

were indeed attracted to the warm thermal plume, particularly in the cooler months. There was, however, no deleterious effect of the elevated temperatures

-17-that was ever noted on the fishpopulations. Temperature increases were not great enough to produce fishkills; therewas no difference in growth rates or disease levels for fish shocked inthe thermal plume areas versus those shocked elsewhere in the river.



# - PH Fish and other aquatic species have limited tolerance of pH changes and limited pH ranges within which they can survive, normally between 6 and 9 pH units. The Missouri River is typical of alkaline buffered surface waters with pH's ranging just above the neutral point. The only river pH variations observed between 1971 and 1982 were at site 7. The discharge at site 7 was usually within 0.5 pH units of ambient river pH but occasionally inthe 1973 to 1975 period pH's as low as 

### 5 pH units below background 'and 1.4 pH units above background river pH were observed. River pH occasionally dropped into the high pH 7 range but was usually between 8.0 and 8.4 pH units. In the period between 1971 and 1982 the Neal 1-3 and Neal 4 plants were observed to have no effect on river pH. The outflows of both plants always had pH's within a few tenths of the ambient river pH. Turbidity/Solids Much of the "muddy Missouri's" sediment load is being deposited behind the mainstream dams such as .Gavin's Point Dam. The river's sediment load is low, although it is significantly affected by run-off from the surrounding predominately agricultural environs. Turbidities inthe river typically ranged between 20 to 30 (N.T.U.) but under heavy run-off conditions the turbidities were frequently as high

as 100 to 280 (N.T.U.). Without exception the turbidity at the outflows

-18-

# 1 

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# 1 of Neal Units 1-3 and Neal Unit 4 have not differed from background river turbidities. In a closely related test, the total solids in the river were consistently in the 500 to 600 mg/l range and filterable (dissolved) solids were inthe 450 to 550 range. Higher values were found under heavy run-off conditions. Studies of the Neal 1-3 units between 1973 and 1978 showed, within experimental error, no impact of the plant on river solids. Likewise, studiesbetween 1979 and 1982 for Neal 4 indicate the plant has no effect on river solids. Dissolved Oxygen The maintenance of dissolved oxygen levels above 5 mg 02/liter 

### is essential for the support of active fish populations. The Missouri River has thorough mixing with the air and is accordingly near saturation levels with respect to dissolved oxygen. The primary threats to dissolved oxygen levels would be point sources of organic contamination such as sewage treatment plants or food processing facilities or feedlots. Since the amount of oxygen inwater is temperature dependent, the temperature of an outflow into the river can affect the dissolved oxygen level. The dissolved oxygen (DO) levels inthe river varied with river temperature from lows around 7 mg/l in the summer months tohighs around 14 mg/l in the winter months. River DO'S averaged about 0.7 mg/l below saturated DO levels. The only significant drops observed inriver DO were at site 7 inthe period between 1972 and 1976 when this outflow was monitored. Drops inDO between 0.5 and 3 mg/l were common with sume drops running as high

as 6 to 9 mg/l. None of the Neal power plants significantly affected river DO levels. Between 1972 and 1978 the Neal 1-3 outflows averaged about 0.5 mg/l below ambient river DO and had returned to ambient values typically within 80

-19-to 700 feet below the outflow. Between 1971 and 1980 the sampling sites 700 to 1000 feet downstream from the Neal 1-3 outflow were within a few tenths of ambient river DO levels. The same trends were observed with the Neal 4 unit. The outflow ranged from 

### 0 to 2.5 mg/l below ambient river DO; the drops reflect the 

### warmer temperatures of the outflow compared with the intake temperatures. By 

### 700 to 1000 feet downstream of the outflow the river DO was within a few tenths of the background DO levels. 

### No large drops in DO were ever observed at the outflows from any of the Heal units. Chemical Oxygen Demand The chemical oxygen demand (COD) test measures organic compounds a which can be oxidized by dichromate and is one of the common methods of monitoring organic contamination of a water supply. Municipal treatment plants are the primary sources of COD, but certain inorganic chemicals can also contribute to the COD. The Missouri has very low organic levels and thus has low COD's except during heavy run-off whereupon the organic content 

### of the river can increase significantly. Chemical oxygen demand values for the river were typically in the 9 to 14mg/l range with increases into the 30 to 40 mg/l range during heavy run-off. In the period between 1973 and 1977 significant increases in river COD were observed at site 7 discharge upstream of Neal 1-3. Increases of COD in the 40 to 60 mg/l range were common while COD's in the low 100's mg/l were frequent and several COD's were observed as high as 

### 550 to 600 mg/l. By contrast in the period between 1973 and 1978 there was no significant difference between the COD's at the Neal 1-3 outflow and the ambient river COD's. (Experimental variations in this test are on the order of +20%.) -20-Likewise,between 1979 and 1982 on only four occasions were the outflows from Neal 4 above ambient river COD'S, and these increases were not significant, i.e., increases of 

### 4 to 17 mg/l. Nutrients: Ammonia and Nitrate Nitrogen and Phosphate 

# + The nutrients, ammonia 

### (NH 3 or NH4 ), nitrate nitrogen and phosphorus, (several forms such as phosphate, polyphosphate and organic phosphate),

are of concern because of their role in the eutrophication of surfacewaters. This concern is more critical, however, for isolated water environments such as lakes than it is for free flowing waters such as rivers which can flush out their nutrients. 

### In the midwest it is nitrate nitrogen that is watched most closely because of its involvement in the disease, infant methemoglobinemia. Many water environments in Iowa are contaminated with nitrate levels in excess of the recommended 10mg/liter standard. Fish

are sensitive to ammonia nitrogen levels; the ammonia nitrogen level in the Missouri is quite low, but levels in the feeder streams such as the Big Sioux and the Floyd Rivers can exceed recommended limits. Phosphorus is classified as the "limiting" nutrient in the eutrophicationprocess and for that reason is of interest. On the Missouri River the phosphorus levels are low. The concentration of ammonia and nitrate nitrogen containing compounds followed similar patterns. Background river ammonia nitrogen values were typically in the (0.1 to 0.3 mg N/1 range with increases into the 0.5 to 1.5 mg N/1 range common during spring run-off. River nitrates were typically 60.2, but during spring run-off, values in the 0.7 to 1.5 range were common. The most significant changes in river nitrate and ammonia were observed at site 7. Between 1971 and 1976 ammonia nitrogenwas commonly in the 

### 20 to 

### 300 mg N/1 range with some readings as high as 1000 mg N/1. Between 1971 -21-and 1974 nitrates at the site 7 were commonly inthe 10 to 70 mg/l range, but then they began to drop off and between 1975 and 1977 rarely exceeded 4 mg N/1. Between 1971 and 1978 the Neal 1-3 unit was found tohave no effect

on river nitrate or ammonia nitrogen values. Those readings downstream of the plant were consistently equal to or lower than those upstream of the plant. Likewise, no effect was found at the Neal 

### 4 plant in the period between 1979 and 1982. Typical background total phosphate values for the river are inthe range 0.05 to 0.2 mg/l with values sometimes in the range 0.3 to 0.5 during the spring run-off. The site 7 outflow had the only detectable effect on river total phosphate values. Readings at this outflow in the 0.2 to 0.6 mg/l range were common between 1971 and 1978 with occasional readings running higher. No effect on river total phosphates was detected at the Neal 1-3 plant between 1971 and 1978 or at the Neal 4 plant between 1979 and 1982.

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# 1 1 1 1 1 I Microbiological Studies Monthly determinations 

### of total coliform, fecal coliform and fecal streptococcus bacteria which are commonly used as indicators of bacterial pollution have been made since the inception of the study. The presence of large numbers of these bacteria is an indication of contamination by human and animal wastes and the possible presence of pathogenic bacterial forms. The Iowa water quality standard for the Missouri River (Class 

### B waterway) is

no more than 2000 fecal coliformsper 100 milliters of water sample. Coliform levels have shown a marked decline during the last ten years (Figure 3). Total coliform numbers have dropped from a yearly average of 

### 60,000organisms per 100milliters to C3000 organisms per 100 milliters. Mean fecal coliform levels have also declined. This rather significant decline is due primarily to improvements in water quality from point source discharges in the Sioux City area (12-15 river miles upstream of the study area). Of these discharges the effluent from the Sioux City sewage treatment plant appears to have had the most significant effect on downstream indicator bacteria levels. Recent improvements to the plant, expanded primary treatment in November 1978 and secondary treatment in June of 1979, have resulted in improved effluent water quality especiallywith regard to coliform levels

as indicated by Figure 3. 

### Two other major factors which influence bacteria levels are runoff and river flow. Runoff from heavy rains and snow melt can cause significant increases in coliform and fecal streptococcus numbers which is not unexpected in an agricultural area. The slight increase in mean total coliform levels for 1982 (Figure 3) was due to three months (June, July and October) when

-24-heavy rains prior to sampling resulted in very high bacteria counts. Flow rates appear to have a diluting/concentratingeffect on bacteria levels during high/low flow periods. Counts during the low flowmonths of December and 3anuary have been consistentlyhigher for the years 1973-82 when compared to other months for those years. High flows appear to have the opposite effect as indicated by the reduction in bacteria levels for 

### 1975 (Figure 3) when flow rates were well above normal. Station operation does not appear to enhance or reduce indicator bacteria levels. 

### No significant differences between inflow and outflow bacteria levels were indicated from the data for the years for which inflow/ outflow samples were collected.

-25-

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# a II I d Plankton Two major groups, zooplanktonand phytoplankton, comprise the plankton found in the Missouri River aquatic ecosystem. The purpose of the plankton studieswas to describe the species compositionand abundance of the Missouri River plankton community found throughout the study area. Plankton populations were sampled monthly by passing five gallons of river water through a Wisconsin Planktonnet (No. 80 Nytex with 

### 173 meshes/inch). The plankton groups collected in this manner represent primarily phytoplankton. True river environments are not conducive to increasing or maintaining microcrustacean zooplanktonpopulations (Hynes, 1970), thereforemuch larger quantities of water would be needed to collect representativepopulations of zooplankton. As documented by other studies of Missouri River phytoplankton (Reetz, 1982) diatoms (Bacillariophyta) comprise the major portion of the plankton populations. Diatoms are abundant in plankton samples throughout the year. The winter and spring communitywas comprised almost exclusively of diatoms. Asterionella alone or in combinationwith centric diatoms such as Cyclotella and Stephanodiscus composed as much as 95% of the total phytoplankton. Asterionella, a cold water form, underwent severalblooms or large population increases during the winter and spring months. During the summer other genera including Fragilaria, Melosira, Nitzschia, and Navicula were abundant. Green algae (Chlorophyta) were present during late spring, summer and fall with Ulothrix,Ankistrodesmus,Actinastrum, Closterium and Scenedesmus being most common. Blue-green algae (Cyanophyta), euglenoids (Euglenophyta) and dinoflagellates (Pyrrophyta) were present during the summer months but

were never common. Zooplanktonwere most abundant in summer samples. These -27-

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# I included microcrustaceans such as Calanoid copepodites, Cyclopoid copepodites and Daphnia as well as numerous genera 

### of Rotifera. Although plankton population fluctuations are influenced by water temperatures, nutrient levels and run-off, upstream reservoir discharges appear to be most significant in determining species composition and abundance. Lewis and Clark Lake, the closest mainstem reservoir upstream from the study area, has been cited by Cowell (1970) as the major source of organisms found in downstream plankton assemblages. According to Reetz (1982) relatively minor modifications to the downstream species composition can be attributed to production in backwater areas of the unchannelized river, input of phytoplankton from tributaries and scouring of periphytic forms. No studies of the effects of entrainment iL-the once through cooling system of the George Neal Station units was conducted. These studies would considermechanical effects such as abrasion and pressure changes and sudden thermal increases experienced by the plankton during condenser passage. Phytoplanktonresponses are generally assessed by measurement of photosynthetic rates. However, phytoplankton entrainment studies conducted by other researchers have shown a tendency toward stimulation of primary production during winter and inhibition during summer with the degree of inhibitionbeing affected by absolute discharge temperature and duration of exposure (Gurtz and Weiss, 1974 and Smith et. al. 1974). Plankton numbers and compositionwere fairly consistent from site to site with no apparent effect of plant operation on the river plankton community. Occasional increases in epiphytic forms such as Nitzschia, which grow attached to substrates,were found in outflow samples. A list of phytoplankton genera enumerated during this study will be found in Table 6.

-28-

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### 6

LIST OF PHYTOPLANKTON AND ZOOPLANKTON GENERA COLLECTED 1972-1982 Phytoplankton Blue-green algae (Cyanophyta) Anabaena Anacystis Aphanizomenon Aphanocapsa Calothrix LYngbYa Nodularia Oscillatoria Spirulina Stichosiphon

Green algae (Chlorophyta) Actinastrum Ankistrodesmus Chlamydomonas Chlorella Chlorella-like Chlorococcum Cladophora Clo

### sterium Coelastrum Cosmarium Eudorina Gloeocapsa Gloeocystis Micractinium Oocystis Pandorina Pediastrum Phacus Pleurococcus Quadrigula Rhizoclonium Scenedesmus Selenastrum Sphaerocystis Spirogyra Staurastrum Stigeoclonium Synura Tetraspora Treubaria Green algae cont. Ulothrix Volvox

Diatoms (Chrysophyta) Achnanthes Amphipleura Amphora Asterionella Caloneis Cocconeis Cyclotella Cymatopleura Cymbella Diatoma Diploneis Epithemia Eunotia Fragilaria Gomphonema Gyrosigma Melosira Meridion Navicula Neidium Nitzschia Opephora 

### Pinnularia Pleurosigma Rhoicosphemia Rhopalodia Stauroneis Stephanodiscus Surirella Synedra Tabellaria

-29- Zooplankton Cladocera Bosmina Daphnia Diaphanosoma
Microcrustaceans Calanoid Cyclopoid Cyclops Diaptomus Hydra Larval watermite

Protozoa Actinophrys Amoeba Ceratium Coleps Didinium Dif

### flugia Dinobryon Euglena Flagellates Heliozoa Stentor Suctoria Volvox Vorticella

Rotifers Keratella Platyias Synchaeta

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I i Macroinvertebrates Studies of macroinvertebrate populations were conducted during the years 1972-1979, excluding the year 

### 1978. Rock filled substrate baskets

(Hilsenhoff type) were used as artificial substrate samplersuntil 1979 when Hester-Dendy multiple plate type samplers were employed. Samplers

were placed along the revetment shoreline in groups of three at sites above and below the Neal 3 outflow except for 1979 when the Neal 4 outflow

area was sampled. The samplers were allowed a minimum of four weeks between samplings for recolonization. The results of this study presented in Table 7 indicate a diverse ,communityof macroinvertebrates (44 taxa identifLed) dominated by Trichoptera (caddisflies), Diptera (flies and midges), Ephemeroptera (mayflies), Turbellaria (planaria) and Hydrozoa (hydra). Smaller numbers of Crustaceans, Plecoptera (stoneflies) and Gastropoda (snails) were also observed. In order to determine the effects of station operation on the macroinvertebrate community a comparison of the average number of organisms collected per sampler per year was made between the samples collected above and below the outflows (Figure 4 ). The figure illustrates that in every sample year the number of organisms per samplerwas consistently greater for the substrates in the plume when compared to those just upstream. The greater per sample averages for the years 1973 and 1977

was due in part to the presence of large numbers of hydra and planaria especially for the in-plume samples. Numbers of Trichoptera,Diptera and Ephemeropterawere more consistent for all the sample years. Macroinvertebratepopulations in the channelized Missouri River have been affected by physical changes in the river which have resulted from

-30-

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# I 1 channelization. Most benthic habitat has been lost due to constriction of the channel, the loss of off-channel habitat and the increased current velocity which continually scours the riverbed preventing colonization by benthic organisms. At present the greatest concentration of macroinvertebrates is associated with the "aufwuchs" communitywhich has colonized the rock rip-rap shoreline areas constructed as part of the channelization plan. This rip-rap has provided a good substrate for a variety of forms ranging from the chironomids, which are more tolerant of polluted water; to crustaceans, hydra and planaria which have a wider tolerance; to such pollution intolerant forms such as the mayflies and caddisflies. Even small numbers of stoneflies (Plecoptera) which generally inhabit only pristine areas were collected during the study. This diversity of invertebrateswas also observed by Kallemeyn and Novotny 

### (1977) who found densities to be greater in the channelized river when compared to the unchannelized reach upstream of Sioux City. They cited the favorable Substrate along with greater quantities of organic detritus (food source) as factors contributing to the greater densities. Studies at the Fort Calhoun and Cooper nuclear power stations (Carter et. al. 1982) found similar families and densities when compared to data from the present study. Seasonal distribution of the abundant taxa was similar for both studies. Carter et. al. noticed a variability in relative abundances for the two types of substrate samplers used. The rock basket samplers were dominated by chironomids while the multiple plate samplers

were colonized to a greater extent by Hydropsychidae (caddisflies). This trend

was also observed in comparing sample relults from the present study. In conclusion it would appear that stati.cnoperation does not adversely affect the invertebrate population. Comparison 

### of data from above and below the thermal discharge may indicate greater productivity within the plume influenced area.

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-34-

LB 

### PFISHERIES STUDIES Introduction Objectives for the fishery studies were to 1) determine species composition and relative abundances of fishes in the study area; 2) obtain natural history informationrelative to these species; 3) assess the impacts of station operation on fish populations; and 4) to develop methods to estimate the population sizes of the dominant Missouri River fish species. Specific study components are discussed as follows. Adult Population Surveys Sampling for species composition and relative abundancewas conducted

once during spring, summer and fall for the years: 1974-1982. This schedule allows some assessment of pre-spawning populations along with later sampling to determine spawning success. Figure 

### 5 illustrates areas which were sampled during the 1974-82 period. Additional sample areas not common to all study years were omitted from the discussion. Of the three basic sampling techniques electroshocking was the preferred method and provided the most representative data. Bag seining was suitable only for small Cyprinid species and young-of-year of other species since sandbars and small pockets were the only habitats which could be sampled by this method. Gill and trammel netting was used more extensively during the early years when more off-channel habitat was available. In recent years use of these nets has all but been discarded due to lack 

### of suitable sample areas hence only the electroshocking data will be used in the following discussion. Total numbers and relative abundances of all species collected by electroshocking during the years 1974 to 1982 is presented in Table 8. From the data it is apparent that fish populations in this reach of the 

### -35-river are characterized by large numbers of a small number of dominant fish species. Six species: carp, carpsucker, gizzard shad, goldeye, shorthead redhorse and smallmouthbuffalo collectively comprise nearly 90%of all fish collected. It should be noted that this data is not representative of the true size of the catfish abundance. This type of electroshocking is inefficient for sampling flathead and channel catfish and more specialized samplemethods indicate that sizeable populations of the two species do exist. Some yearly fluctuationwas apparent for some of the more abundant species (Figure 6). During the high water year of 1975 carp abundance declined while gizzard shad numbers increased substantially. Those trends are probably related to the increased amount of quicx water habitat created by the high water conditions, Conversely such main channel species as carpsucker, goldeye and shorthead redhorse did not exhibit such drastic fluctuations in abundance. Numbers of sauger and flathead catfish have increased slightly while smallmouth buffalo numbers have declined. Catch per unit efforts calculated from the 

### 1978 through 1982 electroshocking data indicate higher CPUEs along the traildike (revetment) habitat when compared to the wingdike habitat (Figure 

### 7). A comparison of yearly 

### CPUE averages between the three traildike areas (each 2300' in length) illustrates that in nearly every instance more fish were found below Neal 3 when compared to the Neal 4 and above Neal 3 sites (Table 9). This preference may be attributable to increased growth of periphyton and invertebrates (food source for many forage fish> and the thermal attraction of fish to the plume influenced areas. As of December 1982 a total of 52 species of fish have been collected in the Port Neal area since the beginning of the study, Table 10. Other 

# I -36- 

# Iresearchers: Morris, et. al. (1972) and Schmulbach et. al. (1975) 

# - 50 species each and Kallemeyn and Novotny (1977) 

# - 46 species, found similar numbers and species to this present study from this reach of the channelized Missouri River. The most recent additions to the species list included the brassey minnow (Hybsgnathus hankinsoni), the blacknose dace (Rhinichthys atratulus), the golden shiner (Notemigonus crysoleucas), the sicklefin chub (Hybopsis meeki), and the grass carp (Ctenopharyngodon idellus). All of these species can be classified as uncommon to rare within the'study

area. The collection of the sicklefin chub brings the list of endangered

or threatened Iowa fishes (Roosa, 1977) collected in the study area to three. The two other species were the pallid sturgeon (Scaphirhynchus albus) and the skipjack herring (Alosa chrysochloris). 

### It should be noted that with the possible exception of the pallid sturgeon these species

are increasing in abundance and are no longer on the protected lists of neighboring stateswhich border on the Missouri River.

I I

-37-Neal 1-3

Figure 5 FISHERIES MAP backwater and shoreline areas

wa Public Serv rice

Backwater and Spur Dike Sampling Sites B-J Shoreline Revetments shocked xxxxxx

-38- 

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### $ $ -39-Figure6 Yearly Average Abundances for Selected Species Collected by Electroshocking During 1974-82 40

30

20

10 

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Shorthead redhorse 

## _­ --Sauger

-.­ i -75 76 77 78 79 80 81 82 Years

I 

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### I \Smallmouth buffalo -Flathea$ catfish 1 I I t 1 I 1 I 74 75 76 77 78 79 80 81 82 Years -40-Figure 7 Comparison of Electroshocking C.P.U.E.'s Between Wingdike and Traildike Habitats for the Years 1978-1982

100-

Year 1978 1979 1980 1981 1982 Traildike



# -Wingdike

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## - 129 226 220 140 160 

### 148 221 356 128 140 132 120 233 241 172

c *Catch per unit effort

-4 1-Table 

### 10 FISH SPECIES LIST



# J

1 Scientific Name Scaphirhynchus albus (Forbes and Richardson) Scaphirhynchusplatorynchus (Rafinesque) Polyodon spathula (Walbaum) Lepisosteus osseus (Linnaeus) Lipisosteus platostomus Rafinesque Anguilla rostrata (LeSueur) Alosa chrysochloris (Fainesque) Dorosoma cepedianum LeSueur Hiodon alosoides Rafinesque Osmerus mordax (Mitchill) Esox lucius Linnaeus Ctenopharyngodon idellus (Cuvier & Valenciennes) Cyprinus carpio Linnaeus Hybognathus hankinsoni Hubbs Hybognathus nuchalis Agassiz Hybopsis gracilis (Richardson) Hybopsis meeki Jordan and Evermann Hybopsis storeriana (Kirtland) Notemigonus crysoleucas (Mitchell) Notropis atherinoides Rafinesque Notropis lutrensis (Baird and Girard) Notropis stramineus (Lope) Pimephales promelas Rafinesque Pimephales vigilax (Baird and Girard) Rhinichthys atratulus (Hermann) Semotilus atromaculatus Mitchill Carpoides carpio Rafinesque Carpoides cyprinis LeSueur Carpoides velifer Rafinesque Catostomus commersoni (Lacepede) Cycleptus elongatus LeSueur Common Name Pallid sturgeon Shovelnose sturgeon Paddlefish Longnose gar Shortnose gar American eel Skipjack herring Gizzard shad Goldeye Rainbow smelt Northern pike Grass carp Carp Brassey minnow Silvery minnow Flathead chub Sicklefin chub Silver chub Golden shiner Emerald shiner Red shiner Sand shiner Fathead minnow Bullhead minnow Blacknose dace Creek chub River carpsucker Quillback Highfin carpsucker White sucker Blue sucker

-42-

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### 10 cont. Scientific Name Ictiobus bubalus Rafinesque Ictiobus cyprinellus Valenciennes Moxostoma macrolepidotum LeSueur Ictalurus melas Rafinesque Ictalurus natalis LeSueur Ictalurus punctatus Rafinesque Noturus flavus Rafinesque Pvlodictis olivaris Rafinesclue Lota lota Linnaeus Morone Chrysops Rafinesque Lepomis cyanellus Rafinesque Lepomis humilis Girard Lepomis macrochirus Rafinesque Micropterus salmoides Lacepede Pomoxis annularis Rafinesque Pomoxis nigromaculatus LeSueur Etheostoma nigrum Rafinesque Perca flavescens Mitchill Stizostedion canadense (Smith) Stizostedionvitreum Mitchill Aplodinotus grunniens Rafinesque Common Name Smallmouth buffalo Bigmouth buffalo Shorthead redhorse Black bullhead Yellow bullhead Channel catfish Stonecat Flathead catfish Burbot White bass Green sunfish Orangespotted sunfish Eluegill Largemouth bass White crappie Black crappie Johnny darter Yellow perch Sauger Walleye Freshwater drum

-43­ 

# iThermal Attraction Studies



# 1

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# 1 1 To determine the possible attraction of fish to the thermal discharge two thermal attraction studies were conducted in 1974 and 1980. In 1974 three 2300 foot shoreline segments (above, in and below the Neal 2 plume)

were sampled by electroshocker bimonthly from June to November. In 1980 three 1500 foot segments above, at and below the Neal 4 outflowwere sampled weekly from September to November. Fish in both studieswere marked with a fin clip to monitor any movement from segment to segment. During the 1974 study, 40%of all fish collected (850 of 2099 total fish)

were taken in the plume area. This percentagewas even greater for the 1980 studywhen 68% (614 of 904 total fish) were found in the plume area. Graphs comparing the percentage of all fish (all three Legments) found in the plume

area to the ambient water temperature for each sample date for both years are presented in Figures 8 and 9. The figures illustrate that as ambient water temperaturesdecrease the percentage of fish in the plume area increases. This would indicate the thermal attraction of fish to the plume influenced areas especiallywhen river ambient temperatures fall below 20°C. Most recaptured fish from both years had remained in the areas in which they were originally marked. The apparent thermal attraction exhibited by fish in both studies could be related to feeding activitywhich is prolonged by the effects of elevated temperatures. Forage fish attracted to the w2r-2-water are available as a food source for pisciverous species (sauger,walleye and flathead catfish). Also, the increased productivity of the macroinvertebrate and periphyton communities provides an additional food source utilized by such grazers as carp, carpsucker,buffalo, goldeye and gizzard shad. It would appear that in this reach of the channelized Missouri River the thermal attraction is of benefit to the fishery community. -44­ 

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-46-

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# I 1 1 1 I I I Larval Fish Studies Extensive larval fish studies were conducted during the years 1977 through 1981. The 1977-79 studies were designed to determine the composition of larvae in the main channel drift. Cross-channel samplingwas conducted at a transect just upstream of the Neal 4 intake structure 

### R.M. 717.7 using metered 0.5 m and 0.75 m 0 mesh plankton nets. Two additional transectswere sampled in 1978 (at Yankton 

### S.D. 

## - R.M. 808 and above Sioux City

# - R.M. 736.8)

as part of a cooperative study with three other utility companies in order to study changes in the drift population along a 400 mile river reach from Yankton to Kansas City. Studieswere conducted in 1980 and 1981 to assess larval productivity from local off-channel areas and document their contributions to the main-channel drift. Sampleswere ccjllected with a 360 gpm trash pump (off-channel areas) and 

### 0.5 m plankton nets (main-channel samples). Numbers and relative abundances of all larvae collected at the Neal 4 transect for the years 1977 through 1979 are presented in Table 11. Drum larvae dominated the collections for all three years which is not unexpected since this species is a pelagic (main-channel) spawner. Catostomids and Cyprinids were also collected in large numbers for all three years. Carp

were more abundant in the 1978 collectionswhile greater numbers of gizzard shad were collected in 1977. Sauger 

## - walleye numbers increased slightly from 1977 to 1979. Seasonal distribution of all larvae for the three years (Figure 10) illustrates earlier peaks in larval distribution for the year 1977. This was probably related to warmer early seasonwater temperatures (Figure 11) which resulted in earlier spawning activity compared to the other two years. Larval numbers and abundances for the three transects (plus the Big Sioux River) sampled in 1978 are given in Table 12. A comparison of total -47­ 

# 53larvae between the R.M. 808 and 

### R.M. 736.8 transects indicates that a significant number of larvae are contributed to the drift by the unchannelized reach of the Missouri River which lies between the two transect locations. Of the most abundant taxa only the Cyprinid group (minnows) failed to show any increase in abundance between the two transects. Drum was the most abundant larvae at all three Missouri River transects while carp larvae were most abundant in the Big Sioux River. Results from the 1980 and 1981 off-channel studies indicate differences in species composition and abundance between the main-channel and off-channel habitats for both study years (Tables 13 and 14). Drum dominated the mainchannel collections for both years while Notropis sp. (shiners) were the most abundant off-channel larvae. Other species more abundant in the mainchannel were carpsucker (Caproides) and Catostomid and Cyprinid prolarvae. Species more abundant in the off-channel collections included Percidae or Etheostoma (darters), Moxostoma (redhorse) and Dorosoma (gizzard shad). Although greater numbers of larvae were collected from the main-channel during both years, the actual larval densities (#fish/m 3 water sampled)

were greater in the off-channel habitats. Off-channel densities were 2.46 3 and 0.85 fish/m in 1980 and 1981while main-channel densities were 0.63 and 3 0.59 fish/m

# . Comparisons of productivity between types of off-channel habitats sampled (Tables 15 and 16) found the notched wingdikes followed by the creek habitats as most productive. In summary,Missouri River ichthyoplankton populations are dominated by Drum 

# - a pelagic or open water spawning species. A large majority 

### of larvae in the drift in the plant area come from the unchannelized reach of the river. Input of larvae from local off-channel areas can occur, but is limited by the small amount of this habitat that currently remains. -48-

# 1 

# 1 I i J 

# 1 

# 1 

# 1 1 

# 1 1 

# I 1 

# II 

# J J 

# 1 1 1 4 I 

# 1 Table 11 COMPARISON OF TOTAL NUMBERS AND RELATIVE ABUNDANCES (%) OF ALL LARVAL FISH COLLECTED IN THE CHANNEL BY INTERCEPT SAMPLING UPSTREAM FROM THE NEAL 4 SITE (1977

# - 1979).

Ap1 odin0tus g runniens

.(Drum) Catostomidae (Suckers) Cyprinidae (Minnows) Cyprinus carpio (Carp) Dorosoma cepedianum (Gizzard shad) Stizostedion (Sauger-Walleye) Percidae (Darters) Perca flavescens (Yellow perch) Morone chrysops (White bass) Polvodon spathula (Paddlefish) Lepomis (Sunfish) Pomoxis (Crappies) Other Unidentifiable Total Tota1water volume sampled: 1977 1978 1979 

# - R. M. 716.66 R.M. 717.6 R.M. 716.75 No. % No. % No. 

# x 6826 69.9 7193 75.9 9586 67.3 2031 21.5 1582 16.7 4217 29.6 

# *

- 109 1.1 109 .8 99 1.0 466 4.9 111 .8 619 6.3 43 .5 59 .4

18 .2 38 .4 45 .3

3 

### < .I 9 .1 33 .2 3 

## < .1 15 .2 11 .1 56 .6 6 

## < .1 28 .2

1 

### < .I 4 

### c .1 10 .1 2 

### <.1 7 

## < .1 17 .1 10 .1 4 .? .1 6 

### <.1

5** 

## < .1 5*** (.1 13**** 

### .1 23 .2 2 4.1 9768 9481 14247 18986 m3 14377m3 18146rn3 

# * Cyprinidae included with Catostomidae in 1977 

# ** Includes: Goldeye, Channel catfish, Centrarchidae 

# *** Includes: Goldeye, Channel catfish, Flathead catfish, Rainbow smelt 

# **** Includes: Goldeye, Channel catfish, Black bullhead, Redhorse

## ,Rainbow smelt

-49­ 

# 552.5

2.0

1.5

1.0

.5
0

2.5

2.0

1.5

1.0

.5 

# I 

# 1

0

2.5

2

### .o

1.5

1.0

.5

0 15 &Y 1977 

### R.M. 716.66

I I 30 15 30 15 30 June July Figure 10 Seasonal Distribution of all Larvae at the Port Neal Trgnsects -50-35

30

25

0 0 a k 9 U 20 a k a a fi PI H
15

10

5 Figure 11



# -- 1977



# -1978

--0- 1979

' ) I # 1 1 1 I 1 1. ,- - : April 

# ' May Junp August

Water Temperatures for the Larval

Fish Sampling Seasons (1977 

## - 1979)

-51-Table 12 Total Numbers and Abundance of All Types of Larval Fish Collected During 1978 at Each Sample Transect

R.M. 808 R.M. 736.8 R.M. 717.6 Taxa # Ab. # 

### Ab. # 

### Ab.

Freshwater drum 2552 71.6 8310 79.8 7193 75.9 Catostomidae 548 15.3 1125 

### 10.8 1582 16.7

(Sucker family) Cyprinidae

(Minnow family) 226 6.3 225 2.2 209 1.1 Carp 142 3.4 612 5.9 465 4.9 Big Sioux River # Ab.

20 

### 17.7 25 22.1



### 9 

### 8.0 39 34.5

0 0 0 0 0 0 

### 16 

### 14.1

0 0 0 0 0 0 3 

### 2.7 1 0.9 0 0



## - 113 Sauger-Walleye Darters



## . Yellow perch Gizzard shad White bass Crappie Sunfish

' Paddlefish Other* Unidentifiable 11 .3 34 .3 38 

### .4 5 .1 24 .2 9 .1 1 .1 16 .2 15 .2 

### 16 

### .4 27 .3 43 .5

3 

### .1 11 .1 5 .1 3 .1 11 

### .L 4 .1 

### 14 .4 9 .1. 7 .1

2 .1 1 S 7 A 4 .1 0 2

. .1 

### 5 .1 40 1.1 0 0 ':I 0

. ._.­ 3,563 10

## ,408 9 3.84.

*Includes: Goldeye, Channel catfish, Flathead catfish, Burbot, Rainbow smelt.

-52-

## -- 

# ---

---
--- Table 13 Total Numbers and Abundance of Larval Fish Collected From the Main-Channel and Off-Channel Areas During 1980 

# 1 

# I 1 1 1 Taxa Aplodinotus grunniens Catostomidae* Cyprinidae* Cyprinus carpio Stizostedion Dorosoma cepedianum Morone Chrysops Percidae (darters ) Perca flavescens Ictiobus Moxostoma macrolepidotum Carpoides Notropis Semotilus atromaculatus Pimephales promelas Lepisosteus Lepomis Pomoxis Polyodon spathula

TOTAL Main-Channel Off-Channel % Abundance # % Abundance 1,145 77.6 7 0.6 116 7.9 1 0.1

68 4.6 3 0.3

6 0.4 33 2.9 4 0.3 1 0.1 3 0.2 11 1.0 6 0.4 5 0.4 3 0.2 86 7.7 1 0.1 13 0.9 14 1.2

1 0.1 87 7.7 73 4.9 9 0.8 35 2.4 849 75.6 11 1.0

1 0.1 1 0.1 3 0.3 1 0.1 1 0.1 1,475 1,123

*Early prolarvae not identifiable

to Genus -53-

# I Table 14 

# i TOTAL "MBERS AND ABUNDANCE OF LARVAL FISH COLLECTED FROM MAIN-CHANNEL AND OFF-CHANNEL AREAS DURING 1981 

# J Main-Channe 1 Of�-Channel 

# J Taxa Number % Abundance Number % Abundance Aplodinotus grunniens 1129 62.5 115 23.2 

# 1 Catostomidae 

# 1 Carpiodes 

# 1 Dorsoma cepedianum Notropis Ictiobus Stizostedion Moxostoma macrolepidotum Etheostoma Cyprinus carpio Cyprinidae 

# J Morone Chrysops 

# J Polydon spathula Lepomis Perca flavescens Cycleptus elongatus Unidentified 408 22.6 14 2.8 80 4.4 4 

### .a 56 3.1 80 16.1 32 1.8 122 24.6 16 .9 8 1.6 16 .9 13 2.6 11 .6 30 6.O

8 .4 55 11.1 5 .3 3 .6 2 .1 15 3.0 .1 1 .2 .1 .1 .1



## - 

# - 1 .2 39 2.2 

## - 35 7.1 Total 1807 496



# II -54­

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# I I -56- 

# 11.8 Impingement/Entrainment Studies Impingement studieswere conducted at all three Neal Station cooling water intake structures on the following dates; Units I and I1 

# - February 1974 to February 1975, Unit I11 

# - January 1976 to August 1977, and Unit IV

# - July 1979 to December 1980. Sampling for the three studies was accomplished by placing a collectingbox in the sluicewater trough from the traveling screens which carries screen washings out of the intake structure. These washings are composed of debris and fishwhich are collected on the traveling screens and dislodged by a spray wash system. Weekly collections were made during six four-i.icmr shifts spaced throughout the week. Shiftswere conducted at all time ~72s throughout a 24 hour day. Collected fishwere identified, weighed and measured and checked formotility. Data from the three studies is presented in Table 17.

Table 17 Impingement Data for Neal Units 1-2, 3 and 4 Total Fish Length Morta1ity 

### # Fish/hr Unit Collected 

### # Species %<15cm %)15 cn 

### X Alive % Dead Sampled 1-2 812 26 94 0 56 44 l.O1 3 2914 34 87 13 63 37 4 11575 43 97 3 35 65 8.6

I li Impingement rates were low for all three inteke structures although the rate at Neal 4 (8.6 fish/hr) was greater than I' :'? other two intakes. Most of the impinged fish at all three intakez ':'?re of small size (less than 15 cm). Mortality rates were similar. a.; Antakes 1-2 and 3 at Neal North (R.M. 718.4) but were greater at the Unit 4 intake at Neal South (R.M. 716.4). Species composition of impinged fish was similar at'.allintakes. Of the fivemost frequently impinged fish at each intake four species; gizzard shad, freshwater drum, river carpsucker and channel catfish; were -57- 

# Icommon to all three studies. Bluegill (Neal 1-2), carp (Neal 3) and rainbow smelt (Neal 4) were the other species abundant inthe collections. Of the most abundantly impinged fish species, five (rainbow smelt, gizzard shad, carp, freshwater drum and river carpsucker) are non-game

or forage fish. These fish are quite prolific and are probably able to compensate for high mortality rates that occur. Rainbow smelt comprised 30%of the total number of fish impinged. This fish has only recently moved into the Middle Missouri from upstream reservoirs. It is difficult, therefore, to assess the significance of the rainbow smelt impingement, since it does not represent a portion of the balanced indigenous population. Open cycle cooling appears tohave a minfmleffect upon the biota of the channelized Missouri River. Locating tilt: intake structures along the main-channel border avoids the more productive quiet water habitat used by fish as spawning and feeding areas. Although larger numbers of fishwere impinged at Neal 4 than at Neal 1-2 and 3, nearly allwere young-of-year with expected highmortality rates and over 80%were rough fish species of littlevalue to the sport fishery. Low numbers of game fish (sauger, walleye, crappie, largemouth bass9perch and white bass)

were collected. These trends have also beeri obserced in studies of other open-cycle power plants on the Missouri River Xing 1977 and Lewis 1975). Plant operation has no direct effect upon fish habitat availability which Schmulbach (1975) and Kallemeyn and Novotny I* zonsider as the major factor affecting the size and abundance of fr, %33pulitionsin the channelized Missouri River. Habitat loss due to chs.r~~el~ization has adversely affected the overallproductivity of the river, Creel census studies by Groen (1973) found an annual harvest rate of 0.26 fish per hour in'the channelized Missouri compared to a 0.5 fishper hour rate for the unchannel­

-58-

# 1 

# 1 

# L 1 J 

# 1 

# 1 1 1 

# 1 1 

# 1 i d 

# J



# 1 1 1 

# 1 1 

# 1 

# 3 ized river reaches. Likewise, Schmulbach found greater abundances of fish in the unchannelized Missouri compared to the channelized river. Longterm studies of Fort Calhoun and Cooper generating stations have found no discernible effects on local fish populations attributable to station operation. The numbers of ichthyoplankton entrained at the Neal 4 stationwere estimated using the results of 1979 larval fish studies, the percentage of Missouri River water withdrawn during plant operation, and current and projected flow data. The entrainment estimate was made by calculating the volume of river water entrained and the number of larvae in that volume based on observed larval densities in the r ver at the time of withdrawal. Based on average summer river flows and designwithdrawal rates, the percentage of withdrawal when compared to total river flowwas 2%. 

### At the peak 1979 larval density of 3600 larvae/second in the entire river, only 2%or 72 larvae/second are subject to entrainment. A similar entrainment percent removal of 3.2%was reported by Hergenrader et. al. (1982) for a study on the Fort Calhoun Station in 1977. These are extremely.’j low exploitation rates especially when compared to the expected natural mortality rates for fish larvae in a natural system. Thus the effects of entrainment from the George Neal Power stations is expected to be minimal due to the low removal rate.

-59-Thermal Plume Studies Quarterly thermal plune studies have been conducted to map the downstream 2nd cross channel distribution of heated water entering the Missouri River from the Neal Station outflows. A summary of all thermal plume studies including electrical output, coolingwater discharge and plume dimensions is presented in Table 18. Thermal discharges fromNeal North have been mapped since 1972. Plume maps for each thermal study were reported by Tondreau (1982). at summer flow conditions for Units 1-3 are best illustrated by the July High output

20, 1977 thermal studies (Figure 10). On this date Neal North was generating at 

### 96% capacity (918 mw) with a river flow of 31.,300 cfs. The 10" 

### F isotherm extended 50 feet offshore and 175 feet downstr

- The 5" 

### F isotherm extended 70 feet offshore and 400 feet downstreamwith the 1.5" 

### F isotherm reaching 160 feet offshore and 1200 feet downstream. A winter low flowplume for high plant output was mapped on December 1, 1977 (Figure 12). 

### At this time output fromNeal North was 884 megawatts (93%capacity) and the low river flowwas 14,200 cfs. The 10" F isotherm extended 30 feet offshore and 800 feet downstrezim, The 5" 

### F isotherm extended 80 feet offshore and more than 1200 feet downsrream, The 1.5' 

### F isotherm

was 150 feet at its widest point and ccntinuec! zcnmstreampast the 1200 foot mapping mark. Neal 4 plumes have been mapped during m~' slant output at navigation season river levels for both one -YOpmpoperation. On July 9, 1980, with maximum generating 

### capciL- and twc circulatingwater pumps, the Unit 

### 4 10" 

### F isotherm extended 200 feet downstream and 80 feet offshore at its widest point (Table 18). The 5" 

### F isotherm extended 1100 feet downstreamwhile the 1.5" 

### F isotherm continued downstream for 5000

-60-feet (Figure 13). A Unit 4 plume study at maximum generating capacity and one pump operation occured on March 25, 1981 (Figure 13). In this

case the lO'F isotherm continued 225 feet downstream and was 80 feet at its widest point. Both the 5'F and 1.5'F isotherms were found to continue past the 5000 foot downstream point. The 5OF isotherm had a maximum width of 125 feet while the 1.5'F isotherm extended 325 feet offshore at its widest point. Since Neal 

### 4 is only 

### 1.8 miles downstream from Neal North, possible plume overlaps between the discharges from Neal North with the downstrean Unit 4 station have been considered. A sligkt overlap of the Neal 2-3 and Neal 4 plumes was recorded on August 2, 198% rl'ver flows of 

### 31,700 cfs. The overlap was observed only at the 1.5'F isorn-rm and was confined to the immediate shoreline. At both stations 5'F isocherm extensions were minimal. The 1.5'F isotherm from Unit 4 extended 5.5 miles downstream and was 300 feet offshore at its widest point. In summary,heated outflows from both stations are restricted from cross-channelmovement by the high velocity currents on the channel side of the river. The heated discharge is carried quickly downstream along the shoreline. Temperatures mapped at 

### 1, 5 and 10 foot depths indicate that considerablemixing occurs within each plume; :iZtle stratificationhas been detected.



### -61-h, a'u saJa 0 In m 00o m ua*d 0 N h mu3 O N d 44m m ro. 0 000000 0 000000 0 00 000, n n C m lnvl cnm A A A 4 N h

0 00o m 00 0 du) 4cv m m d d ddd

00o m 0 00 000-4 0 00 00cnN 

# J

d d4 r n h 

# ­ d ddmto l-l 

# 1

u *I4 0 0 0 0 0 m 0 m 0*5memCOr.bCOhI 

# 1 mu HWC U 

# 1 uU T I C P 

# 1 I c U 7 0 m a, Do M (d 0 0 c c c c, 0 c 0 MC- 0 0 0 0 0 0 0 0 0 alum 0 0 d Pl m. u', u3 m h >mw n rn rn * n e a r n ­ 1-I-rlu m 0 h cr) Is3 Il e d 4 &!a- u u- cv m cp, I-+ m m m

ma UaJ 

# z L hi c H 

# 1 1 1

cn cr 0-l cn b cc d h r. I 0 i 03 I-.! N I I rT) a, in I 03 co m to N 4 I N m I I u d hl I cn I N. P. cv (d I I cv I 0 I I I !a h cn d r. 4 c) r. 03 -62-40 Figure 12 Thermal Plume Maps of Neal 1-3 for July 20, 1977 and December 1, 1977

Distance Downstream (feet)

July 20, 1977

200' River Flow 34,300 cfs Gage 

### 14. -E$:c 918megawatts

10°F or greater 

# RT-9 5°F 

# k_J 1.5"F el IS Distance Downstream (feet)

200' River Flow 14,200 cfs Gage 12.6 feet 884 megawatts

-63-

# 1 

# 1 1 

# 1 

# II 1 

# J 

# 1 1 1

M 

# 1 F 

# I 1 J 

# 1

MO 

# J 

# 1 1 1

0 0 0 0 m



## 6

# 1 

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# 1 

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# 1 1 

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# 1 

# 1 1 

# 1 1 I I Brown's Lake Study Beginning in October of 1979, Iowa Public Service Company initiated

a project to provide an additional water source to the Brown's Lake oxbow which is located one-forth of a mile east of the Neal 4 plant site. Thermal effluent from the Neal 

### 4 plant was carried by underground conduit and discharged into a shallow drainage ditch and allowed to flow into the upper end 

### of the lake (Figure 14). In order to monitor this discharge and its possible effects on the water quality and aquatic life, a six-month study was conducted from June-November 1980. Parameters measured included temperature, dissolved oxygen, pH, nitrates and green and blue-green algae. The results from the study indicated no significant effect by the effluent upon the parameters investigated. No increaser; in water temperatures at the north (discharge) end of the lake were measured. In fact,water temperatures at this site were in most cases cooler than those measured at other locations

on the lake. It is probable that the lengthy overland flow of the discharge prior to reaching the lake results in considerable heat transfer to the air, thus minimizing the thermal effects. This lack of an elevated temperature

zone did not cause the expected reduction in dissolved oxygen levels or increases in algal populations. The dense macrophyte populations present in Brown's Lake, as discussed by Johnson (1979), would also tend to limit algal populations by tying up the available nutrients

# - nitrates and phosphates which were measured at consistently low levels during the sssple periods. Overall, the additional water supply has Lesnbeneficial to the water quality and aquatic life in Brown's Lake. Ey increasing the surface area and average depth,more areas of primary productivity have been created while minimizing the chances for winter-kill which threatens most of the.Missouri River oxbow lakes. The success of this project has prompted the Iowa Conservation Commission and Iowa Public Service to initiate a similar project

on the nearby Snyder Bend oxbow. -65-

# 1 

# 1 I 

# 1 J J 

# 1 

# 1 1 1 4 

# I rl 

# J J J Figure 

### 14 Brown's Lake Sampling Sites 

# 1

NORTH

L_

1000 feet 

# 1 drainage 

# 1 canal 

# 1 1

-66-SUMMARY 

### AND CONCLUSIONS Hydrological Conditions Above average mean flows during the ten year period were influenced by three years (1972, 1975 and 1978) of very high flow rates which affected both the summer and winter flow periods. These above normal flows contributed to the problem of river bed degradation on the Missouri River in the study area. The degradation and resulting drop inwater surface elevation (estimated tobe 7.2 feet inthe Sioux City area since 1961), has resulted in the loss of most of the productive backwater and side-channel habitats which were present at the beginning of this study. This habitat loss hEL ?everely impacted many fish and wildlife specieswhich rely an these habitats for spawning, nursery and feeding areas. Also lost are the aquatic plants and lower aquatic lifeforms inthese areas which contribute to the primary productivity of the river ecosystem. No plant related effects on the river hydrology have been observed during the ten year study. However, the drop inwater surface elevation has resulted inthe loss of effectivewater depth within fixed water intake structures which include the cooling water Fntzxes for the Neal Units 

### 1-4. Water Quality Water quality of the Missouri River in tb. c+,>dyarea is influenced by run-off and to a lesser degree by point-sour- -,scharges in the Sioux City

area upstream of the study area. RuR-o~~ fz

- heav7 precipitation or snowmelt can cause significant increases in COD, ammonia, nitrate, phosphate, turbidity, solids and indicator bacteria levels. Indicator bacteria levels have decreased markedly due primarily to improvements to the waste water

-67-treatment facility for the city of Sioux City. Station operationwas found to have no effect on any of the chemical and physical parameters measured during the ten year study. At no time did the outflows from the plants exceed present water quality standards. Plankton Plankton populations in the Missouri River are characterizedby low numbers of zooplanktonand larger numbers of phytoplankton of which diatoms

are the dominant group. This trend is typical of riverine systems. Most researchers cite the upstream reservoirs as the primary sources of plankton to the downstreampopulations. No significant differences in numbers ox :L,,arsity were observed between sample sites above and below the plants for the ten-year period. Macroinvertebrates Channelizationand degradationhave nearly eliminated the benthic (bottom) macroinvertebrate community. However, a diverse "aufwuch" community is supported by the rock rip-rap shoreline areas constructed as part of the channelizationplan. This favorable substrate along with larger amounts of organic detritus {food source) has resulted in greater densities observed in the channelized river compared to the unchannelized reaches. Data from artificial substratesplaced above and below plant outflows consistently found greater numbers of organisms in the plume influenced areas. Fisheries Quarterly population survey data for the :.7nars 1974-1982 for fish collected by electroshocker indicates a stable population characterizedby large numbers of a soall number of dominant fish spedies. Carp, carpsucker,gizzard shad, goldeye, shorthead redhorse and buffalo sp. collectively composed nearly 90%

-68-

### I 

## J

nJ



# I 

# 1 1 1 1 

# 1 

# d 

# d 1

I 1 3



## I of all fish collected. Good numbers of flathead and channel catfish are also present. Of the 52 species collected during the study these eight have most readily adapted to present conditions in the channelized Missouri River. Many of the remaining species have declined in abundance due to the loss of off-channel habitat which is necessary for spawning, nursery and feeding areas. Most fish are now found along the revetment shorelines and the pockets below and above the wingdikes. Thermal attraction studies conducted in 1974 (Units 1-3) and 1980 (Unit 4) found that fish are attracted to the warm water areas below the outflow, especiallywhen ambient river temperetures are colder (below 2OoC). The maintenance of feeding activity enhanced k-- the warmer water is a major

reason for the exhibited thermal attraction. No adverse effects to the thermally attracted fish were observed during either study. Larval fish studies conducted from 1977 to 1981 found drum and members of the minnow and sucker families as most dominant in the main-channel drift. Based on results of the 1978 studies, the unchannelized river reach above Sioux City is the major contributer of larvae to the downstream river. Input of larvae from local off-channel areas can occur but is limited by the small amount of this habitat that currently remains. Impingement/Entrainment Studies Fish impingement at the Neal Station intake structures appears to have little or no effect on fish populations. The ~135,ilpingementrates ((10 fish/hr), the types of fish collected (mostly rough fisk. and the small size of the fish impinged, results in aminimal impact KO the fish community. Entrainment of larval fish at the Neal Station Units is minimal due to the small amount of the total river flow (less than 3%) that is subject to entrainment. -69-

# J Thermal Plume Studies Thermal plume mapping of the discharges at both Neal 1-3 and Neal 4 has found that the heated water is restricted from cross-channel movement by the high velocity current on the channel side of the river. The most elevated temperature areas remain close to the shoreline which allows fish tomove upstream without entering the thermal zone. Temperatures taken at one, five and ten foot depths show minimal stratification and indicate that considerablevertical mixing occurs within each plume. Brown's Lake Study In cooperation with the Iowa Conservation Commission, the Iowa Public Service Company has initiated projects to provick additionalwater supplies to nearby oxbow lakes whose depth and surface ---c2have been reduced due to degradation. A sixmonth study on Brown's Lake on the possible physical and chemical effects of the discharge from the plant found no adverse effect upon the lake and its biota. The increase in lake depth and surface area has created more areas of primary productivity while reducing the threat of "winter-kill" which plagues most Missouri River oxbow lakes. The success of thisproject has prompted the initiation of s. similar project on the Snyder Bend oxbow. Conclusion The results of this ten year study indicate that little, if any, detrimental impact to the Missouri River ecosy::::?.:. can be attributed to the operation of George Neal Units 1-4. A h&rmGT?i.;i:iC;balance between industry and nature is being maintained through. consci-ntisus effort and study by Iowa Public Service Company and Morningside College,

-70- 

# 1

# 1 

# 1 1 1 

# J J 

# 1 1 1 

# 1 

# II L 

# rl J 

# 1

I 

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# 3 I I LITERATURE CITED Carter, S.R., K.R. Bazata and D.L. Andersen, 1982. Macroinvertebrate Communities of the Channelized Missouri River Near Two Nuclear' Power Stations. Pages 147-178 in L.W. Hesse, G.L. Hergenrader, H.S. Lewis, S.D. Reetz and A.B. Schlesinger, editors. The Middle Missouri River. The Missouri River Study Group. Cowell, B.C., 1970. The influence of plankton discharges from an upstream reservoir on standing crops in a Missouri River reservoir. Limnology and Oceanography 15: 427-441. Groen, C.L., 1973. 

### "A Creel Census Survey of the Missouri River Sport Fishery." M.A. Thesis, University of South Dakota,Vermillion, S.D. Gurtz, M.E. and C.M. Weiss, 1974. Effect of thermal stress on phytoplankton productivity in condenser cooling water. Pages 490-507 in J.W. Gibbons and R.R. Sharitz, editors. Thermal Ecology. U.S. Atomic Energy Commission,Washington, D.C. Hergenrader, G.L., L.G. Harrow, R.G. King, G,F, Cada and A.B. Schlesinger, 1982. Larval Fishes in the Missouri Riw- md. the Effects of Entrainment. Pages 185-221 in L.W. Hesse, +*L.Hergenrader, H.S. Lewis, S.D. Reetz and A.B. Schlesinger, editors. The Middle Missouri River. The Missouri River Study Group. Johnson,M., 1979. "The Limnological Characteristics and Management of Four Western Iowa Oxbow Lakes." Unpublished Master's Thesis. Iowa State University,Ames, Iowa. Kallemeyn, L.W. and J.F. Novotny. "Fish and Fish Food Organisms in Various Habitats of the Missouri River in South Dakota, Nebraska and Iowa." Biological Services Program FWS/BS-77/25. 

### U.S. Dept. of the Interior. King, R.G., 1977. "Fish Larvae and Distribution Study." In: Fort Calhoun Station Unit 

### No. 1 Five Year Report. Ornzha Public Power District, Omaha, Nebraska. Lewis, H.S., 1975. "The Evaluation of Themal Effects in the Missouri River near Cooper Nuclear Station." Nebraska Public Power District. Morris, 

### J., L.A. Morris and A. Witt, 1972. The Fishes of Nebraska. Nebraska Game and Parks Commission,Lincoln,Nebre:..- Reetz, D., 1982. Phytoplankton Studies in the 1:3ssouT-iRiver at Fort Calhoun Station and Cooper Nuclear Station. Pa, 

### . 71-81 in L.W. Hesse, G.L. Hergenrader, 

### H.S. Lewis, S.D. Reetz and 

### +-.a. Schlesinger, editors. The Middle Missouri River. The Missouri River Study Group. Roosa, 

### D.M., 1977. "Endangered and Threatened Fish of Iowa." Special Report of the Preserves Board, No. 1. Iowa. Conservation Commission.

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# 1 4 1 Schmulback,

### J.C., G. Gould and C.L. Groen, 

### 1975. "Relative Abundance and Distributionof Fishes in the Missouri River, Gavin's Point Dam to Rulc, Nebraska." Proceedings, South Dakota Academy of Science, 54: 194-222. Smith, R.A., 

### A.S. Brooks and L.D. Jensen, editor, 1974. Effects of condenser entrainment on algal phytcsynthesis at mid-Atlantic power plants. Pages 113-122 in L.D. Jensen, editor. Proceedings of the Second Entrainment and Intake Screening Workshop. Johns Hopkins University Report Number 

### 15. Electric Power Research Institute, Palo Alto, California. Tondreau, R., 1982. "Summary Report of Thermal Plume Studies 1972-1981." Aquatic Studies,Morningside College, Sioux City, iowa. U.S. Army Gorp of Engineers. 1981. Supporting Technical Report 

# - Missouri River Degradation. Washington, D.C.: GPO. 

### U.S. Department of the Interior Geological S~rvey. 1974. Water Resources Data for Iowa. Washington, D.C,: GPO, U.S. Department of the Interior Geological S, -.* 1979. Water Resources Data for Iowa. Washington, D.C.: GPO.