-- 

~UURIRIVER AQUATIC 

ECOLOGY STUDIES 

Ten Year Suihmary 

(1972 -1982 ) 

n R 

by Morningside College, 

Sioux City, Iowa 

-a 

for 

Iowa Public Service Company, 

Sioux City, Iowa 
AQUATIC 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, IOWA 
ABSTRACT 

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 in this 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 operation was 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. Macroinvertebrates have become established on the rock rip-rap 

shoreline areas with channelization nearly elbinating the benthic (botton 

dwelling) forms. Numbers were consistently gre.aLer in the plant outflow 

areas. Of 52 fish species collected in the 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 

especially when river temperatures are colder. No adverse affects to the 

fish from this attraction have been observed. Fish impingement and 

entrainment by the plant intake structures was found to be 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. 

3 
TABLE OF CONTENTS 

Page 

i 

Abstract 

Introduction 

Description of the Missouri River and Study Area 

The George Neal Station Units 1-4 

Description of the Sample Sites 

Results 

Hydrology 

Water Quality 

Introduction 

Standard Methods 

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 Study Area 

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Table of Contents cont. 

Figures cont. Page

2 Channel Depth Profiles Near Neal 1-3

3 

4 

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6 

7 

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11 

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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 

Fisheries Map - backwater and shoreline areas 

Yearly Average Abundances for Selected Species 

Collected by Electroshocking During 1974-1982 

Comparison of 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 

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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 Zooplankton Genera 

Collected 1972 - 1982 

7 Total Numbers 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) 

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63 

64 

66 

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Tables cont. -

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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 

Impingement Data for Neal Units 1-2, 3 and 4 57 

Thermal Plumes - Neal South - Unit 4 62 
INTRODUCTION 

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 Protection Agency 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 structural measures 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 five mainstream reservoirs are located in Montana, 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 to partially 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 in backwaters. The 

river bottom is hard packed and scoured. 

River flows are regulated to provide 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 feet wide at the Neal 

Station (Units 1-3), river mile 718.43. 

The George Neal Station Units 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 

in the 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 in the 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-
included in this report. The total generating capacity of all four units

is 1538 megawatts. Table 1 contains general specifications including 

completion dates, electrical generating capacity, cooling water flow, 

condenser temperature rise and location of all four units. 

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Table 1 General Specifications for the George Neal Electrical 

Generating Units 1-4 

Nameplate Design Cooling Condenser 

Commercial Rating Water Flow Temperature 

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. 

Description of 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 

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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 farthest upstream, served as a control or indicator of water 

quality coming from upstream into the study area. The most frequently 

sampled sites designated as farthest downstream were 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 years water samples were collected matnly from the Iowa side, 

about 10 feet offshore at each site. 

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Figure la 

Water Quality Sampling Sites 

from 1972 - 1976

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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 from Neal 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 
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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 in reservoir 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 1981 were preceded 

by the dry years of 1976 and 1980 whose 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 in the study area are dependent on discharge (flow) 

rates, the cross-sectional position within 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 in bend radius. The main channel 

velocities for the river reach included in the study area are among the 

lowest observed in the entire Missouri River from Sioux City, Iowa (R.M. 732) 

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to Rulo, Nebraska (R.M. 540). Velocities in the main channel border and 

off-channel areas typically range from 0.5 to 3.0 fps. 

The phenomenon of river bed degradation has been in evidence within 

the study area. The confining of the river channel to an average width 

of 700 feet in the study area along with the corresponding increases in 

current velocities has resulted in the 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 in the vicinity of Sioux City has been 7.2 feet since 1961. Of 

this amount 3 feet (42% of the total) of surface elevation was lost in the 

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 in the Sioux City area is 2 to 3 feet 

of additional bed loss by the year 2000. In the 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 in water 

temperature,.a change in elevation of approximatel-y 1.5 feet is indicated 

by the differences in river gage heights and measured channel depth. 

The profiles also indicate that the channel confiyuration remained 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 in the amount of off-channel 

-10­

k 
habitat - 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 

structures which 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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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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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 six months 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 (heavy metals 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 study monitors 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 in levels 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 to be 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 to be significantly higher 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 to heavy precipitation just 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 exception was 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 outflow was 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 

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that was ever noted on the fish populations. Temperature increases were 

not great enough to produce fishkills; there was no difference in growth 

rates or disease levels for fish shocked in the 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 in the 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 in the 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 

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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 in the 

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, studies between 

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 0

2

/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 in water is temperature dependent, the temperature of an outflow into 

the river can affect the dissolved oxygen level. 

The dissolved oxygen (DO) levels in the river varied with river temperature 

from lows around 7 mg/l in the summer months to highs 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 in river DO were at site 7 

in the period between 1972 and 1976 when this outflow was monitored. Drops 

in DO 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 

-1 9-
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 14 mg/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 (NH3 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 surface waters. 

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 10 mg/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 eutrophication process 

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 nitrogen was 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 in the 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 to have 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 in the 

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. 

-22-
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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 coliforms per 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 100 milliters 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 especially with 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/concentrating effect on bacteria levels 

during high/low flow periods. Counts during the low flow months of 

December and 3anuary have been consistently higher 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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Plankton 

Two major groups, zooplankton and phytoplankton, comprise the plankton 

found in the Missouri River aquatic ecosystem. The purpose of the plankton 

studies was to describe the species composition and 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 Plankton net (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 zooplankton populations (Hynes, 

1970), therefore much larger quantities of water would be needed to collect 

representative populations 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 community was comprised almost 

exclusively of diatoms. Asterionella alone or in combination with centric 

diatoms such as Cyclotella and Stephanodiscus composed as much as 95% 

of the total phytoplankton. Asterionella, a cold water form, underwent 

several blooms 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. Zooplankton were most abundant in summer samples. These 

-27-
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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 consider mechanical effects such as abrasion and pressure changes 

and sudden thermal increases experienced by the plankton during condenser 

passage. Phytoplankton responses 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 inhibition being affected by absolute discharge temperature and duration 

of exposure (Gurtz and Weiss, 1974 and Smith et. al. 1974). 

Plankton numbers and composition were 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. 

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TABLE 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 

Closterium 

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 

Difflugia 

Dinobryon 

Euglena

Flagellates 

Heliozoa 

Stentor 

Suctoria 

Volvox 

Vorticella 

Rotifers 

Keratella 

Platyias 

Synchaeta 
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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 samplers until 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 sampler was 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 Ephemeroptera were more consistent for all the sample years. 

Macroinvertebrate populations in the channelized Missouri River have 

been affected by physical changes in the river which have resulted from 

-30-
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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" community which 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 invertebrates was 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.cn operation 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. 

-31-
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-33-
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for the Above Plume ( - ) and in Plume ( -- ) Sites 

for the years 1972 - 77, 1979 

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Year 

-34-

LBP 
FISHERIES 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 information relative 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 abundance was 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 smallmouth buffalo 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 

sample methods indicate that sizeable populations of the two species do exist. 

Some yearly fluctuation was 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-

I 
researchers: 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 states which border on the Missouri River. 

I 

I 

-37-
Neal 1-3 

Figure 5 

FISHERIES MAP 

backwater and shoreline areas 

wa Public Servrice 

Backwater and Spur Dike 

Sampling Sites B-J 

Shoreline Revetments 

shocked xxxxxx 

-38-

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a *rl rl rl rlm (d k 0 k m m rn .a m a mu U a L9 L9 GI PI rn $ $ 

-39-
Figure 6 

Yearly Average Abundances for Selected Species 

Collected by Electroshocking During 1974-82 

40 

30 

20 

10 1Shorthead redhorse 

_­--Sauger 

-.­

i -75 76 77 78 79 80 81 82 

Years 

I

i 

I 

10 -. 

Goldeye 

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 

4 I 1 

Table $3 

* 

Yearly C.P.U.E. #/hr. 

N4 Below N3 Above N3 -

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) 

Scaphirhynchus platorynchus (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-
1 

1 

a 

1 

J 

1 

1 

1 

1 

1 

1 

1 

1 

J 

1 

J 

1 

1 

Table 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) 

Stizostedion vitreum 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

i 
Thermal Attraction Studies 

1 

J 

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 outflow were sampled 

weekly from September to November. Fish in both studies were 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 percentage was even greater for the 1980 

study when 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 

temperatures decrease the percentage of fish in the plume area increases. This 

would indicate the thermal attraction of fish to the plume influenced areas 

especially when 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 activity which 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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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 sampling was 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 transects were 

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. Studies were conducted in 1980 and 1981 to assess 

larval productivity from local off-channel areas and document their contributions to the main-channel drift. Samples were 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 collections while 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 season water 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

53 
larvae 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/m3 water sampled) 

were greater in the off-channel habitats. Off-channel densities were 2.46 

3 and 0.85 fish/m in 1980 and 1981 while 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-
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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). 

Ap1od in0tus g runniens 

. (Drum) 

Catostomidae 

(Suckers) 

Cyprinidae 

(Minnows) 

Cyprinus carpio 

(Carp) 

Dorosoma cepedianum 

(Gizzard shad) 

Stizostedion 

(Sauger-Walleye) 

Percidae 

(Darters) 

Perca f lavescens 

(Yellow perch) 

Morone chrysops 

(White bass) 

Polvodon spathula 

(Paddlefish) 

Lepomis 

(Sunfish) 

Pomoxis 

(Crappies) 

Other 

Unidentifiable 

Total 

Tota1 water 

volume sampled: 

1977 1978 -

1979

R. M. 716.66 R.M. 717.6 R.M. 716.75 

No. % No. % No. x 

6826 69.9 719 3 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

55 
2.5 

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 

Aplod inotus grunniens 1129 62.5 115 23.2 1 

Catostomidae 

1 Carpiodes 

1 Dorsoma cepedianum 

Notropis 

Ictiobus 

Stizostedion 

Moxostoma macrolepidotum 

E theos toma 

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 49 6 

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1.8 

Impingement/Entrainment Studies 

Impingement studies were 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 collecting box in the sluice water trough from 

the traveling screens which carries screen washings out of the intake 

structure. These washings are composed of debris and fish which 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. Shifts were conducted at all time ~72sthroughout a 24 

hour day. Collected fish were identified, weighed and measured and checked 

for motility. 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 

3 2914 34 87 13 63 37 l.O1

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'.all intakes. 

Of the five most frequently impinged fish at each intake four species; 

gizzard shad, freshwater drum, river carpsucker and channel catfish; were 

-57-

I 
common to all three studies. Bluegill (Neal 1-2), carp (Neal 3) and 

rainbow smelt (Neal 4) were the other species abundant in the 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 to have a minfml effect 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 

fish were impinged at Neal 4 than at Neal 1-2 and 3, nearly all were 

young-of-year with expected high mortality rates and over 80%were rough 

fish species of little value to the sport fishery. Low numbers of game 

fish (sauger, walleye, crappie, largemouth bass9 perch 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 overall productivity 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 fish per hour rate for the unchannel­

-58-
1 

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1 

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1 

1 

1 

1 

1 

1 

i 

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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 station were 

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 design withdrawal 

rates, the percentage of withdrawal when compared to total river flow was 

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, cooling water discharge and 

plume dimensions is presented in Table 18. 

Thermal discharges from Neal 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 downstream with the 1.5" F isotherm 

reaching 160 feet offshore and 1200 feet downstream. 

A winter low flow plume for high plant output was mapped on December 1, 

1977 (Figure 12). At this time output from Neal North was 884 megawatts 

(93% capacity) and the low river flow was 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! zcnmstream past the 1200 foot 

mapping mark. 

Neal 4 plumes have been mapped during m~' slant output at 

navigation season river levels for both one -YO pmp operation. On 

July 9, 1980, with maximum generating capciL- and twc circulating water 

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 downstream while 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-channel movement 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 

considerable mixing occurs within each plume; :iZtle stratification has 

been detected. 

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h, a'u saJa 0 In m 00 o m ua*d 0 N h mu3 O N d 44 m m ro. 

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-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 918 megawatts 

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 

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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 Lesn beneficial 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-
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Figure 14 

Brown's Lake Sampling Sites 

1NORTH 

L_ 

1000 feet 

1 drainage 1 canal 

1 

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-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 in water surface elevation (estimated to be 7.2 feet in the 

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 species which rely an these habitats for spawning, nursery and 

feeding areas. Also lost are the aquatic plants and lower aquatic life forms 

in these 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 in water surface elevation 

has resulted in the loss of effective water 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 operation was 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 characterized by low 

numbers of zooplankton and 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 downstream populations. 

No significant differences in numbers ox :L,,arsitywere observed between 

sample sites above and below the plants for the ten-year period. 

Macroinvertebrates 

Channelization and degradation have 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 

channelization plan. 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 substrates placed 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 characterized by large numbers 

of a soall number of dominant fish spedies. Carp, carpsucker, gizzard shad, 

goldeye, shorthead redhorse and buffalo sp. collectively composed nearly 90% 

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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, especially when 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 ~13 5,ilpingement rates ((10 fish/hr), 

the types of fish collected (mostly rough fisk. and the small size of the fish 

impinged, results in a minimal 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 to move upstream without entering the thermal zone. Temperatures 

taken at one, five and ten foot depths show minimal stratification and indicate 

that considerable vertical 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 additional water supplies 

to nearby oxbow lakes whose depth and surface ---c2 have been reduced due to 

degradation. A six month 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 

this project 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, 

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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-i River 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. 

-71-
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Schmulback, J.C., G. Gould and C.L. Groen, 1975. "Relative Abundance 

and Distribution of 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.