Historical Review of Avian Botulism at Stillwater

HISTORICAL REVIEW OF AVIAN BOTULISM AT STILLWATER WILDLIFE MANAGEMENT AREA 1949-1985 regular- monthly, meetine Mondavi .IV ; one which Included '•' The report describes- other "tracts pi", 'land : on " the Newlands project . Doriner; Jake.s at 10,000 : acres oi .bought ^severaK; FALLON STANDARD which, "It :isv.said,f mlghtJvbeXput-- to claimed .in the Still-' Tru'ckeeârsdn/i "use 1 or'war-time food production. ! : OCTOBER 6, 1943., i6rth oi the Indian 'and ;,the; Sierra .: ; • ^The AOCâcres'^f "idle/ or;fallo'k eh, led ;.to; plans foii ;p" any; !o; provide 1 arid Irrigating;; by lands " .; Tepbrted : ; on ; the-- -•: Newlands . 6r/;-^;^ V.^K\;:v!:v.' project," -the rfeport^cpntlnuesyr in- 1,000 -acresj- ^<>fef allow. purchase was foi- 'ere made; [through of; the •Truckee ' chamber- of ^ conv I . modeled/ wheat lands which are :: thrown out rf the" University of m^rce Jin;; protest, against lowering ' rricultural Êxpert- of = cultivation ; one s year 'In.'twtf'/or the,;!ake-level. • dMhe'~>AgWcultural; three ;tQ;'.restbre ?{hev/structure^ of: puddled'soils; type";bfviand.:ls announced e, :' agencies:;: of ; the sometimes f rpnv ., the .: Fallon:. office; of the' irriga- nistratipn;. andi'the1 tion;; district that the lowered level of : of: Agriculture. > ins tead' ; of 'f alloêd^. with; about .the ; the. lake would'oocur .diiring;the^nbrK s£tme' effect;. upori/:rthe::osuaieeding; vacation Reason ; and that eyen5"theh wheat crop; ""More bi:this;.;.would b^] the, vscenic ; beauty , of the place would dorie^lf ':m6re'. of " the wheat; 1 'arniers i for reclaiming; the nQîSUffer; the Truckee -chamber car-: tie; Indian-reserva- kept livestock. If farmers were fur- rushed, clover : seed .for -the fallow ied-_lts,;iase.to the. California oham-! /ored^;byVthe' local ber of commerce. : Aiineeting -:was acreage /they.;; would! probably "plant ; board; -As'i' a mat- held, by. that larger.: group some two irectors here^ have it and : later, find livestock" to., con- sume iC;; ;;.:• ;?n::;;::^;i;;;;^>:- .••.:';:?.c:.,i'^.^; '•'•••• .weeks ago, when the federal fish and vay to bring this wild' life. , ;,seryice / were-: represented, The balance.: of f allow/- landi In tion for some four also, -the California : fish and game this: valley is mostly second /class -V ;.;.;: ;*;:<-/V - : -r. • • '"•' •':•" commission, .•-..;. ;..;,;•'. -.,••. •.:,";v ...;/..;... ; ardman-Clark por- land formerly in alfalfa where the stand has been lost. It has not been Wallace's report to the board Mon- says:";. ,. ;"-'::. -y reseeded to alfalfa because of the day included avstatement that, an i of the Indian res- low, 'productivity of the land, the excavating machine and crew, had e most frequently been sent to the lake to handle the are development. scarcity of: labor and machinery, excavating. .• :,'.-V-. / .-• •.-.•••- .. - this tract is about and the probability of but . a short- lived stand of alfalfa. Some of this TO HOLD CCC CAMP BUILDINGS 1 Rev. J. J. krimmer, pastor 'of ' al estimates have . the Full Gospel Mission church. : ) Probably half land is pastured but the carrying The larger of the buildings at the HTS •ropped each year capacity is- low. • .' CCC Camp Carson river, which have IE , without getting SUOGESTS PASTURES been turned over to the irrigation Duck Botulism NbtS and We. . "Probably the highest adaptability district and to Churchill county, are star larg VG NEEDED of most of this land is for improved to be kept intact until it is deter- Carried to Humans, pasture grasses and legumes. Such mined if they may be of use as Will for ' this land is use would also, in most cases, im- sleeping quarters for workmen or whe y or other small prove the organization of most of others employed in connection with Says U.S. Bureau now 'ould require very the farms having this type of land. the U. S. navy project at the Fallon held 'f leveling and ir- There has been a well developed airport. ^ ; ..... Many Express Concern': schc It has never been trend in this direction but it might It was announced that the irriga- over Disease in Small ed v /ation because of be accelerated to good advantage." tion district directors had decided In •d. It has a very not to dispose of these buildings at Area North of Fallon :;:^: mov- ieep drainage by this time, also that the county com- Brie; . be of doubtful missioners had agreed to a similar Humans cannot contract " that 3roa .tion of crops to Local Tax Rate procedure. * ... form of botulism which has been Sunc ~egulation of irri- Half of the smaller buildings un- killing numerous ducks in the Peli- time ably prevent the Lowest in Years der ownership of the irrigation dis- can island area north of Fallon, ac- ty.th dnage difficulties trict are to be sold. Bids are to be cording to the U. S. fish and wild Janu Free use of the - Churchill county and the city of received by the board, and the bids life service. , ...... " lar nd guarantee of Fallon have the lowest tax rate in are to be opened October 18. State Game Warden Vernon Mills le v ome equipment more than a quarter of a century. Many inquiries have been received and Ray Alcorn have received many Kasp t inducement to Since the state tax commission at the district office from persons inquiries since it was announced a and it of this tract." recently fixed the final 1943 levy, who would buy this material. week ago that this disease had af- Pa; the new total, including state, flicted the birds in a shallow-water an a county, Consolidated B school dis- portion of the swamplands nearby. lime ied a section on trict and the city of Fallon combine Concerned hunters and others had ivas Lahontan bench to make a rate of $3.03 on the $100 Greenhead Annual suggested that the area be roped off and p e south bank of of valuation. It has not been many to prevent hunters from entering engag leiow Lahontan years ago that the boards for all HMtisOct.24 and carrying the disease to humans. sever; ind Clark's esti- four political subdivisions got into The types C and D botulism, The 1 of 5,500 to 6,800 an annual huddle to keep the rate Sunday, October 24 was the date which thrives during warm autumn was h able, as has been below the legal limit of $5. set for the opening shoot of the weather where there is decaying not b "probably 3,000 The final rate fixed for the county 'Greenhead club this year, with Leo vegetable and animal matter, is not :owns maximum which is $1.85. That for the state is 58 Likes and Lyle Beeghly as captains the type which appears in impropei--. Sue iltivation in 1945 cents and the city of Fallon rate is of the teams. The gates to the pas- ly processed canned foods, according Rev. 3 ling costs. This 60 cents, this being levied for little ture .will be open at 4 a. m. to the authorities. The C and D bo- who lands . . . which other than bond interest and , re- - The banquet will take place at the tulism has been known frequently Durin d for settlement demption. The city is largely sup- Sagebrush on 'Saturday evening for. many years in shallow r water churc: the limitey supported by profits from its power October 30 with Francis Wildes, areas, but its appearance heretofore South nch lands in late and water distribution systems. / Merritt Yeoman and William Foster has not been so marked as around Charli J. C. Allard, chief clerk and statis- in charge. All ducks will be left at Pelican island. and a short distance were the Sagebrush as formerly. ••••.; east. It is not affecting ducks iii Strasc reason that, this tician for the state tax commission, the Carson lake pasture district nor that It •et with favor of based the, lowered rate for .the in other more popular hunting nation s. Water can be county on a somewhat higher valua- grounds, according .to Mills. -;-r ^ ial.sp gravity through tion to approximately $8,923,485.' - Verl Hendrix Goes Technical bulletin No. 411 of the able r. from 'the lower fish and wild live service is quoted precfa canal at Lahon- Message Comes Through toEF.A.Meet to show that humans are in no dan- churcl and underneath ger of this type of botulism: ;;^^ The south bank. Japanese Red Cross Verl Hendrix, who holds the high ."There has been .no instance pf next p ind Clark indi- A message from friends of the K^ position of secretary In the national human beings contracting botulism long* 1 a. water supply Ito family of St. Clair district came organization of Future Farmers of through eating- flesh ''of bird church Dns at Boca and last week through the Japanese Red America, left yesterday morning for victims of duck sickness. In view step o rights, the atti- Kansas City to attend the annual of the fact that in the days of mar- the coi rs here is that Cross at Tokyo to T. V. Conner, convention. - ket hunting in California, it was streets may not be in chairman of the local Red Cross.' Last week from Sunday to Thurs- common knowledge that unscrupu- home. •ing a series of The message which came'through day he was a guest at the annual lous hunters made it a practice to . 'Mr. Geneva, Switzerland was dated Jan- meeting of the California F.F.A. at have 1 was experienced uary 6, 1943 and was from the town gather birds affected with of recent decade ago. The Fresno. . . v ly dying from the disease, fired lea< ing, w. on this project of Aichiken, Japan. It contained an Verl is the son of Mr. and Mrs. shot into their bodies and offeree church inquiry .as to the well being of the Thora Hendrix of Harmon district. them for sale. There is no qusetlon spiritu for delivery of Itos. .:... that- ducks so .affected have been preciat ench was by an An answer from them to Japan eaten by human beings. ; friends •ral with Lahon- saying they were well and at the Third Birthday of W.S.C.S. Fallon. not be in oper- same address'returned by the local chairman.. The third anniversary of the W. Attends Brothers' Funeral; CHABr ay be incapable Mr. Conner said that the Itos and S. C. S. will be celebrated this after- Mrs. J. F. Bowman attended the operating con- Kitos had been generous corrtribu noon at the regular social meeting funeral of her brother . Gordon of the e a woodstave tors to the local Red Cross chapter of the group at the Methodisl Campbell in Lodi on Sunday. He had Mrs. feet long across church. Mrs. C. B. Likes is to have lived 'in California lor forty .or Gumm, i might be re- There are eighteen species of toa( the lesson and Mrs. W. P. Clark more years and had visited his sis- Render native to- this country. . [. is chairman of ;the refreshments. ter many, times In Fallon, the last ALFALFA" The organization Is planning a time in December. He Is survived fey Heath, nitely • excellent Dinosaurs reached a length; b; holiday bazaar to "be held early In a wife and family.^ •• - • 'f Okhota t be adapted to seventy* Jeet. ., .•-•• -,•''-.'•' December.1.- ;•>'.:.-*< :-?L':.^''."'J-^*; "V-. :- •-. •;-.'.*-•*": -.1. " -, .". r •.-••/ '•.-..: - • . '•- - ".-v> . FALLON STANDARD , .-; •-.. • -V.V -.,•:>• *~ -> •: •••». '..-i' .-•••-.-• '-. ••• " ' .. . .Yv.-V^ 'f '•'"••'• .^'•V-r-VV: ••;-;:. : '' ----.-,. ' SEPTEMBER 29, 1943 • ' • • ;,-;.,;:,;.:;. .-••;;••'"•'-' ...... , '•'•. \••• '•...; -i ;.-.:,. \ :. ." . •'-•: : '\ • •'••"- - ' ' :J"

'Churchill County's Pioneer Newspaper

FALLQN, NEVADA, WEDNESDAY, SEPTEMBER 29, 1943 Substitute for HeU Ducks Plentiful War Pi Around Fallen Reclaii Despite Disease Largest Hatch in Years Prominent Coi Reported; Early Flights Married in Rei from North Are Heavy A wedding of much Fallon people took pla There will be an abundance of o'clock Sunday evening in ducks in the sloughs and swamps principals' were Miss Haz surrounding Fallon despite the out- attractive daughter of M: break of a type of botulism in the Paul Pruder and E. J. I* shallows of\he Pelican island area prominent business man reported last'week by Vernon L-. mony was performed Mills, state game warden who was Brewster Adams at his h accompanied on his survey by Ray presence of Miss Lois IV Alcorn. ter of the bridegroom, Thousands of birds were estimat- Johannesen, cousin of thi ed dead in a portion of the Carson M. Armanko of Reno. sink area from Pelican island east- A wedding dinner folio ward a few miles. Colombo and the coupL Alcorn says the type of botulism at home on South Maine : which has afflicted the ducks is not Mrs. Maupin is a grad the same that attacks humans local high school and wa through tainted food. The organism, of the Dodge Constructs he explains, develops during warm four years. Mr. Maupin J weather in areas where decayed ani- of the Dodge Constructio mal and vegtable life is left in the is a prominent Mason. shallower water. Some of the dead son of Mr! and Mrs. E. birds were found in water some and has resided here n wounded soldiers await evacuation. Flat on their backs, in the steaming three feet deep. life and is an influentia plague" the air and ants and mosqUito«s torment weary bodies, they dream Its prevalence this year is- believ- the community. 1 the touch of cool, comforting hands. You can help provide modern hospi- ed to be due to the continued warm heir recuperation fey putting every dollar you can into War Bonds during weather through September when U. S, Treasury Department the bacteria produce highly toxious excreta. Cooler weather, it is said, Farmers, Spor is expected to bring relief. .. Cowle Ranch in Adventist School The disease is not uncommon, and Program Prov has been known in shallow water of ^heckler is Sold is Now Open with many localities during the late sum- Ammunition f Mr. and Mrs. Lawrence Parmen mer. It has appeared here on sever- Good Attendance al prevous occasions, but not as Local Dealers Ui f Smith Creek have purchased the marked as .now. . 'owle ranch in-Sheckler district and Under Direction of Prof. There were no indications of the to Get Merchand: xpect to take possession the last of disease in the Carson lake pasture Farmers Apply i his week. '• and Mrs. R.-N. ^Gardner; area south of Fallon, nor in deep- The Towle Brothers, the late A. E. Classes Are Growing er waters in other parts of the coun- A program has been . nd Charlie Towle, bought the ranch try. "...-••' der which approximately i September; 1917 from Fleming The Fallon SJXA. school opened Alcron describes the quantities of shotgun shells, 12 millior IcLean brother of Ed McLean who this year -with the largest enroll- ducks here this year as "more than rTfle cartridges and 100 loved at that time to Idaho. The ment since abut 1928. The enroll- ever before." The hatch through the caliber -rim fire cartrid, 'owles before that had owned 2800 ment this year being 35 students in season has been especially large, he available for distribution cres of-land along Carson river grades 1 to 10. Effort was made to said, and the. birds that fly early through regular trade c ear old Ft.-Churchill. obtain a teacher to relieve Prof. R. appear to be coming in from the ginning immediately, ac The ranch since divided dates back N. Gardner from teaching this year, north in greater numbers. :, ...... announcement "by the v 1879 when.,it belonged to-Thomas he" being the local pastor of 'the through the U. S. depart oomey-and Willard Pike.";..i:. " *"; church, but due to shortage of teach- riculture.tp county'.war Mr; "•ahcl.tiMrs; -Parmen recently ers 'Prof/ Gardner is • -teaching the men, .but dealers at Fallc 3ld their Smith Creek ranch to; An- Off for Service upper grades and Mrs. f Gardner is haye been unable to get v: y Drumin,'jr. •: - - :•••- /.., . teaching :the lower grades^ - ; ; ;-;;£; nition.. .so...far for.;.;;far ;VA number of projects are planned which to exterminate pr mals.S-;.-r-?2-/Zi-j.Zi* •,•.'/.: for the year, some of which are the Miss: Euôra Toft left Sunday /ev- loney Crop Short installation.-. :6f <>' some ', Vniore • pjay :i-Under:this.program ai ening.; to. reporj; .for. .army,, duty: at the; .U.S.P.A. ,on Septenr ground ; equipment • arid ', the : enlarge- Salt :Lake . City-'on ;Mciriday;; She preV n State This Year ment , of class-rpofri'.f acilities. Addi- "dealers: ".will" have ami .yjously,,had . received^ vvord that she stock'which may be sol ',•'-. • ' •" •"• •• - ;:..' tional deskisl:have alrejady been iin- would ^not/beycalledt before ^Nov.: 1, The;honey, crop .is short ;alL: over sentation iof"a certificate Stalled/And before -,th£^: school, .open-; 'andx;was.; leisurely making plaris;-to '! evada tliisvyearpbut better^ln ».tlie. certificate is for farmer; 'many,.of :the church members ;as- dispbse;;bf her house .and.belorigirigs, allpnvvicmity. than in other local!-' !ers and;:is;:;an:,:applicat jsisted; in getting the Scho6ltin reaî-' On Saturday :;a message .came -for is, according' to Walter r:Nygren, nessiJEqr ;'the;-y;ear.; ;';:' . 5,' ".'>>-'^.;1 -':•...'• more .than fifty ~.22 carti her to .. report 'by the' 26th.'" „. ty, center -tire, rifle cai IB ;of the principal; producers. ' .She expected to be sent;oh;to Fty "It looks-like - the shortest, crop: 25 .."shotgun shells.;.. The The • curriculum;^ 'vrfollbNyed; -J;in ':;.va gleliio^,; Georgia :; to .attend; offi- rancher.vsigris that -he is e state ever, had," Nygren addedr cer's, candidate"" school. _F.or; several 'daring that he-is uriabêi-to; state "ctiuirch school is -yef y.:'clpse ;toi that in the food,produ'cing'liri oi 'the public, schoolîVVithithe ;iaddi« years-.Miss Toft -has "'been ia,. highly ajting a victory garden ie reasons.^He Indicated that the regarded teacher ...at; the Data .; Park te spring: and cold ;iweather- may tiori;:'of the teaching of Bible, sub- is the only., person ion t ive had something to do with this jects; riOne. Bible "subject being Re- and was':active.; in ;- civic and .social thorized to; arrange fq quired 'fori'each grade.; $eventh-

RAMON VEGA, STUDENT TRAINEE

STILLWATER WILDLIFE MANAGEMENT AREA • P.O. BOX 1236 FALLON, NV 89406-1236 (702) 423-5128

** Cover picture: Dead waterfowl on shoreline at Pelican Island 1952.

August 1987 I

Acknowledgements The author wishes to thank those individuals who helped develop this report. I would like to give special thanks to Steve P. Thompson, Wildlife Biologist, Stillwater NWR, for his encouragement, full support, guidance, editing and numerous suggestions during the preparation of this report. Credit is due to Ken Merritt, Assistant Manager, Stillwater NWR, for his inputs and editing. Recognition is also given to Tim Bowman, Assistant Wildlife Biologist, Stillwater NWR, for his editing contributions. Special thanks also goes to Carolyn I Harriman, Clerk-Typist, Stillwater NWR, for the countless hours and efforts put into the preparation of this report. Table of contents Map I History 1 Introduction 2 Methods 2 Discussion and Results 2 Literature Cited • • 5 I Tables i Figure v Appendix II Narrative Information 1 I Photographs i I

I 1 FALLON NATIONAL WILDLIFE REFUGE

I .HISTORY The Stillwater Marshes are a remnant of ancient Lake Lahontan that was in existence during the Pleistocene Period. The lake covered approximately 8,900 square miles. The present Stillwater Wildlife Management Area boundary encloses approximately 200,000 acres, including over 40,000 acres of private in holdings. Within the boundaries, approximately 24,000 acres have been set aside by agreement between the Nevada Department of Wildlife and United States Fish and Wildlife Service as the Stillwater National Wildlife Refuge. All lands are managed cooperatively with the Nevada Department of Wildlife under a 1948 agreement with the Truckee-Carson Irrigation District (TCID). The Service provides the staff, equipment and most of the funding for the project. The entire area is superimposed on public lands withdrawn for reclamation purposes. There is no fee title land within Stillwater's boundary, or public lands that have been withdrawn for refuge purposes. Development, of the Stillwater Marsh has been a joint project of the Pish and Wildlife Service and the Nevada Department of Wildlife. Since 1949 when development began, a total of over 3.3 million dollars have been spent in construction of 60 miles of road, 25 miles of dikes, 37 miles of canal and 200 water control structures. This has resulted in 16 waterfowl units with a potential developed water acreage of over 18,000 acres and three developed pasture areas of 2,420 acres. The Stillwater Marsh area has been an historic stopover point for migratior waterfowl during their spring and fall migration, as well as an important nesting site for many waterfowl, marsh and shorebirds. Peak numbers of 250,000 ducks occur during good water years; under ideal nesting conditions, waterfowl produce up to 15,000 young. Cinnamon teal, gadwall, and redhead are the principle nesting species. Stillwater is unique in providing a fall migration stopover and feeding location for an average of over 30% of the winter Pacific Flyway population of canvasback with a high of 56% in 1970. Also approximately 3,500 redhead young can be produced each year under good marsh conditions. Increasingly Stillwater is being recognized for its contribution to flyway goals for waterfowl and shorebirds production and for migration.

1 INTRODUCTION

Avian Botulism is a disease caused by an anaerobic bacterium (Clostridium botulinum) which produces a toxin as a byproduct of its metabolic activities. The toxin, when consumed by birds, has a devastating effect on their neuromuscular system. Symptoms include inability to fly, limber or weak neck, inability to eat, weakness of wing muscles, ceasing of the rhythmatic function of the nictitating membrane and greenish bile staining of the vent (Bellrose 1980). The disease is commonly known as avian botulism, but other names used include western duck sickness, limber neck and alkali poisoning. Avian botulism has been prevalent in the western regions of North America, but reports of outbreaks have been documented in some eastern states (Bellrose 1980). Other regions of the globe, such as South Africa, Uruguay and Australia, have also documented avian botulism outbreaks (Wobeser 1981). Studies have revealed that outbreaks develop as a result of one or more of the following conditions: flooding of dry areas during warm weather, receding water levels and infected decaying carsasses. Throughout the years, these conditions have occurred frequently at Stillwater National Wildlife Refuge (NWR), the Wildlife Management Area (WMA) and adjacent areas in Churchill County, Nevada.

The purpose of this report is to review historical information on avian botulism at Stillwater Wildlife Management Area (WMA). This report includes incidental reports of avian cholera and lead poisioning. The focus of the report will deal with climatic conditions and water conditions immediately prior to and during avian botulism outbreaks.

METHODS Information used for this report was attained by reviewing refuge narratives (1949-1985), disease files and available waterfowl literature. J. R. Alcorn, retired Wildlife Biologist and Norman Saake, Waterfowl Biologist, Nevada Department of Wildlife, were consulted. Consultations on present studies of avian botulism and pathological cycles of the bacterium spores were attained from Dr. Kathryn Converse and Dr. Toni Rocke of the National Wildlife Health Laboratory, Madison, Wisconsin. Pictures and Tables were duplicated from refuge narratives and disease files.

DISCUSSION AND RESULTS Avian botulism has been the most devastating disease at Stillwater Wildlife Management Area since and before its development. This disease has occurred virtually every year in one area of the marsh or another. Adjacent areas, off refuge, have also exhibited outbreaks. The earliest documented report dated back to the summer of 1921 with reports appearing once again in the summers of 1941 and 1943 (Alcorn 1944). Two locations were documented as having avian botulism outbreaks in Churchill County, Nevada. The earliest documented outbreak occurred in the Carson Sink during the summer and fall of 1921. Reports from livestock ranchers and hunters indicated that thousands of birds were seen sick or dead along the shorlines and mud flats of the Sink. Another epidemic of avian botulism was reported at Soda Lake between July 26, 1941, and August 19, 1941, (Alcorn 1942). From the description of the outbreak, it was apparent that the bacteria was being transferred via the maggot cycle. Birds were observed feeding on what appeared to be dead bodies and larvae of soda flies (Ephydra hians) (Alcorn 1942). (See Table I for species accounts). August through December, 1943, was yet another period of avian botulism on the Carson Sink (Alcorn 1944). The outbreak occurred along a three mile stretch at the mouth of the Carson River encompassing both the shorlines and mudflats. An examination of other areas of the sink revealed that this was the only area affected by the epidemic. Conditions of the area at the time of the dieoff were optimal for culturing the bacteria; that is, the presence of warm, stagnant, shallow waters and exposed mudflats. An estimate was made of more than 10,000 affected birds with 19 species identified as being victims. The outbreak reached its peak between August and September and ended in early December. However, it appeared that many birds had been stricken after cold weather had frozen over some of the area (Alcorn 1944). (See Table II for species identified and actual counts'). SWMA was established in 1948, with the first avian botulism outbreak reported in the summer of 1949. There was an outbreak reported seven consecutive years from this point, with the worst losses occurring during 1952. Of 36 years of historical data reviewed, 28 years were marked by avian botulism outbreaks. Only four consecutive years weren't plagued by an outbreak, these being the years of 1975 through 1978. The receding and flooding of mudflats that caused the death of aquatic and teristerial invertebrates were the most profound conditions that existed during the outbreaks. The dead invertebrates provide the nutritional median required by the spores for germination. One other factor that apparently contributed to disease outbreaks was intense wind conditions. During the outbreak of the summer of 1954, it was noted that outbreaks flared up after a two to three day period of comparatively strong winds. The wind action could have exposed mudflats long enough to allow spores to germinate, thus contaminating the areas. One outbreak that occurred did not follow the trend of conditions as specified previously. This event occurred during the summer of 1959 in the Stillwater WMA. The outbreak was unusual in that the area was receiving an ample amount of fresh water prior to and during the outbreak. Cattail Lake was affected the most and it was kept at optimal operational, levels during the entire year. However, this summer was characterized as being unusually hot and dry with below normal average precipitation for the area. The number of birds affected was small and the duration of the outbreak was short. The largest botulism outbreak for Stillwater occurred during the period of 1983, when an estimated 52,000 birds died. The management area had been engulfed by flood waters of previous years and this year marked the beginning of a receding trend. The outbreak had a slow start, but as temperatures escalated the die-off exploded at an uncontrollable rate. The most affected areas were the Carson Sink, Pintail Bay, Nutgrass and Big Water. These areas were the first to recede after being inundated by floodwaters. The water was considered of poor quality and stagnant with salinity conditions registering above desirable levels. This dieoff demonistrated how little is understood .and how confusing the disease can be when it deviates from the presumed germination conditions. Current studies by the National Wildlife Health Laboratory, on avian botulism, are centered around the microbiology activity between the bacteria and its invertebrate host. The studies are also investigating inhibitory effects on the bacterium by other forms of bacteria. •

Avian cholera for the first time was documented on Stillwater WMA during a March 1980 bird die-off in Nutgrass pond. Unfortunately no .. data are available into species or numbers affected. The second documented outbreak occurred in January 1987, when approximately 1500 birds died in the Carson Sink. The outbreak appeared to be the most concentrated near the mouths of both the Carson and Humboldt Rivers. Species affected are listed in Table III.

The most significant finding of this report is the identification of the most hazardous areas for avian botulism outbreaks. Although no area has been exempt from an outbreak, several ponds have a recurring history of disease outbreaks. During water surplus years, the Carson Sink, Pelican Island and Battleground Point area can become death traps for waterfowl and shorebirds. This area is used as a dumping unit for excess water from reservoirs upstream. When supplied with water, the Pelican Island area can be a highly productive feeding area for waterfowl, attracting birds in large numbers. On Stillwater WMA, ponds with reoccurring outbreaks have been 'Big Water, Pintail Bay, Nutgrass, Lead Lake and Tule Lake. These ponds are susceptible to abrupt water draw downs during summer water shortages. Water will be conserved for units in the primary refuge marsh. Water, during shortage years, was dumped into refuge ponds first often resulting in 'water deficiencies for ponds outside the refuge. Areas of concern on the refuge are Foxtail and Dry Lakes, which have been hazardous during years of low water levels. (See Table IV).

RECOMMENDATIONS

Manipulation of water may be the most important factor to be considered in controling or preventing avian botulism outbreaks. Recommendations include: 1. Designing water management plans that specify precise timing of water manipulation. 2. Flooding should be done when water temperatures are cool. 3. Problem areas should be subject to surveillance during summer months. 4. Bird carcasses should be disposed of to break the maggot cycle. 5. Accurate records of species affected per unit should be kept to identify trends and allow for predictability of future outbreaks. In order to understand avian botulism at Stillwater, consideration must be given to climatic conditions, irrigation water demands, water manipulation requirements and water quality.

LITERATURE CITED Alcorn, J. R. 1942. Birds affected by botulism at Soda Lake, Nevada. The Condor 44 (2): 80-81. Alcorn, J. R. 1944. Botulism in the Carson Sink, Nevada. The Condor 46 (6): 300. Bell-rose, F. D. 1980. Ducks, geese and swans of North America. Stackpole Books Harrisburg, Pa. p. 540. Wobeser, G. A. 1981. Diseases of wild waterfowl. Pelnum Press, New York and London, p. 300. Table 1. Species affected by avian botulism at Soda Lake, Nevada, July 26', through August 19, 1941.

Species Number affected .

American Avocet 49 Black-necked Stilt '16 Kill deer 10 Western Sandpiper . 9 Wilson Phalarope 2 California Gull 2 . American Coot • 2 Mallard 2 ' Northern Pintail 2 Northern Shoveler 1 Gadwall 1 Green-winged Teal 1 Cinnamon. Teal 1 Ruddy Turnstone 1 Snowy Plover 1 Solitary Sandpiper 1 Black Tern 1 Bonaparte's Gull ,1 .Western Meadow!ark -1

Total 104 Table 2. Species identified as affected by avian botulism at Carson Sink August through December-1943.

Species Affected Actual Counts

American White Pelican 5 Snow Geese 25 Mallard ' 4 Gadwall 3 American Widgeon 9 Northern Pintail ' 249 Green-winged Teal 76 Cinnamon Teal ' 2 Northern Shoveler 125 Redhead 1 Ruddy Duck 1 Kill deer ' 4 American.Coot 10 Greater Yellow-legs 1 Least Sandpiper 1 Long-billed Dowitcher 1 Western Sandpiper 8 Marbled Godwit 1 .American Avocet 15

Total ~ 541 'Table 3. Species composition affected by avian cholera on the Carson and 'Humboldt Rivers. 1987 j ; Area Am. White.Pelican Carson and Humboldt D.c. "Cormorant " " G.B. Heron G. Egret C. 'Goqse Mallard . - " " N. Shoveler . -.• :"•.. " .• :' ~ N, Pintail :" .:" : ' ..'•'-. Ruddy.daek • .. . . ;' ,: V ?I ' - : 'Jl ",.;; Com.---Merganser ' '• •' '-. • . " . . G.y.. ^Teal - ;?' ' "- ••:- Am. -Wigeon . ;" : . " ; : Calif:. Gull • n, ..... i,

Am! .,Coot I

Table 4. Historical review of »v1«n botulism outbreaks 1n Churchill County, Hevada, :987.

Precipitation Conditions I Avian Avian Lead Areas Year Spring Summer Fall Winter Botulism Cholera Poisoning Affected 1921 Unknown Unknown .Unknown Unknown 1,000 Carson Sink 1941 Unknown Unknown Unknown Unknown 109 Soda Lake 1943 Unknown Unknown Unknown Unknown 10,000 Carson Sink 1949 Wet H«t Dry Het 6,000 10 Biq Hater Unit SHMA 1950 Dry Dpy Het Dry 2JDOO Nutqrass Unit, Big Hater SHMA 1951 Wet Normal Het Het 200 Big Hater Unit, Lead Lake SI-MA 19b2 Normal Normal Normal Normal 28.500 Pelican Island Marsh, Carson Sink. Fallen HUR 1953 Dry Het Normal Dry 425 All areas of marsh, Intensively 1n Pintail Bay, Nutgrass and Pelican Island marsh. 1954 Wat Dry Normal Het 600 Pintail Bay, Nutgrass Unit, Pelican Island marsh. SHMA 1955 Normal ' Dry Het Normal 1,300 1 Tule Lake, Stlllwater Point Reservoir SHWR 1956 Wet . Wet Dry Het 0 1957 Dry Dry Normal Dry 40 Nutqrass Unit SHMA 1958 Dry Het Dry Dry 1,000 Nutgrass Unit, Cattail Lake Pelican Island SHMA 1959 Dry Dry Dry Dry 300 All areas of marsh, Intensively at Cattail Lnke SNHR 1960 Dry Dry Dry Dry 0 1961 Dry Het Normal Dry 50 Canvasback Club, Lead Lake SHMA I 1962 Wet Het Dry Het 0 1963 Normal Het Normal Normal 2.500 Dry Lake, Tule Lake, Nutgrass Unit, Foxtail Lake SWMA 1964 Normal Normal Normal Normal 5,250 1965 Normal Wet Het Normal 80 1966 Normal Normal Dry Normal 145 Nutgrass Unit, Pintail Bay Tule Lake 1967 Wet Wet Dry Dry 0 1968 Normal Normal Normal Normal 0 1969 Dry Dry Wet Het 4.050 Greenhead Club, PlntH Bay Unit, Nutgrass Unit, Goose Lake w/ii . Fig. 1 Chronology and estimated numbers of birds affected by avian botulism on Still water WMA 1949-1984. (1965, 1971, 1972 and 1974 data not available) Estimated Number Affected

.-•-•.•'• 6,000 1949- • •'••'.-•• ' ' 1950- 2,000 ..'.-...•''•••*''•' • Ii 200 1951- • : ..•:-•- • r 1 • . • • • 1 ' 28,500 1952- : ' ' 11 -11 " • 1 • - I 425 1953 •- ' " •'.'-' . 1 600 1954- • '-.,.-•-.:. . -' • . 1 1 1955-. 1,300 1957- 40

' : 1 1 1,000 1958 '.-"..- • I 1 II , 300 1959- •--...'. II 1961 •••.'•••-.• , *• 50 : -2,500 1963- ' "' ' •.-••••••'•.• -^-- ' •• . ' 1 1964- 5,250 1965- 145 1966 , ' •..,.-• ' 1 11 1969- -4,050; 1970- • " : V 2^,400

' > J. 1971r *, 1972-^ 1974-

•-•-.'.. V I 3,6-96 1979 ' 1 • • :' • . *** 1980- * 50 ' ""••: •'"' ' •'• : '- • 463 ; 1981 • •-•' • , ... '_' . • < ' '-' *,."pt^|^-,^"-*i - • ' :'..'. I 'i '"*",-, f 314 1982 -.,..•- •--..-• 1 - 1 .,-,,,-**,. 1983 - >:•: , ? . -- : - •' • y | V™i^£iA -*£L S" , 52,000 : .;-;::-: " •' ,: ; . ** , *^'j"'" • 11,618 1984- --".,-. _ . * 1 x - -,'-*. _f" ^ I

J J MONTHS * Carson Lake and SWMA * Carson Lake v * SWMA and Canvasback Club NARRATIVE INFORMATION

NR 1-3 CY 1949 CLIMATIC CONDITIONS: The area's worst winter in fifty years of record keeping occurred during 1948-49. Temperatures dropped to -25 degrees F, which set a record low temperature for the area. Precipitation in the form of snow as 1.95 inches for the reporting period. Spring began with intense cloudiness and heavy rainfall, which exceeded the normal average. These^conditions prolonged the spring season and delayed the beginning of the irrigation season. The summer months were considered hot and dry, with little rainfall recorded during those months. The total precipitation for the period was 2.13 inches. Fall was marked by having the warmest temperatures in the last 45 years. There was little wind with clear skies. Only four cloudy days were noted during the 50 day hunting season. The warm trend abruptly ended in December as temperatures dropped and snow flurries preceeded the cold fronts. Total precipitation was 0.23 inches, which was below the normal average of 1.89 inches.

WATER CONDITIONS: The main storage area, Stillwater Point Reservoir, was kept approximately 30 inches below full capacity. All developed marsh units were kept at optimal operational levels. Due to the delay in the irrigation season, Stillwater.Marsh was receiving Lahontan Reservoir spills, which maintained Stillwater Point Reservoir and all marsh units at operational levels. The dry summer months increased irrigation water demands, increasing drainage water inflows to the marsh. This resulted in Stillwater Point Reservoir reaching extremely high levels, the outflow was kept 80 to 90 cfs for an extended period of time. Evaporation rates were great enough to dry the shallower ponds on the lower end of the marsh. Water supply for the year was considered excellent, due to the high spring moisture content and high irrigation water ' demands during the summer. Drought conditions that had begun in the summer resulted in an increase in irrigation drain inflows to the marsh. Water was being received from surplus water of the Paiute Canal and the drain flows of the Canvasback Club, which resulted in flooding of outlying areas that had not been flooded since 1915. The main reservoirs that store water had reached the lowest levels since 1934. ' BOTULISM (1949): This year's outbreak occurred sometime between September 28 and October 9 in the Big Water area. Losses were estimated at 6,000 birds. The epidemic was unusual in that it struck suddenly, terminated abruptly and there was no lingering of sickness. The majority of the carsasses were found on the east shorline of Big Water and Nutgrass dike. Very few sick birds were noted during this outbreak. The area was considered a botulism hazard because of the feather-edge on the flat shorline and high winds caused intensive wave actions that temporarily exposed

1 mudflats. An unknown disease caused the death of an estimated 30 ring-billed gulls, while water and food conditions were considered good. A postmortem was made on several birds, with the following observations made: digestive tracts were empty except for a greenish fluid, death was slow and took several days as the bird gradually weakened, the birds lacked fat and no parasites were observed. LEAD POISIONING (1949): Symptoms of lead poisoning were exhibited in only a few birds on the marsh. The adjacent areas to Stillwater were noted as having a higher incidence of lead poisioning because they were subject to higher hunting pressures.

NR 4-6 CY 1950 . ' I CLIMATIC CONDITIONS: Temperatures for this winter were considered moderate to mild by area standards. Precipitation was well below the normal average of 2.19 inches, with the area receiving only 0.76 inches. Spring winds were high and persistent throughout the spring period. Cool temperatures prevailed through spring and early summer, but the normal hot temperatures existed through the remainder of the summer season. Precipitation again was well below the normal average of 1.26 inches, with the area receiving only 0.55 inches during this period. Fall was considered as wet, foggy, cool and cloudy. Precipitation was above normal average of 1.89 inches with the area receiving 2.25 inches. WATER CONDITIONS: Despite the drought conditions that prevailed in the area during the year, the water supply was considered very satisfactory. ' Heavy snowfalls in the Carson and Truckee River water sheds were credited with supplying ample water to the marsh. Water to the units was closed off earlier in the year to facilitate maintenance of water delivery canals, causing water levels in the .developed marsh units to be below optimal operational levels. The start of the irrigation season provided the marsh with more water than usual, but high evaporation rates off set the gains. As a result many of the shallower units became dry. Accordingly, Nutgrass and Big water areas were reduced in size and retained very little surface water. Water flows increased by the end of the summer. The late fall rain resulted in early floods which yielded a surplus of water that was released to the marsh and the Carson Sink area. All developed units were kept full to overflowing and Stillwater Point Reservoir was filled to maximum capacity. Surplus water from the marsh units was dumped into the Big Water area which, had been greatly reduced during the previous summer. BOTULISM (1950): The outbreak was first noted during the latter part of August, with the first losses being very small. Big Water area was patrolled with a total of 100 birds found dead and three sick during September 6 and 7. The outbreak continued until October 18, when the last sick birds were observed. It was I estimated that 85% of the carcasses were found in ponds and channels adjacent to the Nutgrass unit and some within one mile of the exposed Big Water mud flats. It was theroized that birds picked up the toxin in the Big Water area and flew to the Nutgrass . area as part of their daily migration. As a result, the toxin acted on the birds when they were occupying the Nutgrass unit. The estimation of losses was as follows: 1,000 ducks and 1,000 shorebirds. .NR 7-9 CY 1951 CLIMATIC CONDITIONS: The winter and early spring periods were characterized as being cool and damp. Cloudy weather presisted over most of the period, but precipitation was still below the normal average. The windy spring conditions were at a minimum which reduced evaporation rates. The summer weather was considered near normal with the exception of a noticeable decrease in windy conditions. Precipitation was slightly above the normal average of 1.26 inches with the area receiving 1.32 inches. There was a decrease in evaporation rates due to the increase of precipitation and decrease in winds. Pall was characterized as being wet and warm compared to normal. Most of the period was marked by cloudy days and above average rainfall. Total precipitation was 2.41 inches, well above the normal average of 1.89 inches. WATER CONDITIONS: The flood carry-over from the previous fall and low evaporation rates kept the marsh water levels high. Water levels were reported as higher than needed in the marsh. The east portion of the marsh was being dried out to permit work with heavy equipment; the majority of the work was being done in Pintail Bay area. The Big Water area had filled to the point that water was flowing westward to the Sand Dune vicinty and into the Carson Sink. Throughout the year water levels in the west side of the marsh had been extremely high due to water being withheld from the Pintail Bay and Nutgrass ponds. This was compounded by abnormal inflow from increased irrigation water demands. Normally, the fall water supply dropped rapidly in August and September, but due to high irrigation water demands, the drop off occurred later. The excessive water volume entering the marsh was not reduced until October. Water -levels continued to rise in the extreme western portion of the marsh in late December. BOTULISM (1951): The outbreak occurred from July 20 through Sept. 1; approximately 100 ducks were lost to botulism. There were no large bird die—off reported at any one time. Five birds were reported to have died from feeding in the mud flat along the north side of "D" Dike. All other deaths occurred along the Big Water area. No control measures other than pick up were taken. Less than 100 ducks died from botulism in a flooded alkali weed area near the junction of Navy Cabin Road and Lead Lake Canal. This occurred on Oct. 20th, with the outbreak being sudden and ending within a short period of time.

NR 10-12 CY 1952 CLIMATIC CONDITIONS: Climatic conditions were considered normal with temperatures fluctuating only slightly from the normal average. Presipitation was slightly above the normal average of 2.19 inches with the area receiving 2.71 inches. Spring and summer were marked as being very close to normal in regard to temperatures. Precipitation was slightly below the normal average of 1.26 inches, with the area receiving 0.78 inches during this period. Fall had a mixture of normal conditions during the early part of the period to stormy conditions during the latter part. The stormy conditions were characterized by cloudiness and wind. Precipitation varied only slightly from the normal average of 1.90 inches, with the area receiving 1.62 inches.

WATER CONDITIONS: The calender year of 1952 had been characterezed' by high water conditions. Inflow remained high until the last 2 weeks of December, which was unusual since tapering of inflow occurs at the end of the irrigation season, about November 15. The continued inflow was a result of the diversion of power plant water inflow, TCID also diverted water from the lower river to accomodate for repairs to the Sagouspe Dam; approximately 200 acre feet of water was diverted to the Stillwater Marsh during this time. The flow was cut off on November 29, after which, the volume of water received began dropping back towards the normal winter low. During the latter part of the year, marsh water levels had remained high inundating • low-lying peripheral lands. Continued construction in the Big Water and Nutgrass units prevented utilization of these natural sump areas for disposal of surplus waters. Instead, Pintail Bay was being used as a marsh outlet. From this point water was flowing into the Sand Dune areas and out into the Carson Sink. The most serious concern at this point was the continual water accumulation in the Carson Sink. TCID was also releasing surplus water from the Lahontan Reservoir into the lower Carson River for disposal purposes at a flow of 1400 cfs. This flow aided in creating a lake at the sink estimated to be at least 140,000 acres in size. BOTULISM (1952): The first outbreak of the year was noted on July 9th at Pelican Island, which was earlier than anticipated. The outbreak apparently started about July 1st and continued on through early November. The water in this area was approximately a foot or less in depth, which resulted in an abundance of food plant production. A large concentration of waterfowl utilized the area continually thru this period. The water gradually receded with minor flucuations during which water rose for short periods. Water eruptions were a result of wind action and daily changes in evaporation since the inflow into the area remained the same. Changes in water levels varied as much as six inches. The areas primarily affected were the shorlines extending from the sand dunes of Pelican Island to the north shore of Battleground Point. The birds were found dead or sick along the shoreline and in the adjacent vegetation in about equal numbers. The shorelines affected were moderately sloped and sandy. The losses are based on sample counts of dead made along measured segments of the shorline and transects placed across a water area. The final count for duck and goose losses amounted to 27,000 and an estimated 1,700 birds of other species. (Table I and II). The outbreak was first detected during early July and losses averaged about 100 birds/ but by late July and early August the losses had escalated to 2,500 ducks with an average of 132 per day. Within the next 13 days, losses had peaked with non waterfowl birds averaging 215 dead per day and ducks averaging 700 per day. By the 17th of September, herding operations had begun and a drop in losses was noticed but the drop was not entirely attributed to this operations. The herding procedure required a large scale operation using as airboat, rifles, flares, a 50 caliber machine gun, a searchlight and an airplane. The tool that was most effective in the scare tactic was the 50 caliber machine gun, on loan from the Nevada National Guard. The weapon was mounted atop of a high dune in the Battleground Point area and shot from the west towards the east. It was noted that a single burst from the gun would almost entirely clean all birds of the area for approximately 3 miles. The only herding device used at night was a searchlight, which covered a square mile. Consequently, the birds turned to feeding at night outside the range of the searchlight... Losses after the herding operations began were attributed to night feeding tactics. Losses by this time had tapered off to 115 of all species per day, but the die-off still continued. By the 23rd of November, herding operations had ceased and there still remained many sick birds in the area despite below freezing temperatures at night in the marsh. The water in the Sink was entirely covered by ice except for small openings, which appeared for a short time during the warmest part of the days. It was presumed that the birds getting sick in November were receiving sublethal doses of toxin and recovery was quite high. One notation made was that the sick were to lively to catch but too sick to fly. The area affected by this outbreak encompassed approximately 10 sq. mi. of the Pelican Island Marsh, Carson Sink and Fallen Refuge. Affected to a lesser degree were some 20 sq. mi. on the eastern sections of the management area. Once the hunting season had begun on October 17, herding operations became less effective as hunting pressure forced the ducks to move to other areas. At this point, efforts were turned to treatment of the sick ducks and geese. A total of 3,281 sick ducks and geese were hospitalized, of which, 552 died, recovery rate of 73%. The hospital consisted of a fenced area along the Carson River in the shade of a large willow tree. The fence extended into the area, so that 50% of the enclosed area was in fresh running water. They were fed daily on barley placed at the edge of the water. The birds were not given fresh water through a syringe because they did well on their own. Antitoxin inoculations were given; however, due to the large number of birds affected/ the expensive treatment did not seem warranted. (Photos 1-4). The large percentage of botulism losses was attributed to the birds feeding away from the shoreline. Feeding did not occur extensively along the shorelines except during the initial stage of the outbreak. Carcasses were present up to two miles from inland before herding was started. A consideration that should have been taken into account was the possibility that the first carcasses in the water might have served as a median for disseminating the bacteria. The •shorebird losses occurred at the beginning of the outbreak, but decreased for the last six weeks partly because they fed along the shoreline once they became habituated to the herding disturbance. Coots and ducks continued to feed away from the shorelines and eventually succumbed to the toxic disease. Pelican Island water levels, as measured near Battleground Point, fluctuated up and down over a three inch range during the outbreak. The lowest level was a result of heavy winds on September 4 and 5. There was a noticeable increase in sick and dead birds which appeared after this event.

Table -1. •-Estimated losses by species for ducks and geese 1952 Species Estimated Numbers Mallard 2,160 Gadwall 270 American Widgeon 270 Pintail 11,610 Green-winged Teal 5,940 *Cinnamon Teal 810 Shoveler 5,130 Redhead 270 Ruddy Duck 270 **0thers 270 Total Number 27,000 *May include some blue-winged teal **Includes Canada geese, snow geese and canvasback. Table 2. Estimated losses of non-waterfowl species 1952. Species Estimated Numbers White-faced Ibis 44 Killdeer 140 Black-billed Plover 2 Least Sandpiper 93 Marbled Godwit 1 Avocet 595 Black-necked Stilt 151 Wilson's Phalarope • 25 California Gull 18 Ring-billed Gull 46 Forester's Tern 70 Eared Grebe 10 Am. White Pelican 10 Snowy Egret 10 Am. Coot 668 Dowitcher 75 Western Sandpiper 10 Northern Phalarope 75 Yellow-headed Blackbird 1 Total Numbers 1,700

NR 13-15 CY 1953 CLIMATIC CONDITIONS: The winter began drier and warmer than normal, but consecutive cold spells, occurred during late winter and early spring, resulting in slow growth of marsh and desert plants. Consequently, a larger waterfowl population overwintered at Stillwater than in winters characterized by long periods of subzero temperatures. May was the wettest and coldest ever recorded with rainfall being heavier than the normal for the I entire reporting period, and 1.59 inches of rainfall was received. The weather returned to normal by June followed by the usual dry hot summer. The winds were less than normal and there was a noticable decrease in evaporation rates. The Newlands Experimental Station had been discontinued, which ment that wind movement and evaporation rates were no longer available. Temperature and precipitation data was then obtained from Fallen Naval Air Base. Fall weather conditions were considered normal. WATER CONDITIONS: The Lahontan Reservoir was at full capacity at the beginning of the spring runoff which resulted in a temporary surplus of water. Because the local farmers had had two good water years, no effort had been made to conserve any water, and the marsh received above normal water inflows. Lahontan Reservoir 7 had the highest winter carryover of irrigation water since its construction. The reservoir held 214,340 acre feet on January 1, as compared to maximum capacity of 290,000 acre feet. By April 15, storage had increased to 280,128 acre feet which necessitated dumping to prevent spillage over the flashboards. This resulted in increased inflow into the Carson Sink via the Carson River, which supplied water to the same area which had created the botulism outbreak the previous year. Water conditions in the Stillwater Marsh had been unusual considering the flood of the previous past two years. Water levels had dropped down close to normal after purposeful water manipulation. This was done inorder to produce good nesting habitat and propagate salt grass, another marginal plant which had been all but drowned out by the floods. Construction of dikes and ponds dictated the management of water at Stillwater Marsh. Because of this construction, waterflow patterns were not comparable with past years. However, an abrupt rise in the marsh water level occurred due to abnormaly high rainfall, which decreased irrigation water demand resulting in water dispersal into drains for disposal. By June, upstream impoundments quickly filled up and water was released into Nutgrass pond, which had been dry. The western sections of the marsh did not recieve any water during early spring due to construction. Well into June, irrigation was renewed and the amount of water entering the refuge decreased. Water was diverted from Nutgrass into the west area during July, but evaporation was so pronounced that only a slight rise was obtained. During late July, a botulism outbreak began in Pintail Bay. Water flow was cut to Pintail and diverted to the west marshes until they reached maximum capacity. When the west marshes filled, water flows were diverted back to Pintail. This water management technique was implemented throughout the botulism season. The Carson Sink had a marked resession of water during the summer despite a comparatively long spill from Lahontan Reseroir. By early September, the Sink had shrunk to about half of its former size of 140,000 surface acres. The remaining water occurred in the center of the Sink and had receded from the higher shorelines which served as the focal point for botulism the previous year. By mid fall Carson Sink was filling and spreading again after the shrinking that had occurred during the summer. Due to the close of the irrigation season, the water required to run the hydro- electric plant at Lahontan was now being diverted via the Carson River into the Sink. By mid-winter hydro-electric plant was shut down inorder to conserve water for the irrigation season, thus elimination the flow into the Carson Sink. BOTULISM (1953): The aftermath of the previous summer's epidemic resulted in an early spring die off at Pelican Island. Sick and dead ducks were reported from mid-Feburary through March with the outbreak peaking in mid-March. The peak was observed in the Battleground Point area where 150 sick and 150 dead ducks were located with a total die-off of about 300. An aerial survey indicated that this was the only area affected. ; Sporadic outbreaks occurred practically everywhere that muddy shorelines existed. The first sick ducks were found at Pelican Island in late June, where an estimated 100 ducks died. On July 13, botulism was noted in the newly flooded Nutgrass Unit with the death of 75 ducks and 100 shorebirds and coots. Shortly after the Nutgrass outbreak the Pintail Bay Unit was hit and 50 ducks died. On the west marsh high water levels had killed the lower area of saltgrass shorlines resulting in mud flats. This was believed to lead to optimum conditions for 'botulism. Scattered botulism victims were found in these areas of the marsh during August; 100 ducks died. No records of species were kept. NR 16-18 CY 1954 CLIMATIC CONDITIONS: Winter weather was considered moderate to normal and received 3.21 inches of precipitation, which was near the annual average; the wet condition continued through early spring. The trend ended by the start of the summer with hot and dry conditions prevailing. Conditions worsen as the summer progressed and the Governor had declared Churchill County a candidate for emergency drought relief funds. Mean temperatures of 65.98 degrees was conducives for marsh habitat development and waterfowl nesting and rearing activities. Winds were reported as being moderate for this period. On July 6, and August 23, two major earthquakes struck Fallon/Stillwater area with a magnitude of 6.75 and 6.00 intensity. Their epicenter was on the Stillwater Wildlife Management area with the Stillwater Work Center sitting directly above the main fault. The fault extended northward along the East Canal, across the Division Road, Navy Cabin Road, Swan Lake Dike and trrough Pintail Bay, - President Eisenhower had then declared the Fallen area a disaster area; it was estimated that the total damage to the Lahontan Basin had exceeded over $2,000,000. Moderate to favorable weather conditions prevailed during the fall with temperatures and precipitation approaching normal for the area. Winds were extremely moderate for this period. WATER CONDITIONS: In January the water outlook was anticipated as being well below normal since there had been only a small fraction of snowpack on the Sierras. Water levels in the Carson Sink had begun to drop in March and April as flow in the Carson River had deminished. The constriction of this lake was welcomed in view of the botulism problems this area had caused, but the spillage down the Carson River in the latter part of spring would inundate the mud flats. The diversion of the Carson River waste water to the Paiute Canal and the Stillwater marsh ponds had been recommended for the stabilization of water management in these ponds during .the late winter and spring period when insufficent water was avilable from other sources. Incidental to this would be the reduction of the botulism hazard of the Carson Sink. The west pond water levels were lowered to accomadate construction, thus, water was diverted to the Nutgrass Unit and reflooding of the Big Water Unit occurred. The second earthquake in August damaged the water system within the Paiute Indian Reservation to such extent that flow in the Paiute Canal was ceased until repairs were completed. The reduced water flow in the -lower Carson River had aided in drying up the Carson Sink lake to an estimated 640 surface acres. The snow pack in the Sierras during December was the deepest recorded for this time of the year. This snowpack broke the drought condition that had been experienced the prevoius year. At the close of the irrigation season, Novermber 15, the Lahontan Reservoir was storing 73,165 acre feet of water. Storage steadily increased to 116,000 acre feet of water by the end of fall. The increased flows premitted the hydro-electric power plant to be operated at full capacity. The power water was then released down the lower Carson River and into the Carson Sink reforming the impoundments that had .been partially dried the previous summer. Outflow from Stillwater Point Reservoir was 106 cfs for September, October and November. The flow was reduced by December to 83 cfs, as the irrigation canals were dewatered. The completion of Ole's Reservoir east of Fallen brought hope that the power and Carson flood waters would be diverted to the Stillwater Marsh via the Paiute Canal to augment winter water supply. BOTULISM (1954): Pintail Bay was the first area struck with botulism on July 16, with the victim being a mallard. Since that time three distinct outbreaks occurred between July 16 and August 13. The areas that were affected were fortunately small in size, thus received limited use. On July 29, the Nutgrass Unit had 25 sick and 5 dead birds all found on the dike. A reoccurence happened on August 13, with 15 sick and 5 dead ducks counted in the same area. The third flare-up happened on August 23, with 15 dead and 60 sick ducks reported along the Nutgrass Dike and 5 sick ducks observed in the Pintail Unit. Pelican Island, as usual, was affected with an outbreak during this period. On August 18, during an aerial survey of the area approximately 100 sick ducks (nearly all Pintails) were observed in an area of shallow ponds; no dead ducks were seen, thus, it was presumed that the birds were receiving only small doses of toxin. Preparations for a explosive outbreak were taken by August 23, when it was evident that the epidemic was on an increase. Sick birds were penned-up in a mobil hospital at the headgate of the Foxtail supply ditch and carcasses were properly disposed. A trapping and banding project which had been underway was ceased, but banding of recovered ducks was performed before they were released. At the end of this period 600 ducks were estimated to have become sick of which 150 died. The hospital had a holding capacity of only 70 ducks at anyone time, which reduced rescue efforts; no other treatments were administered other than fresh water supply and adequate food source. It was estimated that the hospitalization process had an 83% success ratio. The continuation of the summer's outbreak appeared in September, with the severity of the outbreak peaking at mid-month. It lasted through mid-November when there was a warm spell; control measures used included manipulation of water 10 levels, pick-up of carcasses and hospitalization of sick ducks. (Photos 5-6). NR 19-21 CY 1955 CLIMATIC CONDITIONS: The winter was cold and severe conditions existed during this period. The normal mid-January thaw did not occur until the end of February. The average wind velocity was below the 50 year average. The few windy days that did exist reached average wind velocities of 60 mph. Average precipitation as 1.91 inches. May was uncharacteristic with abnormal cloudiness, rain, snow and wind which resulted in a marked delay in plant growth and waterfowl nesting activities. The temperatures rose to above average for the summer with August showing the peak. There were only three days in which the temperatures were below 90 degrees F; May was the only month in which rainfall was noted. The average rainfall for this period was 1.26 inches, no rain was recorded during June, July and August. Fall ended the drought conditions of the summer with unusually heavy rains and snowfalls. The drought conditions had quickly changed to flood conditions with Stillwater WMA receiving large amounts of surplus water following one of the driest years on record. The marsh ponds became frozen earlier than usual on an intermittent basis. WATER CONDITIONS: The expected heavy snowfall characteristic of February did not materialize thus, only 70% of the normal water was produced. The TCID reduced the irrigation quotas to the local farmers by 25% inorder to conserve water. Stillwater Point Reservoir outlet was closed to conserve water and permit construction at Foxtail. Fresh water supply was provided through the Indian Lakes and Shoffner Drain via the Paiute Canal to the west and east ponds. The Stillwater Reservoir was receiving 50 to 60 cfs, which was below the normal average of 100 cfs. Flows of drain water had become not only smaller but also more stabilized with daily inflow not flucuating as greatly as before. Fringes of the Nutgrass, Big Water and Pintail Bay ponds were dried inorder to conserve water. Tule Lake pond was being dried also in conjunction with the water management program. Water scarcity had affected all sections of the Stillwater WMA. The Pelican Island marsh had been completely dried throughout the summer. All ponds that could be filled to full capacity were filled via the Paiute Canal, since the Stillwater Point Reservoir outflow was closed to conserve water for 1956. BOTULISM (1955): The low water conditions had reduced the threat of an outbreak in areas where botulism had been a problem. There were still mud flats and shorlines exposed plus stagnant ponds that cultured botulism. By the end of August 100 birds had died with the most severe outbreak occurring in the Tule Lake Unit. Due to the water shortage no reflooding could be done, thus herding and hospitalization were the tactics used to control the 11 outbreak. A few ducks were found at the Stillwater Point Reservoir and in the south'end of Pintail Bay where ponds remained close to the inlet structure. During the early part of September, there was an outbreak in Tule Lake that affected 1,100 birds. An airboat was used during the peak of the outbreak for herding and pick-up of sick ducks that were hospitalized. Water fluctuation as a means of control could not be implemented since the objective of the dewatering was done for management purpose. Furthermore, the adjacent pond had been kept at low levels to prevent wave action from damaging dikes. The hospital used during this outbreak was a fenced enclosure built along the edge of the marsh near the refuge work center. Total hospital mortality was higher than previous years, possibly due to the difference in species composition. Table.3. An estimation of the mortality rate. Tule Lake 1,100 Other Areas 100 Total 1,200

LEAD POISONING: One pintail male with symptoms of lead poisoning was picked-up. An autopsy was performed upon death, but no shot was found in the gizzard. Botulism Duck Hospital and Recovery Pool: Construction of the recovery pool was started in September with the removal of 1,000 cubic yards of earth, which were excavated with the TD-18A, tractor and dozer. Approximately 620 yards of riprap was hauled and graded on the slpes of the pool and resting island for erosion control and use of smaller gravel pebbles by waterfowl. Construction of the hospital was started in October and completed in November. (Photos 7-8). The structure design called for it to be 48 feet long and 10 feet wide, having a holding capacity of 500 ducks. (Photos 9-11). During the period of May through August, the hospital water control system and predator fence posts were installed. A system of pipes and gates, including the supply and drain ditches, were constructed and installed. Metal posts for the enclosure were installed in concrete bases and the eradication of 10 ft. high chain link fence was completed in November (Photos 12-15).

NR 22-24 CY 1956 CLIMATIC CONDITIONS: Winter weather was characterized by an abundance of moisture and moderate temperature. Warm periods in ' January caused an early heavy runoff from the Truckee and Carson River water-sheds. March brought an erratic fluctuation of 12 temperatures and abnormal high winds. As April came, the winter moisture provided an excellent growth of the desert and marsh flora. Moderate temperatures prevailed over the spring and summer. Precipitation for this period was above normal with an overall average of 1.21 inches. The beginning of a severe drought for this area was the mark of the fall. The U.S. Weather Bureau had issued a warning that for this time of year, this drought would be one of the driest recorded in 50 years. The Sierras were almost devoid of snow and serious forest fires occurred in the lower elevations. September was uncharacteristicaslly hot and the warm temperatures continued through October, when the spell was finally broken. Throughout November and December temperatures were consistently below normal with very few warm breaks. WATER CONDITIONS: The Lahontan Reservoir reached a capacity of I 200,000 acre feet from the heavy runoff very quickly. The hydro- electric plant was kept in maximum operating capacity with the surplus water going to the Carson Sink. The stored water on the Carson River watershed was measured at 70-80 percent above the 1938-52 normal. The Stillwater P. R. was lowered two feet in elevation to provide a storage cushion against pending dumpage to the unit. The surplus of water was pushed through the marsh ponds on to the Big Water Unit. By the end of April the discharge rate from the reservoir had bottomed out at 54 cfs, which allowed it to rise 12 inches during this entire period. The Canvasback area and the Paiute Canal water surplus had filled the west marsh ponds to operating capacity by the end of April. The Tule and Cattail units were dewatered to facilitate management improvement procedures. BOTULISM (1956): No outbreaks were reported dispite the drought conditions.

NR 25-27 CY 1957 CLIMATIC CONDITIONS: Winter and Spring temperatures were considered to be below normal. Minimum temperatures were the lowest recorded in many years. Freezing of ponds extended from January through February. Precipitation was scarce for this period with an overall average of 1.26 inches. Precipitation for the past two years had been at an all time low (average 5.28") with 1955 at 3.51 and 1956 at 4.01". Temperatures for the summer period were considered moderate and favorable with maximum temperatures ranging in the mid-ninties to mimimums in the 50's. Daily fluctuations of approximately 40 degrees was considered slightly above normal. June 28 set a new record for the highest temperature of the year at 102 degrees in 1951. The total precipitation had reached .51 inches by the end of summer. Winds .were uncharacteristic for this time of year, they were moderate with a lack of any strong winds being recorded. September 17, marked the first precipitation since June, with precipitation totaling more than a year ago for the same time. Temperatures 13 averaged higher than a year ago; the first killing frost was on ' October 6, earlier than usual. Total precipitation was 1.48, slightly lower than normal.

WATER CONDITIONS: Ample supply of irrigation drain water was available to the marsh from the Newlands Project. By the end of the summer, various ponds were at full capacity and a sufficient surcharge was available for the reflooding of Tule and Cattail Lakes. Pelican Island was also receiving a surplus of water via the Carson River. Stillwater PR was kept at maximun capacity and a discharge of 5,000 acre feet of water was released to the marsh during the summer months. Excess water in the amount of 625 acre feet had been passed through Pintail Bay to the Sand Dune area in August. Approximately 60 percent of-the Sand Dune area had been flooded, but Big Water was dry. A problem arose at the end of October with the disposal of surplus water, brought on by increase flows and decreased evaporation rates. An emergency canal was dug from Pintail Bay to the Sand Dune area to divert the water; an additional 10,000 acre feet of water was dumped in the area. Big Water was also reflooded to an estimated 3,000 acres; water levels at each pond were allowed to rise above operational level from November through December.

BOTULISM (1957): The Nutgrass Unit was the site for this summer's outbreak beginning in early August. Two sick Pintails were found first, then 35-40 were found dead or sick in the latter part of August. Water was diverted to the unit and the outbreak never reached a serious proportions.

NR 28-30 CY 1958 CLIMATIC CONDITIONS: The winter was mild with no stormy periods occurring over the entire winter. Precipitation was below normal (2.12) at 1.59 with infrequent snow falls and a minimal of overcasted days. Spring and summer were uncharacteristicly hot with temperatures above normal. Temperatures reached from 100 degrees to a high of 101 degrees three times during mid-summer. Precipitation was well above the normal 1.22 average, the average was 3.01 inches. June brought a series of scattered showers which had an average total of a 1.40 inch of precipitation. A total of 1.62 inches was received through the remainder of the summer. The fall period was considered very dry with a total of .49 inches received during the period, well below the 1.61 normal average. Temperatures were mild with record setting readings of 83-85 degrees reached in mid October. WATER CONDITIONS: Water supply was more than adequate for the year and all units were maintained at high levels. An estimated 12,860 acre feet of surplus water was dumped through Pintail Bay of which most went to Sand Dune and Big Water. The marsh remained relatively ice free as a result of the mild winter. The Lahontan Reservoir reached a storage capacity of 295,954 acre feet in

14 June, which made this an exceptionally good water year. Irrigation demands lowered the reservoir to 206,256 acre feet . which was still higher than the 163,415 acre feet of a year ago. Water surplus was released to Big Water through August; the release was discontinued as a botulism prevention measure. The Sand Dune area continued to get water via Pintail Bay. BOTULISM (1958): An outbreak of botulism was first experienced in the Cattail Lake area on July 15, and subsided on the last week of July. A total of 200 dead birds were picked up and buried; 33 sick birds were hospitalized and 22 survived. Water level at Cattail Lake was raised with hope that it would be instrumental in controlling the outbreak, which it apparently did. Another outbreak occurred at Pelican Island during the last two weeks of August. A total of 500 ducks died, mostly Mallards, Pintails and Green-winged Teals. A total of 75 ducks were picked up for hospitalization; 26 of the most seriously sick duck were vaccinated with an anti-toxin of which 23 survived. Also during the third week of August, 90 dead and 40 sick ducks were picked up in the Nutgrass Unit. The water level was raised 0.1 inch above summer operational level thus, reducing the botulism hazard by freshening the unit. A total of 1,000 ducks were lost to Botulism at SWMA.

NR 31-33 CY 1959 CLIMATIC CONDITIONS: The winter featured mild temperature and an almost complete lack of precipitation. The total precipitation for this period was 0.70 inches, far below normal which averages 2.12 inches. Spring weather was cooler than normal and the spell extended into mid June. A rapid change occurred with temperatures exceeding 100 degrees; the heat wave was a long term event for the area, there were 19 days of exteremly high temperatures recorded. Precipitation was at an all time low for this period with an average of 0.67 compared to the normal average of 1.22 inches. The entire year was marked as a dry spell. Fall began where summer left off "dry". The abnormally dry period produced only 0.29 inch of precipitation compared to the period's average of 1.61 inches. The fall began with exceptionally mild temperatures through October, but quickly changed in November with colder than normal temperatures. WATER CONDITIONS: Supply of water continued to be favorable for the marsh which was above normal for the winter. Surplus water from the west marsh and Pintail Bay was still being dumped in the Sand Dune area which received quite a bit of use during spring migration. Water which could not be retained in the Sand Dune area flowed west across the Carson Sink and spread out reaching Pelican Island. A surplus of water to the marsh continued throughout this year and all units were kept slightly above operational levels. The Carson River dumped its surplus flow in Pelican Island vicinty which resulted in shallow flooding of 15 vegetated areas consisting of 1,000 acres with excess water going to the Carson Sink. BOTULISM (1959): July was the beginning of this summer's outbreak with a loss of 300 ducks over the entire Management Area. A total of 100 dead ducks were collected at Cattail Lake which had been maintained at stable levels and had continuously received fresh water.

NR 34-36 CY 1960 CLIMATIC CONDITIONS: Winter temperatures were below normal and extended into March; a 10 day warm spell broke the trend, but an April cool spell returned with record setting lows for the month. Precipitation continued to remain very low, averaging 0.68 inches as compared to the period average of 2.12 inches. U.S. Weather Bureau indicated that Fallen had only received 2.83 inches in the past 20 months. Summer weather continued to be uncharacteristic of the area with temperatures above 100 degrees during 17 days of the summer. An early fall frost was experienced August 23, which caused considerable crop damage. Precipitation for the summer was still below the normal average of 1.22, the average for the period was 0.58 inches. Mild fall temperatures were recorded for September and October; as winter entered colder temperatures prevailed. Precipitation was slightly below normal for this period reaching only 0.98 inches compared to the normal of 1.61 of an inch; November received 0.63 inches. WATER CONDITIONS: The water outlook at Stillwater was the poorest it had been since the initiation of the project in 1949 and at this point the marsh was completely dependent upon irrigation drainage. The Sierras runoff this spring was 45 percent below the average normal. The water stored at the Stillwater PR during the winter facilitated the restoration of ponds dewatered primarily for the elimination of the carp; the units included Foxtail, Dry, Cattail and Division Pond. The Big Water and Sand Dune areas all but dried up during the water shortage along with most of the Pelican Island area. Habitat conditions on the marsh ponds had not improved, the irrigation drain flows were not' measuring up to the marsh's water demands. Deterioration of waterfowl habitat was occurring at an alarming rate on the primary marsh area. Foxtail and Dry Lake ponds were the only productive ponds and food sources were rapidly depleted once pond levels dropped. A restoration effort was made on the Nutgrass unit by using water from the Canvasback Club, but this pond failed to receive any waterfowl use. A decision was made to maintain Lead Lake and Tule Lake on the SWMA and only Foxtail on the refuge. BOTULISM (1960): No botulism outbreaks were reported despite the fact that water quality was very poor and much of the marsh ponds had receded. It was theorized that the rapid water declined had prevented ideal conditions for spore germination. 16 NR 37-39 CY 1961

CLIMATIC CONDITIONS: Winter temperatures finally approached normal conditions, but there were short periods of abnormally cold temperatures. Winds were noted as being more frequent than normal. Precipitation was finally on an upswing with an average of 1.19 inches. The weather took a change for the worst with a cool May exiting and the hottest June on record entering. The highest temperature was 106 degrees on "June 23 and 26 days throughout the summer had 100+ degree temperatures. Precipitation finally exceeded above the normal average of 1.22 inches to 1.57 for the period, but the 3.74 inches was still below normal for the annual average of 4.95 inches. Fall exhibited temperatures slightly below normal with the first frosts occurring in early September. December entered with below normal temperatures and a • new record low of -3 degrees. Precipitation had improved over the previous year with an average of 1.57 inches.

WATER CONDITIONS: The water supply outlook was the worst it had been in 30 years or more. The Lahontan Reservoir was holding a meir 111,758 acre feet by April 30. Drought conditions prevalent during 1960 and 1961 had inadvertently affected the marsh and the waterfowl. The lack of water was resulting in complete or nearly complete elimination of all waterfowl habitat on the primary marsh portion of the area by the fall. Irrigation water supply was cut to 40 percent of normal delivery which resulted in a serious decline of water to SWMA. A total of 6 to 8 cfs of water entered the Stillwater PR, during most of July and August which quickly disapated on the Reservoir flat. The only source of water for the marsh came from the Canvasback Gun Club which yielded 10-20 cfs to the Lead Lake Unit during May and June. Lead Lake was the only unit on the marsh that contained any water by summer's end. At the start of fall, the only surface water existing within the primary marsh was 350 acres of poor quality water which remained in the deep portions of Lead Lake and habitat deterioration rapidly continued throughout this period. Chanalization of the Stillwater PR produced 6cfs to the refuge area during September; the supply dropped to 3 cfs by mid October.

BOTULISM (1961): The Canvasback Club reported a few sick and dead ducks. Three sick ducks were picked up in the Lead Lake Drain in September of which two survived.

NR 40-42 CY 1962 CLIMATIC CONDITIONS: The winter had been the most severe since the 1948-49 period. The temperature didn't reach the all time low of -25 degrees, but it did come close at -12 degrees. March set a new record with a low of 17 degrees, followed by April with its low of 25 degrees. An unusal combination of humidity and cold resulted in presistant fog conditions that caused a deposition 17 frost on trees, powerlines, etc. Winter and spring marked the end of the drought that had almost destroyed the Stillwater Marsh. February was the wettest month this area had ever experienced. During this month alone 2.83 inches of precipitation were received bringing the period total to 4.02 inches, well over the average normal of 2.12 inches. One extremely windy day was experienced in April, which up-rooted trees and removed some roofs. Spring conditions were moderate and the trend continued through the summer with only one day reaching 100 degrees. Precipitation exceeded tha average normal for the period (1.22") with an average of 2.78 inches. Fall was considered rather mild throughout the season. A single storm period of one or two days•duration occurred during each of these periods. Precipitation for this period was below the average of 1.61 inches with the peak reaching 0.38 of an inch. • WATER CONDITONS: Water supply showed very little improvement; drain flows in general were scant throughout the winter months. The main source of water supply to the primary marsh flowed at a rate of 6 cfs until late April. TCID anticipated an 80% of normal irrigation water at the start of the delayed season. Snowpacks on the Sierras produced a runoff of 137 percent. Lahontan Reservoir stored 168/000 acre feet by the end of April which was somewhat improved from the previous year. Foxtail Lake was restored and was productive. The cooler weather reduced the rate of comsumptive use which permitted higher inflows to the area than had been previously experienced. This allowed for reflooding of a substantial acreage of the previously dried marsh. Moderate flows down the Carson River allowed the flooding of approximately 200 acres at the Pelican Island/Battleground Point area. BOTULISM (1962): No botulism was reported, even though it was expected due to the large amounts of organic material present in some of the reflooded zones, particularly at the South Lead Lake unit. NR 43-45 CY 1963 CLIMATIC CONDITIONS: The winter was colder than would normally be expected, with January dipping to a low of -11 degrees. The month of February began with warmer temperatures than the previous year, but March recorded an all time low for the month of 12 degrees. April continued with the trend of cooler temperatures and only 12 nights of frost free conditions were experienced which was unusal. This event delayed crop planting and inevitablitity the irrigation season. Summer was considered to have moderate temperatures .with no 100 degrees or higher recorded during any time of the period, however, on two days were recordings of 99 degrees. Total precipitation was recorded at 2.64 inches, much higher than the normal of 1.22 inches. Unusally warm temperatures characterized the fall which extended from early September through the middle of November. The fall warmth was abruptly ended by the 18 cold temperatures of December; the mercury dipped as low as 11 degrees. Precipitation was slightly below the seasonal average of 1.61 inches; the area received 1.48 inches. Storms were fairly frequent with rain or snow falling once in September, three times in October, four times in November and twice in December. WATER CONDITIONS: Water was finally becoming available to the marsh which made it possible to replenish units with ample water. The heavy mountainous precipitation produced a surplus of flow into the Lahontan Basin resulting in 36,000 acre feet of water being released into the Carson Sink, which was not of any benefit to waterfowl. The improved water supply allowed for the restoration of 10,800 acres of marsh by August. The steady supply also replenished the Stillwater PR to optimum operational levels. Dry Lake, Cattail Lake and Diovision Pond were filled to operational levels in the refuge and Goose, Tule and North Lead Lake were filled to operational levels in the management area. The steady supply of water continued through the fall permitting a restored of an additional 6,400 acres, to bring the total acreage recovered to 17,200 acres. Units flooded during this period were: East Alkali Flat #2, Swan Lake, Millan Lake and Willow Lake. Pintail Bay unit was also being filled which added another 1,700 acres of habitat. Pelican Island was receiving the so-called flood releases which had begun in February and high volume flow had continued. BOTULISM (1963): The first outbreak of the summer occurred in late August and centered in the Dry Lake area. An estimated 100 birds died during this outbreak and 8 sick ducks were picked up of which 5 recovered. The Pelican Island area was carefully checked but failed to reveal any signs of affected birds. The outbreak continued through September, with only light losses occurring in the latter part of the month. Approximately 300 dead and 100 sick birds were picked up in the Nutgrass pond. Water was diverted to raise the level and freshen the pond to control the outbreak. By mid-October the disease had consumed more birds in the Nutgrass, Tule Lake areas. The outbreak continued through November with the east side of the Nutgrass pond being the only infested area. There were two other units that had received minor outbreaks, those being Dry Lake and Foxtail. The total number of birds 'picked up was 1,955 with an estimated loss of 2,500 for the entire outbreak. Pelican Island showed no signs of the disease. NR 446 CY 1964 CLIMATIC CONDITIONS: Cold temperatures predominated from January through March. During spring, temperatures increased slightly but generally remained cool and delayed crop growth. High temperatures were not experienced until mid-July, and this heat trend extended into October. Winter set in early, and December temperatures rarely climbed above freezing. This month was marked by uncharacteristic gale winds that began on December 19 and

19 I extended through the end of the month. Precipitation for the year, 4.44 inches, was slightly below the normal average of 4.95 inches. The wettest periods were May and June, with above average rainfall. August and September were the driest. WATER CONDITIONS: Water supply at the beginning of the year was adequate for Stillwater, but not optimum for good marsh vegetation production. As the year progressed the water diminished despite the above average storage at the Lahontan Reservoir. Available water was especially limited from April through September. During these months, water quality deteriorated and adversly affected vegetative growth, forced abondonment of two normally productive sub-units -of the Nutgrass pond and amplified problems of botulism control. The most serious problem facing the refuge was not the lack of water but the timing and distribution of the water. BOTULISM (1964): Stillwter experienced the most severe outbreak since 1952, with losses estimated at 5,250 birds. The first signs of the outbreak occurred in July and resulted in a loss of 90 ducks and 30 shorbirds; there were no more reports of sick or dead birds until August. Three two-man crews were organized between the refuge personnel and the Nevada Fish and Game Department to perform the clean up task which terminated in October. Hospitalization of 3,022 ducks resulted in a recovery rate of 86 percent, with many birds responding to fresh water treatments alone. Others were given 1 to 2cc intraperitoneal injections of botulism anti-toxin (Types A, B and C). A total of 7,111 birds were picked up for hospitalization and carcass disposal.

NR #47 CY 1965 CLIMATIC COMDITIONS: Temperatures were normal during winter. Spring began in March and warm temperatures extended into summer. Cool temperatures prevailed throughout autumn. As winter approached, temperatures dropped to normal for this period. . Precipitation this year was high (7.18 inches), almost 50 percent above the normal annual precipitation of 4.95 inches. The wettest period for the year was May through August. WATER CONDITIONS: Water was ample throughout the year timing and distribution were much improved this year. The surplus of water allowed flushing of areas affected by botulism during the prevoius year. Water flows to the marsh were high during autumn and the beginning of winter. BOTULISM (1965): Even though water was in good supply, botulism still occurred at Stillwater WMA, although records did not indicate which units were affected or when the outbreak occurred. At the begining of the outbreak an estimated 40 birds were picked up dead, 20 were coots and grebes, 10 ducks and 10 black-necked stilts and american avocets. An extimated 80 birds died during this outbreak; five ducks were hospitalized, of which three 20 I survived.

.NR #48 CY 1966 \C CONDITIONS: Winter temperatures were normal, but record

high -temperatures were recorded from March through April. As summer approached, temperatures drastically increased with temperatures of 98 degrees in June. This trend continued in July and August with more than ten days of 100 degree temperatures. September was also uncharacteristically warm, the first frost didn't occur until mid-October. Temperatures did not decline until November and December. Annual precipitaion (3.38 inches) was slightly below the normal of 4.95 inches. • WATER CONDITIONS: Another surplus water year occurred, which provided the marsh with an excess of water. During the first part of the year, water had to be dumped into the Sand Dune, Carson Sink and Big Water areas for the first time in many years. However, beginning in March, the marsh experienced a water deficiency. The primary marsh received less water from March through October, the most critical months for waterfowl. Water was being diverted down the Carson River to the Pelican Island area during the latter part of the year which was also a first in many years. BOTULISM (1966): A mild outbreak occurred during July and August in the Nutgrass, Pintail Bay and Tule Lake ponds and affected an estimated 215 birds. Drying of the flooded mud flats and cool nights in September were credited for ending the outbreak. Seventy ducks were hospitalized of which 71 percent recovered. Table-4, • Birds that were picked up dead. ' 36 Ducks 12 American Coots 12 American Avocets 5 Gulls 3 Western Grebes

Total 68

An estimated 145 birds died during the outbreak.

NR #49 CY 1967 CLIMATIC COMDITIONS: Winter was dry with moderate temperatures. Spring began with lower than normal temperatures and above normal precipitation. March and April received the most moisture in the form of snow and temperatures remained lower than normal. The cool temperatures delayed farming activities as well as waterfowl nesting by a month. During fall, temperatures and precipitation 21 I decreased and dry conditions prevailed through the remainder of the year. December was cold and ice formed early on marsh ponds. WATER CONDITIONS: Water supply to the marsh was adequate and kept the primary units at operational levels. Lahontan Reservoir surplus was being diverted to the Carson Sink/ which did raise concern. The Pelican Island area received a large amount of surplus water from the Lahontan Reservoir. BOTULISM (1967): No diseases were observed during the entire year. NR #50 CY 1968 CLIMATIC CONDITIONS: Weather conditions were not reported for the year, other than that it was considered a normal year. Annual precipitation was 4.84 inches, close to the normal average of 4.95 inches. WATER CONDITIONS: A sizeable acreage of the marsh was drained in early spring and intensive efforts were made to economize the available water. By mid-spring, Stillwater PR had no water in storage and did not get any until late spring. The water shortage was severe during the summer months, and certain areas that supported aquatic growth were lost. Pelican Island also showed a deficiency, in that only 1,238 acre feet of water was released into the area. Ducks, geese and shorebirds used this area in fair numbers until mid-June. BOTULISM (1968): No evidence of disease was observed during the entire year. NR #51 CY 1969 CLIMATIC CONDITIONS: Winter had above normal precipitation and cold temperatures. During January and February precipitation totalled 3.08 inches, 50 percent more than the normal precipitation for that period. Colder than normal temperatures presided until May. The summer was unusually warm, and this heat trend prevailed into the autumn season. The first frost did not occur until October. Cold weather prevailed through the remainder of the season. Annual precipitation (5.77 inches) exceeded the normal average (4.95 inches). WATER CONDITIONS: Water was adequate throughout the year. All units were at operational levels except for Willow-Millen and Swan Lake ponds. Releases down the Carson River continued to the Pelican Island area from March through June at a rate of 400 to 700 cfs. Little water was released during summer to the Big Water area. Water was circulated through the unit which reduced stagnation and salinity. The Willow and Millen Lake units were reflooded in the fall at the end of the irrigation season. 22 BOTULISM (1969): The first outbreak of botulism was at the Carson Lake south of Fallen. Approximately 3,500 birds were affected, 2,000 dead and 1,500 sick. Sick birds were taken to the Stillwater duck hospital. The affected area encompassed approximately 3,000 acres; it was believed that the reflooding of the mudflats caused the problem. At the same time, a minor outbreak occurred at Pintail Bay. Sick or dead birds were also found in Nutgrass and Goose Lake. An estimated 550 birds were affected (250 dead and 300 sick). The principle species affected were Pintail, Green-winged Teal, Northern Shoveler, American Widgeon and Mallard. The outbreak may have been slowed due to diversion of fresh water to Pintail Bay; decreasing night time temperatures and the opening of the hunting season which dispersed birds from the area. The survival rate of hospitalized birds was 90 percent and treatments of anti-toxin injections were given only to the extremely weak birds. NR #52 CY 1970 CLIMATIC CONDITIONS: Winter temperatures were normal. Cooler than normal temperatures prevailed throughout spring and a frost occurred on May 12th. Summer temperatures were normal for this area, but declined by the season's end. A new precipitation average of 5.01 inches was established for this area based on the previous 60-year period. This year's precipitation was 4.16 inches. WATER CONDITIONS: High runoff necessitated a precautionary drawdown of the Lahontan Reservoir in January. This water normally would be released down the Carson River, but due to maintenance on the Coleman Dam, the water was diverted to the Stillwater Point Reservoir. Surplus water filled all units to operational levels. The water supply was adequate until late I August when flows to Willow-Millen and Swan Lake ponds were stopped. By November, all units were again at operational levels.

BOTULISM (1970): A minor outbreak of botulism occurred at the Nutgrass and Pintail Bay areas in September. A total of 685 sick birds were sent to the Stillwater duck hospital, the only treatment given was food and fresh water. Recovery rates were as followed: 82% of the ducks and 61% of the shorebirds. The outbreak consumed 2,200 birds that were picked up. Additional water was diverted to the affected area for freshening and herding was accomplished by harassing birds with Navy helicopters; the problem was cleared by the end of September.

23 I Table 4. Waterfowl affected by botulism based on percentages 1970, Species affected % Green-winged Teal 65 Northern Shovel er 20 Pintail 10 Miscellaneous 5

NR #53 CY 1971 CLIMATIC CONDITIONS: Winter had severe cold weather conditions with temperatures dipping into -9 degrees (F). The cold trend continued through most of the spring, then mid-April the spell broke with warm temperatures. Precipita- tion, up to this period, was 45 percent below normal, but in May the moisture picture changed. It was characterized as the wettest month of the year totalling 1.45 inches of rain over the normal average of 0.59 inches for the month. Most of the summer days were in the high 90's with only two days reaching above 100 degrees. As fall approached the temperatures b'.egan to drop quickly with the first frost occurring on September 18. Autumn was considered warm dispite the early frost, temperatures reached the 80's during mid-October. Annual precipitation, was slightly below the normal average with 4.87 inches of moisture. WATER CONDITIONS: Water supply was excellent this year with all reservoirs holding maximum storage capacities. The Humboldt Sink was full for the first time in many years, which caused a continuous flow into the Carson Sink. Most of the Carson Sink was flooded with water coming south against the Pelican Island perimeter dike. The surplus and good forcast of water caused the Carson Sink to be used as a dumping outlet for surplus water. Stillwater WMA received a surplus of water all year, resulting in all ponds being kept at operational levels. BOTULISM (1971): No outbreaks were reported on the marsh, but Carson Lake again had botulism. As estimated 2,000 birds were affected; sick birds were taken to the Stillwater duck hospital for the usual treatment of fresh water and food. No data was present to indicate species affected or when the outbreak occurred. NR #54 CY 1972 CLIMATIC CONDITIONS: Winter's temperatures were normal for the desert but drier than normally expected. The dry trend continued until May when a total of 0.34 of an inch of rain fell in the area. Cold temperatures and low precipitation marked the entire spring season, then the trend finally changed in June; it received a total of 0.55 inches, slightly above the normal average at 0.41 inches. As the summer progressed, the temperatures increased and the precipitation decreased. Precipitation finally increased during September and October with 3.39 inches of rain falling during this period. The total precipitation for the year was 4.56 inches, which was slightly below the normal 5.01.

24 WATER CONDITIONS: Water supply in the Lahontan Reservoir was 132 percent above normal, which ment that the valley would have a good water year. The dry spring resulted in an early demand for irrigation water, which reduced the early spring flow that normally would be delivered to Stillwater PR. Water was being diverted to the most productive units and by November the Stillwater PR was nearly dry. Late November the outflow was stopped to begin storage of water. The water supply for the marsh was poor, despite the surplus that existeld in the Lahontan Reservoir. BOTULISM (1972): There were no outbreaks reported throughout the year, although some dead birds were found, there was no confirmation of botulism. The Carson . Lake area was again struck with a small, short duration outbreak. The hardest hit area this year was the Humboldt Sink, involving 7-9 thousand dead birds. The Stillwater duck hospital was used for treating the sick; there are no records to indicate survival and loss rates. NR #55 CY 1973 CLIMATIC COMDITIONS: The winter had temperatures and increased precipitation, yielding 3.39 inches compared to the normal average of 1.58 inches. Spring continued with above normal precipitation and warm temperatures. The summer months were considered very hot and dry, which caused high evaporation rates in the marsh. The fall period was considered normal for the area, with moderate temperatures. WATER CONDITIONS: Water supply was rated good for most of the year. September and October were considered the period with the worst water shortage of the year. Water being supplied to the Carson Lake area during this period caused the shortage. BOTULISM (1973): In Stillwater a few dead birds were found, but no evidence of any outbreak was reported. There is no data to indicate the number of birds dying or location of dead birds. NR #56 CY 1974 CLIMATIC CONDITIONS: The weather conditions for the year were considered normal, with no significant changes that abruptly caused any unusal changes at the refuge. WATER CONDITIONS: This year was marked with a shortage of water to the marsh area. The summer months exhibited the most severe shortage of water; impoundments were continually drying out. June was the critical period with five impoundments dried out and the shortage of water continued. July continued with the trend, the operational ponds were maintained below optimal levels. During the month of August, Stillwater PR was completely depleted; two more impoundments dried out, which resulted in seven completely dried. The net water receipts for the year totalled 52,612 acre feet, which was far short of the marsh's requirement of 91,377 acre feet. BOTULISM (1974): Several Birds were found dead at Stillwater, but no evidence or reports of an outbreak occurred. The Carson Lake area was the scene of a

25 small outbreak affecting 650 birds. There were 600 reported dead birds and 50 sick. The sick individuals were treated at the Stillwater duck hospital. NR #57 CY 1975 CLIMATIC CONDITIONS: The weather for most of the year was normal, which had no significant affects on the refuge. The only period that did affect the refuge was an abnormally cold spring, which delayed the irrigation season. WATER CONDITIONS: Water was released from the Lahontan Reservoir in preparation for an expected high runoff. As a result, Stillwater received a large flow of water during this period. The total water for the year was 68,985 acre feet, an increase of 16,373 from the previous year; however, the total was still short of the required 91,377 acre feet required by the marsh. BOTULISM (1975): There was no incidence of disease during the entire year. NR #57 CY 1976 WEATHER CONDITIONS: Weather conditions for most of the year were considered abnormal, with a dry winter and a wet summer. The dry winter affected the marsh significantly, there was a decrease in irrigation drainage water; consequently less water was delivered to the Stillwater PR. The wet summer brought the annual normal average of 5.01 inches to 6,16 inches for the year. . WATER CONDITIONS: The decrease in irrigation water drainage flows caused the Stillwater marsh to have a poor water year. Stillwater is capable of maintaining 22,000 acres of wetlands when supplied with sufficient water, but due to the water shortage only 4,700 acres maintained by the end of the year. The quality of the wetlands that were maintained was considered poor due to the low water levels. BOTULISM (.1976): No-reports of an outbreak. NR #59 1977, 1978, 1979 CLIMATIC CONDITIONS: 1977 - The weather during the winter was considered noraml. The spring began warmer than usual, turning cooler by May. June temperatures escalated slightly above the normal average for the month, but the remainder of the summer was normal. Fall was considered warmer than normal and December continued with the trend. Precipitation was above the annual normal average of 5.01 inches with an annual total of 7.20 inches. 1978 - The warm winter continued with temperatures.averaging above the normal average. The remainder of the year was considered cooler than normal and had the longest prolonged cold spell on record. 1979 - The cold trend continued through this year with an added increase of precipitation. June and July were marked by high rainfall and cool temperatures. Fall broke the cool spell as temperatures increased and precipitation decreased. November exited with cold temperatures that caused early freezes. December temperatures were warmer than normal, which allowed for a higher than average

26 waterfowl useage of the area for the month. WATER CONDITIONS: The water quanity for 1977 was still on a downward trend and more of the marsh dried out. The previous year's 4,000 acres of wetland had been reduced to a mere 1,700 acres. By the end of summer only Cattail Lake, Lead Lake and Dry Lake were provided with water on the refuge marsh. These units were kept at 80 percent of optimum operational'levels. The Ni^t grass porid was operational until the end of September, then it too dried out leaving no units operational in SHMA. 1978 was marked by a slight improvement in water conditions. The 1,700 wetland acres had been increased to 2,627 acres by the beginning of spring. The increased irrigation demands produced the drainage flow necessary to replenish the marsh units that had been dehydrated. The total acreage had reached 4,200 surface acres by mid-summer, with water continually flowing through the Stillwater PR to East Alkali, Swan Lake and all pasture units. The water conditions on the marsh had made a remarkable turn around during 1979, primarily due to the operational spill from the Lahontan Reservoir. This spill would be diverted to the Stillwater PR at a rate of 125 cfs. The increased flow allowed for replenishing of 16,432 wetland acres by the end of April. The high evaporation rates of the summer reduced that acreage to 11,500 by summer's end, but by the end of the irrigation season the acreage had reached 12,000 acres of useable wetlands. Tule Lake and NoYth Nutgrass had been below operational levels, despite the increased water supply to accommodate other more productive units. BOTULISM (1979):, The records reviewed did not indicate any outbreaks for the years of 1977 and 1978, an outbreak was reported during the 1979 period. The first report appeared on September 22, at Tule Lake where an estimated 145 birds were found dead. On September 26, a patrol of the nearby units revealed 190 carcasses at Foxtail Lake. A continuous search of the neighboring units, especially Lead Lake which had historically been a botulism hazard, revealed serious problems. . Lead Lake was also affected by the outbreak and based upon the advanced decomposition state of the carcasses, it was theorized that the outbreak had orginated there. Between September 24 and October 12, a total of 3,040 dead birds and 656 sick birds were removed. The sick birds were hospitalized at the duck hospital and were given no other treatments besides fresh water and food. A recovery rate of 80 percent of the hospitalized sick was noted with only 131 eventually dying. The marsh had had good water conditions during the year on the areas where infected birds were found, thus, there was concern that some other- disease may have caused the die-off. Therefore, three specimens were sent to the National Wildlife Health Laboratory, of which two were diagnosed positive for Avian Botulism Type C. (Total 3,700 affected birds). NR #60 CY 1980 .CLIMATIC CONDITIONS: The entire year was considered cool and wet, with the winter continuing the warm trend experienced in 1979. The increased snowpack in the Sierras and the unusally warm winter temperatures caused an early runoff, which' provided spill water for the Stillwater marsh. Precipitation continued to be above normal throughout spring. This wet condition ceased in mid-July and was

27 not experienced again until September, An abnormal windy condition existed from'March through early fall. WATER CONDITIONS: The marsh received an adequate surplus of water from the beginning of• the year, through the end of spring. Approximately 21,000 acres, of wetlands were flooded during this'period. Due' to the intense windy conditions and summer temperature coupled by a decrease in water flows, the wetland acreage was considered good, but the timing of distribution was the major problem. BOTULISM (1980): The Canvasback Club was the first site of an outbreak in early August. ' The outbreak occurred in a pond that had been drained for aeration and improvement of production of submergent vegetation. The Stillwater Marsh also experienced a small outbreak in the Tule Lake pond on September 10, a few weeks after some dead American White Pelicans were picked up. The outbreak continued through mid-October when it was finally controlled. Dead birds were also found in the Nutgrass and Lead Lake units, but no serious problems developed. The first outbreak of avian cholera reported in the state of Nevada occurred in the Nutgrass unit on the Stillwater WMA during March. Only a few ducks were affected. NR #61 CY 1981 WEATHER CONDITIONS: The winter was characterized by above average temperatures; the trend extended through May. Precipitation during this period was well below the normal average. Temperatures were average during most of the summer, but • did escalate during late August and September. These conditions caused high a evaporation loss in units that suffered from low water inflow. The fall season began with heavy rains that deposited half an inch of rain within three hours. Temperatures were below normal during this period. The total precipitation of 3.8 inches was well below the normal average of 5.01 inches; windy conditions prevailed from spring through summer. WATER CONDITIONS: The water conditions for the year were considered poor. The year began with 19,000 acres of wetlands which were reduced to an estimated 8,500 acres. The lack of precipitation prevented a cancellation of irrigation water; thus, reducing the spill water that otherwise would have been diverted to 'the Stillwater Marsh. The long, hot summer coupled by the windy conditions attributed to increased evaporation of water in all units. By November, the Stillwater PR was all but dry; the poorest water conditions existed in Tule Lake and Swan Check area. BOTULISM (1981): The disease broke out early during June and persisted throughout the summer. Patrolling and collecting efforts were attributed to keeping the outbreak from becoming an epidemic. The areas that were affected were: Lead Lake, Dry Lake, Goose Lake, Swan Check, Tule Lake and South Nutgrass. Sick birds were treated at the duck hospital with fresh water and food. Total losses were as follows; Table 5. Waterfowl affected.

28 Species Number affected Ducks 360 Coots 48 Other Species 55 Total 463 NR #62 CY 1982 CLIMATIC CONDITIONS: The winter began with heavy snow storms and lower than normal temperatures. February broke the trend by having mild temperatures and being dry. Spring was characterized as being cold and wet, with early summer following the trend. By mid-summer the hot typical summer temperatures prevailed for the remainder of the season. September was marked by receiving the earliest snowfall since 1930, making it the wettest September since 1918. The remainder of the year was cooler than normal and higher than normal precipitation. The total for the year was 7.83 inches well above the average normal of 5.01 inches. WATER CONDITIONS: Water conditions for the year were considered very good compared to the previous years.' The year began with 8,500 acres of wetlands, which was escalated to approximately 40,000 acres of habitat by the year's end. The year ended with all developed water areas full (22,000 acres) and at optimal operational levels; plus water was dumped into the Carson Sink, Sand Dunes and Big Water areas. The Still water PR was considered over full at the year's end. BOTULISM (1982): This was the third year in a row that the disease consumed birds at surprisingly low numbers. The outbreak was first observed on July 22, when a total of 186 ducks, 86 coots and 14 other species were picked up dead. A total of 131 sick birds were picked up and hospitalized; 28 died and 103 were sub- sequently released. Data relating to areas affected was not available. Total losses were 314 birds found dead in the field and dying in the hospital. NR #63 CY 1983 CLIMATIC CONDITIONS: The year was marked as being the wettest on record, receiving 8.45 inches compared to the average of 5.01 inches. The year began with mild temperatures and frequent cloudiness resulting in continuous rains. February was marked by high windy conditions, followed by March with its heavy rains. April continued the trend with severe storms occurring almost every other day. Most of the Sierra snow stations were recording new records in depth and/or water content. The summer was characterized as near normal in both temperatures and precipitation, but quickly changed in late August re- turning to the cool wet trend, from September through December the same wet cool condition prevailed. WATER CONDITIONS: Water releases from the Lahontan Reservoir and inflows to the marsh exceeded all previous records during this year. The year had begun with 140,000 surface acres and ended with water covering an estimated 180,000 surface acres. For the third year in a row aTl units were full or over run with water.

29 The Increase flows for all purposes exceeded that needed for habitat maintenance; the marsh took in 17 percent of the Lahontan Reservoirs outflow. The Carson Sink and Battleground Point together encompassed 180,000 surface acres by the end of September. Water to the-Carson sink was also contributed via spills from the Humboldt Sink. The overfill in the Big Water area had caused adverse effects to units preceeding it; water was backed up completely sub- merging all impoundments and structures leaving only Division Road unsubmerged. The primary marsh was also kept at above operational levels along.with the Still water PR. BOTULISM (1&83): The largest outbreak ever experienced at Stillwater occurred during this year with losses escalating to an estimated 52,000 affected birds. The outbreak was first noted in late August in the Nutgrass pond. Over 200 birds composed of coots, ruddy, cinnamon teal, p'intails and redheads were picked up dead in the unit. The hazardous Carson Sink area was carefully patrolled via aerial surveys in anticipation of an outbreak. By late September the outbreak was noted along the east Nutgrass shoreline, with a large number of birds found • dead. Personnel were pooled from several refuges to aid in the clean-up operation of the outbreak, which had rapidly escalated. The large mud flats of the Carson Sink affected more least sandpipers, western sandpipers and american avocets than ducks. Between September 24 and October 31 a total of 43,257 birds were picked up in the Carson Sink alone.- In the marsh units a total of 3,879 birds were picked up. In addition, 581 sick birds were picked up from the marsh units and 826 were picked up in the Carson Sink. These birds were placed in the duck hospital and were supplied with fresh water and grain food; of the above total 442 did not survive. The marsh units affected were Pintail Bay, Nutgrass, Big Water and Goose Lake units, with the largest losses occurring in the Pintail Bay pond. Carcasses were buried in a high ground pit. Table 3. Waterfowl affected by avian botulism. (1983) Species Number affected Northern Pintail 17,549 American Coot 711 Mallard 1,476 Cinnamon Teal 545 Green-winged Teal 2,499 Ruddy duck 1,388 Gadwall 517 Northern Shoveler . 230 American Widgeon 247 Redhead 4,103 Canvasback 353 Ring-becjed 89 Unknown 426 Total 30,133

•30 Table 4. Shorebirds affected by avian botulism. (1983) Species Number affected Western and Least Sandpiper 12,738 American avocet 1,413 Dowitcher 69 G. Plover 18 Black-necked Stilt 4 Western Grebe 36 Eared Grebe 13 Gulls 142 Snowy Egret 1 L.B. Curlew 5 Least Tern 3 D.c. Cormorant 1 Blackbird 1 Unknown Shorebirds 1 Total 14,456

NR #64 CY 1984 CLIMATIC CONDITIONS: The winter was characterized by above normal temperatures and below normal 'precipitation. The trend continued until July; strong winds were also experienced during this month. The remainder of the summer was considered normal by area standards. The fall was -characterized as being cool and wet with moisture being in the form of snow. WATER CONDITIONS: Water in the marsh area was considered excessive for habitat maintenance. Inflow finally ceased to the marsh during February due to low snow pack in the Sierra. Since water was not needed in the lower marsh, the pasture areas were flooded to facilitate geese habitat. The Humboldt River continued to provide the Carson Sink with water throughout the year. This flow caused a six inch rise of water which rose the surface acreage to 188,000; water from the . marsh units were also released to the Carson Sink. The Stillwater PR remained at maximum capacity throughout the year. BOTULISM (1984): The outbreak this year occurred in the Carson Lake area where a estimated 4,061 total dead birds were lost. The losses continued until December when temperatures dropped to nearly freezing levels. Stillwater had an outbreak that was estimated at 4,061 dead and 557 sick birds of which 150 died. Data was not available as to when the outbreak started, but the areas that were affected were; Pintail Bay, Nutgrass, Big Water, Swan Lake, Goose Lake, Swan Check, West Marsh, Tule Lake, Dry Lake and East Alkali.

31 Table 5. Waterfowl affected by avian botulism. (1984) Species Number affecteid Northern Pintail 1,314 American Coot 843 Mallard 527 Cinnamon Teal 149 Green-winged Teal 265 Ruddy duck 212 Gadwall 123 Northern Shoveler 166 American Wigeon 328 Redhead 480 Canvasback 32 Unknown 329 Total 4,917

NR 165 CY 1985 CLIMATIC CONDITIONS: The winter exited with snow storms and cloudy day's, but the average precipitation was slightly below the normal average. Spring began with cooler than .normal temperatures, but then climatic conditions returned to normal status for the area. As May approached temperatures decreased slightly along with a decrease in precipitation; by the end of May the temperatures had increased, and precipitation remained the same. The summer b;egan hotter than normal with a new recorded high temperature being set at 106 degrees F. Precipitation was below the normal average for the period. July broke the warm spell wt.th cooler than normal temperature, but still lacked precipitation. The trend continued through September and extending through the fall; precipitation was finally on the increase, but was only slightly above the normal average. . December was marked as being colder and wetter than would normally be expected. WATER CONDITIONS: The lower marsh units were still submerged from the previous 'years' floods, thus the upper marsh units were kept at optimum operational levels throughout the year despite a decrease in inflows. The decrease of water to the marsh had little affect on the units, and the Stillwater PR had a noticeable drop. At the beginning of winter, water was shut off to all units to

32 allow for filling of the reservoir. The Carson Sink had finally began to recede despite a continuous flow from the Humboldt River; it was theroized that wind action had increased the evaporation rates. BOTULISM;(1985): No botulism outbreaks were noted.

33 1. Setting the 50 cal. machine gun at Battleground Point used for herding birds - 1952.

2. Refuge personnel demonstrating the use of the successful herding 3. Clean-up on Carson Sink - 1952

4. Temporary avian botulism hospital on the Carson River - 1952.

ii I

5 & 6. Views of hospital enclosure for ducks sick with avian botulism. Upper photograph shows original size of enclosure; lower, the extended size which doubled its capacity.

i-ii \. Construction of the housing unit of the hospital - 1956.

Aerial view of housing structure and outline of recovery pond - 1956.

iv I

11. Recovery pond flooded and ready for use

12. Waterfowl patients in recovery pond - 1957.

vi 9. Completed housing structure with fresh water system - 1956.

10. Refuge personnel crew erecting 8 ft. chain!ink fence around recovery pond - 1956. 13. Vegetative growth establishing on pond island and shorelines - 1959.

14. Temporary hospital used on the Carson River during botulism outbreak - 1955

vii i i

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17. Botulism Bay on the Carson Sink inundated by flood waters - 1983 15. Clean-up operation during avian botulism outbreak - 1983.

16. Carson Sink during high water year 1983.

VII 1