## DETAILED STUDY OF IRRIGATION DRAINAGE IN AND NEAR WILDLIFE MANAGEMENT AREAS, WEST-CENTRAL NEVADA, 1987-90



## Part B. Effect on Biota in Stillwater and Fernley Wildlife Management Areas and Other Nearby Wetlands

Robert J. Hallock and Linda L. Hallock, Editors U.S. Fish and Wildlife Service

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 92-4024B

U.S. GEOLOGICAL SURVEY, U.S. FISH AND WILDLIFE SERVICE, U.S. BUREAU OF RECLAMATION, and U.S. BUREAU OF INDIAN AFFAIRS

Carson City, Nevada 1993

### U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY DALLAS L. PECK, Director

Any use of trade names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.



### For additional information write to:

District Chief U.S. Geological Survey 333 West Nye Lane, Room 203 Carson City, NV 89706-0866 Copies of this report can be purchased from:

U.S. Geological Survey Earth Science Information Center Open-File Reports Section Box 25286, MS 517 

### Denver Federal Center Denver, CO 80225-0046

# CONTENTS

Page

ABSTRACT

.......................................................................................................................................................................... 1 INTRODUCTION

.............................................................. 3 Background

............................................................................................................................................................... 3 Purpose and Scope

..................................................................................................................................................... 4 Study Area ..........................................................................................................................................................^ 5 Acknowledgments

..................................................................................................................................................... 5

ESTIMATED HISTORICAL CONDITIONS OF THE LOWER CARSON RIVER WETLANDS

..................................................................................................................................... 7 Linda L. Kerley, GeoffreyA. Ekechukwu, andRobertJ. Hallock U.S. Fish and Wildlife Service Estimated Historical Carson River Flow and Wetland Sizes

................................................................................................ 7 Unregulated Flow ofthe Carson River

...................................................................................................................... 7 Average Historical Size ofCarson Lake

................................................................................................................... 10 Flow Through Stillwater Slough

............................................................................................................................... 11 Average Historical Size ofStillwater Marsh

............................................................................................................. 11 Estimated Flow into Carson Sink Wetlands

.............................................................................................................. 12 Estimated Size ofCarson SinkWetlands

.................................................................................................................. 12 Estimated Historical Water Quality

...................................................................................................................................... 13 Vegetation .............................................................................._^ 17 Wildlife

................................................................................................................................................................................. 18 Present/Projected Wetland Conditions

.................................................................................................................................. 19

TOXICITY OF IRRIGATION DRAINAGE AND ITS EFFECT ON AQUATIC ORGANISMS

........................................................................................................................................ 21 Susan E. Finger, Steven J. Olson, andAnn C. Livingstone U.S. Fish and Wildlife Service Methods

............................................................ 21 Sample Collection

..................................................................................................................................................... 21 Toxicity Assessments

................................................................................................................................................ 23 Chemical Analyses

................................................................................................................................................... 23 Results ofToxicity Tests

....................................................................................................................................................... 25 Paiute Diversion Drain and D-Line Canal

................................................................................................................ 25 TJ Drain

..................................................................................................................................................................... 25 Well Near TJ Drain

.................................................................................................................................................... 28 Hunter Drain............................................................................................................................................................... 29 Lead Lake ......................................................................................................................................................^ 31 Stillwater Point Diversion Drain and Stillwater Point Reservoir

.............................................................................. 32 Effect ofIrrigation Drainage on Aquatic Organisms

............................................................................................................ 35 Ionic Composition

..................................................................................................................................................... 37

CONTENTS

### Page

BIOLOGICAL PATHWAYS: MOVEMENT OF SELENIUM AND MERCURY

........................................................................................................ 39 RobertJ. Hallock, HowardL. Burge, andPeterL. Tuttle U.S. Fish and Wildlife Service Study Areas

.......................................................................................................................................................................... 39 Approach and Methods

......................................................................................................................................................... 44 Results

.................................................................................................................................................................................. 44 Bioaccumulation and Biomagnification ofSelenium and Mercury

.......................................................................... 45 Selenium and Mercury Pathways

.............................................................................................................................. 46 Duration ofSelenium Contamination

....................................................................................................................... 50 Contaminant Source Areas

....................................................................................................................................... 51 EFFECTS OF BORON, MERCURY, AND SELENIUM ON WATERFOWL PRODUCTION

.............................................................................................................................. 55 LindaL. Hallock, C. Anne Janik, andLindaL Kerley U.S. Fish and Wildlife Service Approach

.............................................................................................................................................................................. 55 Methods

................................................................................................................................................................................ 55 Hatch Success and Teratogenesis............................................................................................................................... 57 Trace Elements in Eggs

............................................................................................................................................. 57 Trace Elements in Juvenile Duck Livers

.................................................................................................................. 59 Nest Success......................................................................................................................................................^ 62 Waterfowl Production

............................................................................................................................................... 63

MERCURY AND SELENIUM IN EDIBLE TISSUE OF WATERFOWL

.......................................................................................................................................................... 65 RobertJ. Hallock, HowardL. Burge, andPeterL. Tuttle U.S. Fish and Wildlife Service Approach and Methods

......................................................................................................................................................... 65 Mercury Accumulation in Waterfowl

....................................................................................................................... 66 Selenium Accumulation in Waterfowl

...................................................................................................................... 68

OVERALL SUMMARY OF EFFECT OF IRRIGATION DRAINAGE ON BIOTA

......................................................... 71 RobertJ. HallockandLindaL. Hallock U.S. Fish and Wildlife Service

REFERENCES CITED

........................................................................................................................................................ 72 SUPPLEMENTAL WATER-QUALITY DATA FROM TOXICITY STUDY

.................................................................... 77

Figures

1. Map showing general physiographic features in the study area and western Nevada........................................... 2 2. Reproduction ofearly map showing configuration ofthe lower Carson River basin before development........... 8 3. Graph showing mean monthly flow and quartile statistics, Carson River gage near Fort Churchill, water years 1919-69.............................................................................................................. 9 4. Map showing locations oftoxicity sampling sites and importanthydrologic features in and near Stillwater Wildlife Management Area.................................................................................. 22

IV CONTENTS

### Page

5-7. Graphs showing: 5. Cumulative mortality offreshwater organisms in undiluted surface-water samples collected in and near StillwaterWildlife Management Area........................................................... 35 6. Changes in specific conductance in Lead Lake and selected drains during toxicity study........................... 36 7. Relations between specific conductance and mortality ofbluegills, fathead minnow larvae, and daphnids........................................................................................................................ 37 8-10. Maps showing locations of: 8. Sampling sites for drift and biota in and near Stillwater Wildlife Management Area................................... 40 9. Sampling sites for drift and biota in and near Fernley Wildlife Management Area...................................... 41 10. Additional sampling sites for detritus and algae in and near Stillwater and Fernley Wildlife Management Areas and Carson Lake................................................................................. 42 11-13. Diagrams showing arithmetic means, medians, and ranges ofselenium

concentrations in composite samples from: 11. Input drains, Lead Lake, and downgradient wetlands, and generalized flow path in Stillwater Wildlife Management Area....................................................................................................... 47 12. A-Drain, South Pond, and downgradient wetlands, and generalized flow path in Fernley Wildlife Management Area.......................................................................................................... 48 13. Hunter Drain, Stillwater Wildlife Management Area.................................................................................... 50 14. Map showing selenium concentrations in detritus samples from in and

near Stillwater and Fernley Wildlife Management Areas..................................................................................... 52 15. Map showing mercury concentrations in detritus samples from in and near Stillwater and Fernley Wildlife Management Areas............................................................................................. 53 16-18. Diagrams showing: 16. Concentrations ofselenium in duck eggs and liver tissue of juvenile ducks................................................. 62 17. Concentrations ofmercury in edible portions ofshoveler ducks................................................................... 67 18. Concentrations ofmercury in edible portions ofvarious duck species.......................................................... 68

Tables

1. Estimated historical (predevelopment) wetland acreage compared to projected wetland acreage at Carson Lake and the combined wetlands of Stillwater Marsh and Carson Sink

....................................................................................................................... 11 2. Estimated historical (predevelopment) and recent orprojected water quantity and dissolved-solids concentrations and loads for Carson River, Carson Lake, and Stillwater Marsh

............................................................................................... 15 3. Concentration factors between wetland units and recent and projected concentrations ofdissolved solids, Stillwater Wildlife Management Area

................................................................................................................................................ 20 4. Analytical reporting limits for selected inorganic constituents in water

.............................................................. 24 5. Cumulative mortality ofbluegills, fathead minnow larvae, and daphnids after exposure to water from Paiute Diversion Drain diluted with reconstituted water and water from D-Line Canal

..................................................................................................................................... 25 6. Ranges ofwater-quality measurements in surface-water samples collected daily, August 10-18, 1988, for aquatic toxicity tests...................................................................................................... 26 7. Cumulative mortality ofbluegills, fathead minnow larvae, and daphnids exposed to water from TJ Drain diluted with reconstituted water

..................................................................................... 27 8. Cumulative mortality ofbluegills, fathead minnow larvae, and daphnids exposed to water from TJ Drain diluted with water from D-Line Canal

........................................................................... 28 9. Concentrations ofinorganic constituents in ground water collected from U.S. Geological Survey well DH-102B in the vicinity ofTJ Drain, August 17, 1988

........................................ 29 10. Cumulative mortality ofbluegills, fathead minnow larvae, and daphnids exposed to water from Hunter Drain diluted with reconstituted water

.............................................................................. 30 11. Cumulative mortality ofsaltwater species exposed to water from Hunter Drain diluted with reconstituted water

........................................................................................................................... 31

CONTENTS \Page

12. Cumulative mortality ofbluegills, fathead minnow larvae, and daphnids exposed to water fromLead Lake diluted with reconstituted water

.................................................................................. 32 13. Cumulative mortality ofbluegills, fathead minnow larvae, and daphnids exposed to water from Stillwater Point Diversion Drain diluted withreconstituted water

................................................ 33 14. Cumulative mortality ofbluegills, fathead minnow larvae, and daphnids exposed to water from Stillwater Point Diversion Drain diluted with water from Stillwater Point Reservoir

.................. 34 15. Sampling sites for drift, detritus, and algae

.......................................................................................................... 43 16. Hatch success ofartificially incubated waterfowl eggs collected in the study area, 1988

................................... 57 17. Summary ofdata on concentrations ofboron, mercury, and selenium, including minimums, maximums, andmeans, for waterfowl eggs collected in the study area............................................ 58 18. Effect levels and characteristics ofboron, mercury, and selenium concentrations in waterfowl eggs andjuvenile waterfowl livers

.................................................................................................. 59 19. Summary ofdata on concentrations ofboron, mercury, and selenium, including minimums, maximums, and means, forjuvenile waterfowl livers collected in the study

................................... 60 20. Nest success ofducks in the study area, 1988

...................................................................................................... 63 21. Nest-success rates from various other studies and from thepresent study

........................................................... 64 22. Estimated waterfowl production in the study area, 1988

...................................................................................... 64 23. Water-quality measurements for daily composite water samples from Paiute Diversion Drain, August 1988

................................................................................................................... 78 24. Water-quality measurements for daily composite water samples from TJ Drain, August 1988

.......................... 79 25. Water-quality measurements for daily composite water samples from D-Line Canal, August 1988

................... 80 26. Water-quality measurements for daily instantaneous water samples from Lead Lake, August 1988

.................. 81 27. Water-quality measurements for daily composite water samples from Hunter Drain, August 1988

................... 82 28. Water-quality measurements for daily composite water samples from Stillwater Point Diversion Drain, August 1988

.................................................................................................................... 83 29. Water-quality measurements for daily instantaneous water samples from Stillwater Point Reservoir, August 1988

............................................................................................................................... 84

VI CONTENTSCONVERSION FACTORS, VERTICAL DATUM, DEFINITION, AND ABBREVIATED WATER-QUALITY UNITS

Multiply By To obtain

acre acre-foot (acre-ft)
acre-foot per acre (acre-ft/acre)
acre-foot per acre per year (acre-ft/acre/yr)

acre-foot per year (acre-ft/yr)

foot (ft)
foot per year (ft/yr) gallon (gal)
inch (in.)
mile (mi) ounce(oz)

square foot per second (ftVs)

square mile (mi2)

ton per year (ton/yr)

yard 4,047

1,233
0.3048
0.3048
0.001233
0.3048
0.3048
3.785
25.4
1.609
0.02957

0.9072

2.59
0.9072
0.9144 square meter cubic meter cubic meter per square meter cubic meter per square meter per year cubic hectometer per year
meter

meter per year liter
millimeter
kilometer
liter

square meter per second

square kilometer

megagram per year
meter

Temperature: Degrees Celsius (°C) can be converted to degrees Fahrenheit (°F) by using the formula °F = [1.8(°C)]+32.

Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929, formerly called "SeaLevel Datum of 1929"), which is derived from a general adjustment ofthe first-order leveling networks ofthe United States and Canada.

Definition: Theterm "wateryear"referstothe 12-monthperiodOctober 1 through September30,duringwhich acompleteannualhydrologic cycle normally occurs. The water year is designatedby the calendaryear in which it ends. Thus, the year ending September 30,1988, is called the "1988 water year."

Abbreviated water-quality units used in this report:

L (liter) |lg/g (microgram per gram)
mL (milliliter) mg/L (milligram perliter) ppt (part perthousand)
NTU (Nephelometric turbidity unit) mg/kg (milligram perkilogram) (1m (micrometer) |lg/L (microgram perliter) g(gram) (iS/cm (microsiemen per centimeter at 25°C) g/L (gram per liter) kg (kilogram)

CONTENTS VII

# DETAILED STUDY OF IRRIGATION DRAINAGE IN AND NEAR WILDLIFE MANAGEMENT AREAS, WEST-CENTRAL NEVADA, 1987-90



# Part B. Effect on Biota in Stillwater and Fernley Wildlife Management Areas and Other Nearby Wetlands

Robert J. Hallock andLinda L. Hallock, Editors 

# Abstract

A water-quality reconnaissance investigation during 1986-87 found high concentrations ofseveral potentially toxic elements in water, bottom sediment, and biota in and near Stillwater Wildlife Management Area (WMA). These results prompted the U.S. Department ofthe Interior to initiate a more detailed study in 1988 to determine the hydrogeochemical processes that control water quality in the StillwaterWMA and other nearby wetlands, and the resulting effects on biota, especially migratory birds. The average historical size ofthe natural wetlands at Carson Lake and Stillwater Marsh, the water quantity, and the average dissolvedsolids concentration and load in the water in these wetlands were estimated. Present wetland size is about 10 percent ofhistorical size; the dissolvedsolids load in these now-isolated wetlands has increased only moderately, but the concentration has increased more than seven-fold. Wetland vegetation has diminished and species composition has shifted to predominantly salt-tolerant speciesinmany areas. Decreasedvegetativecover for nesting is implicated in declining waterfowl production. Decreases in numbers or virtual absence ofseveral wildlife species are attributed to degraded water quality. Toxicity tests established that water in

some drains and wetland areas was acutely toxic to some fish and invertebrates. Toxicity is attributed to the combined presence ofarsenic, boron, lithium, and molybdenum. Rapid fluctuations in specific conductance and atypical ionic composition, which may increase acute toxicity, were observed in some drainwater. A strong relation

was foundbetween trace elements andboth daily and average specific conductance. Biological pathways are involved in the transport ofmercury and selenium. Concentrations ofselenium and mercury in drainwaterwere very low to below analytical reporting limits, but these elements hadbioaccumulated in plants, and selenium hadbiomagnified in one trophic level (invertebrates) up to 10,000-fold. Selenium and mercury accumulatedinplants, detritus, andinvertebrates had been transported through irrigation drains to large wetland areas frequented by waterfowl and other wildlife, but no evidence of expectedlong-term seleniumbuild-up since developmentwasfoundin thewetlands. Several source
areas ofselenium and mercury were identified.

Abstract 1

### Hatch success ofboth artificially incubated and field-reared duck eggs was 90 percent or greater; no teratogenesis was observed. Boron and selenium concentrations in eggs were generally low allbelow adverse effect levels. Mercury concentrations were also low except in eggs from Stillwater WMA, where about 30 percent ofthe eggs contained concentrations above the adverse effect level. Boron, mercury, and selenium concentrations in pre-flight juvenile ducks ranged from insignificant to levels associated with impaired survival. Boron concentrations were at or below effect levels in various duck species, but above effect level in coots (Fulica americana). Mercury concentrations in birds from Stillwater WMA, Carson Lake, and Carson Valley were above effect levels. Mean concentrations ofselenium ranged from 30 to 77 micrograms per gram (Jig/g) in birds from Fernley WMA and Massie and Mahala Sloughs, all above effect level. Survival of juvenile birds that had accumulated selenium, however, was not reduced. Field nest success was 26 percent and estimated overall production was about 2,400 ducklings from 6,800breeding pairs. This poor production was attributed primarily to drought conditions and dissolved-solids accumulation that caused vegetative loss and exposed the nests to predators. Maximum concentrations ofmercury in muscle and liver tissue ofwaterfowl harvested from Carson Lake and Fernley WMA were 15.5 and 38.9 Jig/g, wet weight, respectively, which exceeded the established human health criterion of 1.0 Jig/g. Selenium concentrations in livers of

juvenile waterfowl from Fernley WMA and Massie Slough were four times the established criterion for human health.



# INTRODUCTION

In the last several years, concern has been increasing aboutthe quality ofirrigation drainage, and its potential adverse effects on human health, fish, and wildlife. Recent studies at several National Wildlife Refuges and Wildlife Management Areas (WMA) throughout the western United States have identified elevated concentrations ofselenium and other trace elements that are a potential threat to biota within the management areas (Knapton and others, 1988; Lambing and others, 1988; Peterson and others, 1988; Radtke and others, 1988; Schroeder and others, 1988; Stephens and others, 1988; Wells and others, 1988; Hoffman and others, 1990; and Setmire and others, 1990). In 1988, the U.S. Department ofthe Interior (DOI) directed the U.S. Geological Survey, U.S. Fish andWildlife Service, U.S. Bureau ofReclamation, and theU.S. BureauofIndianAffairsto implementdetailed studies that would provide information useful for mitigatingthenegativeeffects ofirrigation-drainagewater. The detailed studies were to provide information on (A) toxic constituents, (B) their effects on biota, and (C) a summary of significant findings. The StillwaterWMA (and other nearby wetlands) in west-central Nevada (fig. 1) is one of several areas in the western United States selected for detailed examination ofthe mobilization, transport, and fate ofpotentially toxic constituents involving the biotic and abiotic environment.



### Background

The changes that have occurred in the wetlands associated with the Newlands Irrigation Project in the Carson Desert are widely recognized and are partly summarized in a report by the U.S. Department of the Interior (1988). An overview ofthe increment of changethatmay be ascribedto irrigation drainage was needed to place the related DOI irrigation-drainage studies in perspective. Priorto these investigations, few studies had documented the effects ofthe toxic components ofirrigation drainage on biota in and near StillwaterWMA. The first comprehensive study ofirrigation-induced water-quality problems was made during 1986-87 by Hoffman and others (1990). Henny and Herron (1989) studied irrigation-drainage-related contaminants in white-faced ibis (Plegadis chihi) at Carson Lake. Several contaminants found in irrigation drainage are known to directly affect fish and invertebrates, and thus indirectly, birds; both fish and invertebrates are important in the diets ofmany migratory birds at StillwaterWMA. Aquatic invertebrates are
a frequent food source forbirds during reproduction because ingested invertebrates provide high energy food forrapid growth ofyoungbirds inpreparation for migration. Salinity is often high at StillwaterWMA, and both water and biota contain elevated levels of

2 Detailed Study of Irrigation Drainage Effect on BiotaHumboldt WMA

Carson City J? f /

Garson Valley

EXPLANATION

OPEN WATER WETLANDS, INCLUDING OPEN WATER PLAYA GENERALIZED AREA OF CARSON DESERT

----- GENERALIZED BOUNDARY OF

WILDLIFE MANAGEMENT AREA (WMA) A GAGING STATION 10312000

NEAR FORT CHURCHILL
Figure 1

. General physiographic features in the study area and western Nevada (Modified from Lico, 1992).

INTRODUCTIONpotentially toxic trace elements (Hoffman and others,

1990, p. 76-77). At StillwaterWMA, Largemouthbass (Micropterus salmoides), which once supported a popular sport fishery, are gone and the diverse fish forage base supporting American white pelicans (Pelecanus erythrorhynchos) is greatly reduced (U.S Fish and Wildlife Service, 1988, p. 132).
Some water-quality components associated with irrigationdrainage may directly affectmigratorybirds. Both selenium and mercury have bioaccumulated and biomagnified in migratory bird tissues from the study

area to the extent that reproduction may fail (Hoffman and others, 1990, p. 60,67,72,77; Eisler, 1985, p. 38). High concentrations ofselenium were found injuvenile migratory birds confined to wetlands that commonly containedless than the analytical reporting limit (<1.0 fig/L) ofdissolved selenium concentrations in water. In these same wetlands, selenium concentrations in sediment (< 1.2 fig/g) were well below the level ofconcern (4.0 fig/g) recommended by Lemly and Smith (1987, p. 9). Seleniumwas foundin shallow ground water affected by irrigated agriculture in and

near the headwaters ofTJ Drain (U.S. Bureau of Reclamation, 1987, p. B14). Most ofthe mercury in the study area originated from 19th century mining and milling practices in the middle Carson Riverbasin (Smith, 1943, p. 247). The distribution ofmercury throughout the study area is associated with floodways and channels ofthe Carson River that existed beforeconstruction oftheNewlandsIrrigationProject. Low concentrations ofmercury were found in filtered sample water from the study area. The highest concentration ofmercury in water, reported by Hoffman and others (1990, p. 36), was 1.1 fig/L in Lead Lake in StillwaterWMA. Reproductive life phases are typically sensitive and vulnerable to the effects ofcontaminants. Traceelementtoxicity is apossible contributing factorto the steady decline in waterfowl production in wetlands maintained by drainage from the Newlands Irrigation Project (U.S. Department ofthe Interior, 1988, p. E-7-E-10). In addition to the white-faced ibis found to be accumulating selenium and mercury in the breeding grounds at Carson Lake (Henny and Herron, 1989, p. 1032), deformed ibis chicks have been observed at Stillwater WMA (U.S. Fish and Wildlife Service, Fallen, Nev., unpublisheddata, 1987). Dead and dying waterfowl found in Carson Sink and in various parts ofthis study area (StillwaterWMA, HumboldtWMA, and Carson Lake) had selenium levels in liver tissue sufficiently high to cause toxicosis (> 30 fig/g), although necropsy reports did not identify selenium toxicosis as the immediate cause ofdeath (Rowe and Hoffman, 1990, p. 39; Hoffman and others, 1990, p. 74). The primary effect ofexcessive dietary selenium on mallards (Anasplatyrhynchos) is reproductive reduced reproductive efforts, hatch rates, and duckling survival (Lemly and Smith, 1987, p. 5). Chronic sublethal mercury concentrations are also related to reduced reproductive success (Heinz, 1979, p. 398; Finley and Stendell, 1978, p. 54). Laboratory studies ofboron as adietary supplement showed reduced hatch rates, hatch weights, growth rates, and duckling survival (Smith and Anders, 1989, p. 943). Selenium, mercury, andboron were foundin migratory birds, food-chain organisms, and sediment in the study

area during the reconnaissance study by Hoffman and others (1990, p. 58, 62). Wildlife from study-area wetlands have been used as food by humans for more than 4,000 years (Kelly, 1988, p. 11). Although the wetlands no longer support a popular fishery, harvest and consumption of waterfowl continues. When potential toxic elements, such as mercury and selenium, accumulate in waterfowl tissues, a concentration may be reached at which human consumption is inadvisable. During 1986-87, Hoffman and others (1990, p. 77) found indications thatjuvenile migratory birds, including waterfowl, in and near StillwaterWMA and Carson Lake were accumulating mercury and selenium in liver and muscle tissue. Some ofthe concentrations exceeded established criteria for human health. Cooper and others (1985, p. 56) identified apossible threat to human health from mercury in fish fillets taken from various wetlands in the Newlands Irrigation Project area, including Stillwater WMA.



### Purpose and Scope

This report presents findings ofthe five detailed study elements that evaluate general and specific effects ofirrigation drainage on biota and mechanisms or linkages related to these effects in wetlands in and near StillwaterWMA. The primary purpose in studying these wetlands was to assist remediation efforts in support ofmigratory waterfowl, a Federal trust responsibility; the common theme of these five elements is the possible adverse effects ofirrigation drainage on migratory waterfowl. The five study elements, in order ofpresentation in this report, examine the historical conditions ofthe wetlands compared to the present, determine which

4 Detailed Study of Irrigation Drainage Effect on Biotapotentially toxic trace elements are present in the
area, explore pathways by which the trace elements

move through the wetlands, determine the effects ofthe contaminants on waterfowl production, and consider human-health implications. Because ofthe length and scope ofthis report, those primarily interested in the collective findings of all the studies may wish to pass the detailed sections andproceeddirectlyto the summary section attheback ofthis report. The more technically oriented reader may wish to examine the individual sections for more detail.This investigation was made and the report authored by U.S. Fish and Wildlife Service scientists. The report is published by the U.S. Geological Survey to maintain continuity with the other detailed-study reports for the area (Rowe and others, 1991; Lico, 1992; and Hoffman, in press). While the period of study was 1988-90, some biological data collected in 1987 wereusedto assess theconcentrations ofmercury and selenium in waterfowl.



### Study Area

The Carson Desert hydrographic area (Rush, 1968, pi. 1) occupies a mostly flat area ofabout 2,020 mi2 in the lower Carson River drainage basin. The area is about 70 mi east ofReno, and is one of the largest basin-fill valleys in northern Nevada. The Carson Desert includes natural wetlands at Carson Lake and withinthe artificialboundaries ofStillwater WMA Stillwater Marsh and the southern part ofthe Carson Sink (fig. 1). The Carson Sink is a nearly barren, flat, salt-encrusted playa occupying an area of about 400 mi2 on the northern boundary ofStillwater WMA. In abnormally high precipitation years, wetlands may emerge in the Sink, supported by flow of the Carson River and, on occasion, overflow from the Humboldt River. Historically, these wetlands were supported primarily by the Carson River, but since completion ofthe Newlands Irrigation Project, additional water has been imported from the Truckee River drainage basintotheCarsonRiverbyway oftheTruckeeCanal. The Carson River is a major tributary draining the eastern slopes ofthe central Sierra Nevada. As with most rivers associated with the Great Basin, its annual discharge patterns are highly variable. Biological samples were collected from additional wildlife areas because oftheir proximity to Stillwater WMA, and because they are maintained by a combination ofground water and drainage from DOI irrigation projects. These other areas include the largely Project-created wetlands atFernley WMA near Fernley, Nev., about 30 mi west ofStillwater WMA; Massie and Mahala Sloughs, about 25 mi west of StillwaterWMA; andthenaturalwetlands atHumboldt WMA (fig. 1). Summary descriptions ofclimate, geology, soils, wateruse, hydrologic setting, wetland areas, and wildlife use were reported by Hoffman and others (1990) and Lico (1992).



### Acknowledgments

The authors ofthis report gratefully acknowledge the following individuals who provided valuable assistance during the course ofthese investigations: Ron Crunkilton, Missouri Department ofConservation, for providing bluegills for the study; Rod Parrish, U.S. Environmental Protection Agency Laboratory, GulfBreeze, Fla., for providing saltwater species; and Eugene Greer and Glenn Wylie, National Fisheries Contaminant ResearchCenter, Columbia, Mo., forprovidingfathead minnow larvae and daphnids, respectively. The maintenance staffatthe StillwaterNationalWildlife Refuge provided valuable assistance in setting up the mobile toxicity testing facility. Mark Kaiser assisted in the analysis ofdata and provided valuable suggestions

on parts ofthis report. The following people also assisted in the study by providing data, information, or technical reviews ofparts ofthis report: Roy Leach and Norman A. Saake, Nevada Department ofWildlife; James J. Cooper, NevadaDivision ofEnvironmentalProtection; Theodore G. Roefs and Thomas Strekal, U.S. Bureau ofReclamation; RonaldM. Anglin, Timothy Bowman, C. Clifford Creger, Gerald Deutscher, Leslie Dubec, Eugene E. Duffney, Charles J. Henny, Earnest Lantos, Delven D. Lee, A. Dennis Lemly, Kenneth Merritt, Craig Stockwell, and Steven P. Thompson, all with the U.S. Fish and Wildlife Service; and Lyman F. McConnell and Willis Hyde ofthe Truckee-Carson Irrigation District. And, finally, we thank Ray J. Hoffman, Study Team Leader, and Carol A. Myers, Technical Editor, ofthe U.S. Geological Survey for their substantial efforts in making this a more concise and cohesive document.

INTRODUCTION

# ESTIMATED HISTORICAL CONDITIONS OF THE LOWER CARSON RIVER WETLANDS

To evaluate the effect ofirrigation drainage

on the wetlands ofthe lower Carson River, Carson Lake, StillwaterMarsh, and associated intermittent wetlands in the Carson Sink (fig. 1), an estimate was needed ofthe conditions prevailing before the onset of irrigation anddevelopment. These estimatedhistorical wetland conditions were then comparedto present and projected wetland conditions. To do this, it was necessary to distinguish between effects resulting from irrigation and those resulting from wetland management practices. Climatic changes, extreme variability ofthe streamflow ofthe Carson River, the cyclic nature of this variation, and the presence oflands irrigated with Carson River water upstream ofthe Newlands Irrigation Project are important considerations for the determination ofhistorical conditions.
The historical flow, seasonal variation, average wetland size, and water quality were estimated on the basis ofextrapolations from data in existing records, reportsby earlyexplorers, and archaeologicalfindings. Early reports and evidence from archaeological sites

wereused to estimate the types and abundance ofvegetation and wildlife historically present. Present conditions were determined from data collected for this study and from other recent State and Federal reports and data, particularly data analysis compiled in April 1988 by the U.S. Fish andWildlife Service atStillwater Wildlife Management Area for OCAP (Operating Criteria and Procedures) ofthe Newlands Project (U.S. Fish and Wildlife Service, 1988), which are summarized in Appendix E ofthe Final Record of Decision (U.S. Department ofthe Interior, 1988). ESTIMATED HISTORICAL CARSON RIVER FLOW AND WETLAND SIZES

Commonly, the flow path of the unregulated Carson River was to Carson Lake, out through Stillwater Slough into Stillwater Marsh, then terminated in Carson Sink, as discussedby Morrison (1964, p. 104) and Russell (1885, p. 44-45) and shown in figure 2. That flow pattern will be followed in this discussion, with alternating consideration ofinflow quantities, wetland sizes, and probable water losses along the downgradient flow path.

Unregulated Flow of the Carson River

Systematic records ofstreamflow and water quality ofthe Carson River and associated wetlands have been kept only during this century. Data extrapolated from the existing streamflow records were used
to estimate arepresentative annual average volume of waterinflow to the wetlandsbefore the initiation ofirrigation (pre-1860) in the Carson Desert. This predevelopment inflow was then used to estimate an average wetland acreage that would have been maintained primarily by inflow ofthe Carson River. Because the annual streamflow ofthe Carson River is highly variable, the extrapolation included the following information, estimates, and assumptions:

lrThe term "average" is usedhere to indicate arepresentative situation sometimes stable, sometimes subject to extreme fluctuation; it does not mean a mathematical average or a usual or "normal" situation.

ESTIMATED HISTORICAL CONDITIONS Kerleyandothers

# '&/£ *%*M

_^_ fo!-~Vvi£ -X^ --- .-z^'V'-ii-""'^ I1 .rv-te i;i - -- * ;- -- jff~i ' - ; ;.. ^C«%^ pj\. ^saJ^^?^^- -.£*-:-::-.;./7^Js:

-1^-

-:^

_ _ /-'u- V"*IQJ '^^^ ->=Zs <- -i«=:."*»s- i

. i-i'-K-, i'l v -._ - JT

. -^1 

# - ^s^w r^fe^V®^^ ^^-:J/^VH:-^- <*xv. S^ %^s^ &%> ?m? '-7:1.^1- 

# g^^^l4§^^t| r':;^%; V"

'

*

Lahontan Beach Playas 4^> Julius Bien & Co. Llth. CARSON DESERT, NEVADA.

Scale oIMIes Interval between Contours 1000 feet.

Figure 2. Reproduction of early map showing configuration of the lower Carson River basin before development (1880's). Note differences in
name designations: in particular, "North Carson Lake," which is now part of Stillwater Marsh and Carson Sink, and "South Carson Lake," now designated simply Carson Lake. (Illustration was published in 1885 as Plate VII by I.C. Russell in U.S. Geological Survey Monograph 11, a report on ancient Lake Lahontan.)

8 Detailed Study of Irrigation Drainage Effect on Biota(1) The average annual streamflow ofthe Carson River near Fort Churchill (U.S. Geological Survey station 10312000, approximately 50 river miles upstream from Carson Lake; fig. 1) was about 270,000 acre-ft (rounded) for the period ofrecord, 1911-88 (Pupacko and others, 1989, p. 117).
(2) The average annual streamflow ofthe Carson River to Carson Lake and the connected Stillwater Marsh before agricultural development (pre-1860)

was estimated to be equal to the present average annual streamflow nearFort Churchill plus the average annual flow ofall water now consumedby agriculture upstream ofthat point. Other historical water losses, primarily seepage and evapotranspiration from the formerly more extensive wetlands associated with the upper river, were probably equal to other modern losses. These losses include seepage and evapotranspiration from reservoirs and canals, municipal
uses, and agricultural uses in excess ofthe Alpine Decree1 (Garry Stone, Federal Water Master, oral communication, 1990).

lrThe Alpine Decree is the adjudication ofthe Carson River water rights (California Department ofWater Resources, 1991). (3) About 56,000 acres are irrigated along the Carson River above Fort Churchill, with an annual evapotranspiration rate of2.5 acre-ft/acre, as calculated from the Alpine Decree (California Department ofWater Resources, 1991, p. 126), which results in

an estimated 140,000 acre-ft ofwaterbeing diverted from the Carson River and consumed annually. This amount is in agreement with the findings ofBrown and others (1986, p. 30) that about 137,000 acre-ft of water may be consumed annually from the area above Lahontan Reservoir. Thus, adding the estimate ofagricultural consumptive use (about 140,000 acre-ft) to the Carson River discharge at Fort Churchill (about 270,000 acre-ft), the historical, unregulated annual averagedischarge oftheCarson RiveratFortChurchill

was approximately 410,000 acre-ft. Based on the 1911-1988 period ofrecord, the flow ranged from about 90,000 acre-ft/yr (sum ofCarson River inflows above Fort Churchill [U.S. Geological Survey, 1978]) to about 940,000 acre-ft/yr (800,000, rounded [Frisbie and others, 1984, p. 127], plus 140,000). Seasonal variations in Carson River flows for the period of record (1919-1969) are discussed by Glancy and Katzer (1976, p. 34-42) and shown for the Fort Churchill station in figure 3 ofthis report.

1,600

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEP Figure 3. Mean monthly flow and quartile statistics, Carson River gage near Fort Churchill, USGS station 10312000, water years 1919-69. Modified from Glancy and Katzer (1976, p. 35).

ESTIMATED HISTORICAL CONDITIONS Kerleyandothers

### Average Historical Size of Carson Lake

The areal extent ofwetlands at Carson Lake when maintained by the entire average annual flow ofthe Carson River was dependant primarily on the annual evapotranspiration rates, wetland morphology, and magnitude ofseasonal inflow. Natural variation in the course ofthe river where it entered the Carson DesertisdiscussedbyMorrison(1964,p. 104). During recent geologic time, the Carson Riverusually flowed southeastward toward Carson Lake. As observed by Russell (1885, p. 44-45) in the mid 1800's, the Carson River also flowed northward to Carson Sink (North Carson Lake in fig. 2). The frequency of such flowpath changes over geologic time is unknown. From his camp on Stillwater Slough in 1859, Simpson (1876, p. 85) observed a distinct line ofcottonwood trees along the Carson River where it entered Carson Lake. E.M. Kern, a topographer with the FremontExpedition of 1845, alsoreported seeingtrees, probably cottonwoods, at the mouth ofthe Carson River from across the lake (Spence andJackson, 1973, p. 51). These trees, large enough to be visible from a distance ofat least 5 mi, as calculated from the map in figure 2, are an indication that a relatively stable geographic configuration ofthe lower Carson River had existed for 20-50 years prior to Kern's visit. For purposes ofthe present analysis, Carson Lake is assumed to have been a permanent wetland feature. The maximum depth ofCarson Lake at full pool is 10 ft, with the lake-bottom altitude at 3,909 ft above sea level (Hart and Bixby, 1922, p. 13) and the rim altitude at 3,919 ft (Morrison, 1964, p. 104). The maximum surface area ofCarson Lake at the rim is about 34,000 acres. Russell (1885, p. 44-45; 1895, p. 108) observedthe Carson Desertin the early 1880's, after the onset ofearly irrigation and after the Carson River had split with one part bypassing Carson Lake, thus reducing inflow to the lake. He described Carson Lake as varying in size and depth with the alternation ofthe seasons, generally outflowing through Stillwater Slough (1885, p. 68-69). The lake was discharging through the slough in June 1881, had an open water

area ofabout 26,000 acres in 1882, and by September 1883, much ofthe lake appeared to be a swamp (Russell, 1885, p. 45, 69). Because emergent vegetation in this region is typically found where water depths are lessthan 3 ft,by September 1883 the surface ofCarsonLake probably was at least 7 ftbelow its natural rim. This inferred difference in water level is greaterthan the evapotranspiration rate of5 ft/yr (U.S. Department ofthe Interior, 1988, p. A-31). Outflow from Carson Lake in 1882 was nonexistent,

as noted by Russell (1885, p. 45, 69). Apparently, the lake, at the time ofhis estimate ofabout 26,000 acres,
was smallerthan its maximum of34,000 acres. About

one fourth ofthe adjacent marsh, which was above the normal maximum lake-surface altitude, was probably intermittently flooded and may have covered about 4,000 additional acres (fig. 2). Forpurposes ofthis discussion, then, the maximum wetland acreage of Carson Lake and the adjacent marsh land is estimated to have been about 38,000 acres. Large variations in the Carson River streamflow, both seasonal and annual, would have affected the size ofCarson Lake seasonally. Typically, the seasonal flow patterns vary fromlow flow fromAugustthrough November, to a slow increase through March, and finally to a springpeaklate inAprilthatfalls offbyJuly (fig. 3). Seasonally diminishing streamflows ofthe Carson Riverusually limit agriculture in the basin above Fort Churchill by July 15 (Carry Stone, Federal Water Master, oral comrnun., 1990).
The summer and fall streamflow in the Carson River may regularly have been insufficientto maintain Carson Lake, and the lake size may have peaked atthe rim in early summer, then decreased. The estimated 4,000 acres ofadjacent marsh is assumed, forpurposes ofthis discussion, not to change in size. The seasonal variation noted by Russell (1885, p. 68-69) may have been usual. Richard Burton, in 1860 (1963, p. 551), found the water to be about a mile away from a Pony Express station (at the southwestern edge ofthe lake), but the following summer DeQuille (1963, p. 28) observed thatthe water was againup to the dock ofthe station. A summer-fall evaporative loss of3 ftin depth would have reduced the surface ofCarson Lake from a possible maximum ofabout 34,000 acres to about 29,000 acres. The lake size also has been periodically reduced by drought (Morrison, 1964, p. 104; Russell, 1895, p. 108). Thus, on the basis ofthe discussion above, the historical average wetted surface area of both open water and adjacent marsh at Carson Lake

was less than the historical maximum, 38,000 acres, and is conservatively estimated to be 27,000 acres (table 1). This lesser acreage amount is used in the subsequent water-consumption estimate for Carson Lake.

10 Detailed Study of Irrigation Drainage Effect on BiotaTable 1

. Estimated historical (predevelopment) wetland acreage compared to projected wetland acreage at Carson Lake and the combined wetlands of Stillwater Marsh and Carson Sink

{All values have been rounded]

Wetland Acreage

Wetland area Predevelopment estimate (1845-60) Projected

average1 Range Average

Carson Lake (South Carson Lake in figure 2)

Stillwater Marsh and Carson Sink (North Carson Lake and adjacent marsh lands in figure 2)

TOTAL (rounded) 225,000-338,000 27,000 5,000

20-200,000 120,000 4 11,000

150,000 16,000

1 U.S. Fish and Wildlife Service, 1988, p. 19, fig. 21. 2Estimated minimum size associated withthe 1911-88 period ofCarson River flow records. 3 Includes about 4,000 acres ofadjacent marsh land. 4Includes 3,000 acres ofhistorical Stillwater Marsh located within the Canvasback Gun Club (C. Clifford Creger, U.S. Fish and Wildlife Service, written commun., 1992).

Flow Through Stillwater Slough

In 1861, DeQuille described Stillwater Slough

as 60 ft wide, with vertical banks 8-10 ft high, having

no grass along the stream, and cutting through the barren sandy plain with only scattered clumps ofsage and greasewood, which is typical ofan intermittent waterway in this area (DeQuille, 1963, p. 36-37). The absence ofhydrophytic vegetation in this channel also supports the contention that summer-fall flow in the Carson River was regularly insufficient to maintain flow through Stillwater Slough. Evapotranspiration losses at Carson Lake reduced the flow ofthe Carson River before it discharged through Stillwater Slough
to Stillwater Marsh. These losses also decreased the duration offlow in the Carson River systembelow Carson Lake. With 27,000 acres average surface area and an evapotranspiration rate of5 ft/yr, Carson Lake would have consumed about 140,000 acre-ft ofwater peryear. Subtracting this fromtheunregulated average annual flow in the Carson River, about410,000 acre-ft, leaves an annual average flow of270,000 acre-ft to pass through Stillwater Slough into the wetlands StillwaterMarsh plus Carson Sink. Average Historical Size of Stillwater Marsh

The wetted area ofStillwater Marsh and the downgradient playa wetlands (much ofCarson Sink)

were more variable in size than Carson Lake because ofthe cumulative evapotranspiration losses in these shallow, sequentially distributed wetlands (Morrison, 1964, p. 104). Because there are no early quantitative estimates ofthe size ofStillwater Marsh a series of interconnecting wetlands and ponds flowing generally from south to north, the average size ofthe Marsh must be estimatedusing other approaches. Archaeological evidence and pollen cores indicate that a relatively permanent marsh existed in the Stillwater area for the last 4,000 years (Kelly, 1988; Warburton and others, 1990, p. 74), an area known to have been regularly inhabited by man, and by other waterdependent species. Stillwater Marsh was called StillwaterLakes by Morrison (1964, p. 104). That observation implies enough water depth (at least 3 ft) to possibly preclude the growth ofemergent vegetation and maintain open water areas. Minor variations in topographic elevations (5-15 ft) may be responsible for the formation ofthese "lakes" at StillwaterMarsh (Raven andElston, 1989, p. 33). These depressions, by their proximity

ESTIMATED HISTORICAL CONDITIONSKerleyandothers 11to flow from Stillwater Slough and by retaining

water, gave a degree ofpermanence to these wetlands compared to the relatively flat areas ofCarson Sink.
Raven and Elston (1989, p. 64, 69) have defined two broad categories ofhistorical wetlands
at Stillwater, namely "marsh" and "playa," based

on soil types and hydrologic characteristics. Both wetland types supported human occupation and waterdependant biota. "Marshes" were those areas which characteristically had enough differences in topography to maintain a combination ofopen water, emergent vegetation, and upland sites suitable for human habitation. In the absence ofdetailed land
surveys prior to development ofLahontan Valley, the historicalamount ofeachwetlandtypeisuncertain. Elevations determined from U.S. Geological Survey 7.5-minute quadrangle maps indicate that up to 55,000 acres ofwetlands were possible in what is

now (1993) the Stillwater National Wildlife Refuge. Therefore, wetland acreage could have ranged from 0 to 55,000 acres. Classification ofwetland types on currentU.S. Geological Survey 7.5-minute quadrangle
maps indicates that wetlands at full pool consisted of

an average ofapproximately 15,000 acres ofmarsh and 40,000 acres ofplaya (C. Clifford Creger, U.S. Fish and Wildlife Service, Fallen, Nev., written commun., 1992). These areas are consistent with a predictive model based largely on soil types, hydrology, and topography developedby Raven andElston (1990, p. 123-34).
Carson River inflow through Stillwater Slough

was seasonally intermittent. Parts ofStillwaterMarsh

were subjected to seasonal drying, as were the margins ofCarson Lake. Although a graded change in evaporationlosses wouldbepredicted asthemarshdiminished, it is conservatively estimated that 75 percent ofthis wetland, about 11,000 acres, would remain wetted and lose water at a rate of5 acre-ft/yr. This lesser acreage is used only in the subsequent water consumption estimate for Stillwater Marsh.
Stillwater Marsh would have been dry only

once during the period ofrecord for the Carson River (1911-1988), resulting fromthe drought ofwater-years 1976-77. 

### Estimated Flow into Carson Sink Wetlands

Average water loss by evapotranspiration from the estimated 15,000 (full-pool) acres ofStillwater Marsh would have been 56,000 acre-ft, assuming that 25 percent ofthe area was seasonally dry. Thus, the 270,000 acre-ft ofCarson River water entering the marsh by way ofStillwater Slough each year wouldbe furtherreduced to an average of about 210,000 acre-ft before entering wetlands in the Carson Sink.



### Estimated Size of Carson Sink Wetlands

Wetland acreage in the Carson Sink maintained by Carson River water was, as it is now, generally ephemeral. Ephemeral wetlands are typically shallow, receiving only afew inches ofwateratthe distaledges, and tend to evaporate completely or nearly so before the next inflow season. Underunregulated conditions, average Carson River flow would have refilled Carson Lake and Stillwater Marsh and begun to flow into the Carson Sink during winter. Most flow would have reached the sink following spring snow melt or occasional rain-on-snow events. During the spring, wetlands in the southeastern portion ofthe Carson Sink may have been characterized by having large volumes offlowing water relatively low in dissolved solids. This portion ofCarson Sink wetlands may have been wetted for as long as 6 months in most years. In response to decreasing Carson River inflow and increasing evapotranspiration rates in the summer, the palustrine regime would have ceased and the wetlands would have rapidly receded in size and depth to

zero or some variable minimum size. Wetlands at the advancing edge ofwater during peak flow events would have been the most ephemeral, persisting only

a few weeks. Approximately 40,000 acres ofplaya wetlands

on the Carson Sink within the confines ofthe present (1993) Stillwater National Wildlife Refuge also contain human occupation sites and evidence ofwaterdependent biota (C. Clifford Creger, U.S. Fish and Wildlife Service, Fallen, Nev., written commun., 1992).Two accounts ofwater on the Carson Sink provide abasis from which to estimate an average wetland depth. This, combined with the average Carson River inflow, is used to estimate the average size of wetlands in the Carson Sink.

12 Detailed Study of Irrigation Drainage Effect on Biota

### During September 1929, Sperry (1929, p. 1-3) surveyedthe wetlands onthe Carson Sinkatthe mouth ofthe CarsonRiver. Atthattime,theriveremptiedinto the Sink in the vicinity ofwhat is now Fallen NWR, adjacent to Stillwater and topographically similar mostly flat with shallow sloughs and low rises. Sperry considered the water supply to be deficient that year and below normal, and reported the water to be mostly less than 1 ft deep, with a few ponds 2.5-3 ft deep. In addition to alkalibulrush (Scirpusmaritimus) beds, he saw blackened basal stalks that "coat long reaches ofthe higher ground andindicate an enormous extension ofbig beds during wet seasons." His observation of "carpets" ofsago pondweed (Potamogeton pectinatus), some in mature fruit, left exposed by the receding waters, indicates that the waterreceded rapidly and suggests fairly rapid decreases in wetland size in the fall. During the 1980's, the Carson Sink was inundatedby flood flows from both the Carson and Humboldt Rivers. This is considered an anomalous event; floodingonthatscalelastoccurredinthe 1860's. The 1980's occurrence created unusual physical and water-quality conditions, and is ofinterest here primarily because ofobservations ofwater depth made at various times during the inundation. Between July 1984 and February 1985, flood water inundating Carson Sink and Stillwater Marsh covered about 212,000 acres ofsurface area to a maximum depth ofnearly 12 ft (Rowe and Hoffman, 1990, p. 37). Atthat size, the average depthwouldhavebeen 8 ft and the volume about 1,700,000 acre-ft. In midJanuary of 1987, water in the Carson Sinkhadreceded to less than 180,000 surface acres, with an average depth of2 ft and a maximum of6 ft (Rowe and Hoffman, 1990, p. 37). The volume ofwater in the Carson Sink wouldthen have been less than 360,000 acre-ft. Although it is recognized that wetlands on the Carson Sink were dynamic, an average depth is needed to estimate the extent ofwetlands which may typically have been maintained by the Carson River. Based on the observations by Sperry (1929) and Rowe and Hoffman (1990), 2 ft is areasonable estimate for an average depth. Using this 2-ft depth, the 210,000 acre-ft inflow from the Carson River could have seasonally flooded an average of 105,000 surface

acres ofwetlands on Carson Sink. This arearepresents an average ofmaximum wetland sizes that could be anticipated from the flows ofthe 1911-1988 period ofrecord for the Carson River.
The Carson Sink wetlands may have varied in size from 0 to 190,000 surface acres, based on fluctuations ofthe Carson River alone during the 78-year period ofrecord. The low point, zero, would have occurred with flow similar to that ofwater-year 1977 (the second year ofthe 1976-77 drought) when the Carson River flow would not have reached the Carson Sink. The maximum, 190,000 acres, is based

on the flow ofthe Carson River during water-year 1983. The adjusted flow ofthe Carson River at Fort Churchillinwater-year 1983 was about940,000acre-ft (800,000 acre-ft, rounded [Frisbie and others, 1984, p. 127], plus 140,000 acre-ft from assumption no. 3 in the subsection "Estimated Historical Carson River Flow andWetland Sizes"), and the inflow to the sink from the Carson River through Stillwater Marsh is estimated to have been about 750,000 acre-ft. Based upon a linearrelationship ofsurface areas and water volumes observed by Rowe and Hoffman (1990), this 750,000 acre-ft would have inundated about 190,000 surface acres on the Carson Sink, with

an average depth ofnearly 4 ft and amaximum of8 ft. Some ofthis water wouldbe expected to remain on the sink into the following year. Under these extreme hydrologic conditions, parts ofStillwater Marsh also would be flooded.

ESTIMATED HISTORICAL WATER QUALITY

Little information about the historical water quality ofthe lower Carson River system exists, but explorers and local residents ofthe mid to late 1800's reported good water (presumably potable, in the historical sense), plentiful vegetation, and abundant wildlife at various locations in the lower Carson River basin and its wetlands.
In June 1859, Simpson (1876, p. 85) visited Carson Lake and wrote the following:

ESTIMATED HISTORICAL CONDITIONS Ker/ey and others 13We are encamped at the head of the

outlet from Carson Lake into the sink of Carson, where our onlyfuel is dry rush. This outlet is about 50 feet wide and 3 or 4 feet deep, and voids the lake rapidly into its sink, which is some 10 or 15 milestothe northeast of us. The water is of a rather whitish, milky cast, and though not very lively, is yet quite good. The Carson River to the northwest, where it empties into the lake, can be seen quite distinctly, marked out by its line of green cottonwoods. The name of the river and lake was given by Colonel Fremont, in compliment to Kit Carson, one of his celebrated guides. The alluvial bottom about Carson Lake is quite extensive and rich, as the luxuriant growth of rushes shows, and could, I think, be easily irrigated. The only drawback to its being unexceptionableforcultivation in every part is its being somewhat alkaline in places, particularly toward its southern portion. Curlew, pelican, and ducks, and other aquatic birds frequent the locality, and the lake is filled with fish. Wuzzie George, a Native American residing in Lahontan Valley in the early 1900's and a keen observer ofnatural things, referred to the abundance of submergent vegetation in the Stillwater marshes (U.S. Fish and Wildlife Service, 1952, p. 19), an indication ofwater clarity. Hart and Bixby (1922, p. 15) found Carson Lake in 1922 to be slightly alkaline, with very little accumulation ofsalts on the edges, and with "vegetation [that]... indicates the absence ofan excess ofharmful salts." At Stillwater Marsh, the remains of freshwater clams (Anadonta sp.\ fish, mink (Mustela 5/7.), and river otter (Lutra sp.) in archaeological sites indicate the marsh hadhigher water quality than at present. The wetlandecosysteminthe southern inflow

area ofStillwaterMarsh would have flourished with natural flushing, but water in the ephemeral wetlands

onthe Carson Sink wouldhave accumulated salts. The fluctuating north and west margins ofthis ephemeral marsh probably resembled the barren areas associated with current managed wetlands, where water with dissolved solids concentrated beyond the tolerance level ofaquatic plants is disposed ofthrough evaporation. Historical water-quality conditions were estimated using period-of-record data on streamflow and dissolved solids for the Carson River at the Fort Churchill gage. The average measured dissolvedsolids concentration at the Fort Churchill gage for the period 1970-88, the only data available, was 218 mg/L and ranged from 70 to 454 mg/L (Ray J. Hoffman, U.S. Geological Survey, written comrnun., 1990). Although the average Carson River streamflow measured at Fort Churchill has decreased because ofupstream diversions, the recent average dissolvedsolids load at Fort Churchill (about 90,000 ton/yr) is assumed, forthe purpose ofthe present analysis, to be about equal to the average historical dissolvedsolids load. Although predevelopment loads did not include post-development contributions ofdissolved solids from irrigation returns and sewage disposal, this assumption should result in a reasonable estimate ofan upper limit forpredevelopment dissolved-solids loads and concentrations. The average historical (1845-1860) concentration ofdissolved solids entering Carson Lake is estimated to be about 170 mg/L. This concentration was determined by computing the ratio ofthe average volume ofwater forthe period 1970-88 to the historical volume ofwater, then multiplying by the average dissolved-solids concentration for the period ofrecord and adding an estimate for natural accretion (see footnotes 7 and 8 in table 2):
(300,000 acre-ft/ 410,000 acre-ft) 218 mg/L

+ 10 mg/L = 170 mg/L (rounded).1
Historically, an estimated annual average of about 410,000 acre-ft ofwaterreached Carson Lake by way ofthe Carson River; most ofit overflowed
to Stillwater Marsh. The water entering Carson Lake, with an estimated dissolved-solids concentration of 170 mg/L, carried a probable dissolved-solids load ofabout 95,000 ton/yr to the wetlands (table 2). This estimated load to the wetlands provides abenchmark forunderstanding baseline water-quality conditions that existed in Carson Lake, StillwaterMarsh, and the Carson Sink.

lrThe estimated historical dissolved-solids concentrations presented in this section are intended solely as ahistorical baseline for comparison with existing water quality ofwetlands in the lower Carson Riverbasin receiving irrigation drainage. Because ofvariation offlow and the highevaporation rate, the average conditions described herein may have been greatly exceeded at times; thus, the estimated predevelopment concentrations should notbe used to set downstream waterquality standards.

14 Detailed Study of Irrigation Drainage Effect on BiotaTable 2. Estimated historical (predevelopment) and recent or projected water quantity and dissolved-solids concentrations and loads for Carson River, Carson Lake, and Stillwater Marsh. (Estimated historical dissolved-solids concentrations should not be used to set water-quality standards for wetlands in the study area)

[Abbreviations: acre-ft, acre-feet; ft/yr, foot per year; mg/L, milligrams perliter; ton/yr, tons per year]

Carson River at Fort Churchill gaging station Carson

Lake Stillwater

Marsh

Water quantity (acre-ft)

Historical (1845-60) ^10,000 2410,000 3270,000

Recent (1970-88) or projectedby OCAP4 5300,000 625,000 655,000

Dissolved-solids concentration (mg/L)

Historical (1845-60) 7 160 7'8 170 7'8270
Recent(1970-88) or projectedby OCAP4 7220 91,170 9 1,170

Dissolved-solids load (ton/yr)10

Historical (1845-60) 89,000 95,000 99,000

Recent (1970-88) or projectedby OCAP4 90,000 40,000 88,000

1Estimated historicalunregulated discharge atFort Churchill gage (average annual streamflow forperiod ofrecordplus upstream consumptiveuse; seetext for details). 2All ofCarson River flow estimated to enter Carson Lake. 3Water entering StillwaterMarsh estimated by using total inflow to Carson Lake (410,000 acre-ft), minus evaporation rate (5 ft/yr) multiplied by average wetland acreage ofCarson Lake (27,000, rounded; table 1). 4OCAP (Operating criteriaandprocedures forNewlands Project)projection for 1992 and beyond (U.S. Fish and Wildlife Service, 1988). 5Recent (1970-88) annual average (R.J. Hoffman, U.S. Geological Survey, written commun., 1990). 6Estimated acreage projected for OCAP (table 1) multiplied by evaporation rate (5 ft/yr). L 7 Calculated from quantity and loads: C = Of
where Cis concentration, in mg/L; L is load, in ton/yr; Q is quantity (streamflow), in acre-ft; and /is factorfor converting mg/L to tons (0.00136). 8Estimateincludes calculatednatural accretion ofdissolved solids alongthe stream channel (R.J. Hoffman, U.S. Geological Survey, written commun., 1990). 9U.S. Fish and Wildlife Service, 1988, p. 51. 10All values calculated from estimated discharge and concentration (L = CXQXf).

ESTIMATED HISTORICAL CONDITIONS /Cer/ey andothers 15The average wetted surface area ofCarson

Lake (27,000 acres) would have lost, through evapotranspiration, about 140,000 acre-ft ofwater annually. This loss ofwater from Carson Lake would have increased the dissolved-solids concentration in the remaining 270,000 acre-ft ofwaterto about 260 mg/L

as it discharged through Stillwater Slough. Because of its shallow depth and shape, Carson Lake would have exchanged water easily with the inflow. The average flow ofthe Carson River was about 2.5 times greater than the lake's maximum volume, thus long-term concentration ofdissolved solids in Carson Lake would not have occurred, and the dissolved-solids load leaving the lake would have been similarto the inflow, about 95,000 ton/yr. Because the average volume ofthe outflow from Carson Lake is about 10 times the volume ofStillwater Marsh, essentially the same dissolved-solids load would have passed through the Marsh into Carson Sink. The dissolved-solids concentrations, however, would have been higher and more variable in these lower wetlands than in Carson Lake.
Several early reports are available that describe water quality in Stillwater Slough and Carson Lake. Kern (Fremont Expedition of 1845) said ofthe water at the outlet ofCarson Lake that it was "indifferently good" (Spence and Jackson, 1973, p. 52). Stillwater Slough water was described as "quite good" by Simpson (1876, p. 85). DeQuille, in the summer of 1861, described the water at the south end of Carson Lake as having the taste ofdecayed tules, but found the water in the upper slough to have a "touch ofalkali" and at the lower end at the mouth ofthe sink, "a strong alkali twang"; he sent an Indian several hundred yards into the marsh fordrinking water (1963, p. 28, 38, 42). After 60 years ofagricultural activities (1862-1922), the dissolved-solids concentration ofthe water in Carson Lake was still only about 1,000 mg/L (Hart and Bixby, 1922, p. 15). Forcomparison, the maximum permissible dissolved-solids concentration in Nevada public water supplies is 1,000 mg/L. Dissolved-solids concentrations wouldhave fluctuated seasonally when the lake surface regularly dropped below its natural rim in the fall and during droughts. As an example, Professor F.W. Clarke found a dissolved-solids concentration ofabout 1,500 mg/L in a water sample collected from Carson Lake in October 1863, a year after the Carson River was diverted from the lake during the floods of 1862 (Russell, 1885, p. 44, 69). Approximately halfthe streamflow ofthe Carson River would have come during peak snowmelt runofffrom April through mid-July, then in most years would have diminished abruptly. This pattern wouldhave resulted in dissolved-solids concentrations that were more variable in StillwaterMarsh than in Carson Lake. In most instances, dissolved-solids concentrations in Carson Lake and much ofStillwater Marsh would not have been a limiting factor to the biotaknown to have existed in the system. From examination ofpollen in a core ofLeadLake sediment, scientists oftheDesertResearchInstitutefoundthatthe wetland waterhad been alternately brackish and fresh (Warburton and others, 1990, p. 73-74). Because of the irregular topography ofStillwater Marsh, some wetland areas may have been poorly flushed and occasionally bypassed by the flow ofthe Carson River. Although Carson Lake and StillwaterMarsh currently are hydrologically isolated, the dissolvedsolids loads projected under OCAP were summed (128,000 ton/yr) and compared to historical load (99,000 ton/yr) to assess the extent ofchange. While the projected load is estimated to increase somewhat about 30 percent overthe historical load, the projectedconcentrationwouldincrease greatly about 400 percent. Such a large increase in concentration is significant because living organisms respond physiologicallytoconcentrationratherthantoload. Although the historical dissolved-solids concentration in Carson Lake would have increased as aresult ofevapotranspiration, the concentration in the water as it was flushed into Stillwater Marsh may have averaged 270 mg/L (see footnotes 7 and 8 in table 2) because ofthe higher riverflows atthattime. This concentration wouldhave been representative ofconditions throughout most of Stillwater Marsh following the spring flow peak.
The extrapolated estimates and existing reports indicate that the predevelopment water supply was probably adequate and of suitable quality to support healthy wetlands and their associated plants, fish, and wildlife. In the absence ofagricultural irrigation, which has been shown to mobilize salts and trace elements such as arsenic, boron, selenium, molybdenum, andlithium (Hoffmanandothers, 1990,p. 31-38), and a corresponding increase in dissolved-solids concentrations, the waterreaching Carson Lake and Stillwater Marsh in predevelopment time (pre-1860)

was ofbetter quality than water reaching the wetlands today.

16 Detailed Study of Irrigation Drainage Effect on BiotaHistorical water quality in the ephemeral wetlands ofCarson Sink, however, would have varied greatly. Under a representative average condition, 210,000 acre-ft offresh water (about 270 mg/L, dissolved solids) would have passed into these ephemeral wetlands, flushing the area near StillwaterMarsh. Regular flushing in the spring would have created conditions favorable for aquatic vegetation and many forms ofwildlife. Sperry (1929, p. 1-2) reported a wide variety ofboth submergent and emergent vegetation and wildlife in the sink, including extensive beds ofalkali bulrush and sago pondweed. Alkali bulrush tolerates brackish water ranging from a specific conductance of995 uS/cm (about 650 mg/L, dissolved solids) to 25,800 uS/cm (about 16,800 mg/L, dissolved solids). Sago pondweed grows in water containing as much as 16,800 mg/L, dissolved solids (25,800 uS/cm; Stewart and Kantrud, 1972, p. D5, D21, and D25). Archaeological sites that were occupied by humans

are found in the playa habitat within the Carson Sink. These sites are similar to those in StillwaterMarsh, indicating the presence ofwetland plants and animals (C. Clifford Creger, U.S. Fish and Wildlife Service, Fallen, Nev., written commun., 1992). Thus, these sitesprobablyhadpotablewater,inthehistorical sense, during periods ofhuman use. Water-quality characteristics are different when the Carson Sink is filled. Such an event, anomalous under current managed conditions, occurred between 1982 and 1988 when large quantities ofrelatively dilute flood water from both the Carson and Humboldt Rivers filled Carson Sink to a depth ofnearly 12 ft (average 8 ft). In July 1983, specific conductance offlood water in the Carson Sink near Humboldt Slough was 4,700 uS/cm (about 3,100 mg/L, dissolved solids), butby January 1987 water in the Carson Sink had reached a dissolvedsolids concentration of20,000 mg/L (Rowe and Hoffman, 1990, p. 37). This concentration cannot be accounted forby evaporative water loss alone; much ofthe dissolved solids probably resulted from redissolving salts previously deposited in the sink. During this event, no vascular aquatic plants grew in the sink. Fish flourished during the first years, then perished when the dissolved-solids concentrations ofwater became intolerably high as the water evaporated. A similar cycle probably occurred in the 1860's; the water in Carson Sink was 20 ft deep in 1863, according to Morrison (1964, p. 104). In summary, the historical condition ofthe Carson River-Carson Sink system was a flushthrough pattern with most ofthe runoffoccurring in the spring. Runoffflowed into Carson Lake, overflowed into StillwaterMarsh, and then created extensive ephemeral wetlands in the Carson Sink. Almost the entire 410,000 acre-ft (average annual flow) of CarsonRiverwithaprobablelow average (<300mg/L) concentrationofdissolved solids,enteredthewetlands. The wetlands would have been largest in the spring, decreasing by evapotranspiration through the summer and fall. Salts depositedprimarily inthe sinkby evaporating water would have been redissolvedby the flushing action ofsubsequent spring peak flows and carried farther out into the sink. The distal edges ofthe wetlands would normally have been brackish, and the farthest reaches, at times, even more saline.



### VEGETATION

Early reports ofthe study area describe a biologically productive marsh with a great diversity ofvegetation. In 1845, when Kern reported timber at the mouth ofthe Carson River, he also described Carson Lake as bordered by "a thick growth" of bulrush about 30-40 yards wide at the mouth ofthe river (Spence and Jackson, 1973, p. 51-52). Simpson (1876, p. 85-86) called the alluvial bottom around the lake in 1859 "extensive and rich, as the luxuriant growthofrushes shows." Bailey (1898, p. 3) described StillwaterMarsh as "... halfshallow lake, halftule swamp [which] extends for 20 miles along the valley bottom and furnishes enough salt grass, sedges, and tules to winter many thousand head ofstock and a breeding ground for great numbers ofwater and shore birds." Early in this century, Sperry (1929, p. 1-3) described the vegetation in the southwestern part of Carson Sink. At that time, alkali bulrush dominated the marsh, and cattail (Typha sp.) was common. Spike rush (Eleocharis acicularis) was abundant. Open water areas contained abundant stands ofsago pondweed, horned pondweed (Zannichelliapalustris), and algae. The old high-water line was marked by iodine brush (Allenrofea sp.), below that was abank ofpickle weed (Salicornia sp.), and all around, even out in the mudflats, were patches of salt grass (Distichlis spicata).

ESTIMATED HISTORICAL CONDITIONS Ker/ey and others 17Wuzzie George described Stillwater Marsh of

the early 1900's as abundant in both submergent and emergent vegetation; alkali bulrush was the most

common emergent, followed by hardstembulrush (Scirpus acutus) and cattails (U.S. Fish and Wildlife Service, 1952, p. 19). At Stillwater Marsh, inflow water was sufficient to maintain luxurient wetland vegetation until 1967 when regular winter water releases from Lahontan Reservoir for power generation were discontinued. During the early 1950's, cattails were the dominant emergent species in the marsh, followed by alkali bulrush, then hardstem bulrush, at a ratio of4.5:1.5:1 (U.S. Fish and Wildlife Service, Fallen, Nev., 1952, written commun.). A quantitative survey in Stillwater Marsh in 1959 found a diversity ofvegetation. Emergent vegetation was then dominated by alkali and hardstem bulrushes and submergent plants by horned pondweed, sago pondweed, and western pondweed (Potamogetonfiliformis). Other submergent plants observed by the U.S. Fish and Wildlife Service included coontail (Ceratophyllum demersum), muskgrass (Chara sp.), widgeon grass (Ruppia maritima), andcurly-leafpondweed(Potamogetoncrispus). Some submergent plants, such as horned and sago pondweeds and widgeon grass, are relatively insensitive tohigh concentrations ofdissolved solids (Stewart and Kantrud, 1972, p. D25; Steward and others, 1963, p. 50). The abundance ofthese submergent plants, as well as more sensitive species in Stillwater Marsh in 1959, indicates the presence ofa mixture offresh and brackish water at that time (U.S. Fish and Wildlife Service, 1969). In the Stillwater WMA, coontail and other less salt-tolerant pondweeds that were abundant in the 1959 survey have decreased, not only in total abundance but also relative to the more tolerant species, such as widgeon grass and sago pondweed. The abundance of some plants, such as western pondweed, is correlated with freshwater inflow. Cattails

are extremely sensitive to increased dissolved-solids concentrations, whereas alkali and hardstembulrushes tolerate higher concentrations (Stewart and Kantrud, 1972, p. D21); cattails in Stillwater WMA are now found only in scattered patches. Information from U.S. Geological Survey topographic maps (Carson Lake and Fallen quadrangles) published in 1951 indicates that vegetation has also diminished at Carson Lake by about 50 percent in the last 30 years. Today, much ofCarson Lake is a pasture for livestock. Much ofthe remaining water

area is entirely devoid ofvascular aquatic vegetation, and emergent vegetation is reduced to relatively small stands ofbulrush near the inflow from drains.

WILDLIFE

Historically, the wetlands ofthe Carson LakeStillwater area supported a large and diverse assemblage ofanimals as well as plants. Archaeological studies have determined that the wetland areas were used extensively by native people for a period exceeding4,000 years (U.S. Department ofthe Interior, 1988, p. Fl; Kelly, 1988, p. 11), an indication that the early (pre-1860) wetlands were a more productive and reliable habitat than those existing today. Little information is available to quantify the abundance ofwildlife in the study areaprior to irrigation diversion, but reports from early explorers and archeologists indicate that populations and diversity ofwildlife were much greater than exist today. According to Simpson (1876, p. 85), the marsh supported abundant fish populations. Simpson wrote, "... the lake is filled with fish...[the Indians] have piles offish lying about drying, principally chubs and mullet." DeQuille (1963, p. 33) saw Indians with "several fine strings offish" in 1861 and the Indians fishing nearby were having "first-rate luck"; one had caught four nice fish in a few minutes. Fish bones are commonly found in archaeological sites, suggesting that fish were a significant food source forthe people; skeletalremains oftui chub (Gilabicolor) andtahoe sucker (Catostomus tahoensis) are abundant at archaeological sites in StillwaterMarsh (Greenspan, 1988, p. 315-326). Both fish species are tolerant ofwide ranges ofdissolved solids. Lahontan cutthroat trout (Onchorhynchus clarki henshawi), although not widely distributed, were found in some Stillwater archaeological sites (Smith, 1985, p. 177). Lahontan cutthroat trout are tolerant ofdissolved solids up to approximately 12,000 mg/L (Taylor, 1972, p. 7), but

are sensitive to high water temperature. Historical water quality in Carson Lake and the southern part of StillwaterMarsh should nothavebeen alimiting factor in the survival and distribution ofcutthroat trout at mosttimes,butchanginghabitatandwatertemperature resulting from water-level fluctuations may have been.

18 Detailed Study of Irrigation Drainage Effect on BiotaRiver otter and mink, both fish-eating animals,

were present and used by the native people (Schmitt, 1988, p. 272). Pelicans (Pelecanus erythrorhynchos), also fish eaters, were "characteristic" ofthe area (Simpson, 1876, p. 86).
Freshwater clams and aquatic snails (gastropods) were once abundant throughout the wetlands. Simpson (1876, p. 86) observed in 1859 that the shores ofCarson Lake were covered with clam shells, and Russell (1885, p. 69) reported various species offreshwater clams and snails in Carson Lake. Drews (1988, p. 329-333) found evidence that clams

were a food item at various sites in Stillwater Marsh. Sperry (1929, p. 3), surveying the adjoining wetland in Carson Sink in 1929 (now Fallen NWR), found that clams, frogs (Rana sp.), and snails (Physa sp.) were common, and that muskrats (Ondatra sp.) were reported as abundant throughout Carson Sink.
Mink and otters are absent from the wetlands today, as are frogs and turtles. Muskrats are no longer abundant. Fish populations are greatly reduced, and the species composition has changed since historical times. Most ofthe native fishes are now absent from
most areas; Lahontan cutthroat trout are entirely absent. Several species ofnon-native fishes, primarily sport fish, were introduced early in the century, but
most have decreased to remnant numbers. Introduced Largemouth bass (Micropterus salmoides) was a major fishery until the 1970's, when the population virtually disappeared. Today, only remnant populations offreshwater clams remain in Stillwater Point Reservoir and in the D-line Canal, the areas with the lowest dissolved-solids concentration.
Historical references record the abundance ofpelicans, curlews (Numenius americanus), other shore birds, ducks, geese, and other aquatic birds (Simpson, 1876,p. 85-86; Bailey, 1898,p. 3; DeQuille, 1963, p. 28-32). Shore birds, including curlew, are largely insectivorous and tend to frequent shallow, sparsely vegetated ephemeral water areas and mud flats wetland types that historically covered thousands ofacres on the Carson Sink in the spring and

are now scarce. None ofthe birds are entirely absent today, but none could be termed abundant and some, such as the curlew, are uncommon. 

### PRESENT/PROJECTED WETLAND CONDITIONS

Court-ordered Operating Criteria and Procedures (OCAP) for the Newlands Project, to be fully in effect in 1992, were evaluated in detail by the U.S. Department ofthe Interior (1988). An estimate ofprojected wetland conditions was made, based

on data for inflow ofwater from all sources available for wetland maintenance between 1967 and 1986 and

on surveys ofvarying reliability, made in September for many years, ofall major wetlands in the area. The managed wetlands at Carson Lake and Stillwater Marsh (StillwaterWMA and Canvasback Gun Club) under the 1992 institutional (OCAP) constraints, are usedheretorepresentpresent/projected wetlandconditions. It is important to note that the Carson River

no longer flows through Carson Lake and thence to Stillwater Marsh. Both wetlands are isolated; are maintained with drainwater, operational releases, and occasional flood flows; and are manipulated with man-made water-control structures.
Recent (1967-1986) average wetland sizes for Carson Lake and Stillwater Marsh were 10,000 and 14,000 acres, respectively. Under OCAP, flow to these primary wetlands, and their average size, are reduced about 50 percent (U.S. Department ofthe Interior, 1988, p. E5; U.S. Fish and Wildlife Service, 1988, fig. 5, p. 52). Underprojected managed conditions, an average 25,000 acre-ft ofwater would maintain about 5,000 wetland acres at Carson Lake, and

an average 55,000 acre-ft ofwater in StillwaterWMA Marsh (including the Canvasback Gun Club) would maintain about 11,000 acres ofwetlands. This projected total ofaverage wetland sizes in Carson Lake and StillwaterMarsh (16,000 acres) is about 11 percent ofthe estimatedhistorical sum of 150,000 average wetland acres in and near Carson Lake, StillwaterMarsh and Carson Sink. Present wetland conditions are not directly comparable to historical conditions because most ofthe water now available is used for maintenance ofpermanentwetlands. Incontrastto thenatural pattern ofthe unregulated, historical Carson River (fig. 3), with an abrupt spring runoffpeak, the water to StillwaterWMA, dictated by agricultural practice,

comes in a reduced, protracted flow from March throughNovember, without a substantial flushing flow in the spring (U.S. Fish and Wildlife Service, 1988, fig. 8). In addition, much ofthe remaining flow is

ESTIMATED HISTORICAL CONDITIONS Ker/ey andothers 19

### managed by artificial structures to create permanent wetlands consuming about 5 acre-ft/acre ofwaterper year. Because ofthis management, present wetlands

are smallerbut more permanentthan historical wetlands supportedby a given amount ofwater. To allow comparison, under OCAP the average 16,000 acres projected to remainin CarsonLake and Stillwater Marshwouldrequire atleast 80,000acre-ft/yrofwater. However, the dissolved-solids concentrations inthe inflow water ofStillwater Marsh and CarsonLake

are now, respectively, aboutfour to seventimes greaterthan historical concentrations; wetland flushing is restricted only to years with exceptionally high streamflow.
Water quality projected for the wetlands was describedbythe U.S. Fish andWildlife Service (1988, p. 50). Dissolved-solids concentrations in water entering primary wetlands would average 1,170mg/L, as projected for OCAP. The dissolved-solids concentrationofthe Carson Lake inflow is about seventimes the estimated historical concentrationof 170 mg/L of solids for the Carson River, andthe Stillwater Marsh inflow is about four times more concentrated than the estimated270mg/Lhistorical Stillwaterinflowbyway ofStillwater Slough. Again, the reader is cautioned thatthe historical estimates arejust that estimates and should notbe usedbeyond thatintended for this report. In Stillwater WMA, dissolved solids are progressively concentratedthroughevapotranspiration

as inflow wateris storedforwaterfowlusethen moved through sequentially arrangedponds (table 3). These

are historical ponds with water-control structures added. Underpast managementpractices, the initial wetland would concentrate inflowing dissolved solids bynearlyfourtimes,to about4,600 mg/L, andthenext sequentialwetlandwouldfurtherconcentratedissolved solids by six times, to about 28,000 mg/L (U.S. Fish and Wildlife Service, 1988, table 7). Presentconcentrations ofdissolved solids would rarelyhave occurredinthehistorical flow-throughwetlands at CarsonLake and Stillwater Marsh, but they may have routinely occurredinparts ofthe more ephemeral wetlands in the Carson Sink. For example, highdissolved-solids concentrations were measuredin the Carson sinkduringthe 1980's (Rowe andHorrman, 1990, p. 37). Presentwater-quality conditions inparts ofCarsonLake and Stillwater Marsh are limiting to
some aquatic plants and animals. In addition, trace elements toxic to fish and invertebrates are being releasedfromCarsonDesertsoilsby agricultural drainage and areentering these wetlands, as discussedinthe next section ontoxicity. In summary, the pattern ofwater flow, quality ofthe water, and the size andquality ofthe resultant wetlands, as well as vegetation and wildlife, have all changed dramatically since the onset ofirrigation in the late 1800's.

Table 3. Concentration factors between wetland units and recent and projected concentrations of dissolved solids, Stillwater Wildlife Management Area

[Values are based on data collected by the U.S. Fish and Wildlife Service (1988)]

Wetland unit1

Wetland inlet flow Primary unit Secondary unit Tertiary unit Recent average dissolved solids (mg/L) (1967-1986)

600 2,360 14,180 28,400 Approximate

concentration factor

22
4 6 2 Projected

average dissolved solids (mg/L)

1,170 4,610 27,600 55,200

1 Primary, secondary, and tertiary units refer to a series ofshallow ponds thatreceive
water progressively more concentrated with dissolved solids. 2 Initial change in dissolved-solids concentrations resulting from irrigation practices.

20 Detailed Study of Irrigation Drainage Effect on Biota

# TOXICITY OF IRRIGATION DRAINAGE AND ITS EFFECT ON AQUATIC ORGANISMS

The wetlands in StillwaterWildlife Management Area (WMA) are managed primarily to support migratory waterfowl. Many water-dependent migratory birds require a variety offish and invertebrates in their diets. As a result ofirrigation drainage, water in Stillwater WMA has an unnaturally high salinity, and both water and biota contain elevated concentrations ofpotentially toxic trace elements that can affect fish and invertebrates (Hoffman and others, 1990, p. 76-77). Forexample, StillwaterWMAcannolonger sustain a Largemouth bass (Micropterus salmoides) population (U.S. Fish and Wildlife Service, 1988, p. 132), and invertebrate density is low. Toxicity tests were conducted to assess the suitability of water from various drains and wetland areas to support fish and invertebrates.



### METHODS
Sample Collection

Water samples were collected at sites in StillwaterWMA on Paiute Diversion Drain, D-Line Canal, Hunter Drain, Lead Lake, Stillwater Point Diversion Drain, Stillwater Point Reservoir, and TJ Drain (including one USGS well near TJ Drain). Sampling sites are shown in figure 4. Composite water samples were collected daily from each drain location during August 9-18, 1988. Each sample consisted ofwater collected at 15-minute intervals during a 24-hour period by an ISCO model 2710 automatic composite sampler. Water was pumped from the drain through Teflon tubing into 19-L, acid-washed, glass collection containers. The containers were held in ice baths during the collection periodtokeepthe samples at approximately4°Cduring the day. Water samples fromLeadLake and Stillwater PointReservoirwerecollecteddaily as "instantaneous" samples and, as such, represent the quality ofthe water at the time of sampling. Onsite toxicity tests were made with portions ofthese samples collected daily from each location. Principal constituents and properties ofeach water sample (temperature, pH, dissolved oxygen, hardness, alkalinity, turbidity, specific conductance, salinity, andcalcium, sulfate, and chloride) were measured on-site daily. Ammonia and nitrate were measured near the beginning, middle, and end ofthe toxicity tests. A portion ofthe composite water collected daily was used for determination ofadditional inorganic constituents (magnesium, sodium, potassium, silica, phosphorus, arsenic, barium, boron, lithium, mercury, molybdenum, selenium, strontium, vanadium, andzinc). These subsamples werecollected in 1-L, linear polyethylene bottles that had been previously washed with soap and water, rinsed with tap water, soaked in concentrated nitric acid, and rinsed twice with deionized water. Samples were filtered through a 0.4-|im polycarbonate filter and preserved with 2 mL ofultrapure nitric acid for in the laboratory analysis. Chemical analyses ofthe water were made by Environmental Trace Substances Research Center (Columbia, Mo.). Spiked samples, blanks, and replicates prepared onsite were included as qualityassurance samples (Peden, 1986). A one-time collection ofwater from an observation well near TJ Drain was made by U.S. Geological Survey personnelusing abailer and according to standard methods (Claasen, 1982). The well water, whichrepresentedpotential seepagetothedrain,

was tested for acute toxicity and analyzed for traceelement concentrations. A one-time collection ofwater from all drains also was made for analysis ofpotentially toxic manmade organic constituents. Analysis was made by the U.S. Geological Survey National Water Quality Laboratory, Denver, Colo. The data are on file at the U.S. Geological Survey, Nevada District Office, Carson City.

TOXICITY OF IRRIGATION DRAINAGE Fingerandothers 2139°40'

39°30' Fallen National

Wildlife Refuge

R. 29 E. R. 30 E. R. 31 E. R. 32 E.

EXPLANATION

OPEN WATER STILLWATER NATIONAL WILDLIFE REFUGE -- AS defined July 1990. Western boundary is dotted line PRIVATELY OWNED LAND WITHIN REFUGE -Includes Canvasback Gun Club BOUNDARY OF WILDLIFE MANAGEMENTAREA
BOUNDARY OF FALLON INDIAN RESERVATION North boundary coincides with that of adjacent Wildlife ManagementArea SITE OFTOXICITY SAMPLE

Figure 4. Locations of toxicity sampling sites and important hydrologic features in and near Stillwater Wildlife Management Area. (Map modified from Lico, 1992.)

22 Detailed Study of Irrigation Drainage Effect on Biota

### Toxicity Assessments

Toxicity tests were made using a portion of the daily composite water sample from each location to renew the test solution daily throughout the test period. The species tested were bluegills (Lepomis macrochirus), larval fathead minnows (Pimephales promelas), anddaphnids (Daphnia magnd). Daphnids and fathead minnow larvae were obtained from cultures at the National Fisheries Contaminant Research Center (NFCRC), Columbia, Mo., and were maintained onsite in well water (hardness, 283 mg/L as CaCO3; alkalinity, 255 mg/L as CaCO3; pH, 7.8) that hadbeentransported fromNFCRC. Bluegills (<0.1 g)

were obtained from the Missouri Department of Conservation, shipped to StillwaterWMA, and transferred into the NFCRC well water for48 hours of observation prior to use. Using Hunter Drain water, in which salinity exceeded 15 ppt, additional tests were made with salt-tolerant species sheephead minnow (Cyprinodon variegatus) larvae, and mysid shrimp (Mysidopsis bahid). These organisms were obtained from the U.S. Environmental Protection Agency (USEPA) Laboratory in GulfBreeze, Fla. Tests were made as static renewals under appropriate 10-day test procedures (USEPA, 1985; American Society for Testing Materials, 1988). All organisms were fed freshly hatched brine shrimp (Artemid) twice daily. Tests with daphnids and fathead minnow larvae included 2 replicates per treatment and 10 organisms per replicate. Tests with bluegills consisted of2 replicates per treatment and 5 organisms per replicate. Treatments included fullstrengthwateranddilutionsof50,25, and 12.5percent. Dilution water for each test was reconstituted to the appropriate hardness, alkalinity, specific conductance, andpH for thattest-location waterby the addition of major cations and anions using Instant Ocean and deionized water. By reconstituting dilution water to the same ionic composition as the drainwater, consistent concentrations ofconstituents such as calcium, magnesium, sodium, potassium, chloride, and sulfate

were maintained for all treatments for each sampling site. All sampling sites were evaluated using this reconstituted water as a diluent and as a control. In addition, Paiute, TJ, and Stillwater Point Diversion Drains were also assessed by using water into which they discharged (Paiute and TJ into D-Line, and Stillwater Point Diversion Drain into Stillwater Point Reservoir) as diluent and control. The NFCRC well waterprovided a second control to evaluate the condition oftest organisms throughout the tests. Dissolvedoxygen concentrations exceeded 40 percent saturation in all tests. Acceptability ofa test required that control mortality not exceed 10 percent. Evaluation ofpotential toxicity problems in the Stillwaterareaincludedatotal of35 concurrenttests on water samples:

Sample site Dilution source Number of tests

Paiute Diversion Drain

Paiute Diversion Drain

TJ Drain

TJ Drain

StillwaterPoint Diversion Drain Reconstituted water 3

D-Line Canal water 3

Reconstituted water 3

D-Line Canal water 3

Reconstituted water 3

StillwaterPoint Diversion Drain

StillwaterPoint Reservoir

Lead Lake

HunterDrain

D-Line Canal

TJ Drain ground water StillwaterPoint Reservoir water
Reconstituted water
Reconstituted water
Reconstituted water
Reconstituted water

Undiluted water 3

3

3

5

3

3

During the tests, mortality was recorded daily for each species. Bluegills were weighed and measured to assess growth atthe initiation and termination ofthe test. A subsample ofdaphnids was preserved on the first day ofthe test and the surviving adults were also preserved on the final day ofthe test for later examination. For daphnids, time to firstbrood production, total number ofbroods, and number ofyoung per brood were recorded as measures ofreproductive success. Temperature, pH, and dissolved oxygen were measured daily in each beakerprior to renewal oftest solutions.



### Chemical Analyses

Principal constituents and properties, along with ammonia and nitrate, were determined using standard methods (magnesium, sodium, potassium, silica, phosphorus, arsenic, barium, boron, lithium, mercury, molybdenum, selenium, strontium, vanadium, and zinc).

TOXICITY OF IRRIGATION DRAINAGE Fingerandothers 23Filtered water samples to be analyzed for

inorganic constituents were digested in 100-mL borosilicate glass beakers that had been cleansed by a concentrated nitric acid, 30-minute, reflux cycle. About 40 mL ofthe digested sample was combined with 15 mL ofconcentrated nitric acid and 2.5 mL ofconcentrated perchloric acid, then evaporated over low heat until only 1 mL remained. This digestate was diluted to 50 mL with ultrapure water and analyzed for selenium and arsenic by hydride generation atomic absorption. The remaining digestate was analyzed for additional elements with an inductively coupled plasma spectrophotometer. Mercury was determined by cold vapor atomic absorption. Analytical procedures are described in detail by the U.S. Fish and Wildlife Service (1985). All results were within 20 percent ofconfidence intervals for certified or recommended concentrations for the reference materials. Ofthe samples analyzed, 10 percent were blanks and 20 percent were blind replicates and spiked samples. No values for blanks exceeded analytical reporting limits for any element (table 4). Daily water-quality measurements for the seven surface-water sites are presented in the supplemental data tables at the back ofthis report. A summary of ranges is shown in table 6.
Water samples for analysis ofmanmade organic constituents were extracted three times in the laboratory at both acidic and basic pH with methylene chloride. The extracts were concentrated to about 1 mL, combined with an internal standard, and analyzed by gas-chromatography, electron-impact, mass spectrometry. Surrogate compounds were added to each samplepriorto extraction to verify methodrecoveries (Wershaw and others, 1987). The analytical results are discussedin the subsection titled "Stillwater Point Diversion Drain and Stillwater Point Reservoir."

Table 4. Analytical reporting limits for selected inorganic constituents in water (from Environmental Trace Substances Research Center, Columbia, Mo.)

[All units in micrograms per liter, except where indicated; mg/L milligrams per liter]

Element Concentration Element Concentration

Calcium (mg/L) Magnesium (mg/L) Sodium (mg/L) Potassium (mg/L) Sulfate (mg/L)

Silica (mg/L) Chloride (mg/L) Phosphorus (mg/L) Aluminum Antimony

Arsenic Barium Beryllium Bismuth Boron

Cadmium Chromium Cobalt 0.002 .002 .02 1 1

.01 .15 .10 30 40

.5 1 1 60 20

2 10 10 Copper

Iron Lead Lithium Manganese Mercury Molybdenum Nickel Selenium Silver

Strontium Thallium Tin Titanium Tungsten

Vanadium Zinc 2

5 40.5 5

.3 20 100.3 20

4 3 10 4 2

2 2

24 Detailed Study of Irrigation Drainage Effect on BiotaRESULTS OF TOXICITY TESTS

Paiute Diversion Drain and D-Line Canal beryllium, bismuth, chromium, cobalt, copper, iron, nickel, silver, tin, titanium, thallium, and tungsten did not exceed reporting limits.

Water from Paiute Diversion Drain diluted with D-Line Canal water was not acutely toxic to bluegills, fathead minnow larvae, or daphnids (table 5). No substantial mortality occurred in tests with water from Paiute Diversion Drain regardless ofdilution water, andno mortality was recorded for any species exposed to water from D-Line Canal. No sublethal responses
were identified in daphnids exposed to water from either location. Daphnids produced equal numbers of young in all treatments, with one brood produced in every treatment on day 8. For all treatments, mean number ofyoung perbrood ranged from 8.1 to 9.4. Microscopic examination ofadults atthe end ofthe test revealed production ofeggs for a secondbrood and substantiated the continued reproductive development that would be expected in healthy organisms. Concentrations ofconstituents in Paiute Diversion Drain and D-LineCanal waterwere similar, anddaily fluctuations in water quality were minimal during the study period (table 6). Neither mercury nor selenium was detected in any water sample. In addition, aluminum, antimony, TJ Drain

Water from TJ Drain was acutely toxic to bluegills, fathead minnow larvae, and daphnids (tables 7 and 8). Cumulative mortality in 100-percent TJ Drain water was similar for fathead minnows and bluegills, and ranged from 85- to 90-percent mortality after 9 days ofexposure. No mortality was observed in well-water controls, reconstituted-water controls,

or 100percentD-LineCanalwateralsousedascontrol. Daphnids were more sensitive than were fish species to the two highest drain-water concentrations. Total mortality ofdaphnids occurred in full-strength drainwater after 6 days and in the 50-percent dilution by the end ofthe test; no substantial mortality occurred in the 12.5-percent dilution. No daphnid reproduction occurred in the TJ Drain waterregardless ofdilution water. Control daphnids in reconstituted water reproduced on day 8, with a mean brood size of9.6; a first brood (9.3 young) was also produced on day 8 in the D-Line Canal control water.

Table 5. Cumulative mortality of bluegills, fathead minnow larvae, and daphnids after exposure to water from Paiute Diversion Drain diluted with (A) reconstituted water1 and (B) water from D-Line Canal

Cumulative mortality of species after tests (percent)

Species (and number sampled)

Bluegills (10) Fathead minnow larvae (20) Daphnids (20) Proportion of drain water in sample

100 percent 50

percent 25

percent 12.5

percent

A. Drainwater, diluted with reconstituted water

0 0 10 0 0000 0 0 10 0 0 percent

10 0 5 NFCRC

wellwater control2

0 0 0

B. Drainwater, diluted with D-Line Canal water Bluegills (10) Fathead minnow larvae (20) Daphnids (20) 10 0 10 10

0 0

1Deionized waterreconstituted tothe samehardness, alkalinity, specific conductance, andpH as the PaiuteDiversion Drain water. 2Well water from National Fisheries Contaminant Research Center, Columbia, Mo.

TOXICITY OF IRRIGATION DRAINAGE Fingerandothers 25Table 6. Ranges of water-quality measurements in surface-water samples collected daily, August 10-18, 1988, for aquatic toxicity tests1

9 a. CO
I o

CD fi> f» o'

a

(O 

# I [Abbreviations: NTU, nephelometric turbidity units; ppt, parts perthousand; J-lS/cm, microsiemens per centimeter at 25°C; J-lg/L, micrograms per liter; mg/L, milligrams

per liter.]

Specific Conductance (jiS/m) pH, field (units) Turbidity (NTU) Dissolved oxygen (mg/L) Calcium (mg/L) Magnesium (mg/L) Hardness (mg/L as CaCO3 ) Sodium (mg/L) Potassium (mg/L) Alkalinity (mg/L as CaCO3)

Sulfate (mg/L) Chloride (mg/L) Silica (mg/L) Salinity (ppt) Phosphorus (mg/L)

Arsenic (ug/L) Barium (ug/L) Boron (^g/L) Lithium (ug/L) Mercury (ug/L) Molybdenum (ng/L) Selenium (ng/L) Strontium (ug/L) Vanadium (^ig/L) Zinc (ug/L) Paiute Diversion Drain

370-480 7.5-8.6 15-35 6.8-9.7 31-36

10-13 110-140 62-84 2.8-5.4 111-158

52-85 50-70 5.8-7.2 0.1-0.3 <0.1-0.2

10-20 70-90 520-760 50-60 <0.3

<20-20 <0.3 350-410 10 20-70 D-Line

Canal

350-610 8.6-9.4 3-9 9.0-10.3 26-32
9-11 94-130 83-110 5.4-9.4 113-174

47-130 12-50 5.9-7.6 0-0.5 <0.1

40-50 40-60 620-810 50-60 <0.3

<20-20 <0.3 340-370 10-20 10-40 TJ Drain

6,100-14,900 8.4-8.6 2-8 7.4-10.9 140-310

160-410 1,100-2,500 1,900-4,700 29-57 217-319
880-3,600 2,700-6,200 0.1-3.8 4.1-13.0 0.4-1.0

110-170 50-110 6,800-17,000 340-760 <0.3

270-670 0.9-1.6 3,200-7,900 10-20 10-90 Hunter Drain

410-27,500 8.0-8.8 7-37 5.6-8.8 32-390

10-250 110-2,300 98-8,600 4.0-210 102-276
52-2,900 84-13,000 5.0-13 0.0-28 <0. 1-0.9

20-190 50-100 810-49,000 60-2,300 <0.3
20-1,300 <0.3-3.6 390-10,400 10-30 10-90 Lead Lake

5,100-6,100 8.6-8.9 37-96 5.6-9.2 64-74

90-103 570-680 980-1,100 29-33 227-272

360-680 1,200-1,800 5.1-7.5 3.1-4.2 0.20-0.37

100-130 110-140 5,000-6,000 340-390 <0.3

110-130 <0.3 1,800-2,000 20 10-40 Stillwater

Point Diversion Drain

470-720 8.2-8.6 21-54 8.3-9.6 42-51

12-18 140-200 120-270 7.3-13 114-312

110-150 43-63 11-14 0.2-0.8 0.20-0.30

40-50 60-70 860-1,800 60-100 <0.3

30-50 0.4-0.6 450-670 20 40-100 Stillwater

Point Reservoir

1,590-2,510 9.0-9.2 170-580 8.2-10 22-36

16-21 130-170 310-480 15-21 235-300

100-240 300-550 10-12 0.9-1.9 <0.1

80-110 90-120 2,000-3,000 100-130 <0.3

50-70 0.4-0.6 520-570 20-30 10-50

1 Analyzed by Environmental Trace Substances Research Center, Columbia, Mo. These water-quality data do not necessarily conformto U.S. Geological Survey guidelines for reporting significant figures.Table 7. Cumulative mortality of bluegills, fathead minnow larvae, and daphnids exposed to water from TJ

Drain diluted with reconstituted water1

Cumulative mortality of species in tests (percent)

Species Exposure (and number sampled) (days)

Bluegills (10) 1 2 3 4 5 6 7 8 9

Fathead minnow larvae (20) 1 2 3 4 5 6 7 8 9 Daphnids (20) 1 2 3 4 5 6 7 8 9 Proportion of drainwater in sample

100 percent

0 0 20 40 50 70 90 90 90

20 20 20 20 45 45 60 60 85

10 25 25 60 95 100 50 percent

0 0 20 30 30 30 50 50 70

0 0 10 20 20 30 30 40 45

0 0 20 30 30 40 75 80 100 25 percent

0 0 0 10 10 10 30 30 30

0 0 0 10 10 20 20 20 20

0 0 0 10 15 20 25 25 25 12.5 percent

0 0 0 0 0 10 10 10 20

0 0 0 0 0 10 10 10 10

0 0 0 0 0 10 10 10 10 0 percent

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 NFCRCwellwater control2

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

1 Deionized water reconstituted to the same hardness, alkalinity, specific conductance, and pH as the TJ Drain water. 2Well water from National Fisheries Contaminant Research Center, Columbia, Mo.

A dose-response pattern was evident for all species regardless ofdilution water. Although the fluctuating salinity was undoubtedly stressful to test organisms, survival oforganisms in controls with identical salinity fluctuations strongly suggests that mortalities in drainwater did not result from exposure to salinity alone.
Concentrations oftrace elements fluctuated throughout the exposure period, but concentrations of arsenic, boron, lithium, and molybdenum were consistentlyhigherinTJ Drain waterthan inPaiute Diversion Drain or D-Line Canal water, where no mortality was observed. Levels ofarsenic in TJ Drain consistently exceeded 100 |Xg/L and boron concentrations reached

a maximum level of 16,700 |Xg/L. Concentrations of dissolved selenium ranged from 0.9 to 1.6 ^lg/L; the highest concentrations were on day 4 when salinity

was highest, and the lowestconcentrations were on the day oflowest salinity. No mercury was detectedin any sample. In addition, aluminum, antimony, beryllium, bismuth, chromium, cobalt, copper, iron, nickel, silver, tin, titanium, thallium, and tungsten did not exceed reporting limits. Ranges ofconcentrations ofother constituents are reported in table 6.

TOXICITY OF IRRIGATION DRAINAGE Fingerand others 27Table 8. Cumulative mortality of bluegills, fathead minnow larvae, and daphnids exposed to water from TJ

Drain diluted with water from D-Line Canal

Cumulative mortality of species in tests (percent)

Species Exposure (and number sampled) (days)

Bluegills (10) 1 2 3 4 5 6 7 8 9

Fathead minnow larvae (20) 1 2 3 4 5 6 7 8 9
Daphnids (20) 1 2 3 4 5 6 7 8 9 Proportion of drainwater in sample

100 percent

0 0 20 40 50 70 90 90 90

0 10 25 40 60 75 80 80 85

0 0 35 60 100 50

percent

0 0 20 30 30 30 50 50 60

0 0 10 15 20 40 40 40 40

0 0 20 45 50 70 70 100 25

percent

0 0 0 10 10 10 30 30 30

0 0 0 0 5 10 10 10 10

0 0 0 10 15 30 30 30 30 12.5 percent

0 0 0 0 0 10 10 10 20

0 0 0 0 0 10 10 10 10

0 0 0 0 0 10 10 10 10 0 percent

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 NFCRC

wellwater control1

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

1 Well water from National Fisheries Contaminant Research Center, Columbia, Mo.



### Well Near TJ Drain

Ground water from the USGS well DH-102B,

near TJ Drain (Hoffman and others, table 3), was the most toxic ofthe watertested. The test was conducted as a static nonrenewal with the one 5-gal sample. Salinity ofthe ground water was 7.9 ppt and specific conductance was 12,000 ^,8/cm; the water

was tested with bluegills, larval fathead minnows, and daphnids. All organisms exposed to 100-, 50-, 25-, and 12.5-percent ground waterdied within 24 hours of exposure. No mortality occurred in any controls. The ioniccompositionandwaterquality ofTJDrainground water was differentfromthat ofTJ Drain surface water (table 6). The ground water was harder; the calcium level was about two-fold higher than that ofthe drainwaterandwasmorehighlybuffered (higheralkalinity). In addition, the pH ofthe ground water(7.0) was lower than that ofthe drainwater (8.4-8.6).
Concentrations ofarsenic in the ground water (table 9) were higherthan in any drainwatertested. Concentrations oflithium and molybdenum were higheringroundwaterthanthose measuredinTJDrain surface water. No selenium ormercury wasdetectedin the ground-water sample, but concentrations ofboron

were high. Survival offreshwatercontrol organisms in the reconstituted water with a salinity of7.9 ppt indicatesthatthe observed mortality wasprobably induced by the presence oftrace elements in the ground water.

28 Detailed Study of Irrigation Drainage Effect on BiotaTable 9. Concentrations of inorganic constituents in ground water collected from U.S. Geological Survey well DH-102B in the vicinity of TJ Drain, August 17, 19881
[Except where indicated, all values are in micrograms per liter; mg/L, milligrams per liter.}

Element Concentration Element Concentration

Calcium (mg/L) Magnesium (mg/L) Sodium (mg/L) Potassium (mg/L) Silica (mg/L) Phosphorus (mg/L)

Aluminum Antimony Arsenic Barium Beryllium Bismuth

Boron Cadmium Chromium Cobalt Copper 544 268 2,390 87 36.1 0.80

<30 <40 560 48 <1 <60
24,400 <2 <10 <10 <2 Iron

Lead Lithium Manganese Mercury Molybdenum

Nickel Selenium Silver Strontium Thallium Tin

Titanium Tungsten Vanadium Zinc <5

<40 1,640 1,440 <0.3 1,150

<100 <0.3 <20 13,300 <3 <10

<20 <2 <2 57

1 These water-quality data do not necessarily conform to U.S. Geological Survey guidelines for reporting significant figures



### Hunter Drain

Hunter Drain water was acutely toxic to all species tested. This was the only water with salinity high enough to allow tests with saltwater species. Neither freshwater nor saltwater organisms survived in treatments of 100-percent or 50-percentdrainwater. All species died quickly; 90 percent ofthe mysids, daphnids, and sheephead minnows died after 48 hours ofexposure. After 9 days, at least 40 percent ofevery species had died in all dilutions (tables 10,11).
The water quality in Hunter Drain was highly variable (table 6). Salinity ranged from 0 to 28 ppt. The highest salinity was measured on days 3,4, and 5 underconditions oflow flow when there was novisible discharge ofirrigation waterto the drain. During this 3-day period, the seepage ofground water into Hunter Drain was evident along the banks ofthe drain. The addition ofoperational spill waterto the drain on day 6

was apparently responsible forthe reduction in salinity and conductivity. All the bluegills died on day 4, after 24 hours ofexposure to Hunter Drain water when salinity was 28 ppt, which was more than twice as high as on the previous day. Only 10 percent ofthe fish died on day 4 in other treatments exposed to this level ofsalinity, but the cumulative mortality of 20 percent in the controls on day 5 is probably related to the high salinity. Survival, even for one day, ofany bluegill at a salinity of28 ppt was unexpected, based on accepted salt tolerances ofthe species. The ionic content of water in Hunter Drain and other Stillwater locations differed from that ofseawater, which is typically used toestimate salinity tolerances offreshwaterorganisms. Although the test organisms were apparently more tolerant ofsalinity with these ionic ratios than ofa similar salinity in seawater, it is probable that continued exposure to elevated salinity would have reduced survival in control water. It is unlikely that daily fluctuations in water quality ofthe magnitude experienced here would be tolerated by the tested species for an extended period.

TOXICITY OF IRRIGATION DRAINAGE Fingerandothers 29Table 10. Cumulative mortality of bluegills, fathead minnow larvae, and daphnids exposed to water from

Hunter Drain diluted with reconstituted water1

Cumulative mortality ofspecies in tests (percent)

Species Exposure (and number sampled) (days)

Bluegills (10) 1 2 3 4 5 6 7 8 9

Fathead minnow larvae (20) 1 2 3 4 5 6 7 8 9 Daphnids (20) 1 2 3 4 5 6 7 8 9 100 percent

0 0 100

25 40 65 70 100

25 90 100 Proportion of drainwater in sample

50 percent

0 0 10 60 80 80 100

10 50 85 90 90 100

20 50 85 90 90 100 25 percent

0 0 10 10 30 30 50 60 60

0 0 0 20 30 45 60 60 60

0 0 0 15 30 50 50 60 75 12.5 percent

0 0 0 10 10 20 20 30 40

0 0 0 10 10 25 25 25 40

0 0 0 10 10 25 25 25 50 0 percent

0 0 0 10 20 20 20 20 20

0 0 0 0 0 0 0 0 0

0 0 0 0 10 10 10 10 10 NFCRCwellwater control2

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

1 Deionized waterreconstituted to the same hardness, alkalinity, specific conductance, and pH as the Hunter Drain water. 2Well water from National Fisheries Contaminant Research Center, Columbia, Mo.

Tests with saltwater species sheephead minnow larvae and mysid shrimp were initiated when salinity first exceeded 15 ppt on day 3. Total mortality ofboth species occurred in the 100-, 50-, and 25-percent dilutions after 7 days ofexposure (table 11). The saltwater organisms were exposed under conditions of static renewal during the first 72 hours, but because the salinity ofthe drainwater decreased to 7 ppt on day 6, testing continued without renewal for the remainder ofthe 7-day exposure period. Dissolved-oxygen concentrations ofthe test water exceeded 6.4 mg/L throughout the study and pH ranged from 8.4 to 8.5. Mortality ofboth species ofat least 55 percent occurred in all drain-water dilutions;

no mortality occurred in the well-water controls. Higher levels oftrace-element concentrations corresponded with the higherlevels ofsalinity. During days with elevated salinity, concentrations ofarsenic in Hunter Drain were similar to those measured in TJ Drain; levels ofboron and lithium in Hunter Drain

were higher than at any other location, and molybdenum nearly so (table 6). Concentrations ofdissolved selenium ranged from below detection limits
to 3.6 (ig/L and were highest during periods ofhighest salinity. No mercury was detected in samples from HunterDrain. In addition, aluminum, antimony, beryllium, bismuth, chromium, cobalt, copper, iron, nickel, silver, tin, titanium, thallium, and tungsten did not exceed reporting limits.

30 Detailed Study of Irrigation Drainage Effect on BiotaTable 11. Cumulative mortality of saltwater species (sheephead minnow larvae and mysid shrimp) exposed to water

from Hunter Drain diluted with reconstituted water1

Cumulative mortality of species in tests (percent)

Species Exposure (and number sampled) (days)

Sheephead minnow larvae (20) 4 5 6 7 8 9
Mysid shrimp (20) 4 5 6 7 8 9 Proportion of drainwater in sample

100 percent

60 90 100

70 90 100 50

percent

45 65 75 100

50 65 90 100 25

percent

25 40 55 80 100

20 35 50 70 100 12.5

percent

20 35 40 50 55 55

20 15 30 55 60 60 0

percent

0 0 0 0 0 0

0 0 0 5 5 10 NFCRC

wellwater control2

0 0 0 0 0 0

0 0 0 0 0 0

1 Deionized waterreconstituted to the same hardness, alkalinity, specific conductance, and pH as the Hunter Drain water. 2Well water fromNational Fisheries Contaminant Research Center, Columbia, Mo.



### Lead Lake

Water from Lead Lake was moderately toxic to all species tested; the death rate accelerated after 4 days (table 12). Survivalrates ofbluegill andfathead minnow larvae were similar; the lowest level ofeffect occurred in the 25-percent dilution. Daphnids were
more sensitive to the toxic components in the water than were the fish, and died sooner. No species died in the 12.5-percent dilution or in the controls. Total survival ofall organisms in the reconstituted control water, where salinity was similar to that in the Lead Lake water treatments, suggests that salinity alone did not account for the observed mortality. Reproduction ofdaphnids was delayed in all treatments. No young were produced by daphnids in any Lead Lake water treatment and there was no evidence ofdevelopment ofa first brood in any individualsexamined atthetermination oftheexposure. Young wereproducedinboththereconstituted andwell-water controls on day 9. Meannumberofyoungperbrood in these controls was 8.9 and 9.2, respectively. Levels oftrace elements did not fluctuate markedly throughout the exposure period. Concentrations ofseleniumandmercurywerebelowanalytical reporting levels. In addition, aluminum, antimony, beryllium, bismuth, chromium, cobalt, copper, iron, nickel, silver, tin, titanium, thallium, and tungsten did not exceed reporting limits. Concentrations of arsenic, boron, lithium, and molybdenum were consistently higher in Lead Lake water than in either Paiute Diversion Drain or D-Line Canal, where no mortality

was observed. The concentrations ofthese four trace elements, which were associated with water hardness and specific conductance, appearto be strongly influencedby inflow fromTJ Drain. Concentrations ofsalts in Lead Lake may be naturally increased by evaporative loss, but the addition ofwater from TJ Drain does not enhance the water quality ofLead Lake.

TOXICITY OF IRRIGATION DRAINAGE Fingerandothers 31Table 12. Cumulative mortality of bluegills, fathead minnow larvae, and daphnids exposed to water from Lead

Lake diluted with reconstituted water1

Cumulative mortality of species in tests (percent)

Species Exposure (and number sampled) (days)

Bluegills (10) 1 2 3 4 5 6 7 8 9

Fathead minnow larvae (20) 1 2 3 4 5 6 7 8 9
Daphnids (20) 1 2 3 4 5 6 7 8 9 Proportion of drainwater in sample

100 percent

0 20 20 30 30 30 40 40 60

0 20 20 25 25 30 40 60 60

0 20 20 25 30 30 45 60 80 50

percent

0 0 0 0 20 20 20 30 30

0 0 5 5 5 15 20 25 30

0 0 5 5 15 15 30 35 45 25 percent

0 0 0 0 0 10 10 10 10

0 0 5 5 10 10 10 15 15

0 0 5 5 10 10 15 20 20 12.5 percent

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 percent

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 NFCRC

wellwater control2

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

1 Deionized waterreconstituted tothe same hardness, alkalinity, specific conductance, andpH as theLead Lake water. 2Well water from NationalFisheries Contaminant Research Center, Columbia, Mo.



### Stillwater Point Diversion Drain and Stillwater Point Reservoir

Test organisms were differentially sensitive to water from Stillwater Point Diversion Drain. The water was toxic to bluegills and marginally toxic to fathead minnow larvae and daphnids (tables 13 and 14). Mortality occurred after an extendedexposure to drainwater; no mortality ofany species occurred during the first 3 days ofexposure. Bluegill mortality reached 80 percent in undiluted water from Stillwater Point Diversion Drain. In the tests where drainwater was diluted with reconstituted water (table 13), no appreciable mortality occurred in the 12.5-percent dilution, but in tests using water from Stillwater Point Reservoir as a diluent, 20 percent ofthe fish died in the 12.5 percent dilution (table 14). In controls, no bluegills diedin well water, 10 percentdied inreconstituted water (table 13), and 20percentdied in Stillwater PointReservoirwater (table 14). Cumulative mortality offathead minnow larvae and daphnids exposed to Stillwater Point Diversion Drain water diluted with reconstituted water (table 13) was lower than that of bluegills and ranged from 5 to 30 percent. Mortality offatheadminnows anddaphnidsexposedtoStillwater Point Diversion Drain water diluted with Stillwater

32 Detailed Study of Irrigation Drainage Effect on BiotaPoint Reservoir water (table 14) ranged from 10 to 30 percent and was much lowerthanbluegill mortality, but generally higher than in tests using reconstituted water (table 13) as a diluent (5-30 percent), but with

no clearpattern ofdose response. No fathead minnow larvae or daphnids died in the reconstituted orthe wellwater controls, but in Stillwater Point Reservoir water controls, mortality was 25 percent (table 14). The range in concentrations ofthe constituents in StillwaterPointDiversionDrain and StillwaterPoint Reservoirremained less variable during the study than those in TJ and Hunter Drains (table 6). The ambient water was well oxygenated and ofmoderately low specific conductance. Turbidity in Stillwater Point DiversionDrainwas similartoPaiuteDiversionDrain. Concentrations ofconstituents also were similar to those found in Paiute Diversion Drain and in D-Line Canal (table 6). Mercury and selenium concentrations in Stillwater Point Diversion Drain were at orbelow analytical reporting levels. In addition, aluminum, antimony, beryllium, bismuth, chromium, cobalt, copper, iron, nickel, silver, tin, titanium, thallium, and tungsten did not exceed reporting limits.

Table 13. Cumulative mortality of bluegills, fathead minnow larvae, and daphnids exposed to water from Stillwater Point Diversion Drain diluted with reconstituted water1

Cumulative mortality of species in tests (percent)

Species Exposure (and number sampled) (days)

Bluegills (10) 1 2 3 4 5 6 7 8 9

Fathead minnow larvae (20) 1 2 3 4 5 6 7 8 9
Daphnids (20) 1 2 3 4 5 6 7 8 9 Proportion of drainwater in sample

100 percent

0 0 0 20 40 40 40 60 80

0 0 0 5 5 10 10 15 30

0 0 0 0 10 10 15 15 25 50

percent

0 0 0 20 30 30 30 30 40

0 0 0 0 5 10 10 10 10

0 0 0 0 10 10 10 10 10 25 percent

0 0 0 10 20 20 20 20 20

0 0 0 10 10 10 10 10 10

0 0 0 10 10 10 10 10 10 12.5 percent

0 0 0 0 0 10 10 10 10

0 0 0 0 0 0 0 5 5

0 0 0 0 0 0 0 5 5 0 percent

0 0 0 0 0 0 10 10 10

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 NFCRC

wellwater control2

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

1 Deionized waterreconstituted to the same hardness, alkalinity, specific conductance, and pH as the StillwaterPoint Diversion Drain water. 2Well water from National Fisheries Contaminant Research Center, Columbia, Mo.

TOXICITY OF IRRIGATION DRAINAGE Fingerandothers 33Table 14. Cumulative mortality of bluegills, fathead minnow larvae, and daphnids exposed to water from

Stillwater Point Diversion Drain diluted with water from Stillwater Point Reservoir

Cumulative mortality of species in tests (percent)
Species Exposure (and number sampled) (days)

Bluegills (10) 1 2 3 4 5 6 7 8 9

Fathead minnow larvae (20) 1 2 3 4 5 6 7 8 9 Daphnids (20) 1 2 3 4 5 6 7 8 9 Proportion of drainwater in sample

100 percent

0 0 0 30 60 60 60 70 80

0 0 0 10 10 15 20 25 30

0 0 0 10 10 15 25 25 25 50 percent

0 0 0 20 20 20 20 30 40

0 0 0 15 15 20 20 20 25

0 0 0 20 20 20 20 20 25 25 percent

0 0 0 10 10 10 10 20 20

0 0 0 10 15 15 15 15 20

0 0 0 10 10 10 10 10 20 12.5 percent

0 0 0 0 0 0 10 10 20

0 0 0 0 10 10 10 15 25

0 0 0 0 0 0 0 0 20 0 percent

0 0 0 0 0 0 0 10 20

0 5 10 10 10 15 20 20 25

0 5 5 10 10 20 20 25 25 NFCRC

wellwater control1

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0

1 Well water from National Fisheries Contaminant Research Center, Columbia, Mo.

Because mortality in water from Stillwater Point Diversion Drain was higherthan in apparently similar water from Paiute Diversion Drain and D-Line Canal, water samples from all drain sites were collected August 17, 1988, for chemical analysis ofmanmade organic constituents. No organic constituentwas found atconcentrations thatmightbeexpected tocause adverse effects on the test organisms. Consistentlevels ofphenols (2.6-5.4 (ig/L) were detected in every sample, which suggests incidental contamination during sample collection orchemical analysis. Results from these analyses did not explain the mortality observed in Stillwater Point Diversion Drain water. Mortality in undiluted water from Stillwater Point Reservoir was low, but consistent (20-25 percent). No substantial mortality ofany species occurred in dilutions ofStillwater Point Reservoir water. Daphnids reproduced equally in all treatments on day 9, with the mean number ofyoung per broodrangingfrom 8.0to 9.5. Thereservoirwaterwas turbid, ranging from 168 to 580 NTU's, which may have stressed the test organisms in the 100-percent
treatment. Concentrations ofboron, lithium, and molybdenum in the reservoir (table 6) were generally similar to those in Stillwater Point Diversion Drain water. Concentrations ofarsenic were only slightly

34 Detailed Study of Irrigation Drainage Effect on Biotalower than those in Lead Lake and TJ Drain and may have contributed to the observed mortality. Arsenic concentrations in the reservoir were approximately twice those in Stillwater Point Diversion Drain.

EFFECT OF IRRIGATION DRAINAGE ON AQUATIC ORGANISMS

Water from Hunter and TJ Drains and ground water from the well near TJ Drain was acutely toxic to all species tested (fig. 5). On the basis ofeffects of the drainwater on cumulative mortality and daphnid reproduction, the "No ObservedEffect Concentration" (NOEC)1 for both Hunter and TJ Drains was less than 12.5 percent drainwater. Lead Lake water was moderately toxic to all species tested, with an NOEC of 25 percent drainwater for both fish species and an NOEC ofless than 12.5 percent for daphnids. In
tests with Stillwater Point Diversion Drain water diluted with Stillwater Point Reservoir water, where mortality occurred in every treatment, an NOEC

was not established, but in tests with Stillwater Point Diversion Drainwaterdilutedwithreconstitutedwater, the NOEC was 25 percent for daphnids and fathead minnows and 12.5 percent for bluegill. Water samples from Paiute Diversion Drain and D-Line Canal were not toxic to the species tested.

1A time-independent measure that describes the threshold concentration below which predefined effects are not observed.

100

80

60

40

20 BLUEGILLS

FATHEAD MINNOW LARVAE

DAPHNIDS

PAIUTE DIVERSION DRAIN D-LINE

CANAL LEAD LAKE STILLWATER STILLWATER

POINT POINT DIVERSION RESERVOIR DRAIN

Figure 5. Cumulative mortality of freshwater organisms in undiluted surface-water samples collected in and near StillwaterWildlife Management Area, August 1988. Datafor Paiute Diversion Drain and D-Line Canal showed no mortality.

TOXICITY OF IRRIGATION DRAINAGE Fingerandothers 35In both Hunter and TJ drains, dramatic daily

fluctuations in water quality were measured, and specific conductancerangedfrom410to 27,500^iS/cm (about 270 to 17,900 mg/L dissolved solids) in Hunter Drain and from 6,100 to 14,900 ^iS/cm (about4,000 to 9,700 mg/L dissolved solids) in TJ Drain (fig. 6). Control organisms in reconstituted water, where conductance was similarto that ofthedrainwater, survived exposure to daily fluctuations ofsimilar magnitudes. Saltwater organisms, sheephead minnow larvae and mysids, didnot survive in HunterDrain wateralthough the salinity was within theirrange oftolerance. A dose-response relationship was evident in TJ drainwater when diluted with reconstituted water ofa similar salinity and when salinity was decreasedby dilution with waterfromD-LineCanal. From 85 to 100percent oftheorganisms diedinLeadLakewater; controls with similar specific conductance (that is, salinity) showed

no mortality. Although the elevated salinity in tests with drainwater fromboth locations undoubtedly stressed the organisms, theresults suggest that salinity alone does not account forthe mortality observed.

30,000

13 14 15
DATE (AUGUST 1988) 16 17 18

Figure 6. Changes in specific conductance in Lead lake and selected drains during toxicity study August 10-18,1988.

36 Detailed Study of Irrigation Drainage Effect on BiotaIn general, higher concentrations oftrace elements corresponded to higher levels of specific conductance (fig. 7). In addition, subjective comparison ofcumulative mortalities and concentrations of trace elements at each location suggested that the concentrations or arsenic, boron, lithium, and molybdenum were higher at locations where appreciable mortality occurred. No single trace element was present in concentrations that were acutely toxic to the species tested (U.S. Environmental Protection Agency, 1986); therefore, the toxicity is attributed to the interactive effects ofthe aggregate trace elements present. This conclusion is supported by the results ofDwyer and others (1990, p. 18) whoexposed striped bass (Morone saxatilis) to these elements and also to copper and strontium, both by single element and in combination. Individually, these six elements were not acutely toxic to the bass in the concentrations found at Stillwater WMA, but in aggregate were acutely toxic.



### Ionic Composition

In assessing the hazard to aquatic organisms, the ionic composition ofthe water should also be considered. Forexample, in a study subsequentto this one thatused stripedbass inwaterreconstitutedtoresemble Pintail Bay in Stillwater WMA, Dwyer and others (1990, 1992) concluded that the unusually low hardness ofthis saline waterdidnotdiminish toxicity ofthe combined trace elements arsenic, boron, copper, lithium, molybdenum, and strontium.
In the present study, water from the shallow well near TJ Drain was acutely toxic to bluegills, larval fathead minnows, and daphnids. This ground water was classified as hard, with the calcium concentration abouttwo-fold higherthan the nearby TJ Drain water. Mortality is attributed primarily to a combination oftoxic trace elements regardless ofthe benefit of increased hardness. In follow-up work by Dwyer and others (1990, p. 26), using water from five additional wells in and near StillwaterWMA, acute toxicity to striped bass a salt tolerant species was demonstrated. Thus, salinity alone may not explain the mortality observed in certain drainwater, but rather

a mixture oftrace elements and atypical ion ratios (compared to seawater; Ingersoll and others, 1992). 20 I 1 1 I

LLJ

10 2,500 5,000 7,500 10,000 12,500

03 DC LLJ Q_ Q
LLJ Q DC LLJ CO

^ 2

>- K 

### £ DC O 20 o"



### I 15

-J 5 

# i 10

z

Q S5 5
1

0 i i i i i i (H) ~ 

# ©

_

-

- © ©

/-<pL V' i i i i i 2,500 5,000 7,500 10,000 12,500

1 I I I

1 1 1 1 0 2,500 5,000 7,500 10,000 12,500

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER

CENTIMETER AT 25°CELSIUS
Figure 7. Relations between specific conductance and mortality of bluegills (r=0.88), fathead minnow larvae (r=0.93), and daphnids (r=0.97) for water from Paiute Diversion Drain (P), D-Line Canal (DL), TJ Drain (TJ), Hunter Drain (H), Lead Lake (L), Stillwater Point Diversion Drain (D), and Stillwater Point Reservoir (S).

TOXICITY OF IRRIGATION DRAINAGE Fingerandothers 37

# BIOLOGICAL PATHWAYS: MOVEMENT OF SELENIUM AND MERCURY

Some potentially toxic trace elements in irrigation drainage are known to biomagnify up the foot chain, thus affecting wildlife ofan area, particularly waterfowl. Selenium and mercury are important trace elements in the study area and both are known to biomagnify.

STUDY AREAS

Three areas were selected for in-depth study of biological pathways: TJ Drain/Lead Lake and Hunter Drain/GooseLake systems in StillwaterWMA (fig. 8), and A-Drain and ponds ofthe Fernley WMA (fig. 9). These lakes and ponds include emergent wetlands and

are managed with water-control structures. Additional samples were collected from other wetlands and from irrigation drains throughout the Fallon agricultural

area ofthe Newlands Irrigation Project area (table 15, fig. 10) to provide a broader scope ofthe extent of high selenium and mercury concentrations.
LeadLake, which has three majorwater sources, is the mosthydrologically complex ofthe areas. It is a 1,000-acre, initial wetland unit that receives irrigation drainage directly before much ofthe water evaporates and constituents become concentrated; therefore, its water quality is commonly better than that in the connecting wetlands downgradient. However, Lead Lake has a history ofavian botulism and unexplained fish and migratory bird deaths, and most ofthe emergent vegetation has perished in the last 30 years. Selenium

wasfoundin theheadwaters oftherecently constructed (1982-1983) TJ Drain, which ultimately discharges into Lead Lake (U.S. Bureau ofReclamation, 1987, p. B14). Selenium accumulation injuvenile migratory birds from Lead Lake was documented by Hoffman and others (1990, p. 67).
Hunter Drain was included in the pathways study because refuge biologists had noted exceptionally high specific conductance (Steven P. Thompson, U.S. Fish and Wildlife Service, oral commun., 1988) and seleniumconcentrations above effectlevel in some juvenile birds from Goose Lake, at the drain terminus (Hoffman and others, 1990, p. 66). This 9-mile drain, which serves only about 180 acres ofirrigated land, is

arelatively simple flow system. Discharge is typically less than 1 ftVs, but operational releases occasionally

cause flow peaks ofrelatively fresh water. Fernley WMA, near Stillwater WMA, was studied because selenium in livers ofjuvenile migratory birds exceeded effect levels (Hoffman and others, 1990, p. 67). About40 percent ofthe inflow is ground
waterfromTruckee Canal seepage (Van Denburgh and Arteaga, 1985, p. 6), which passes through the same ancient lake-bed sediments as does the drainage from the StillwaterWildlifeManagement Area. Most ofthe
water enters the wetlands through A-Drain (from irrigation drainage) and discharges into South Pond, then into a series ofconnecting ponds (fig. 9).
Most ofthe additional samples for selenium and mercury were collected principally from drains throughout the irrigation area about 60,300 acres servedby about 350 mi ofdrainage ditches. Sites were selected to represent, approximately, each 1- to 2-mi2

area ofirrigated land in the study area. These sites

are shown in fig. 10 and listed in table 15.

BIOLOGICAL PATHWAYS RJ. Hallockandothers 39118°40' 118°30'

39°40'

39°30' Fallen National

Wildlife Refuge

R. 29 E. R. 30 E. R. 31 E. R. 32 E.

EXPLANATION

^B OPEN WATER
HI STILLWATER NATIONAL WILDLIFE REFUGE

- **"*** As defined July 1990. Western boundary is ^^^ dotted line PRIVATELY OWNED LAND WITHIN «ffl REFUGE -Includes Canvasback Gun Club BOUNDARY OF WILDLIFE MANAGEMENTAREA

- - - BOUNDARY OF FALLON INDIAN RESERVATION -

North boundary coincides with that of adjacent Wildlife Management Area -PI SAMPLING SITE, AND NUMBER, FOR DRIFTAND b BIOTA (TABLE 15)
Figure 8. Location of sampling sites for drift and biota in and near StillwaterWildlife Management Area. Sites are listed in table 15. (Map modified from Lico, 1992.)

40 Detailed Study of Irrigation Drainage Effect on Biota119°051

39°40'

39°35'

EXPLANATION

^^| OPEN WATER
[ J^j WETLANDS, INCLUDING OPEN WATER
KXSM PLAYA

- BOUNDARY OF WILDLIFE

MANAGEMENTAREA
69O SAMPLING SITE AND NUMBER (TABLE 15)

Figure 9. Location of sampling sites for drift and biota in and near Fernley Wildlife Management Area. Sites are listed in table 15. (Map modified from Lico, 1992.)

BIOLOGICAL PATHWAYS RJ. Hallockandothers 4139U45118°30'OI<Da(AIOtoD>39U30'3915'EXPLANATIONIOPENWATER>=^WETLANDS,INCLUDING"^^OPENWATERAGRICULTURALLANDSPLAYAWILDUFEMANAGEMENTAREABOUNDARY43R.25E.R.26E.R.27E.R.28E.R.29E.R.30E.SAMPLINGSITEfTABLE15)Figure10.LocationofadditionalsamplingsitesfordetritusandalgaeinandnearStillwaterandFernleyWildlifeManagementAreasandCarsonLake.Sitenamesarelistedintable15.(MapmodifiedfromSeilerandAllander,inpress.)Table 15. Sampling sites for drift, detritus, and algae

[Locations are shown in figures 8, 9, and 10; data werepublished by Rowe and others (1991, tables 20, 21)]

Fallen agricultural area 2. Old Reservoir 3. Soda Lake Drain 4. Upper L Drain 5. South Carson River Drain 6. Sheckler Deep Drain 7. UpperWest Side Drain 8. Upper Diagonal 2 Drain 9. Upper Diagonal Drain 10. Gummow Drain 11. Carson Lake I Extension Drain 12. CarsonLake Drain 13. Carson Lake 1A Drain 14. A1 Drain 15. Mussi Drain 16. F2 Drain 17. Shaffner Drain 18. ERB Drain 19. Lower Soda Lake Drain 20. Paiute Extension Branch 1 Drain 21. Harmon I Deep Drain 22. S-Line Reservoir 23. New RiverExtension Drain 24. Upper Harmon Deep Drain 25. Harmon 2 Drain 26. New RiverDrain 27. Upper New RiverDrain 28. LD Drain 29. Mid L Drain 30. L3 Drain 31.L2Drain 32. Upper Diagonal Drain1 33. Middle L Drain 34. LB Drain 35. L Branch 1 Deep Drain 36. Lower L Drain 37. Mid Carson Lake Drain 38. A-Line Canal 39. Pierson Drain 40. Jl Deep Drain 41. Yarbrough Drain 42. Carson Lake Branch 3 Drain 43. Carson Lake Branch 1 Drain 44. Downs Drain 54. R2 Drain 55. Upper Paiute Drain 58. Harmon Deep Drain 59. S2G Drain 60. Harmon Reservoir 61. SIB Drain 62. Lower Diagonal 1 Drain 63. Lower Diagonal Drain Carson Lake area 45. Lower Carson Lake Drain 46. Holmes Branch 2 Drain 47. Holmes Drain 48. NE Carson Lake 67. Carson Lake, Sprig Pond

Stillwater Wildlife ManagementArea 49. Patrick Drain 50. Kent Lake Extension Drain 51. Lower Stillwater Slough 52. Paiute Branch 3 Drain 53. SI Deep Drain 56. S2C Drain 57. Upper Stillwater Slough 64. Paiute Branch 1 Drain 65. Stillwater Point Reservoir 66. UpperTJ Drain 76. Big Indian Lake 77. Cattail Lake 78. D-Line Canal 79. Dry Lake East 80. Dry Lake West 81. Hunter Drain 82. Hunter Drain South1 83. LeadLake 84. Likes Lake 85. Papoose Lake 86. Paiute Drain 87. Pintail Bay 88. South LeadLake 89. South Nutgrass 90. Stillwater Point Reservoir 91. SwanLake Check 92. TJ Drain 93. Tule Lake 94. West Nutgrass

Fernley Wildlife ManagementArea 68. Lower A-Drain1 69. Upper A-Drain1 70. Fernley drain, west 71. Fernley WMA, East Pond 72. Fernley WMA, North Pond 73. Fernley WMA, South Pond

Background and other sites 1. Sheckler Reservoir 74. North Mahala Slough 75. South Mahala Slough 95. Carson River Below Lahontan

1 Some sites were mislabeled in tables 20 and 21 ofRowe and others (1991): Site 32, UpperDiagonal Drain (sample number 88926), was mislabeled as site 63, LowerDiagonal Drain; site 82, HunterDrain South (sample 89058), was mislabeled as site 81; site 68, LowerA-Drain (samples 89067 and 89202), was mislabeled asFernley Drain; and site 69, UpperA-Drain (sample 88171), was mislabeled as Fernley South Drain.

BIOLOGICAL PATHWAYS RJ. Hallockandothers 43APPROACH AND METHODS

On the basis ofthe findings ofHoffman and others (1990) that concentrations of selenium and mercury in filtered water samples were low, it was thought that selenium, and possibly mercury, were movingthroughbiologicalpathways andthattransport

was through organic rather than inorganic forms. No uniform set ofplants or animals was found in all study sites, and living organisms were not always available; therefore, organically rich detritus was sampled to provide continuity throughoutthe study areas. Because it islightweight, detritustransports easilydownirrigation drainage ditches through routine operational releases and otherpeakflows. Livingplantmaterial,principally filamentous algae, and drift also were collected where available. Definitions ofdetritus and drift and the sampling procedures used are described by Rowe and others (1991, p. 11-13). Qualitative analysis ofthe digestive tracts in birds was made to verify that organisms included in trace-element analysis were indeed diet items of migratory birds. The birds were primarily coots (Fulica americana), black-necked stilts (Himantopus mexicanus), and avocets (Recurvirostra americana), butducks also were examined. The extent ofdigestion ofthe gut contents was a major variable because the elapsed time between collection and preservation varied widely. A one-time estimate ofthe standing crop of vegetation (filamentous algae and submergentvascular plants) throughout the TJ Drain system was made August 27,1990. The drain was divided into 1.0-mi segments, and the width ofthe drain was measured at 0.5-mi intervals. Transects were made atthe midpoint ofeach segment as determined by measuring with a vehicle odometer. The transects consisted ofeither three or five evenly spaced sample sites across the width ofthe drain. Five samples were collected where drain width exceeded 10 ft. A Surber square-foot sampler was used to define the individual sample area. The attached net captured the vegetation after it was severed by the investigator and released into the current. Composite plant samples were frozen in 1-gal jars. Samples were laterthawed, hand rinsed, drained, and weighed wet. Dry weights were obtained by drying in an oven at 104°Cuntil weightremained constant. To determine the source areas ofselenium and mercury, sample points were selected throughout the drainage system in such a way that each point represented drainage from about a 1-2-mi2 area of irrigated land. From these sites, organic detritus and filamentous algae, ifpresent, were collected and analyzed. Although many ofthe managed wetland units were dry because ofthe drought, the wetlands sampled contained water. To identify source areas where selenium and mercury are most available biologically, the data sets forbothdetritus and filamentous algae were displayed through a geographicinformation system.

RESULTS

Examination ofthe upper digestive tracts of 66 migratory birds from Carson Lake and Stillwater WMA confirmed that algae, vegetation, mixed drift, and insects were consumed by migratory birds in the study area. Content ofthe digestive tracts varied considerably between species and between individuals of the same species. Leeches (hirunids), ostracods, and daphnids (Daphnia magna) found in drift were not found in gut contents, but these relatively soft-bodied organisms may have been fragmented in the gizzard and therefore difficult to identify. Seeds ofemergent vascularplants were found indigestivetracts ofducks. Digestive tracts of 11 black-necked stilts were examined and found to contain primarily waterboatmen (corixids). No adultbrine flies (Z)j/?tera)were found in the black-necked stilt digestive tracts examined, but stilts have been observed feeding heavily on brine flies at times in Hunter Drain (Steven P. Thompson, StillwaterWMA, U.S. Fish and Wildlife Service, oral commun., 1988). Becauseplantmaterialdominatedthebiomass in the drains andwetlands, detritus was assumedtobeprimarily ofplantorigin, withassociatedmicroorganisms, and did indeed contain recognizable plant and animal parts. Organically rich sediment, varying in depths at the soil-water interface, was the lightest fraction ofthe bottom sediment (typically 85-90 percent water). Because ofits light-brown color, detritus appeared to be oxygenated and in chemical contact with the water column. Detritus was in direct contact with the most abundant benthic insect larvae in the study areas, midge (Chironomus sp.) and brine flies; invertebrates

were nottypically found in anaerobic sediments below the detrital layers at the sampled locations. All data collected were reported by either Hoffman and others (1990) or Rowe and others (1991).

44 Detailed Study of Irrigation Drainage Effect on BiotaDetritus sampling was a significant factor in establishing the biological pathways by which selenium and mercury moved into wildlife. A total of 112 composite detritus samples from all sites were analyzed. The concentrations of selenium and mercury, respectively, ranged from <0.09 to 8.04 and from <0.04 to 97.8 jig/g, dry weight. Exceptionally high concentrations ofmercury (26-98 jig/g) were found in three detritus samples from Indian Lakes within StillwaterWMA and from ten irrigation-drain samples. Long andMorgan (1990, p. 41) suggestthat concentrations greaterthan orequal to 1.0jig/g mercury, dry weight, in sediment would adversely affect exposed invertebrates. This criterion

was exceeded in 47 of 112 (42 percent) ofthe detritus samples analyzed (Rowe and others, 1991). Lemly and Smith (1987, p. 9) predicted reproductive failure or mortality in fish and waterfowl exposed to sediment containing selenium concentrations greater or equal to 4.0jig/g, dry weight, because offood-chain bioaccumulation. This criterion

was exceeded in only 4 ofthe 112 detritus samples (4 percent); 3 ofthose were from Fernley WMA. Filamentous algae were not present at all detritus sampling sites. The concentrations of mercury and selenium in 87 algae samples ranged from <0.02 to 10.4 and from <0.06 to 5.6 ^ig/g, dry weight, respectively. The criteria used to evaluate mercury and selenium concentrations in algae are based on dietary bioaccumulation in fish and birds. The effect criterion for mercury in bird diets is 0.39 M-g/g, dry weight (Heinz, 1979, p. 395; Hoffman and others, 1990, p. 26), and for selenium in fish diet is 5.0jig/g, dry weight (Lemly and Smith, 1987, p. 9) The mercury criterion was exceeded in 49 of 87 (56 percent) filamentous algae samples. The selenium criterion was exceeded in only two samples. Samples ofdrift were taken for qualitative biological pathway evaluations. The rates ofdrift movement were not quantified and the data are qualitative. Most ofthe 55 samples were taken from the LeadLake, FernleyWMA, and HunterDrain systems. Sample contents and volumes were highly variable between sites andwithin sites sampled atvarious times, butmostmacroinvertebrates and aquatic plants were in drift. The exception emergent aquatic plants were not identified in drift, but may have contributed to the undifferentiated detritus parts. Dominantparts ofdrift included algae, submergent vascular plants, detritus, daphnids, ostracods, amphipods (Gammarus s/?.), corixids, chironomids, brine flies, leeches, and odonates. Selenium was detected in most drift samples, with the highest concentration (10.0jig/g, dry weight) found in daphnids from South Pond in Fernley WMA. Eight ofthe 55 (15 percent) samples contained concentrations of selenium greaterthan the 5.0jig/g dietary criterion that has been shown to cause reproductive failure or mortality in fish through food-chain bioconcentration (Lemly and Smith, 1987, p. 9). Concentrations in seven ofthese samples were greater than 7.0jig/g, dry weight. This concentration in the diet also may cause reproductive failure or mortality in

some migratory birds (GJ. Smith, U.S. Fish and Wildlife Service, oral commun., 1989). Although no attempt was made to establish contaminant loading estimates in aquatic drift, a onetime estimate ofthe standing crop ofall vegetation in TJ drain was made August 27,1990. The instantaneous standing crop ofvegetation in the 17-mi-long TJ Drainwas about 15,500kg (17 tons), dry weight. Using the selenium concentration range of0.61-2.1 jig/g for vegetation, there was at that time between 9.5 and 31.9 g of selenium fixed in vegetation. This estimate

was made several days after a high discharge event when there was visual evidence that large quantities ofalgae and vascularplants had recently been flushed downstream. Selenium is also found in invertebrates and other animals and in detrital matter, but no attempt

was made to estimatethe standing crop ofthese groups because little remained after the discharge. Brine fly adults were sampled where available. Six ofthe twelve samples (50 percent) contained selenium in excess ofthe 7.0jig/g, dry weight, dietary criterion forbirds (GJ. Smith, U.S. Fish and Wildlife Service, oral commun., 1989).



### Bioaccumulation and Biomagnification of Selenium and Mercury

Selenium concentrations in filtered water samples from the general study area, including the lower TJ Drain and Lead Lake, were at or below the analytical reporting limit of 1.0jig/L (Hoffman and others, 1990, p. 77). Higher seleniumconcentrations, as much

as 46 jig/L, were found in filtered sample water from the headwaters ofthe TJ Drain system (Tokunaga and Benson, 1991, p. 20, 28). Similarly, in California at

BIOLOGICAL PATHWAYS RJ. Hallockand others 45the Grasslands Water District and Kesterson National

Wildlife Refuge, dissolved selenium was quickly absorbed into biota, primarily plants, resulting in low concentrations in water (Presser and Ohlendorf, 1987, p. 811,815). Selenium and mercury are not homogeneously distributed in the water or surficial soils within the study area (U.S. Bureau ofReclamation, 1987, p. B14; Ronald R. Tidball, U.S. Geological Survey, oral
commun., 1989). Selenium concentrations in water

are not areliable indicator ofthe magnitude ofcontamination ofselenium in organic matter (Hoffman and others, 1990, p. 77). Evidence ofbioaccumulation of mercury in biota was found where dissolved mercury concentrations in water were below the analytical reporting limit (1990, p. 36, 60). Both selenium and mercury are known to bioaccumulate in detritus. Lemly and Smith (1987, p. 5) discussed the potential importance ofdetritus pathways leading to fish and migratory birds in situations where selenium may not be detectable in water. Depending on waterway morphology and flow, detritus may accumulate and be available to

consumers for several years. Maximum observed concentrations of selenium andmercury indetritus were 8 and98 |ig/g, dry weight, respectively. Sites with high selenium concentrations in detritus correlate with sites where Hoffman and others (1990, p. 67-70) found high selenium concentrations injuvenilebirdlivers and muscle. Thehighest mercury concentration found in detritus was from Indian Lakes, which corresponds to data from Cooper and others (1985, p. 57) that showed elevated mercury concentrations infishandfishfilletsfromIndianLakes. Detritus appears to be a useful medium with which to qualitatively assess the spatial distribution of biologically available selenium and mercury. Filamentous algae and vascular aquatic plants also may bioaccumulate selenium (Presser and Ohlendorf, 1987, p. 811; Lemly and Smith, 1987, p. 4) or mercury (Eisler, 1987, p. 21), or selenium and mercury (Hoffman and others, 1990, p. 62). In this study, concentrations ofseleniumandmercury in algae

were similar to those in detritus at the same locations. Algae were widespread and nearly as useful as detritus in understanding the dynamics ofselenium and mercury movement in irrigation drains and wetlands. Biomagnification of selenium was documented injuvenile black-necked stilts from Lead Lake (Hoffman and others, 1990, p. 67). Data from the following section on waterfowl production show that selenium concentrations injuvenile bird (cinnamon teal [Anas cyanoptera] and coot) tissues were greater than 10,000 times those found in water, and that some migratory birds had accumulated selenium to levels at which mortality or reproductive impairment would be expected.
In the Stillwater study area, bioaccumulation appeared to occurprimarily in the irrigation drains. Biomagnification also occurred in drains, but was
more evident in the initial wetlands, as was the situation in Grasslands Water District, California, where the largest concentrations of selenium were found in animal tissue collected in the initial wetlands to receive selenium-bearing water (Presser and Ohlendorf, 1987, p. 815).



### Selenium and Mercury Pathways

Algae and other aquatic vegetation have been observed moving down the drains. Much ofthis movement appears to be associated with peak discharges resulting from operational spills or heavy rainfall. Assessments ofthe vegetation standing crops in TJ Drain followed a large storm that apparently had flushed large quantities ofvegetation downstream to Lead Lake. About 15,500 kg, dry weight, of vegetation remained.
The biological components actually being transported were isolated in the drift samples. The irregular mixture ofvegetation and invertebrates in these samples makes the data appropriate only for qualitative evaluation. Analysis ofdrift samples indicates that selenium was being bioaccumulated in plants, biomagnified in invertebrates, and that both components in drift and detritus were transported to wetlands by drain flow. Figure 11 illustrates the flow path ofselenium in particulate matterto downgradient wetlands. The TJ Drain appears to be the largest contributor of seleniumto LeadLake. Paiute Diversion Drain seasonally supports large biomasses ofalgae and vascular plants, which also may be an important source of selenium to Lead Lake. Biological samples from wetland sites downgradient ofLead Lake, which are maintained by Lead Lake water, were generally lower in selenium than those from Lead Lake.

46 Detailed Study of Irrigation Drainage Effect on BiotaD-LINE CANAL TJ DRAIN PAIUTE DIVERSION DRAIN

- 0 <I (TO 5 OED £5 4 §£ 2d 3 Z 2 rf2 2o 

### SE5 1 SN 1 1 1 1 1

- -

.

_

.

- 

## T

V» AH



### _ £ * o i T i i i i



## : 1 1 _

^

k. 

### E i

, ^ 

# [ 1 A 

### ^

L ;18.4.

k10.5~ 

## ^ :

c£o 5

2Q 3 LEAD LAKE

±___0 

### \ \ \

2t

2Q 3 DOWNGRADIENT WETLANDS

I I I I I

EXPLANATION

I I MAXIMUM-MINIMUM X MEDIAN A MEAN SINGLE SAMPLE 0 NO SAMPLE COLLECTED

Figure 11. Generalized flow path in Stillwater Wildlife Management Area and selenium concentrations in composite samples from input drains, Lead Lake, and downgradient wetlands. Data from Hoffman and others (1990, table 19) and Rowe and others (1991, tables 20 and 21).

BIOLOGICAL PATHWAYS RJ. Hallockandothers 47A-DRAIN in 0

lie

§£ 2Ho4

"" 4

- I A

k

. I I 1 I 

# .n '\

[ i 1

SOUTH POND 

## i lie OLU
QC

2 Q ~"-rf ^ lo

W n III.

'_

.

-

- 

# fis.o I0.6-

l "

-

_



# ^ \

DOWNGRADIENT WETLANDS

ROGRAMS 'WEIGHT^oo o

20

1< 4

Z fT" ^ H i iii
OT n 1

(INCLUDES NORTHEAST POND) I I I I I

0 0 03
iro 8

P «cc

OT n I

(INCLUDES NORTH POND)
1 1 I I I



## " T "

0 0

\ % \ \- * EXPLANATION \ ^ ^ \%

& \/ | | MAXIMUM-MINIMUM ^ 1J

X MEDIAN A MEAN SINGLE SAMPLE 0 NO SAMPLE COLLECTED

Figure 12. Generalized flow path and selenium concentrations in composite samples from A-Drain, South Pond, and downgradient wetlands, Fernley Wildlife Management Area. Data from Hoffman and others (1990, table 19) and Rowe and others (1991, tables 20 and 21).

48 Detailed Study of Irrigation Drainage Effect on BiotaWater is lost through evapotranspiration from LeadLake andfrommanagedponds orwetlands downgradient to the extent that dissolved solids are concentrated two to six times in each successive wetland (U.S. Fish and Wildlife Service, 1988, p. 51). This process is cumulative, and dissolved-solids concentrations in the last wetland frequently exceed concentrations in seawater. Data on organically bound selenium from this study and on dissolved selenium (Hoffman and others, 1990, p. 37) do not conform to the simple evaporative patterns predicted from these concentration processes. Dissolved selenium is not a conservative variable; it was least present in water in the downgradient wetlands where dissolved solids were the most concentrated. Presser and Ohlendorf(1987, p. 811) also found that seleniumdistribution in sequentially arranged ponds was inversely related to that which wouldbepredictedthroughevaporativemodels. Therefore, evapotranspiration does not appear to be an important mechanism contributing to selenium concentration in surface water. Inorganic sediment deposition also is not believed to be playing an important role in selenium pathways within Lead Lake. Organic pathways were probably more effective at removing selenium from water than inorganic processes in the Grasslands Water District (Presser and Ohlendorf, 1987, p. 811). Although Lead Lake has received selenium-bearing drift for 7 years from TJ Drain and for more than 40 years from Paiute Diversion Drain, selenium concentrations in the upper 2-3.5 in. ofthe bottom sediment in Lead Lake averaged only 0.65 jo,g/g (mg/kg: Hoffman and others, 1990, p. 113), near the median range ofconcentrations in various organisms and detritus in Lead Lake. These concentrations suggest that, in this system, selenium is not accumulating or immobilizingininorganic sedimentoverthelongterm. Roots ofaquatic plants could have an active role in mobilizing selenium out ofinorganic sediment (Lemly and Smith, 1987, p. 4), but most ofthe rooted aquatic plant beds have perished from Lead Lake over the last 30 years. Organically bound selenium concentrations recorded in biota from Lead Lake are similar to those ofthe imported organisms and detritus found in drains (fig. 11). This indicates that an equilibrium between import and export exists in LeadLake, which has been continuously flooded for about 10 years. Even with significant evaporative concentration processes, selenium concentrations in organisms from wetlands downgradient from Lead Lake are lower than those within the lake. Selenium volatilization may be a component ofsuch an equilibrium (Ohlendorf, 1989, p. 139). Frankenberger and Thompson-Eagle (1989, p. 2) have documented volatilization ofseleniumfrom saline evaporation-pond water. The bacteria and fungi thatwere acting on the available seleniumto cause this process were particularly effective in protein-rich environments. Organic detritus is aprotein source and may facilitate volatilization ofselenium in the study areas. The seleniumhazard to fish and wildlife in the Lead Lake system is largely determined by both concentration and length ofexposure. Habitat size and configuration are importantphysical variables that determine the extent ofwildlifeuse and exposure. The TJ Drain system is about 17 mi long, contains about 20 surface acres offlowing water, and attracts small numbers ofmigratory birds, primarily ducks. Conversely, LeadLake covers about 1,000 acres and supports thousands ofwaterfowl. Because ofrelatively limited use, direct exposure ofwaterfowl to selenium in the TJ Drain is oflesser concern. Concentrations ofselenium in all types of biological samples fromFernley WMAwere generally greater than those from the Lead Lake system. The relative concentrations ofselenium in various organisms and spatial relationships are shown in figure 12. The relative concentrations ofselenium in A-Drain, South Pond, and downgradient wetlands resemble the pattern described for the Lead Lake systembut, like the Grasslands Water District (Presser and Ohlendorf, 1987, p. 815), bioaccumulation was greatest in the initial wetland. Concentrations ofselenium in drift, algae, and adultbrine flies in Hunter Drain in StillwaterWMA (fig. 13) are comparable to those inbothFernleyWMA and TJ Drain. Mercury released to the Carson River in the late 1800'sby gold and silvermillingpracticeshascontaminated the river sediment downstream ofthe Comstock mining district near Virginia City, Nev. (Smith, 1943; Cooper and others, 1985). Contaminated sediment is presentovera largepart ofthe Carson Desert, terminus oftheCarson River. Mercury was depositedinthe area through flooding priorto the construction ofLahontan Damin 1915, andremainsbiologically availablewithin Indian Lakes to this day. However, it appears that mercury exportthroughthe D-line Canal, aditch thatfeeds the IndianLakes, was minimal. The medianconcentration ofmercury in composite detritus samples from

BIOLOGICAL PATHWAYS RJ. Hallockandothers 49

### IndianLakes, in StillwaterWMA, was about 53 |ig/g, dryweight. Incontrast, themedianmercuryconcentrationindetritusfromtheD-lineCanaldownstreamfrom IndianLakes was only 0.13 |ig/g, whichis comparable to background sites and at a level about400 times lowerthan that in Indian Lakes. Mercury concentrations found in 89 detritus and 76 algae samples from drains within the area ranged from <0.04 to 38.6 u.g/g, and <0.02 to 10.4, respectively. Most ofthese high concentrations were from drainage/wetland systems notpreviously studied in detail for selenium accumulation. The mechanism(s)throughwhichmercurywas sorbedontoorinto detritus and algae was not determined. Although drift

was not examinedinthese drains, mercury was found in algae anddetritusfromdriftmoving downthedrains in the area. Many ofthe samples withhighmercury concentrations are from sites in drains upgradient of CarsonLake. Juvenile migratory birds have been shown to bioaccumulate mercury in Carson Lake (Hoffman and others, 1990, p. 61). Adult shoveler ducks (Anas clypeatd) feeding in CarsonLake have also been shown to bioaccumulate mercury. (See the sectionin thisreport, "Mercury and SeleniuminEdible Tissue ofWaterfowl.11) Inthethree drainage systems examinedindetail (Paiute, D-Line, andTJDrains),biologicalpathways particularly detritus and algae were associated with the transport ofseleniumfromirrigatedlands (source areas) through drains to managed wetlands. Mercury also accumulatedin detritus and algae in some drains. Because detritus and algae are transported in driftin similar drains inthis project, biological pathways are thoughtto be involved in the movement ofmercury from source areas to managed wetlands.

Duration of Selenium Contamination

Paiute Drain, which discharges to LeadLake, provides additional information onthepossible durationofselenium contaminationin agricultural drainages. ThePaiuteDrain system (fig. 8) was constructed between 1913 and 1950. Median concentrations of selenium in animal driftfromPaiute Drainwere approximately halfthose ofnearby younger TJ Drain and slightly less thanhalfthose from Hunter Drain (figs. 11 and 13).
The release ofhigh concentrations ofselenium in the shallow ground water, ifpresent, in the first 1-5 years following construction ofnew drains, followedbythelong-termreleaseoflowerconcentrations wouldbe expected (Gilliom andothers, 1989,p. 123). The water-qualityhistory ofPaiute Drainis unknown, butitis apparentthat after more than 40 years, selenium continues to be releasedinto the water, incorporatedintobiota, andtransportedtoLeadLake (fig. 11). Similarly, after about40 years ofirrigation drainage, soils near Hunter Drain continue to release selenium intothe water, andbioaccumulationoccursinthisdrain (ng. 13).

HUNTER DRAIN

10

2o I I I 17.9 f /X11.4"
11.1-

% <% ^ Ox \^
% ° &, /A. V ^ %, <«,

EXPLANATION
| I MAXIMUM-MINIMUM X MEDIAN A MEAN SINGLE SAMPLE

FIGURE 13. Selenium concentrations in composite samples from Hunter Drain in Stillwater Wildlife Management Area.

50 Detailed Study of Irrigation Drainage Effect on BiotaContaminant Source Areas

Selenium and mercury are heterogenously distributed in irrigated soils within the Newlands Project area (R.R. Tidball, U.S. Geological Survey, oral commun., 1989). Here, source areas associated with biological pathways are irrigated land upgradient from or at sampling sites in drains that carried concentrations equal or exceeding 1.0 |ig/g, dry weight, of selenium or mercury. Figure 14 shows the spatial distribution of selenium in detritus throughout the study area Selenium concentrations in algae generally correlate with those in detritus. Areas having selenium concentrations >1.0 |ig/g, dry weight, were defined as source
areas or areas ofhigh selenium availability. The 1.0 |ig/g concentration was selected principally because ofthe capacity of selenium to biomagnify up the food chain. This concentration was the average for plants fromTJDrain. Fourgeneral sourceareas ofhigh selenium concentration were identified: near the city ofFallen, north and east ofS-Line Reservoir, Fallen Indian Reservation, and the Fernley agricultural area (fig. 9). Areas ofhigh concentrations ofarsenic and boron in detritus and algae coincided with the same
areas ofhigh selenium concentration (Rowe and others, 1991). Areashaving mercury concentrations> 1.0 |ig/g, dry weight, in detritus, were defined as source areas or
areas ofhigh mercury availability. Mercury concentrations greater than 1.0 |ig/g were found in both detritus (fig. 15) and algae in an area near Carson Lake along the historical Carson River channel, south ofFallen. This fan-shaped area, generally northwest ofCarson Lake, is the area which may have received sediment from the Carson Riverprior to 1900, before the construction ofdams that diverted the flow ofthe river (see fig. 2). Other areas ofhigh concentrations are along the Carson River, Stillwater Slough, and New River Drain. The occurrence ofselenium and mercury in detritus and algae associated with irrigation drainage is indicative ofthe bioavailability ofthose elements, and suggests an upgradient source. Furthermore, the magnitude ofbioaccumulation at one site can be compared with another to indicate source areas ofmore
or less contamination. Additional information on the annual load oforganically bound selenium and mercury from the agricultural drains to receiving wetlands would be more definitive.

BIOLOGICAL PATHWAYS RJ. Hallockand others 5139"45118°30's?CDaCQI(DO39°30'3915EXPLANATIONIOPENWATER.i;-.-IWETLANDS,INCLUDING^*p'1OPENWATERAGRICULTURALLANDSPLAYAWILDLIFEMANAGEMENTAREABOUNDARY0.6SELENIUMCONCENTRATION,INMICROGRAMSPERGRAM,DRYWEIGHTR.25E.R.26ER.27E.R.28E.R.29E.R.30E.FIGURE14.ConcentrationsofseleniumindetritussamplesfrominandnearStillwaterandFernleyWildlifeManagementAreas.(MapmodifiedfromSellerandAllander,inpress.)39°45'118°30'006oogIICAfon§.3930139°15'EXPLANATIONOPENWATERaF^TlWETLANDS.INCLUDING- ^OPENWATER||AGRICULTURALLANDSPLAYAWILDLIFEMANAGEMENTAREABOUNDARY0.6MERCURYCONCENTRATION,INMICROGRAMSPERGRAM,DRYWEIGHTR.25E.R.26E.R.27E.R.28E.R.29E.R.30E.FIGURE15.ConcentrationsofmercuryindetritussamplesfrominandnearStillwaterandFemleyWildlifeManagementAreasandadjacentwetlands.(MapmodifiedfromSeilerandAllander,inpress.)

# EFFECTS OF BORON, MERCURY, AND SELENIUM ON WATERFOWL PRODUCTION

Waterfowl are typically most sensitive to environmental stress during their reproductive phases (egg formation, incubation, andjuvenile growth) and

are more vulnerable to the effects oftrace elements during that time. Trace-element toxicity is a possible contributing factor to the steady decline ofwaterfowl production in wetlandsthat are maintainedby drainage from the Newlands Irrigation Project. Livers from juvenile waterfowl and shorebirds collected from these wetlands in 1986-87 contained concentrations ofboron, mercury, and seleniumthat have been associated with various harmful effects (Hoffman and others 1990, p. 53, 60, 67). The available literature concerning the effects oftrace-element concentrations in eggs andjuvenile waterfowl is limited, but some information is available about the effect levels ofboron, mercury, and selenium. Concentrations of20 trace elements were determined in this study in 1988 and presented by Rowe and others (1991, table 20). Of those elements, this section will consider only boron, mercury, and selenium. Evaluations ofthese three elements in eggs andjuvenile duck livers and of hatch success, teratogenesis, nest success, and duckling production were made to determine the extent ofthe effects ofthese trace- elements on waterfowl reproduction.

APPROACH

Six separate wetlands were included in the waterfowl production study: Stillwater, Fernley, and Humboldt Wildlife Management Areas (WMAs); CarsonLake; andMassie andMahala Sloughs (fig. 1). All ofthese areas receive irrigation drainage, ground water, or both, from U.S. Bureau ofReclamation Projects. Humboldt WMA is maintained primarily by irrigation return flow from the Humboldt Irrigation Project. The other five study areas receive irrigation return flow from the Newlands Irrigation Project (Hoffman and others, 1990). Background sites were selected in Carson Valley, outside the study area, and at S-Line Reservoir,

near the study area. The wetlands in Carson Valley

are about 1,000 ft higher than the valley floors ofthe study area, thus presenting a history of soil development unaffected by ancient Lake Lahontan. Although S-Line Reservoir is located within the Fallon agricultural area, it is maintainedprimarily with Carson River watertaken from Coleman Diversion Reservoir which contains only small amounts ofirrigation return water. This study was made in 1988 during the second year ofa drought. Both irrigation drainwater and operational releases in the study area were greatly reducedbecause ofthe tight management ofirrigation water; agricultural diversions were reduced to 70 percent ofnormal inresponse to the drought. Thousands ofwetland acres driedup, reducing nesting and feedinghabitat. Waterfowl congregated on the remaining wetlands, where reduced vegetative coverexposed nests to increased predation. Dissolved solids, including trace elements, concentrated in the drainwater and remaining ponds as evaporation reduced the water volume. The number ofsamples collected in this study was low, primarily because nests that were not destroyed by predators were extremely difficult to locate in the available habitat. Nest predators were an ongoing problem, commonly destroying previously located nests between study visits. Nests ofsix species ofducks cinnamon teals (Anas cyanopterd), gadwalls (Anas strepera), mallards (Anasplatyrhynchos), pintails (Anas acuta), redhead ducks, andruddyducks (Aythyaamericanaand Oxyura jamaicensis) were surveyed, as were nests ofAmerican coots (Fulica americana).

METHODS
Surveys to locate as many duck and coot nests

as possible were conducted, on foot, in the various nesting habitats from early May through June. Peak

WATERFOWL PRODUCTION L.L Hallockand others 55nesting periods in this area typically range from

April 10 to June 20 for ducks and from May 1 to June 15 forcoots. All study siteshad suitablenestinghabitat for the various waterfowl common to the area. Redhead and ruddy ducks and American coots build nests in and over water in bulrush (Scirpus sp.) and cattails (Typha sp.), and other duck species use a variety of upland and marsh vegetation. After the nests were located and identified by species, one egg was taken from each nest for traceelement analysis. Two additional eggs were collected fromducknests containing seven or more eggs for artificial incubation under controlled conditions to determine hatch success. Nests with six orfewer eggs were revisited and, ifthe clutch size had increased to seven, the additional two eggs were collected at that time. Coot eggs were not collected for artificial incubation because the incubator was adjusted for duck eggs and coots were of secondary interest. All eggs were marked for identification and floated in water to determine incubation stage and expected hatch dates (Westerkov, 1950). Eggs collected for trace-element analysis were immediately refrigerated and those for incubation were placed in a Koolatron (a temperaturecontrolled, padded container) for transportation to the incubator. Eggs for trace-element analysis were volumetrically measured by water displacement. The eggs were then opened, using a scalpel cleansed with acetone followed by a distilled- or deionizedwaterrinse. The circumference ofthe egg was scribed with the scalpel and the contents dropped directly into

a nitric-acid-washed, pre-weighed, 2-oz glassjar. The degree ofembryonic development was recorded, and the samples were weighed, labeled, and frozen for shipment. All egg samples were analyzed for traceelements by the U.S. Fish and Wildlife Service, Patuxent Analytical Control Facility, Laurel, Md.,

or their contract laboratories. The resulting data had appropriatequality-assurancedocumentationattached. All trace elements were analyzed by inductively coupled plasma emission spectroscopy, except for mercury, which was analyzedby the cold-vaportechnique, and selenium, which was analyzed by hydride generation (U.S. Fish and Wildlife Service, 1985). The incubator (a Petersime Model No. 4) was checkedtwice dailyto monitortemperature andhumidity and to remove any newly hatched ducklings. Eggs that remained unhatched approximately 10 days after expected hatch dates, and eggs that pipped but did not hatch, were removed andrefrigerated forexamination. Embryos and ducklings were examined for gross abnormalities ofthe eyes, beak, wings, and feet, and

were then frozen in individual plastic bags. Mallard eggs ofknown age from game-farm birds maintained

on a contaminant-free diet were used as incubation controls. Coot nests were rechecked prior to expected hatch date and a second egg was collected from those nests still containing eggs. Embryos from these eggs
were examined for deformities and then frozen. To determine ifjuvenile birds accumulated trace elements after hatching, livers of juvenile ducks, coots, andblack-necked stilts (Himantopusmexicanus) fromboth background and study-area wetlands were analyzed. Sixty preflight ducklings, 45juvenile coots, and 12juvenile stilts were collected from the study
areas, and 5 ducklings and 6 coots were collected from the background areas. The birds were frozen and later partially thawed for dissection. The liver from each bird was removed using a scalpel rinsed with acetone followed by a distilled- or deionized-water rinse. The liver was placed in a nitric-acid washed, preweighed, 2-oz glassjar, then weighed, labeled, and frozen for shipment. Juvenile stilt livers were so small that two

were combined to make a minimum sample weight; therefore, each data point for liver (figs. 16,17) represents two birds. Nest success is defined as the probability of production ofone ormore livejuveniles from anesting attempt. The nest-success rate was calculatedby dividing the number ofsuccessful nests by the total number ofnests. Todetermine nest success, eachducknestwas checked at 7-10 day intervals for evidence of successful hatching. A feathered-egg membrane pulled away from the shell was used as an indicator of successful hatching. Coot nests were rechecked at least once, either at hatching time orjust after. Duckling production was estimated by conducting brood surveys in each study area from the fourth week ofJune through the third week of July the peak hatching period Survey routes were predetermined to include areas ofhigh brood use, particularly shorelines andclumps ofvegetation, andto

ensure adequate visibility by the investigator. Surveys started about 6:00 a.m., during the most active feeding time. Most routes were walked or driven, using binoculars or a spotting scope as necessary. In areas inaccessible by land, an airboat was used. Data on duck species, duckling numbers, and age classes at each site were recorded.

56 Detailed Study of Irrigation Drainage Effect on Biota

### Hatch Success and Teratogenesis

Duck eggs for incubation and subsequent examination were collected from41 nests; two eggs per nest were collected where possible. A total of 81 eggs were incubated 69 from study-area sites and 12 from background sites. Eggs from the background sites had ahatch-success rate of92 percent. Ofthe 69 eggs from the study sites, 62 hatched a success rate of90 percent. This rate for artificially incubated duck eggs is in the range expected for eggs from healthy populations (Charles J. Henny, U.S. Fish and Wildlife Service, oral commun., 1990). Hatch success is summarized in table 16 by species and area. The eight eggs that failed to hatch seven from the study area and one from the background site were examined for deformities. Five contained embryos, all well developed with no gross deformities (Charles J. Henny, U.S. Fish andWildlife Service, oral
commun., 1990). The three eggs thatfailedto develop may have been infertile. The 62 ducklings were also examined and no gross external deformities were observed. Thirty-one coot eggs from separate nests were collectedjust prior to expected hatch. Ofthese eggs, 24 had well-developed embryos and all 31 appeared to be normal. Based on these data, levels oftrace elements in the eggs probably were below effect levels for teratogenesis and mortality.



### Trace Elements in Eggs

Eisler (1990,1987, and 1985) has summarized the availableliteratureontheeffects ofboron, mercury, and selenium, respectively, on wildlife, including specific references for duck eggs (table 18). One ofthe

common effects that each ofthese trace elements has

on embryonic development is reduced hatch weight.
Concentrations oftrace elements were determined for 62 duck eggs and 68 coot eggs. Five ofthe duck eggs were from the background site in Carson Valley and were well below the effect level for boron, mercury, and selenium. These data

are reported by Rowe and others (1991, table 20) and are summarized in table 17 in this report.

Table 16. Hatch success of artificially incubated waterfowl eggs collected in the study area, 1988

[In each two-line data group, the top number (in parentheses) is total incubated eggs; bottom number is percentage hatched;
, no data; WMA, Wildlife Management Area]

Location

StillwaterWMA

Fernley WMA

Humboldt WMA

Mahala Slough

Massie Slough

TOTAL

Carson Valley Cinnamon teal

(6) 100
(6) 100
(2) 100
(10) 80
(2) 100
(26) 92

~ Gadwall Mallard Pintail

(2) 100

--

(2) 100
(2) 100

--

(6) 100 Study Sites

(4) (4) 75 100

-

(3) 100
(2) 100

--

(9) (4) 89 100
Background Site (12) 92 Redhead

(2) 100
(6) 67
(8) 88

--

(2) 100 (18) 83

-- Ruddy

(2) 100

--

--

(4) 75

--

(6) 83

-- Total, all species

(20) 95 (12) 83
(15) 93
(18) 89
(4) 100
(69) 90

(12) 92

WATERFOWL PRODUCTION /../.. Hallockandothers 57The primary effects ofhigh levels ofboron are

on growth, behavior, and brain biochemistry (Eisler, 1990, p. 19). Mallardducklings fromeggswith aboron concentration of 13 |lg/g, dry weight, showed reduced hatch weights (Smith and Anders, 1989, p. 945). Eggs with boron concentrations of49 |lg/g, dry weight, showed significantly reduced hatch rates andjuveniles from those eggs had higher mortality rates (Smith and Anders, 1989, p. 945). These effect levels came from feeding studies and are the arithmetic means resulting fromexperimentalconcentrations infeed, so no dataon intermediate concentrations are available. The boron concentrations found in eggs in this study (maximum, 19.4 |lg/g, dry weight) were all well below the level known to adversely affect hatch

success (49 |ig/g, dry weight). This correlates with the incubator hatch rate of90 percent observed in this study. Three redhead duck eggs (5 percent), all collected in Mahala Slough, had boron concentrations above 13.0 |ig/g, dry weight, the level associated with reduced hatch weight. Overall, coot eggs had higher boron concentrations than duck eggs. Ten percent of the coot eggs, primarily those fromFernley WMA, had boron concentrations above the effect level for reduced hatch weight.

Table 17. Summary of data on concentrations of boron, mercury, and selenium, including minimums, maximums, and means for waterfowl eggs collected in the study area
[Abbreviations: (ig/g, micrograms per gram; C. teal, cinnamon teal; WMA Wildlife ManagementArea.]

Trace-element concentration (jxg/g, dry weight)

Location Species Number of samples Minimum Boron

Maximum Mean Minimum Mercury

Maximum Mean Minimum Selenium

Maximum Mean

Study Sites
StillwaterWMA

Fernley WMA

HumboldtWMA

Mahala Slough

Massie Slough C. teal

Gadwall Mallard Pintail Redhead Ruddy

Coot C. teal Mallard Redhead

Coot C. teal Gadwall Mallard Redhead

C. teal Gadwall Mallard Redhead Ruddy

C. teal Redhead Ruddy 3

1 2 2 1 2

25 2 1 3

27 2 1 1 6

9 1 3 7 7

1 1 1 3.2 2.0 1.7 2.3 5.7 1.1

5.5 1.7 3.1 3.2

4.4 2.8 3.9 10.2 3.1

1.5 7.6 <0.8 4.2 <0.8

1.7 1.8 2.1 4.8 2.0 2.2 3.7 5.7 1.2

15.7 4.8 3.1 5.4

14.3 5.2 3.9 10.2 9.6

7.6 7.6 0.9 19.4 3.1

1.7 1.8 2.1 4.1 2.0 2.0 3.0 5.7 1.2

9.3 3.3 3.1 4.2

7.7 4.0 3.9 10.2 9.6

4.1 7.6 0.6 11.7 2.1

1.7 1.8 2.1 1.6 0.5 1.7 0.4 1.7 0.2

0.1 0.2 0.2 <0.1

0.1 0.4 0.2 0.5 0.1

0.2 0.3 0.3 0.1 0.1

0.1 0.4 0.1 6.2 0.5 3.7 0.5 1.7 0.5

0.4 0.7 0.2 0.1

1.36 0.5 0.2 0.5 1.74

1.1 0.3 2.1 1.2 2.7

0.1 0.4 0.1 4.5 0.5 2.7 0.5 1.7 0.4

0.1 0.5 0.2 0.3

0.2 0.5 0.2 0.5 0.5

0.6 0.3 1.1 0.6 0.6

0.1 0.4 0.1 2.0 1.8 2.1 2.5 1.8 2.1

4.4 7.6 8.9 8.8

1.9 2.8 3.1 3.0 3.0

2.0 4.6 1.3 1.2 1.2

8.0 3.6 7.4 2.3 1.8 2.1 2.9 1.8 2.9

12.2 10.1 8.9 10.9

4.48 3.7 3.1 3.0 3.7

7.4 4.6 8.4 8.5 5.7

8.0 3.6 7.4 2.2 1.8 2.1 2.7 1.8 2.5

8.7 8.8 8.9 9.9

2.9 3.2 3.1 3.0 3.2

4.4 4.6 4.0 3.7 3.3

8.0 3.6 7.4
Background Site
Carson Valley Mallard 5 <0.8 1.9 0.7 0.2 0.6 0.3 0.7 2.3 1.4

58 Detailed Study of Irrigation Drainage Effect on BiotaTable 18. Effect levels and characteristics of boron, mercury, and selenium concentrations in

waterfowl eggs and juvenile waterfowl livers

[Hg/g, micrograms per gram]

Mercury

Selenium3 Eggs Liver tissue

Constituent

Boron1 Effect level

frig/g, dry weight)

13 49 Characteristic sign

or result

Reduced hatch weight Reduced hatch rate and juvenile survival Effect level (\iglg, dry weight)

17 Characteristic sign

or result

Reduced reproduction and duckling growth

3.1 Reduced hatch rate and

juvenile survival

15 Teratogenesis and embryo

mortality 4.3 Reducedreproduction and survival rates
9 Reduced reproduction and

juvenile survival

1 Smith and Anders, 1989. 2Heinz, 1979. 3 LemlyandSmith, 1987.

Mercury concentrations of3.1 |ig/g, dry weight, inblack duck (Anas rubripes) eggs are associated with significantly reduced hatch rate and duckling survival (Heinz, 1979, p. 398). Mercury residues found in duck and coot eggs in this study were low except in those collected in StillwaterWMA. Three (27 percent) of the 11 duck eggs from Stillwater WMA had mercury concentrations abovethe effectlevel. Thenest siblings ofthese eggs cinnamon teal and pintail hatched in the incubators.
All selenium concentrations found in duck and coot eggs were below 15 |ig/g, dry weight. The level at which teratogenesis or embryo mortality (Lemly and Smith, 1987, p. 9), or reproductive problems in the laying hen (Heinz and others, 1989, p. 427) can be expected is 15-18 |ig/g, dry weight.
The concentrations ofpotentially harmful trace elements in duck and coot eggs in all areas were low, with the exception ofmercury in those from Stillwater WMA and, with that exception, probably are not a factor in waterfowl production. The adults ofthese species normally do not overwinter in these wetlands; they arrive shortly before nesting and apparently

are not sufficiently exposed to the trace elements to accumulate enough to deposit significant amounts in their eggs. 

### Trace Elements in Juvenile Duck Livers

Eisler (1990, 1987, and 1985) summarized the available literature on the effects and concentrations ofboron, mercury, and selenium in livers ofjuvenile waterfowl (table 18). Itwas assumedthatjuvenile waterfowl collected preflight had been feeding in the vicinity and that the trace-element concentrations in their tissues reflected existing conditions in the wetlands. Juvenile ducks, coots, and black-necked stilts were taken from study

areas where eggs had been collected, and livers were analyzed for concentrations oftrace elements. Data

were obtained for 65 preflight ducklings, 52juvenile coots, and 12juvenile stilts. Complete data are presented by Rowe and others (1991, table 20) and are summarized in this report (table 19). In boron feeding studies, mallard ducklings with liver concentrations of 17 |ig/g, dry weight, showedreducedweight gain (Smith and Anders, 1989, p. 945). In this study, boron concentrations in blacknecked stilt livers (6 composite samples) werebelow 4 |ig/g, dry weight. Concentrations ofboron in duck livers also were below the effect level, varying widely throughoutthe study area from 1.1 to 15.1 |ig/g. Coot livers showed higherboron concentrations than duck livers, as high as 34.5 |ig/g. Concentrations ofboron

were at or above effect level in 10 percent ofthe coot

WATERFOWL PRODUCTION LL. Hallockandothers 59

### livers. The highest boron concentrations were from Fernley WMA, where three ofthe seven coots collected had concentrations above effect level, and reduced growth rates could be expected. Boron levels injuvenile birds were not high enough to affect waterfowl reproduction Levels ofboron concentration varied; in some instances concentrations were higher in eggs than in juvenile livers fromthe same area. These data suggest that some adult birds may have acquired boron elsewhere in the flyway prior to their arrival and egg laying in the study areas.

Table 19. Summary of data on concentrations of boron, mercury, and selenium, including minimums, maximums, and means, forjuvenile waterfowl livers collected in the study

[Abbreviations: ug/g, micrograms pergram; C. teal, cinnamon teal; WMA, Wildlife Management Area.]

Trace-element concentration (ng/g, dry weight)

Location Species Number of Samples Minimum Boron

Maximum Mean Minimum Mercury

Maximum Mean Minimum Selenium

Maximum Mean

Study Sites

StillwaterWMA

Fernley WMA

Humboldt WMA

Carson Lake

Mahala Slough

Massie Slough Coot

C. teal Mallard Pintail Redhead Ruddy

Coot C. teal Stilt

Coot C. teal Gadwall Mallard Redhead

Coot C. teal Mallard Redhead Ruddy Stilt

Coot Redhead Ruddy Stilt

Redhead 10

5 2 1 2 1

7 4 3

12 6 1 7 3

10 1 4 4 4 1

6 3 6 2

7 5.8 <2.0 5.1 5.9 5.0 1.8

7.5 2.4 2.0

<2.0 1.8 4.0 2.7 3.0

1.6 7.9 <2.0 0.8 2.1 1.7

3.7 3.7 <0.8 3.4

4.4 22.1 4.4 9.8 5.9 6.0 1.8

34.5 12.1 3.5

8.0 5.1 4.0 10.0 6.1

6.8 7.9 5.3 15.1 3.9 1.7

7.0 9.3 2.4 3.8

13.6 11.1

3.2 7.5 5.9 5.5 1.8

16.8 8.1 2.5

4.5 3.2 4.0 5.9 4.8

4.9 7.9 3.9 5.9 3.3 1.7

5.4 6.5 1.4 3.6

6.8 2.0 1.4 2.7 1.8 2.4 2.1

0.3 <0.1 0.4

0.2 0.4 0.8 0.3 0.6

2.0 5.6 1.4 0.9 <0.1 7.9

0.2 0.1 0.1 2.0

<0.1 5.7

3.5 3.0 1.8 6.4 2.1

0.5 0.1 1.0

3.2 1.6 0.8 0.7 0.8

8.8 5.6 6.0 5.1 2.4 7.9

1.19 0.7 0.5 13.9

0.5 4.0 2.2 5.6 1.8 4.4 2.1

0.4 0.1 0.7

0.7 1.0 0.8 0.5 0.8

5.3 5.6 3.4 2.3 1.5 7.9

0.8 0.4 0.2 8.0

0.3 3.4 4.0 7.4 6.6 6.7 6.4

26.4 26.4 17.0

7.8 11.9 16.0 7.2 9.1

2.6 8.7 4.4 4.4 6.9 13.2

7.6 8.2 5.4 52.0

17.5 5.9 6.8 9.0 6.6 13.9 6.4

36.0 35.3 35.3

13.0 17.5 16.0 23.0 13.3

6.3 8.7 6.6 7.0 8.2 13.2

15.0 20.4 10.4 102.0

43.5 4.4

5.6 8.2 6.6 10.3 6.4

30.9 30.3 28.4

10.1 15.1 16.0 12.8 11.6

4.4 8.7 5.1 5.6 7.6 13.2

9.6 13.5 7.9 77.0

30.7
Background Sites
Carson Valley

S-Line Reservoir Mallard

Coot C. teal 4

7 1 1.2

1.6 1.5 2.8

7.3 1.5 2.2

3.9 1.5 1.3

0.8 9.4 2.4

4.3 9.4 1.6

2.9 9.4 2.3

2.9 5.6 3.5

5.3 5.6 3.0

4.3 5.6

60 Detailed Study of Irrigation Drainage Effect on BiotaData are not available for establishing an effect level for mercury concentration injuvenile waterfowl liver, but for adult mallard liver, an effect level of4.3 (ig/g, dry weight, for decreased reproductive success can be derived from existing data (Heinz, 1979, p. 396; Hoffman and others, 1990, p. 26). Stilt, duck, and coot livers from Fernley WMA and Humboldt WMA and Massie and Mahala Sloughs had mercury concentrations generally below 1 (ig/g. Moderate concentrations ofmercury in ducks, coots, and stilts were found in Carson Valley (mean 1.6 (ig/g, dry weight) and in S-Line Reservoir (3.67 (ig/g, dry weight). Mercury concentrations were abovetheeffect level in 70 percent ofthe coots and 31 percent ofthe ducks from Carson Lake and 40 percent ofthe coots from StillwaterWMA. The highest mercury concentration found in this study, 13.9 |ig/g, dry weight, was in a stilt sample (livers oftwo birds, combined) from Mahala Slough, an anomalous samplebecauseno other samples from Mahala Slough showed high mercury concentrations, and Mahala Slough had not received directCarsonRiverwatercontainingminingdischarge. One ofthe birds in this sample probably was an adult that had moved into Mahala Slough from one ofthe nearby mercury-source areas. The incidence ofelevated mercury concentrations in birds was restricted to areas that had received mercury-contaminated sediment ofthe Carson River before construction ofthe Newlands Irrigation Project, including Carson Lake and StillwaterWMA. Mercury concentrations in bird livers from those areas are high enough that a negative effect on waterfowl production could be expected. Data in the literature on the biological effects ofselenium on waterfowl are more available. The effects are primarily on reproduction, but selenium toxicosis has been documented elsewhere since the 1930's. Seleniumconcentrations of9 (ig/g,dryweight, in livers ofadultbirds areknown to be associated with decreased reproductive success and reducedjuvenile survival (table 19; Lemly and Smith, 1987, p. 8). Selenium concentrations in livers establish 95 percent ofequilibrium with dietary concentration in 7-8 days andreturntobackground level 9-10weeks afterdietary intake stops (Heinz and others, 1990, p. 376). Selenium concentrations in livers ofpreflightjuveniles, therefore, reflect the selenium in the food chain in the area. Selenium concentrations in bird livers from Carson Valley and S-Line Reservoir (background sites), and Carson Lake were below the effect level for reducedreproduction (9.0 |H/g, dry weight). Twenty percent ofthe ducks from Stillwater WMA had selenium concentrations at or above effect level (fig. 16). In birds fromMahala Slough, concentrations ofselenium above the effect level were found in 56 percent ofthe ducks, 33 percent ofthe coots, and both stilt samples. Concentrations in the two stilt samples (composite) were 52.0 and 102.0 (ig/g (mean, 77 (ig/g, dry weight), the highest found in this study and in the range where toxicosis and mortality have been documented elsewhere (Heinz and others, 1987, p. 429; 1988, p. 566). Livers from 83 percent ofthe ducks and 67 percent ofthe coots collected in Humboldt WMA had selenium concentrations above the effect level, as high as 23 |Llg/g, dry weight. High concentrations ofseleniumwere also foundin livers ofcinnamon teal (mean, 30.0 (ig/g, dry weight) and coots (mean, 30.9 |ig/g, dry weight) from Fernley WMA, and in redhead ducks (mean, 30.7 |ig/g, dry weight) from Massie Slough.
The two areas with the highest average concentrations ofselenium in bird livers were Fernley WMA and Massie Slough, where every bird taken had concentrations between 17.0 and 43.5 (ig/g (mean, 30.4 (ig/g, dry weight).
Decreased survival of

juvenile birds is anticipated in areas where liver concentrations are consistently above effect levels. Decreasedjuvenile survival and, thus, decreased waterfowl production, is anticipated in Fernley and Humboldt WMAs and Mahala and Massie Sloughs, and to a lesser extent in Stillwater WMA.
The concentrations ofselenium residues found injuvenile livers were consistently higher than those found in eggs from the same areas, indicatingjuvenile uptake in all areas. The combined effect ofconcentrations oftwo

or more trace elements is not well understood. High boron concentrations were found with high selenium concentrations only in Fernley WMA. Selenium and boron have been considered to biochemically operate independently (Patuxent Wildlife Research Center, 1987, p. 28), but there is recent evidence that boron and selenium interact synergistically to produce more
severe toxicological effects (David Hoffman, Patuxent Wildlife Research Center, written commun., 1990). With the exception ofthe anomalous stilt sample from Mahala Slough, high concentrations ofmercury and selenium, in eggs orjuvenile livers, were not found in the same areas.

WATERFOWL PRODUCTION LL. Hallockandothers 61STILLWATER WMA
EGG
LIVER

FERNLEY WMA

EGG
LIVER

HUMBOLDT WMA

EGG
LIVER

MAHALA SLOUGH

C/"*/"*

LIVER

MASSIE SLOUGH

EGG
LIVER

CARSON VALLEY

EGG
LIVER

C 1

ft i YA 1 Am

1 i

i YA i



### iAX-i

LiJ

§ o !_&_! W njflSi u.
I xg. I LU

LiJ

IJ 1 ) 10 

## I I

I I I I I U| I I I 

# '!i i i YA I 

### XT ' I i 

# ' ! ' i i i i i i |i

LiJ I ^i LiJ SI 

# I I

20 I I

I I MINIMUM-MAXIMUM

A MEAN

X MEDIAN

A Y I

I I

30 40
SELENIUM, IN MICROGRAMS PER GRAM, DRY WEIGHT
Figure 16. Concentrations of selenium in duck eggs and liver tissue ofjuvenile ducks collected in Stillwater, Fernley, and Humboldt Wildlife Management Areas, Mahala and Massie Sloughs, and at the background site. Effect levels for eggs and liver, 9 and 15 micrograms per gram, respectively, are described by Lemly and Smith (1987, table 2) and are summarized in table 18 of this report. Abbreviation: WMA, Wildlife Management Area.

Nest Success

Nest-successrate,by species, foreach study area is summarized in table 20. The nest-success data from all study sites were combined, because ofsmall sample sizes, and compared with data from nesting surveys conducted in StillwaterWMA in 1968-1970 (Napier, 1974), 1983 (Evans, 1983, p. 18-19), and 1987-1988 (Stillwater WMA, unpublished data); these comparisons are shownintable 21. The nest-successratefound in this study, 26 percent for the combined study sites, is comparable to the success rate of25 percent determined for Stillwater WMA by the WMA staff. The nest-success rate at Stillwater has shown a general downward trend from 43-52 percent in 1968-70 to 25 percent in 1988.
No relation could be established between the
nest-success rates in the various study sites and the trace-element concentrations in eggs orjuvenile livers from those sites. The nest failure observed during this study appeared to be caused primarily by predation exacerbated by loss ofhabitat and the lack ofvegetative cover in and near the remaining wetlands.

62 Detailed Study of Irrigation Drainage Effect on BiotaTable 20. Nest success of ducks in the study area, 1988

[In each two-line datagroup, the top number (inparentheses) is total nests examined; bottomnumberis percentage ofnests hatching at least one young; , no data; WMA, Wildlife Management Area.]

Location

StillwaterWMA

Fernley WMA

HumboldtWMA

Mahala Slough

Massie Slough

TOTAL Cinnamon teal

(3) 100
2) 0 (2) 0 (9) 22
(1) 100
(17) 35 Gadwall Mallard

(1) 0

--

(1) 100 

## (1)
0



### -

(3) 33 Study Sites

(2) 50
(1) 0 (1) 100 (3) 33

-

(7) 43 Pintail Redhead

(2) (1) 100 0

(3) 0 (6) 50 (1) 0 (1) 100
(2) (12) 100 33 Ruddy

(2) 0

--

--

(5) 20
(1) 0
(8) 13 Total

(11) 55
(6) 0 (10) 0 (19) 21
(3) 67
(49) 26
Background Site
Carson Valley

- (6) 83 - ~ (6) 83



### Waterfowl Production

A survey ofwaterfowlbreedingpairs, conducted annually in mid-May by the Nevada Department of Wildlife, found 6,810breedingpairs ofvarious species ofducks inthe study area in 1988 (NevadaDepartment ofWildlife, unpublished data, 1988). The low number ofducknests (49) foundinthis study, andthe difficulty experienced in finding even that number, suggests that most ofthe breeding pairs present in mid-May did not nest. Nesting habitat in the study area and in other traditional nesting areas is greatly reduced from that available in the recent past (U.S. Department ofthe Interior, 1988). This lack ofhabitat may be preventing many pairs from nesting. Observed duckling production from all study

areas except StillwaterWMA was 579 birds. Brood production in StillwaterWMA, estimated by the Stillwater staff, was about 1,800 ducklings (U.S. Fish andWildlife Service, Fallon, Nev., unpublished data, 1988), for a total estimated production ofabout 2,400 waterfowl (table 22). The brood counts in Fernley WMA, Humboldt WMA, and Carson Lake were close to estimates made by the StillwaterWMA staff. Duckling production in 1988 was considerably lower than production experienced in previous years (U.S. Fish and Wildlife Service, Fallon, Nev., unpublished data, 1988).
Waterfowl production typically fluctuates, and is dependanton avariety offactors, includingthe availability ofsuitable wetland nesting habitat andpredator populations. Decreased water flow to the wetlands, managementchoices aboutuse oftheremaining water, and elevated dissolved-solids concentrations shown to cause vegetative losses (U.S. Fish and Wildlife Service, 1988, p. 74) are all probable contributing factors to decreases in nesting habitat. The continuing decreaseinwaterfowlproductionobservedinthe study

area in recent years is associated with decreased feeding andnestinghabitatthatresultsinwaterfowlnesting in marginal areas, and to increased predation rates resulting from a concentration ofpredators foraging in reduced wetland areas.

WATERFOWL PRODUCTION LL Hallockand others 63Table 21

. Nest-success rates from various other studies and from the present study

[In each two-line data group, the top number (in parentheses) is total nests examined; bottom number is percentage ofnests hatching at least one young.]
Other studies

_ , . (Stillwater Wildlife Management Area) Duck species

1968-19701 19832

Cinnamon Teal (43-56)

49-56

Gadwall (19-42)

16-43

Mallard (1-7)

0-43

Pintail (2-4)

50-80

Redhead (4-7)

57-100
Ruddy (1-3)

67-100

TOTAL (87-118)

43-54

1 Napier, 1974. 2Evans, 1983. 3 Unpublished data from U.S. (100) 28
(23) 13 (7) 57
(6) 17
(11) 91
(5) 60
(152) 32 19873
(7) 29
(17) 6 (5) 20
(5) 0
(7) 14
(2) 0
(43) 33

Fish andWildlife Service,

Table 22. Estimated waterfowl production in the study area,

Site

StillwaterWMA1 Fernley WMA

HumboldtWMA

Mahala Slough

Massie Slough

Carson Lake

TOTAL Cinnamon

_ .

teal Gadwa"

300 310

31 0

45 36

12 14

50 26

45 18

483 404 1988

Mallard Pintail

66

11

17

12

50

24

180 173

0

0

6

8

1

188 19883
(25) 32
(26) 8 (15) 33
(7) 29
(3) 67
(1) 0
(77) 25

Fallen, Nev.

Redhead

150

0

0

12

50

32

244 Present

study (all sites) 1988
(17) 35
(3) 33 (7) 43 (2) 100
(12) 33
(8) 13
(49) 26

Ruddy Other

690 82

0 0

0 0

30 0

5 0

44 0

769 82 Total

1,771

42

98

86

189

164
2,350

1 Estimates from U.S. Fish and Wildlife Service, Fallen, Nev. (unpublished data). All other data are fromthis study.

64 Detailed Study of Irrigation Drainage Effect on Biota

# MERCURY AND SELENIUM IN EDIBLE TISSUE OF WATERFOWL

The reconnaissance study during 1986-87 found indications thatjuvenile migratory birds, including waterfowl, in andnearStillwaterWMA andCarson Lake were accumulating mercury and seleniumin liver and muscle tissue and some ofthe concentrations exceeded established criteria for public-health warnings (Hoffman and others, 1990, p. 60-62, 66-70). Waterfowl taken from these areas are routinely consumed by hunters. Further sampling done in October 1987 and in 1989 for the detailed study found continued high concentrations ofmercury and selenium in edible tissues ofwaterfowl that could affect public health. Accumulation of selenium and mercury between waterfowl species within wetland systems and between different wetlands supporting the same species varied. This study focused primarily on Stillwater WMA and Carson Lake, the largest public waterfowl-hunting areas associated with the Newlands Irrigation Project, but because waterfowl are also hunted at nearby Fernley WMA and at Massie and Mahala Sloughs, those areas were included in the present study (fig. 1).

APPROACH AND METHODS

Ducks ofvarious ages harvested in mid-October 1989 at the beginning ofwaterfowl-hunting season,
were considered to be representative ofwaterfowl consumed by humans. Most ducks evaluated in this study

were contributed by hunters passing through USFWS check stations near Stillwater WMA and Carson Lake duringthe opening weekends ofthewaterfowl seasons; species included were shovelers (Anas clypeata), mallards (Anasplatyrhynchos), green-winged teals (Anas crecca), canvasbacks (Aythya valisineria), andredhead ducks (Aythya americana). Shovelers, late summerearly fall migrants that rarely nest in the study area, were collected from Carson Lake during August 1989

soon after they arrived and again in mid-October 1989. The mercury and selenium concentrations of the Augustbirds served as a baseline against which to establish the increase in concentration ofthese trace elementsbetween Augustandthe mid-Octoberhunting

season. Green-winged teals also were collected in October 1989 from Carson Lake. Whole ducks were identified, tagged, stored on ice in the field, and frozen in the laboratory on the date ofcollection. The ducks were thawed and later dissected. To prevent cross contamination, rubber gloves

were worn and stainless-steel instruments were rinsed in acetone, then distilled or deionized water. Tissue samples were weighed and refrozen in labeled, nitricacid-rinsed 2-ozjars. Concentrations ofmercury and selenium in muscle, liver, and skin were evaluated. Tissue samples were analyzed by the U.S. Fish andWildlife Service, PatuxentAnalytical Control Facility, Laurel, Md., or its contract laboratories. The resulting datahad appropriate quality-assurance documentation attached. Mercury was analyzed by coldvapor techniques and selenium was analyzed by hydride generation. Associated procedures used are describedbytheU.S. Fish andWildlife Service (1985). Datawerereportedbythe laboratory inmicrogramsper gram, dry weight. Because the purpose ofthis section ofthe report is to compare concentrations found with established criteria or action levels for human consumption, all data have been converted to wet weight, by dividing by 3.6 (Lemly and Smith, 1987, p. 7). An action level is a concentration ofa contaminant in animaltissueusedforhuman foodatwhichresponsible agencies take action. It is derived from a hazard-risk assessment and includes a safety margin for the population deemed most likely to consume the food involved. Typically, with wildlife not involved in
commerce, the action taken is posting ofpublic health

EDIBLE TISSUE OF WATERFOWL RJ. Hallockand others 65warnings. Analysis ofvariance was used to examine

temporal relations ofcontaminant levels. A statistical significance of0.1 was selected. Action levels established by the U.S. Food and Drug Administration (PDA) andthe State ofCalifornia

were used to evaluate the potential threat to human health. The U.S. PDA (1984, p. 1) action level formercury inedible animal tissue is 1.0 |ig/g, wetweight, and the State ofCalifornia action level for selenium is 2.0 ug/g, wet weight (Fan and others, 1988, p. 544). During the October 1987 sampling period, mallards, redheads, and shovelers were collected from both Carson Lake and StillwaterWMA. Canvasbacks

were collected only from StillwaterWMA. The data

werepublishedby Rowe and others (1991). The action level for mercury concentrations was exceeded in almosthalfofthe ducks sampled. Selenium concentrations exceeded the action level in less than 15 percent ofthe samples. Mercury and selenium concentrations

were highestin liver, lowerin muscle, and least in skin samples. Concentrations in skin never exceeded the action levels. Muscle is ofgreatest concern because it is the preferred tissue ofmost humans who consume ducks; liver and skin are less frequently eaten.

Mercury Accumulation in Waterfowl

Hoffman and others (1990, p. 60-62) found that mercury concentrations in liver and muscle tissue of juvenile mallards and liver tissue ofcoots (Fulica americand) and black-necked stilts (Himantopus mexicanus) collected in 1986 and 1987 from Carson Lake exceeded the action level. Juvenile birds, too young to migrate, were assumed to have acquired most ofthis mercury locally through diet. Henny and Herron (1989, p. 1043) documented accumulation of mercury in white-faced ibis (Plegadis chihi) which feed in fields near Carson Lake. Mercury concentrations in liver tissue of

juvenile black ducks (Anas rubripes) were found to nearly double in 4 weeks when the ducks were fed a diet containing 3 |ig/g mercury, and the rate ofaccumulation in liver was greater than in muscle (Finley and Stendell, 1978, p. 60). Mercury concentrations in shoveler ducks collected in October 1987 from Carson Lake exceeded the action level (orpublic-health criterion of 1.0 |ig/g, wetweight; 3.6 |lg/g, dry weight) in every liver sample and in 90 percent ofthe muscle samples (fig. 17). Mercury concentrations in shoveler muscle and liver from the October 1987 data set were the basis for the Nevada State Health Officer's decision topost apublichealth warning specific to shoveler ducks at Carson Lake in 1989. The mean concentrations ofmercury in shoveler muscle and liver from Carson Lake were, respectively, about 6 and 18 times the action level of 1.0 ^lg/g, wetweight. Attherequest ofthe State Health Officer, shovelers were again analyzed by the Department ofthe Interiorin 1989. Theconcentrations ofmercury in muscle were lower, but still averaged three times the action level, and the public-health warning stayed in effect. Concentrations exceeding the action level for mercury were also found in some shovelers from Stillwater WMA (fig. 17), in some green-winged teal from Carson Lake, and in mallards from both locations (fig. 18). The shoveler ducks collected from Carson Lake in mid-August 1989 forbaseline datahad a mean concentration ofmercury in muscle tissue of 1.1 |lg/g, wet weight (fig. 17), significantly lower (p=<0.05) than the 5.9 (Xg/g mercury level found in shoveler ducks collected in October 1987. A lesser, but still significant difference (p=0.08) was found between the shovelers collected in August 1989 and those collected in October 1989. The shovelers collected in October 1989 contained a mean of2.8 |ig/g, wet weight, mercury in muscle tissue. The significant difference (p=<0.05) found betweenthe 1987 andthe 1989 mercuryconcentrations in shovelers from Carson Lake may be related to wetland availability. In 1987, both the Island Unit and Sprig Pond in Carson Lake contained water, but in 1989 only Sprig Pond was flooded. Composite sediment data gathered by Hoffman and others (1990, p. 113) indicated that mercury was twice as abundant in the Island Unit (18 mg/kg) as in Sprig Pond (9 mg/kg). The time ofshoveler arrival and exposure (up to 8 weeks) was similar in both years.

66 Detailed Study of Irrigation Drainage Effect on BiotaCARSON LAKE

Oct. 1987
MUSCLE (10)
LIVER (10)
SKIN (2)

Aug. 1989
MUSCLE (10)

Oct. 1989
MUSCLE (10)

STILLWATER WMA

Oct. 1987
MUSCLE (12)
LIVER (9)
SKIN (2)

H MINIMUM-MAXIMUM

A MEAN

X MEDIAN

0 5 10 15

MERCURY, IN MICROGRAMS PER GRAM, WET WEIGHT

FIGURE 17. Concentrations of mercury in edible portions of shoveler ducks collected at Stillwater WMA and Carson Lake. Number of samples in parentheses. The action level is 1.0 microgram per gram, wet weight (U.S. Food and Drug Administration, 1984, p. 1). 20

Differences in mercury concentrations between duck species was apparent in October 1987, when the widest variety of species was collected (figs. 17 and 18). Shovelers from Carson Lake had the highest concentrations ofmercury, with all liver samples and 90 percent ofthe muscle samples exceeding the action level. Mercury concentrationsinmallardsfromCarson Lake exceeded the action level in 70 percent ofthe liver and 20 percent ofthe muscle samples. Mean and median mercury concentrations were below the action level in muscle tissue ofgreen-winged teal, redheads, and canvasbacks (fig. 18).

EDIBLE TISSUE OF WATERFOWL RJ. Hallockand others 67CARSON LAKE
MALLARD
October 1987
MUSCLE (10)
LIVER (10)
SKIN (2)

REDHEAD
October 1987
MUSCLE (3)
LIVER (3)
SKIN (2)
GREEN-WINGED TEAL

October 1989 MUSCLE (10)

STILLWATER WMA

MALLARD
October 1987 MUSCLE (10)
LIVER (10)
SKIN (2)

REDHEAD
October 1987
MUSCLE (10)
LIVER (10)
SKIN (2)

CANVASBACK
October 1987
MUSCLE (3)
LIVER (3) i I I I I

i \/ A i 1 Xak I

^



### i-X-A i

^

h->^4r< 1



### Y4 YA


# *

jfcj |1 MINIMUM-MAXIMUM

-^^ | A MEAN

*& X MEDIAN



### 1 11

01 234 5

MERCURY, IN MICROGRAMS PER GRAM, WET WEIGHT

Figure 18. Concentrations of mercury in edible portions of various duck species collected at Stillwater WMA and Carson Lake during the opening week of waterfowl season, October 1987. Number of samples in parentheses. The action level is 1.0 microgram per gram, wet weight (U.S. Food and Drug Administration, 1984, p. 15).



### Selenium Accumulation in Waterfowl
Although Hoffman and others (1990, p. 66-70) reported seleniumconcentrations muchhigherthan the action level of2.0 (ig/g, wet weight, in liver tissue of variousjuvenile migratory birds from the study area, less than 15 percent (8 of58) oflivers from various waterfowlcollectedinOctober 1987 fromCarsonLake and StillwaterWMA exceeded 2.0 (ig/g. However, withinthisdata set, 10 shovelerliverstakenon October 17,1987, contained a mean selenium concentration of 2.2 (ig/g and ranged from 0.8 to 3.8 (ig/g. Shovelers

are fall migrants believed to have been in these wetlands up to 6 weeks priorto collection. None ofthe muscle samples from these birds contained selenium concentrations above 2.0 (ig/g (Rowe andothers, 1991, p. 118-151).

68 Detailed Study of Irrigation Drainage Effect on BiotaFernley WMA could not be evaluated during the 1989 hunting season because it was dry by midOctober and, therefore, contained no ducks. However, during July 1988,juvenile cinnamon teal (Anas cyanoptera) and coots with mean selenium concentrations in livers of 8.4 and 8.6 (ig/g, wet weight, respectively,

were collectedfromFernleyWMA. Seleniumin livers of juvenile redhead ducks from Massie and Mahala Sloughs averaged 8.5 (ig/g and 3.7 (ig/g, wet weight, respectively, as reported in the preceding section on waterfowl production. In a study ofmallards, Heinz and others (1990, p. 374) found that after 81 days on a selenium-rich diet, concentrations ofselenium were slightly higher in muscle than in liver tissues. This suggeststhatby October, atthe start ofhunting season, ifthejuvenile ducks had remained in Fernley WMA and Massie Slough they might have had selenium concentrations in muscle that were higher than the concentrations found in July (>8.0 (ig/g), which was already more than four times the established humanhealth criteria. Differing lengths ofwaterfowl residence in the wetlands may accountfor some ofthe variability in the data fromthis study. Other importantfactors determining intake ofpotentially toxic constituents are dietary preferences and the specific wetlands selectedby birds.

EDIBLE TISSUE OF WATERFOWL RJ. Hallockandothers 69

# OVERALL SUMMARY OF EFFECT OF IRRIGATION DRAINAGE ON BIOTA

Important findings of the five biologically related study elements addressing possible adverse effects ofirrigation drainage on biota in and near StillwaterWMA are summarized here. The goal ofthe investigation was to (1) determine the effects ofirrigation drainage on migratory waterfowl that frequent these wetlands and (2) provide information for resource-management decisions and subsequent remediation strategies. Major findings ofthe studies, in order ofpresentation, are: Historical wetlands in Carson Lake, Stillwater Marsh, and Carson Sink averaged about 150,000 acres. Under the Operating Criteria and Procedures mandates, fully implemented in 1992, only about 10 percent, or 15,000 wetland acres, are projected to remain in nearly permanent impoundments. Average dissolved-solids concentration in drainwater entering these wetlands has increased about seven-fold from the estimated historical 170 mg/L to a current average of 1,170 mg/L. This increase in concentration has occurred largely through evapotranspiration associated with irrigated agriculture. Although the annual dissolved-solids load has decreased in these now-isolated wetlands, the increased concentrations have adversely affected the various plants, invertebrates, fish, and wildlife that were once abundant in the historical wetlands. During acute-toxicity tests, organisms in control water survived wide fluctuations in specific conductance that ranged from 410 to 27,500 |LlS/cm (252 to 17,900 mg/L dissolved solids). Organisms in undiluted drainwater samples subjected to similar fluctuations in dissolved-solids concentrations did not survive. Surface water from TJ and Hunter Drains and ground water from a shallow well near TJ Drain were acutely toxic to all test organisms. Analysis ofundiluted drainwater showed that four potentially toxic elements arsenic, boron, lithium, andmolybdenum were representative ofthe overall levels oftoxicity in the water tested. Strong, positive relations were foundbetweenthe aggregate ofarsenic,boron, lithium, and molybdenum and both daily and average dissolved-solids concentration. Thus, specific conductance may be a useful measure ofsurface-water quality for management of fish and invertebrate populations in StillwaterWMA.

Within drains, both mercury and selenium

are being bioaccumulated in plants and plant detritus and biomagnified in invertebrates by factors ofup to 10,000 times the concentrations measured in associated drainwater. Mercury and selenium are being transported in living organisms and their detritus. Transportis fromirrigated land, by way ofirrigation drains, to largewetlands wheremostmigratory birds, fish, and other wildlife are exposed to these elements.

Source areas ofmercury and selenium in the Newlands Irrigation Project area are areas generallyupgradientfrom sampling sites in drains where concentrations exceededconcern levels of 1.0 |Llg/g, dry weight, in detritus. Although selenium continues to be released from some irrigated soils more than 40 years after initiation ofirrigation, and is being carried by plants and invertebrates through the drains, no evidence was found to indicate a long-termbuildup ofseleniumin the sediment and biota ofdowngradient wetlands.

OVERALL SUMMARY 71Potential contaminant concentrations in

waterfowl eggs from the study sites were generallybelowpublishedeffect-level criteria and would not be expected to affect bird production. Consistent with these data, no teratogenesis was observed in embryos or hatchlings. The hatch rate ofwaterfowl eggs was normal, 90 percent or more, at both study and background sites.

Concentrations ofboron, mercury, and selenium at adverse effect levels were found injuvenile migratory birds from several study sites. Concentrations of selenium as high as 30 |ig/g were found in duck and coot livers from Fernley WMA and Massie Slough, and 77 |ig/g in black-necked stilt livers from Mahala Slough. Decreased survival and, thus, production may be expected among birds containing selenium concentrations in this range.

Nest success was poor throughout the study
areas, averaging only 26 percent. Loss of feeding habitat and nesting cover caused by drought, increased dissolved-solids concentrations, and predation are the primary reasons for reduced nest success. Thus, waterfowl production is now much reduced compared to historical conditions.

Shoveler ducks harvested by hunters from Carson Lake had accumulated mercury in muscles and livers, 5.9 and 17.8 times greater, respectively, on average, than the 1.0 |ig/g, wet weight, action level for human consumption. In response to the elevated mercury concentrations, the State ofNevadapostedhumanhealth warnings at Carson Lake specific to shoveler ducks.

Concentrations of selenium injuvenilewaterfowl livers from Fernley WMA and Massie Slough in July 1988 averaged more than 8.0 |ig/g, wet weight, or more than four times the 2.0 ^lg/g, wet weight, criterion for human consumption. Because ofdrought, no birds were present in these areas in October 1989 for collection and evaluation; thus, the potential for human-health concerns in these

areas could not be fully evaluated. 

# REFERENCES CITED

American Society for Testing Materials, 1988, Standard practice for conducting acute toxicity tests with fishes, macroinvertebrates, and amphibians: Philadelphia, ASTM Designation E 729-88, 20 p. Bailey, Vernon, 1898, Nevada: Carson Lake Valley (Wadsworth, Ragtown and Stillwater) Physiography: Unpublished manuscript, Smithsonian Institution Archives, Record Unit 7176, U.S. Fish and Wildlife Service, 1860-1961, Field Reports, Box 69, Folder 14, 3 p. Brown, W.M., Nowlin, J.O., Smith, L.H., and Flint, M.R., 1986, River quality assessment ofthe Truckee and Carson River system, California and Nevada Hydrologic characteristics: U.S. Geological Survey Open-File Report 84-576, 201 p. Burton, R.F, 1963, The City ofthe Saints and across the Rocky Mountains to California: New York, Alfred A. Knopf, Inc., facsimilie ofthe 1861 edition, 654 p. California Department ofWater Resources, 1991, Carson River atlas: Sacramento, Calif., State ofCalifornia, 126 p. Claassen, H.C., 1982, Guidelines and techniques for obtaining water samples that accurately represent the water chemistry ofan aquifer: U.S. Geological Survey Open-File Report 82-1024, 49 p. Cooper, J.J., Thomas, R.O., and Reed, S.M., 1985, Total mercury in sediment, water, and fishes in the Carson Riverdrainage, west-centralNevada: NevadaDivision ofEnvironmental Protection, Carson City, Nev., 96 p. DeQuille, Dan, 1963, Washoe rambles: Los Angeles, Westernlore Press, reproduction ofa series ofarticles published in 1861,169 p. Drews, M.P., 1988, Freshwater molluscs, in Raven, Christopher, and Elston, R.G., eds., Preliminary investigations in Stillwater Marsh Human prehistory and geoarchaeology: Portland, Oreg., U.S. Fish and Wildlife Service, p. 328-338. Dwyer, F.J., Burch, S.A., and Ingersoll, C.G., 1990, Investigation on the combined toxicity oftrace elements and salinity to aquatic organisms at Stillwater Wildlife ManagementArea: Columbia, Mo., U.S. Fish and Wildlife Service, Final Report, 47 p. Dwyer, F.J., Burch, S.A., Ingersoll, C.G., and Hunn, J.B., 1992, Toxicity oftrace elements and salinity mixtures to stripedbass (Morone saxatilis) and Daphniamagna: Environmental Toxicology and Chemistry, v. 11, p. 513-520. Eisler, Ronald, 1985, Selenium hazards to fish, wildlife, and invertebrates A synoptic review: U.S. Fish and Wildlife Service Biological Report 85 (1.5), 57 p.

72 Detailed Study of Irrigation Drainage Effect on Biota1987, Mercury hazards to fish, wildlife, and invertebrates A synoptic review: U.S. Fish and Wildlife Service Biological Report 85 (1.10), 90 p. 1990, Boron hazards to fish, wildlife and invertebrates A synoptic review: U.S. Fish and Wildlife Service Biological Report 85 (1.20), 32 p. Evans, C., 1983, Waterfowl nesting at Stillwater marsh in relation to predation and habitat factors affecting nest site selection: U.S. Fish and Wildlife Service, Unpublished Report, 45 p. Fan, A.M., Book, S.A., Neutra, R.R., and Epstein, D.M., 1988, Selenium and human health implications in California's San Joaquin Valley: Journal ofToxicology and Environmental Health, v. 23, p. 539-569. Finley, M.T., and Stendell, R.C., 1978, Survival and reproductive success ofblack ducks fed methyl mercury: Environmental Pollution, v. 16, p. 51-64. Frankenberger, W.T., and Thompson-Eagle, E.T., 1989, In situ volatilization ofselenium-II evaporation ponds, Executive Summary, San Joaquin Valley Drainage Program: Sacramento, Calif., U.S. Bureau ofReclamation, 6 p. Frisbie, H.R., LaCamera, R.J., Riek, M.M., and Wood D.B., 1984, Water-resources data for Nevada, Water Year 1983: U.S. Geological Survey Water-Data Report NV-83-l,328p. Gilliom, R.J., and others, 1989, Preliminary assessment of
sources, distribution, and mobility ofselenium in the SanJoaquinValley, California: U.S. Geological Survey Water-Resources Investigations Report 88-4186, 129 p. Glancy, P.A., and Katzer, T.L., 1976, Water-resources appraisal ofthe Carson River basin, western Nevada: Nevada Division ofWater Resources, Reconnaissance Report 59, 126 p. Greenspan, R.L., 1988, Fishremains, in Raven, Christopher, and Elston, R.G., eds., Preliminary investigations in Stillwater Marsh Human prehistory and geoarchaeology: Portland, Oreg., U.S. Fish and Wildlife Service, p. 312-326. Hart, R.A., and Bixby, F.L., 1922, Report ofreview of proposed drainage plans for the drainage ofa portion ofthe Newlands Irrigation District at Fallon, Nevada: U.S. Bureau ofReclamation, Smithsonian Institution, Unpublished Manuscript, 27 p. Heinz, G.H., 1979, Methylmercury Reproductive and behavioral effects on three generations ofmallard ducks: Journal ofWildlife Management, v. 43, no. 2, p. 394-401. Heinz, G.H., Hoffman, D.J., and Gold, L.G., 1988, Toxicity oforganic andinorganic seleniumtomallardducklings: Archives ofEnvironmental Contamination and Toxicology, v. 17, p. 561-568. 1989, Impairedreproduction ofmallards fed an organic form ofselenium: Journal ofWildlife Management,

v. 53, no. 2, p. 418-428. Heinz, G.H., Hoffman, D.J., Krynitsky, A.J., and Weller, D.M.G, 1987, Reproduction in mallards fed selenium: Environmental Toxicology and Chemistry, v. 6, p. 423-433. Heinz, G.H., Pendleton, G.W, Krynitsky, A.J., and Gold, L.G., 1990, Selenium accumulation and elimination in mallards: Archives ofEnvironmental Contamination and Toxicology, v. 19, p. 374-379. Henny, C.J., and Herron, G.B., 1989, DDE, selenium, mercury, and white-faced ibis reproduction at Carson Lake, Nevada: Journal ofWildlifeManagement, v. 53,

no. 4, p. 1032-1045. Hoffman, R.J., inpress, Detailed study ofirrigation drainage in and near Wildlife Management Areas, west-central Nevada, 1987-90. Part C Summary ofirrigationdrainage effects on waterquality, bottom sediment, and biota: U.S. Geological Survey Water-Resources Investigations Report 92-4024C. Hoffman, R.J., Hallock, R.J., Rowe, T.G.,Lico, M.S., Burge, H.L., and Thompson, S.P., 1990, Reconnaissance investigation ofwater quality, bottom sediment, and biota associated with irrigation drainage in and near StillwaterWildlife Management Area, Churchill County, Nevada 1986-87: U.S. Geological Survey Water-ResourcesInvestigationsReport 89-4105,150 p. Ingersoll, C.G., Dwyer, F.J., Burch, S.A., Nelson, M.K., Buckler, D.R., and Hunn, J.B., 1992, The use offreshwater and saltwater animals to distinguish between the toxic effects ofsalinity and contaminants in irrigation drain water: Environmental Toxicology and Chemistry,

v. 250, p. 503-511. Kelly, R.L., 1988, Archaeological context, in Raven, Christopher, andElston, R.G., 1988, Preliminary investigations in Stillwater Marsh Human prehistory and geoarchaeology: U.S. Fish andWildlife Service, v. 1, p. 5-20. Knapton, J.R., Jones, W.E., and Sutphin, J.W, 1988, Reconnaissance investigation ofwater quality, bottom sediment, andbiota associated with irrigation drainage in the Sun River area, west-central Montana, 1986-87: U.S. Geological Survey Water-Resources Investigations Report 87-4244, 78 p. Lambing, J.H., Jones, WE., and Sutphin, J.W, 1988, Reconnaissance investigation ofwater quality, bottom sediment, and biota associated with irrigation drainage in Bowdoin National Wildlife Refuge and adjacent

areas ofthe Milk Riverbasin, northeastern Montana, 1986-87: U.S. Geological Survey Water-Resources Investigations Report 87-4243, 71 p.

REFERENCES CITED 73Lemly, A.D., and Smith, G.J., 1987, Aquatic cycling of

selenium Implications forfish and wildlife: U.S. Fish and Wildlife Service leaflet 12, 10 p. Lico, M.S., 1992, Detailed study ofirrigation drainagein and

nearWildlifeManagementAreas, west-centralNevada, 1987-1990. Part A Water quality, sediment composition, and hydrogeochemical processes in Stillwater and Fernley Wildlife Management Areas: U.S. Geological Survey Water-Resources Investigations Report 92-4024A, 65 p. Long, E.R., and Morgan, L.G., 1990, The potential for biological effects ofsediment-sorbed contaminants tested in the National Status and Trends Program: National Oceanic and Atmospheric Administration Technical Memorandum NOSOMA 52, 175 p. Morrison, R.B., 1964, LakeLahontan Geology ofsouthern Carson Desert, Nevada: U.S. Geological Survey Professional Paper 401, 156 p. Napier, L.D., 1974, Report ofwildlife management study Duck nesting success on the Stillwater Marsh: Fallen, Nev., U.S. Fish andWildlife Service, Unpublished final report, 34 p. Ohlendorf, H.M., 1989, Bioaccumulation and effects of selenium in wildlife: Soil Science Society ofAmerica and American Society ofAgronomy, Special Publication no. 23, p. 133-177. Patuxent Wildlife Research Center, 1987, Effects of irrigation drainage contaminants on wildlife: Laural Md., U.S. Fish and Wildlife Service, Annual Report FY 1987, 31 p. Peden, M.E., 1986, Methods for collection and analysis of precipitation: Champaign, 111., Illinois State Water Survey, 260 p. Peterson, D.A., Jones, WE., and Morton, A.G., 1988, Reconnaissance investigation ofwater quality, bottom sediment, and biota associated with irrigation drainage in the Kendrick Reclamation Project area, Wyoming, 1986-87: U.S. Geological Survey Water-Resources Investigations Report 87-4255, 57 p. Presser, T.S., and Ohlendorf, H.M., 1987, Biogeochemical cycling ofselenium in the San Joaquin Valley, California, USA: Environmental Management, v. 11,

no. 6, p. 805-821. Pupacko, A., LaCamera, R.J., Riek, M.M., and Swartwood, J.R., 1989, water resources data, Nevada, water year 1988: U.S. Geological Survey Water-Datareport NV-88-l,265p. Radtke, D.B., Kepner, W.G., and Effertz, R.J., 1988, Reconnaissance investigation ofwater quality, bottom sediment, and biota associated with irrigation drainage in the Lower Colorado River Valley, Arizona, California, and Nevada, 1986-87: U.S. Geological Survey Water-Resources Investigations Report 88-4002, 77 p. Raven, Christopher, and Elston, R.G., 1988, Preliminary Investigations in Stillwater Marsh Human prehistory and geoarchaeology: U.S. Fish and Wildlife Service,

v. 1 and 2. 1989, Preliminary Investigations in Stillwater Marsh Human prehistory and geoarchaeology: U.S. Fish and Wildlife Service, v. 3. 1990, Preliminary Investigations in Stillwater Marsh Human prehistory and geoarchaeology: U.S. Fish and Wildlife Service, v. 4. Rowe, T.G., and Hoffman, R.J., 1990, Wildlife kills in the Carson Sink, western Nevada, winter of 1986-87, in Carr, I.E., Chase, E.B., and Paulson, R.W and Moody, D.W, comps., National water summary 1987 Hydrologic events and water supply and use: U.S. Geological Survey Water-Supply Paper 2350, p. 37-40. Rowe, T.G., Lico, M.S., Hallock, R.J., Maest, A.S., and Hoffman, R.J., 1991, Physical, chemical, andbiological data associated with irrigation drainage in and near Stillwater, Fernley, and Humboldt Wildlife Management Areas and Carson Lake, west-central Nevada, 1987-1989: U.S.Geological Survey Open-File Report 91-185, 199 p. Rush, F.E., 1968, Index ofhydrographic areas in Nevada: Nevada Division ofWater Resources Information Report 6, 38 p. Russell, I.C., 1885, Geological history ofLake Lahontan A Quaternary lake ofnorthwestern Nevada: U.S. Geological Survey Monograph 11, 288 p. 1895, Present and extinct lakes ofNevada: American Book Company, Reprinted by Nevada Historical Society, 1976, as Camp Nevada Monograph No. 3, 132 p. Schmitt, D.N., 1988, Mammalian fauna, in Raven, Christopher, and Elston, R.G., eds., Preliminary investigations in Stillwater Marsh Human prehistory and geoarchaeology: Portland, Oreg., U.S. Fish and Wildlife Service, v. 1, p. 262-290. Schroeder, R.A., Palawski, D.U., and Skorupa, J.P., 1988, Reconnaissance investigation ofwater quality, bottom sediment, and biota associated with irrigation drainage in the Tulare Lake Bed area, southern San Joaquin Valley, California, 1986-87: U.S. Geological Survey Water-Resources Investigations Report 88-4001, 86 p. Seiler, R.L., and Allander, K.K., in press, Water-level changes and directions ofground-water flow in the shallowaquifer,Fallenarea, ChurchillCounty,Nevada: U.S. Geological SurveyWater-Resources Investigation Report 93-4118. Setmire, J.G., Wolfe, J.C., and Stroud, R.K., 1990, Reconnaissance investigation ofwater quality, bottom sediment, and biota associated with irrigation drainage

74 Detailed Study of Irrigation Drainage Effect on Biotain the Salton Sea area, California, 1986-87: U.S. Geological Survey Water-Resources Investigations Report 89-4102, 68 p. Simpson, J.H., 1876, Report ofexplorations acrossthe Great Basin ofthe Territory ofUtah for a direct wagon-route from Camp Floydto Genoa, in Carson Valley, in 1859: U.S. Army Engineer Department; reprinted 1983 by University ofNevada Press, Reno, Nev., Vintage Nevada Series, 518 p. Smith, G., 1985, Thepaleontology ofHiddenCave Fish, in Thomas, D.H., ed., The archaeology ofHidden Cave, Nevada: Anthropological Papers ofthe American Museum ofNatural History, v. 61, no. 1, p. 171-178. Smith, G.H., 1943, The history ofthe Comstock Lode, 1850-1920; University ofNevada Bulletin, Geology and Mining Series no. 37, 305 p. Smith, G.J., and Anders, V.P, 1989, Toxic effects ofboron

on mallardreproduction: Environmental Toxicology and Chemistry, v. 8, p. 943-950. Spence, M.L., and Jackson, Donald, 1973, The expeditions ofJohn Charles Fremont: Chicago, University of Illinois Press, v. 2., 519 p. Sperry, C.C., 1929, Report on Carson Sink (Churchill Co.) Nevada Its duckfoodresources andvalueas aFederal Migratory Bird Refuge site: Smithsonian Institution Archives, Unpublished manuscript, 3 p. Stephens, D.W., Waddell, Bruce, and Miller, J.B., 1988, Reconnaissance investigation ofwater quality, bottom sediment, and biota associated with irrigation drainage in the Middle Green River basin, Utah, 1986-87: U.S. Geological Survey Water-Resources Investigations Report 88-4011, 70 p. Steward, A.N., Denis, L.J., and Gilkey, H.M., 1963, Aquatic plants ofthe Pacific Northwest with vegetative keys (2nd ed.): Corvallis, Oregon State University Press, 261 p. Stewart, R.E., and Kantrud, H.A., 1972, Vegetation ofprairie potholes, North Dakota, in relation to quality ofwater and other environmental factors: U.S. Geological Survey Professional Paper 585-D, 36 p. Taylor, R.E., 1972, The effects ofincreasing salinity on the Pyramid Lake fishery: Reno, University ofNevada, Agricultural Experiment Station Bulletin 15, 8 p. Tokunaga, Tetsu, and Benson, S.M., 1991, Evaluation ofmanagement options for disposal ofsalt and trace element laden agricultural drainage water from the Fallon Indian Reservation, Fallon, Nevada: Lawrence Berkeley Laboratory, under contract with U.S. Bureau ofReclamation, final report 165 p. U.S. Bureau ofReclamation, 1987, Fallon Indian Reservation water quality report: Sacramento, U.S. Bureau ofReclamation, 62 p., 3 appendices. U.S. Department oftheInterior, 1988, Final operating agreement and procedures, record ofdecision, Newlands Project, Nevada-California: Washington, D.C., 22 p., 5 appendices. U.S. Environmental Protection Agency, 1985, Methods for measuring the acute toxicity ofeffluents to freshwater and marine organisms (3d ed.): Cincinnati, Ohio, Environmental Monitoring and Support Laboratory, EPA/600/4-85/013, 216 p., 5 appendices. 1986, Quality criteria for water: Washington, D.C., U.S. Office ofWaterRegulations and Standards, Report EPA-440/5-86-001, [453 p.] U.S. Fish andWildlife Service, 1952, Narrative report, Stillwater Wildlife Management Area January-April 1952: Fallon, Nev., U.S. Fish and Wildlife Service, unpublished report, 33 p. 1969, Refuge narrative report: Fallon, Nev., U.S. Fish and Wildlife Service, unpublished report, 42 p. 1985, Procedures forresource contaminant assessment contract analytical work: Washington D.C., Habitat Resources Instructional Memorandum, 203 p. 1988, Record ofdecision, draft wetlands analysis Newlands Project operating criteria and procedures: Fallon, Nev., U.S. Fish andWildlife Service, 141 p. U.S. Food and Drug Administration, 1984, Compliance policy guide for methyl mercury in fish: Report 7108.07, Federal Register, v. 49, no. 45663, 1 p. U.S. Geological Survey, 1978, Waterresources data, Nevada, Water Year 1977: U.S. Geological Survey Water Data Report NV-77-1, 334 p. Van Denburgh, A.S., andArteaga, F.E., 1985, Revised water budget for the Fernley area, west-central Nevada: U.S. Geological Survey Open-File Report 84-712, 17 p. Warburton, J.A., and others, 1990, Studies ofclimatic variations and their impact in the Great Basin: Final report on Contract NA 87AA-D-CP114 by Desert Research Institute, Reno, Nev., for National Oceanic and Atmospheric Administration, 94 p. Wells, F.C., Jackson, G.A., and Rogers, W.J., 1988, Reconnaissance investigation ofwater quality, bottom sediment, and biota associated with irrigation drainage in the Lower Rio Grande Valley and Laguna Atascosa National Wildlife Refuge, Texas, 1986-87: U.S. Geological Survey Water-Resources Investigations Report 87-4277, 89 p. Wershaw, R.L., Fishman, M.J., Grabbe, R.R., and Lowe, L.E., eds., 1987, Methods for determination oforganic substances in water and fluvial sediments: U.S. Geological Survey Techniques ofWater-Resources Investigations, Book 5, Chapter A3, 80 p. Westerkov, K., 1950, Methods for determining the age of gamebirdeggs: Journal ofWildlifeManagement, v. 14, p. 56-61.

REFERENCES CITED 75

# SUPPLEMENTAL WATER-QUALITY DATA

FROM TOXICITY STUDY

SUPPLEMENTAL WATER-QUALITY DATA FROM TOXICITY STUDY 77Table 23. Water-quality measurements for daily composite water samples from Paiute Diversion Drain, August 1988

[Concentrations in milligrams per liter except as indicated. All mercury concentrations were below analytical reporting limit. Abbreviations: ug/L, micrograms per liter; uS/cm, microsiemens per centimeter at 25°C; NTU, Nephelometric turbidity units; ppt, parts perthousand.]

Date

August 10 11 12 13 14 15 16 17 18

Date
August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18 Specific conductance (uS/cm)

420 370 480 390 400 400 400 383 430

Hardness

120 110 130 120 130 140 130 130 130
Salinity (ppt)

0.2 .2 .3 .2 .1 .1 .1 .1 .2

Lithium

0.06 .05 .06 .06 .06 .06 .06 .06 .06 Field

PH

7.5 8.4 8.3 8.0 8.3 8.5 8.5 8.6 8.6

Sodium

72 62 84 68 75 79 72 82 73

Nitrate asN

<0.01

<.01

<.01

Molybdenum

0.02 <.02 .02 <.02 .02 .02 <.02 <.02 .02 Onsite

mobile lab PH

8.2 8.2 8.4 8.3 8.1 8.4 8.5 8.6 8.6

Potassium

3.8 2.8 3.9 4.9 5.4 5.3 4.4 4.7 3.9

Ammonia asN

0.16

.06

.04

Selenium (H9/L)

<0.3 .3 .3 .3 .3 .3 .3 .3 .3 Turbidity

(NTU)

31 35 33 32 16 15 25 20 18
Alkalinity

142 111 146 133 138 145 158 135 157

Phosphorus

0.1 <.l .1 .1 .1 .1 .1 .2 <.l

Strontium

0.37 .35 .40 .37 .40 .41 .38 .41 .40 Dissolved

oxygen

6.8 8.9 7.7 7.3 9.7 8.9 8.8 9.0 8.7

Sulfate

85 68 64 60 72 72 52 52 60

Arsenic

0.01 .02 .02 .02 .02 .02 .02 .02 .02

Vanadium

0.01 .01 .01 .01 .01 .01 .01 .01 .01 Calcium

33 31 35 33 35 36 35 35 36

Chloride

63 58 50 55 60 60 65 70 65

Barium

0.08 .08 .08 .08 .09 .08 .07 .07 .08

Zinc

0.07 .03 .03 .05 .04 .05 .03 .02 .03 Magnesium

11 10 12 11 12 12 11 13 11

Silica

5.8 6.3 7.0 6.7 6.6 6.9 6.8 7.2 6.6

Boron

0.58 .52 .76 .58 .60 .63 .60 .55 .61

78 Detailed Study of Irrigation Drainage Effect on BiotaTable 24. Water-quality measurements for daily composite water samples from TJ Drain, August 1988

[Concentrations in milligrams per literexcept as indicated. All mercury concentrations were below analytical reporting limit. Abbreviations: ug/L, micrograms per liter; uS/cm, microsiemens per centimeter at 25°C; NTU, Nephelometric turbidity units; ppt, parts perthousand.]

Date

August 10 11 12 13 14 15 16 17 18

Date
August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18 Specific conductance (uS/cm)
8,100 12,000 11,800 14,900 11,000 6,100 7,200 13,700 14,300

Hardness
1,300 1,900 2,000 2,500 1,800 1,100 1,300 1,900 1,700
Salinity (ppt)

6.5 10.0 10.0 13.0 9.2 5.0 4.1 8.9 9.2

Lithium

0.40 .62 .57 .76 .55 .34 .38 .67 .46 Field

PH

8.5 8.5 8.6 8.5 8.6 8.4 8.4 8.5 8.6

Sodium
2,000 3,500 3,300 4,700 3,400 1,900 1,900 4,000 2,900

Nitrate asN

<0.01

<01

<01

Molybdenum

0.32 .54 .45 .67 .45 .27 .38 .67 .46 Onsite mobile lab PH

8.5 9.0 8.5 8.3 8.4 8.1 8.3 8.4 8.4

Potassium

29 42 40 57 43 29 29 50 39

Ammonia asN

0.11

.02

.16

Selenium (H9/L)

1.2 1.3 1.2 1.6 1.1 1.1 .9 1.3 1.5 Turbidity

(NTU)

2 3 2 3 2 4 4 3 8
Alkalinity

232 289 263 319 276 224 217 292 244

Phosphorus

0.7 1.0 .8 1.0 .8 .4 .4 1.0 .8

Strontium

4.0 6.2 5.8 7.9 5.7 3.2 3.5 7.0 4.9 Dissolved

oxygen

7.4 8.4 8.7 8.7 9.2 8.3 8.9 8.7 10.9

Sulfate
1,400 2,900 2,900 3,600 1,600 880 1,500 1,600 1,600

Arsenic

0.11 .13 .12 .17 .15 .13 .11 .14 .12

Vanadium

0.02 .02 .02 .02 .02 .02 .01 .02 .02 Calcium

180 260 240 310 230 140 160 290 210

Chloride
2,700 4,800 4,900 6,200 4,700 3,800 5,800 4,900 4,800

Barium

0.08 .11 .11 .10 .07 .05 .05 .11 .08

Zinc

0.05 .07 .09 .01 .03 .02 .02 .02 .02 Magnesium

200 320 300 410 290 160 180 360 250

Silica

2.1 .9 2.0 .6 .1 3.7 2.9 .8 3.8

Boron

7.8 13 12 17 12 6.8 6.8 14 10

SUPPLEMENTAL WATER-QUALITY DATA FROM TOXICITY STUDY 79Table 25. Water-quality measurements for daily composite water samples from D-Line Canal, August 1988

[Concentrations in milligrams per liter except as indicated. All mercury concentrations were below analytical reporting limit. Abbreviations: ug/L, micrograms per liter; jiS/cm, microsiemens per centimeter at 25°C; NTU, Nephelometric turbidity units; ppt, parts per thousand.]

Date

August 10 11 12 13 14 15 16 17 18

Date
August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18 Specific conductance (uS/cm)

600 490 610 400 425 380 350 445 470

Hardness

94 100 110 100 120 110 98 130 110
Salinity (ppt)

0.5 .4 .5 .0 .2 .1 .0 .0 .1

Lithium

0.06 .06 .06 .06 .06 .05 .05 .05 .05 Field

PH

8.6 9.3 9.2 9.2 9.2 9.0 9.0 8.7 9.4

Sodium

110 110 100 97 110 84 87 96 83

Nitrate asN

<0.01

.01

.01

Molybdenum

0.02 .02 .02 .02 .02 .02 .02 .02 <.02 Onsite

mobile lab PH

8.7 9.0 9.0 9.0 8.9 8.1 9.1 8.7 9.3

Potassium

9.4 8.6 8.3 8.2 8.4 6.3 6.2 5.4 6.5

Ammonia asN

0.10

.04

.05

Selenium (H9/L)

0.3 .3 .3 .3 .3 .3 .3 .3 .3 Turbidity

(NTU)

4 5 4 3 4 3 6 9 9 Alkalinity

149 156 165 155 157 135 125 174 113

Phosphorus

<0.1 <.l <.l <.l <.l <.l <.l <.l <.l

Strontium

0.37 .34 .36 .34 .37 .34 .34 .36 .34 Dissolved

oxygen

9.2 10.0 9.5 9.2 10.3 9.8 10.0 9.0 9.9

Sulfate

110 110 60 56 130 68 47 100 48

Arsenic

0.05 .05 .05 .05 .04 .04 .04 .05 .04

Vanadium

0.02 .02 .02 .02 .02 .01 .01 .01 .02 Calcium

30 26 28 26 29 28 27 32 30

Chloride

50 12 50 43 47 40 36 45 45

Barium

0.06 .05 .05 .04 .04 .05 .05 .05 .05

Zinc

0.03 .01 .01 .01 .01 .01 .01 .04 .02 Magnesium

11 11 11 10 11 10 10 10 9

Silica

6.9 7.0 6.6 5.9 5.9 6.0 7.2 7.3 7.6

Boron

0.76 .78 .74 .79 .81 .70 .77 .75 .62

80 Detailed Study of Irrigation Drainage Effect on BiotaTable 26. Water-quality measurements for daily instantaneous water samples from Lead Lake, August 1988

[Concentrations in milligrams per liter except as indicated. All mercury concentrations were below analytical reporting limit. Abbreviations: ug/L, micrograms per liter; uS/cm, microsiemens per centimeter at 25°C; NTU, Nephelometric turbidity units; ppt, parts per thousand.]

Date

August 10 11 12 13 14 15 16 17 18

Date
August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18 Specific conductance (uS/cm)
6,100 6,000 5,900 5,300 5,600 5,100 5,300 5,900 5,300

Hardness

580 570 630 580 600 600 610 640 680
Salinity (PPt)

3.5 3.5 3.8 3.2 3.5 4.2 3.1 3.5 3.3

Lithium

0.36 .36 .37 .34 .37 .34 .36 .39 .34 Field

PH

8.9 8.8 8.9 8.8 8.6 8.9 8.9 8.9 8.9

Sodium
1,000 1,000 1,100 1,000 1,100 980 1,000 1,100 1,100

Nitrate asN

<0.01

.01

.05

Molybdenum

0.11 .11 .12 .11 .12 .11 .11 .12 .13 Onsite

mobile lab PH

8.8 9.2 8.9 8.8 8.8 8.8 8.9 9.0 8.9

Potassium

32 32 33 31 33 30 31 33 29

Ammonia asN

0.14

.14

.24

Selenium 

### fog/i.)

0.3 .3 .3 .3 .3 .3 .3 .3 .3 Turbidity

(NTU)

62 96 59 63 53 37 53 50 43
Alkalinity

227 272 257 266 256 249 258 258 227

Phosphorus

0.2 .2 .2 .2 .2 .2 .2 .4 .2

Strontium

1.9 1.9 1.9 1.8 1.9 1.8 1.8 2.0 2.0 Dissolved

oxygen

9.2 7.2 6.8 5.6 7.1 5.7 6.9 8.5 8.6

Sulfate

430 600 680 400 520 470 360 410 560

Arsenic

0.12 .12 .13 .11 .11 .10 .11 .11 .10

Vanadium

0.02 .02 .02 .02 .02 .02 .02 .02 .02 Calcium

67 69 71 65 68 64 67 68 74

Chloride
1,300 1,400 1,200 1,700 1,400 1,300 1,800 1,800 1,800

Barium

0.14 .13 .13 .12 .13 .12 .13 .13 .11

Zinc

0.02 .04 .01 .02 .02 .02 .02 .04 .02 Magnesium

96 97 100 92 98 90 96 103 103

Silica

6.9 7.5 6.9 6.8 6.8 6.3 6.4 7.3 5.1

Boron

6.0 5.4 5.6 5.2 5.5 5.0 5.3 5.7 5.4

SUPPLEMENTAL WATER-QUALITY DATA FROM TOXICITY STUDY 81Table 27. Water-quality measurements for daily composite water samples from Hunter Drain, August 1988

[Concentrations in milligrams per literexcept as indicated. All mercury concentrations were below analytical reporting limit. Abbreviations: H-g/L, micrograms per liter; ^.S/cm, microsiemens per centimeter at 25°C; NTU, Nephelometric turbidity units; ppt, parts perthousand.]

Date

August 10 11 12 13 14 15 16 17 18

Date
August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18 Specific conductance (nS/cm)
12,000 13,900 27,500 22,000 25,000 8,000 410 600 1,200

Hardness

860 1,100 2,300 1,800 200 660 110 140 170
Salinity (ppt)

9.5 12 28 18 23 7.0 .0 1.0 1.0

Lithium

1.0 1.2 2.0 2.2 2.3 .86 .06 .08 .08 Field

PH

8.3 8.4 8.5 8.8 8.7 8.7 8.0 8.3 8.2

Sodium
3,600 4,500 7,600 8,200 8,600 3,200 98 180 200

Nitrate asN

<0.01

.04

.05

Molybdenum

0.46 .59 1.1 1.2 1.3 .47 .02 .04 .06 Onsite

mobile lab PH

8.2 8.9 8.4 8.7 8.5 8.6 8.0 8.2 8.3

Potassium

89 110 180 200 210 76 4.8 4.9 4

Ammonia asN

0.30

.10

.15

Selenium (^9/L)

2.2 2.3 2.1 3.5 3.6 2.1 <.3 <.4 .4 Turbidity

(NTU)

14 7 37 13 8 14 19 14 10
Alkalinity

223 250 242 255 276 179 255 124 102

Phosphorus

0.6 .6 .6 .8 .9 .6 <.l <.l <.l

Strontium

5.0 6.0 9.6 10.2 10.4 4.1 .39 .51 .89 Dissolved

oxygen

7.0 6.2 7.4 6.3 5.6 7.5 8.2 8.4 8.8

Sulfate
1,200 1,300 2,000 2,900 2,900 1,200 52 130 200

Arsenic

0.06 .07 .11 .17 .19 .06 .02 .02 .03

Vanadium

0.02 .02 .02 .03 .02 .02 .01 .01 .02 Calcium

190 220 350 380 390 160 32 35 38

Chloride
4,200 7,000 11,000 10,000 13,000 3,700 84 190 310

Barium

0.10 .09 .10 .09 .09 .07 .08 .05 .05

Zinc

0.09 .06 .01 .06 .01 .08 .02 .02 .02 Magnesium

100 130 230 240 250 100 10 13 15

Silica

5.0 13 14 13 14 9.0 7.6 6.8 6.8

Boron

20 25 43 46 49 18.81 1.3 1.2

82 Detailed Study of Irrigation Drainage Effect on BiotaTable 28. Water-quality measurements for daily composite water samples from Stillwater Point Diversion Drain,

August 1988

[Concentrations in milligrams per liter except as indicated. All mercury concentrations were below analytical reporting limit. Abbreviations: |4.g/L, micrograms per liter; |4.S/cm, microsiemens per centimeter at 25°C; NTU, Nephelometric turbidity units; ppt, parts per thousand.]

Date

August 10 11 12 13 14 15 16 17 18

Date
August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18 Specific conductance (|xS/cm)

700 550 620 710 470 520 510 580 720

Hardness

140 200 150 150 150 150 140 160 160
Salinity (PPt)

0.5 .5 .5 .8 .5 .2 .2 .2 .4

Lithium

0.06 .07 .06 .10 .06 .06 .06 .06 .07 Field

PH

8.4 8.5 8.3 8.4 8.2 8.3 8.4 8.6 8.5

Sodium

140 150 130 270 120 140 120 120 160

Nitrate asN

<0.01

.05

.04

Molybdenum

0.03 .03 .03 .05 .03 .03 .03 .03 .04 Onsite mobile lab pH

8.4 8.3 8.4 8.4 8.4 8.3 8.4 8.4 8.5

Potassium

8.8 8.8 8.6 13 8.6 7.9 7.7 7.3 8.6

Ammonia asN

0.21

.50

.44

Selenium (^9/L)

0.4 .5 <.4 .6 .5 <.4 .5 <.4 .4 Turbidity

(NTU)

39 36 35 32 54 25 37 23 21
Alkalinity

234 227 114 312 211 210 210 221 245

Phosphorus

0.2 .2 .3 .3 .2 .2 .2 .2 .2

Strontium

0.52 .51 .48 .67 .46 .47 .45 .46 .52 Dissolved

oxygen

9.0 8.5 8.4 8.3 8.9 8.7 8.9 9.6 8.4

Sulfate

130 140 120 110 110 120 140 150 140

Arsenic

0.05 .05 .04 .04 .04 .04 .04 .04 .05

Vanadium

0.02 .02 .02 .02 .02 .02 .02 .02 .02 Calcium

48 47 45 51 43 42 43 44 47

Chloride

60 63 63 58 50 55 55 43 48

Barium

0.07 .07 .07 .06 .07 .07 .07 .07 .07

Zinc

0.04 .06 .05 .10 .04 .06 .07 .04 .04 Magnesium

14 14 13 18 12 13 12 13 14

Silica

13 14 12 12 12 11 12 12 13

Boron

0.99 1.2 1.1 1.8 .86 .99 .88 .91 1.1

SUPPLEMENTAL WATER-QUALITY DATA FROM TOXICITY STUDY 83Table 29. Water-quality measurements for daily instantaneous water samples from Stillwater Point Reservoir,

August 1988

[Concentrations in milligrams perliter except as indicated. All mercury concentrations were below analytical reporting limit. Abbreviations: Ug/L, micrograms per liter; ^iS/cm, microsiemens per centimeter at 25°C; NTU, Nephelometric turbidity units; ppt, parts perthousand.]

Date

August 10 11 12 13 14 15 16 17 18

Date
August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18

Date

August 10 11 12 13 14 15 16 17 18 Specific conductance (uS/cm)
2,510 1,950 1,710 2,270 2,000 2,210 1,590 1,720 2,020

Hardness

160 160 160 150 170 140 170 160 130
Salinity (PPt)

1.7 1.2 1.3 1.5 1.2 1.9 .9 1.1 1.2

Lithium

0.11 .12 .10 .13 .12 .13 .10 .11 .13 Field

PH

9.1 9.0 9.1 9.1 9.1 9.2 9.1 9.0 9.2

Sodium

360 480 310 440 410 460 310 340 420

Nitrate asN

<0.01

.01

<.01

Molybdenum

0.05 .07 .05 .06 .06 .07 .05 .05 .06 Onsite

mobile lab PH

8.9 9.0 9.1 9.1 9.0 9.1 9.1 9.1 9.2

Potassium

17 21 15 19 18 20 15 15 18

Ammonia asN

0.15

.18

.18

Selenium (H9/L)

0.5 .6 .6 .4 .4 .5 .6 .5 .4 Turbidity

(NTU)

410 580 390 280 200 260 190 240 170
Alkalinity

261 263 289 298 300 292 291 292 235

Phosphorus

<0.1 <.l <.l <.l <.l <.l <.l <.l <.l

Strontium

0.57 .55 .54 .54 .55 .52 .54 .53 .57 Dissolved

oxygen

8.8 8.9 8.2 8.3 8.3 8.2 8.8 8.4 10.2

Sulfate

120 240 150 180 140 190 100 190 190

Arsenic

0.09 .11 .08 .11 .10 .11 .08 .09 .10

Vanadium

0.03 .03 .03 .03 .03 .03 .02 .02 .03 Calcium

35 24 35 26 30 22 36 31 28

Chloride

300 310 310 550 380 480 480 410 450

Barium

0.10 .11 .11 .10 .10 .09 .09 .09 .12

Zinc

0.01 .01 .05 .02 .01 .01 .01 .02 .02 Magnesium

18 20 16 18 18 18 16 17 21

Silica

11 11 12 10 10 10 10 11 11

Boron

2.2 3.0 2.3 2.9 2.6 2.9 2.0 2.2 2.7

84 Detailed Study of Irrigation Drainage Effect on Biota