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minus of the Humboldt River in Nevada (see the map in Plate ... In 1997 the total amount of water pumped by open-pit gold mines in the basin exceeded ...
WATER RESOURCES RESEARCH,

VOL. 35, NO. 11, PAGES 3489-3494, NOVEMBER

1999

Recreational damages from reservoir storage level changes Eric Huszar, W. DouglassShaw, and Jeffrey Englin Department of Applied Economicsand Statistics,Universityof Nevada, Reno

Noelwah

Netusil

Department of Economics,Reed College,Portland, Oregon

Abstract. Severalextremeeventsaffectingrecreationhave occurredin the Humboldt River Basin of northern Nevada. In 1992, agriculturaluserscompletelydrained Rye Patch Reservoirkilling millionsof fish.Additionally, since1990 gold mineslocatedin the basin havepumpedand dischargedwater into the Humboldt River; in recentyears,discharges have equaledapproximately60% of the river's annualflow. In this paper we developand estimatea joint model of fish catch and recreationdemand,both of which dependon water levels,to assessthe lossesand gainsfrom water level changestied to eventsin the basin.

weather conditionsand the needsof farmers servicedby the water district(see Plate 2). In this paper we developand estimatea joint model of fish The droughtconditionsthat precipitatedthe drawdownof catch and recreation demand that incorporateswater 1½v½1s.Rye Patch in 1992 may reoccur.However, the chancethat a This model is used to assessthe lossesand gainsfrom several completedrawdownwill take placewithin the next20-30 years water-related eventsthat have taken place in the Humboldt has been greatly reducedbecauseof substantialupstreamwaRiver Basin of northern Nevada. ter discharges by open-pitgold mines(again,seePlate 1). The pumpingand dischargingof water by mines,known as In July of 1992 Rye Patch Reservoir,located near the terminusof the HumboldtRiver in Nevada(seethe map in Plate "dewatering,"is required to extractore and stabilizepit walls. 1), was completelydrained.Severedroughtconditions,which In 1997 the total amount of water pumped by open-pit gold 1.

Introduction

started in 1987, reduced water 1½v½1s in the reservoir to criti-

minesin thebasinexceeded 214,000acre-feet (264,076,000 m3)

[NevadaDivisionof WaterResources, 1998].After beingtreated to meet Nevada drinking water standards, approximatelyhalf 179,000acre-feet(220,886,000 m•), had onlya few hundred acre-feetby the beginningof 1992 [U.S.Departmentof Interior, of the pumped water was dischargedinto tributariesof the 1998]. 1992].In Julyof 1992the PershingCountyWater Conservation Humboldt River [NevadaDivisionof WaterResources, Discharges in 1997 represented approximately 60% of the District drew down the reservoir and delivered the water to Humboldt River's average annual flow (195,000 acre-feet) agriculturalusars. (240,630,000 m3)at Imlay,a townlocated justupstream of Rye This completedrainingrepresentsan extremeeventsinceall PatchReservoir.Theseadditionalflowsare large enoughthat, of the fish in the reservoir,consideredin goodyearsto be one even if a drought reoccurred,the amount of water reaching of the stat½'spremier fishcriesfor walleye, bass,trout, and Rye Patch Reservoirfrom mine dischargesshouldsustainircrappi½,were killed. Interestingly,it mightbe assumedthat the rigators in the surroundingarea and recreators using Rye Bureauof Reclamation,whichoperatesthe dam at Rye Patch, Patch Reservoir. would managethe r½scrvoir's water level for the public'sinIn this paper we use data on recreationalanglingvisitsas terestsunderthe publictrustdoctrine.The CaliforniaSupreme reportedby the Nevada State Parks Department to developa Court applied the public trust doctrinein NationalAudubon time seriessingle-siterecreationdemandmodel. This model is SocietyversusSuperiorCourtorAlpine City [1983]. In its deci- usedto calculate(1) the users'lossin consumer's surplusfrom sionthe Court barred the Departmentof Water and Powerof drainingRye PatchReservoirin 1992,(2) the increasein users' the City of Los Angelesfrom claiminga vestedright to divert consumer'ssurplusdue to currentmine discharges that end up waters from tributaries of Mono Lake when the diversions in Rye PatchReservoir,and (3) the lossin consumer's surplus harmed interestsprotectedby the public trust. However, no that will occur when mines stop dischargingwater. We acone in Nevada ever took legal actionto stopthe drawdownof knowledgethat in our revealed preference model, all losses Rye Patch Reservoir. and gainsreflect anglinguse valuesonly. Less severe fluctuations in the r½scrvoir's water level are also A single-site,as opposedto multiple-site,recreationmodel of interestto our studysincethey may affect recreationactiv- is used because few alternative recreation sites exist in the ities such as fishing,boating, and camping and production studyregion that would be viable substitutefisheries.Though activitiessuchas farming.The amountof water storedat Rye the Humboldt River runs in the region, accessto stretchesof Patchfluctuatesgreatlyfrom year to year reflectingunderlying the river is mostlyprivate. Site characteristicsare usuallynot incorporatedinto a singlerecreationsite analysisbecausethe Copyright1999 by the American GeophysicalUnion. data are often cross-sectional and thus do not vary. However, cally low 1½v½1s; the reservoir,with a total storagecapacityof

Paper number1999WR900235.

with time series information

0043-1397/99/1999WR900235 $09.00

water levels on demand can be investigated.Additionally, 3489

on water

levels the influence

of

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Goldmines

Gold mines discharging water into

ElkoCounty

the Humboldt River ortributaries oftheHumboldt River in1997

• Recreation Sites

•'•

Humboldt County **•*'•Z ..,'•,•*• ..•

'

'Z --- 1 I•,•

Wlnnemucc_a_ • , •. •

u•



•.•

Wells

Pershing •, Coun•

• Rese•oir

/

• •

umboldt Sink/

Camon Sink Eureka Coun•



White Rne

Churchill / Lander • Coun•



Coun•

''

'

35

Coun•

70

Miles Plate 1. Map of Humboldt River Basin.

1600

1200 1000 800

200 o

1945

1955

1965

1975

Year Plate

2.

Humboldt

River

flows over time.

1985

1995

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while economistsoften strugglewith the real meaning of a "chokeprice" which simulatesthe eliminationof a recreation site,we canmeaningfullyand simplyexaminethe impactof the 1992 drawdownthat virtually eliminated recreation at Rye Patch Reservoir.

2.

cross-sectional

information

on individual

visitors has

never been collected.

Unlike otherbasins,verylittle hydrologicandfishingquality data existfor the Humboldt River Basin.Using the available data,it wouldhavebeennearlyimpossible to generateenough demandandwater levelvariationto obtainmeaningfulresults unless a multiple-site/multiple-destination model was developed where water levelsdiffered substantiallyat each recreation site [e.g.,Bishopet al., 1989;Cameronet al., 1996;Cordell and Bergstrom,1993;Fadali and Shaw,1998;Jakuset al., 1999; Ward et al., 1997]. Alternatively,statedpreferencedata could be usedinsteadof revealedpreferencedata, but no revealed preferencestudyhasbeen conductedfor Rye Patch. The Nevada State ParksDepartmentcollectsdata on visits to Rye Patch becausethere is an entrancefee for usingthe reservoir; this allows us to estimate the number of visitors from

origincountiesaroundthe state.Models of recreationdemand that use monthly visitation patterns combined with crosssectionaldata have been developed[e.g., Loomis and Creel, 1992; Cameronet al., 1996].A limited number of time series modelsof recreationdemandthat use countylevel data have been developed[Hellerstein,1993; Cooperand Loomis, 1990; Petersonet al., 1985]. Fishing Demand

Begin with demandfor a trip to Rye Patch at time t, Qt. Assume

that

Qt = f(P,, C,, WL,, e,),

(1)

wherePt is the price of a trip to Rye Patch at time t, C, is a measureof fishingqualityfor all speciesof fishat Rye Patchat time t, WLt is the minimumannualwater storagelevel at time t, and et is a randomterm. The priceis, asusual,proxiedusing the travel coststo and from the recreationdestinations,yielding the popular"travelcostmodel" descriptionof (1). 2.2.

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CHANGES

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includedto createan explanatory variablein the equation.We use poundsor biomass,rather than total fish stocked(which includesthe numberof fry), becausewe do not knowthe actual biologicalgrowth processfor speciesstockedat Rye Patch; stockingfry maynot leadto catchablefishfor severalyears.We alsoincludethe minimumwaterstoragelevelat time t to proxy assume that CPUE

The developmentof the joint modellooselyfollowsprevious work of Englinet al., [1997]that linksthe fishcatchprocessto recreationaldemands.The model presentedin this paper is more simplethan theirs in somewaysand was developedto take advantageof the availabledata; time seriesinformation on anglersand water levels is availablefor Rye Patch, while

2.1.

STORAGE

those environmental

Model

detailed

RESERVOIR

factors correlated

with water levels. We

at time t is a function

of stock mass size

Ct : g(St, WEt, ].Lt) ,

(2)

(and water levels):

wheret7representsa catchfunction,St is stocksize,WLt is the water level, and tzt is a randomelementfor the catchprocess. In the empirical applicationwe add a dummy variable for oddlylow storageeffectin 1992,the year that the reservoirwas emptied,and we alsointroducea squaredterm for the stock weight or mass. Equations(1) and (2) each may take specificfunctional forms, both in terms of the deterministicspecificationand statisticalspecification.The normal distributionmight be assumedto hold for either or both equations,and this has acceptablepropertieswhen the dependentvariableis CPUE. We thereforeusethe normaldistributionfor the CPUE empirical equation.Englin et al. [1997] assumethat both demandand catchfollow a Poissonprocessfor the statisticalspecification, but theyusetotal fishcaughtasthe dependentvariable.This is a frequentassumption in travelcostmodeling[see,e.g.,Hellerstein, 1991]. The two equationsabove can be specifiedand estimatedseparately,but we make an effort to empiricallylink them in section 2.3.

2.3.

Joint Model

Englin et al. [1997] estimatedthe fish catch and demand modelsas structurallylinked; one likelihoodfunctionwas developedwhich allowsthe determinantsof catchto jointly influencedemand.Their modelis not fully simultaneous because predictedeffort simplyfeeds into the catch function during estimation.The likelihood functionwe develophere also assumesindependence betweenthe twoprocesses: catchandtrip demand.Suppress the countysubscript (i) andlet demandsbe expressedas

Prob(Qt= qt) = e-'•tTQt/Qt !,

(3)

where]/t ----exp(Xt/3). As we note in section2.2,we simplylet CPUE be distributednormally.One couldpotentiallyestimate thesetwo equationsby estimatinga singlelog likelihoodfunction. Supposethe CPUE contributionto the likelihoodfunction is L•, the combinedlog likelihoodfunctioncan now be simplywritten as

Fish Catch

• ---ml + •/t + Qt(Xt]3) q- In (Qt!)

(4)

Followingseveralother authors[seeEnglinet al., 1997,and referencestherein;Morey and Waldman,1998], we recognize that Ct is itself a functionof effort, which dependson visitation. We specifythe dependentvariable as catchper unit of effort (CPUE), whichis catchdividedby total daysspent.It may be better to model total catchas a functionof measured

whereX includesprice, a constantterm, the minimumwater storagelevel at time t, and an expectedfishingquality measure,in our case,aspredictedby the normallydistributedcatch model. Any statisticsor econometricstext showsthe form for L•, and usingthis,the estimationof (4) is an approachthat is

effort, but one must have a measure of effort that is different

consistent with full-information

maximum

likelihood.

Another

than the measureof trips demandedto do without the model estimationapproachis to estimatethe catch function sepacontainingremainingendogeneity,and we have no suchdata. rately, save the estimatesof predicted catch, and then feed likeliIn mostof Nevada'ssurfacewatersthe Nevada Department these into the demand function. This limited-maximum of Wildlife (NDOW) stocksfish, and we have data on the hoodapproachiswhatwe implement,asit is easierto estimate poundsof fish stockedeachyear, so this informationis also the parametersin sucha nonlinear model.

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Table 1. Empirical Results First-Stage CPUE

ExplanatoryVariable* CPUE

constant

Model? 1.62

(0.280$ Water level/1000 acre-feet

0.0002

(0.0003) 1992 Dummy variable on water level

-0.015

(0.034) Pounds of fish stocked/10,000 fish

0.063

(0.098) Poundsfish squared

-0.076

(0.096) Sigma(SE)

5.21

(2.•5)$ Demand

constant

Annual storagewater level/10,000 acre-feet

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measuresomit this,and potentialbiasfrom that fact shouldbe noted.(Welfaremeasures providea foundationfor the analysis Second-Stage of both the benefitsand the costsof environmentalchangeand Demand are a measuredconsumer's surplus.)One mightarguethat trip Model demandis both conditionalon but separatefrom labor/leisure choicedecisions[seeShawand Feather,1999]. Second,angler trips (reportedin total daysfrom eachcounty)were assumed to be 1-daytrips,whichis reasonablegiventhe countyof origin for most Rye Patch visitors.The trip price variable may be poorly definedfor the few visitorsin the samplefrom faraway counties,leadingto somemeasurementerror, but we have no data to ascertainhow often overnighttrips occur and, if so, how to better measurethe trip price [Shawand Ozog,1999]. U.S. CensusBureauestimatesof eachcounty'spopulationin eachyear were usedto constructthe weightsfor the aggregate 1.59 model. Finally, water levels for each month were obtained (0.422)$ 0.039 from the U.S. GeologicalService;stockingdata for Rye Patch (0.014)$

Travel cost/S100

FROM

were obtained

from NDOW.

-2.58

(0.33)$ Log countypopulation

1.55

(0.123)$

4.

Empirical Results

The catch model is estimatedseparatelyin a first stage. Estimatesfor thismodelare reportedin the secondcolumnof -657.95 - 106123 Log likelihood at convergence Table 1. Maximumlikelihoodestimation(MLE) methodsare usedfor eachmodel, eventhoughusingordinaryleastsquares Oneacre-foot equals1234m3. *Variables were scaled in estimation to make units of variables producesthe sameparametersas MLE for the CPUE model. compatible.The first-stagefishcatchper daymodelis estimatedusing In the separateCPUE model the signsare as expected:The maximum likelihood. linear stock (poundsof fish) variable is positivelyrelated to ?Numbersin parenthesesare White's standarderrors, which are CPUE, asis the linearwater storageleveleffect.Exceptfor the robustto functionmisspecifications. constantand the standarderror the variablesare not strongly $Value is significantat the 1% level. significant,but White's asymptoticstandard errors [White, 1982] are reported,which are robust to specificationerrors. One final adjustmentin the likelihood function is made to Our main concernis how the predictedCPUE can be usedin accountfor the factthat the data(discussed in section3) are at the demand model; the mean prediction using the normal the countylevel. The adjustmentis simplyto use the county distributionof courseequalsthe mean for the actual CPUE. The second-stagemodel parameter estimatesfor the depopulationas a weight in the demandmodel to preservethe propertiesthat the county-levelmodel has in a Poissonde- mandt•unctionare reportedin the third columnof Table 1. All mandmodel[seeHellerstein,1991].One cansimplyincludethe parametersare stronglysignificanteven usingWhite's errors, populationas a regressorin the demandfunction,andwe take exceptthe predictedCPUE variable, which is weakly significant but with the anticipatedpositiveinfluence on demand. this approachbelow. The water storagevariableis positive;people are attractedto the reservoir.The travel costparameterin this model is negPredicted

CPUE

0.144

(o.•o

3.

Data

ative, as it should be, and is used in the calculation of welfare

During our 17-yearstudyperiod, 1980 to 1996,the Nevada effects(changesin consumer's surplus).Theseeffects,aswell in State ParksDepartment recordedapproximately67,730visits asthe calculationsusedto obtainthosefigures,are discussed per year at Rye Patch.Informationon eachvisitor'scountyof section 5. origin was also recorded. Visitors came from each of the 17 countiesin Nevada, althoughcountiesin the southern(and most populated)part of the state "sent" an extremelysmall 5. Lost Benefits/Consumer'sSurplus number of individuals. We have no information on the exact The single-sitePoissonmodel allowsthe very simplecalcunature of the trips taken by thesevisitors. lation of per trip and per seasonconsumer'ssurplus(CS), County-levelvisitationdata are usedin the modelby making corresponding to a "choke"price.At or abovethe chokeprice a few assumptions. First, travelcosts(Pt) are constructed that the sitedemandis equalto zero.The formulasare simply1/13tc vary by origin of the visitor and over time becauseof changes and expectedtrips/13tc, respectively.However,with our aggrein vehicleoperatingcosts.Per-mile costswere obtainedusing gatedcountyversionof the countmodel,"per-trip" resultsare data compiled from the American Automobile Association misleading,and, in fact, the advantageof the model is that by (A. Balicki,personalcommunication, 1998).Costsvariedfrom havingdata for all countiesin the state, the populationesti21.1 centsper mile (1.609 km) in 1980 to 42.6 centsper mile mate of lost or gainedbenefitsis simplyobtainedby summing (1.609km) in 1996.Travel costswere obtainedby multiplying the seasonalwillingnessto pay (WTP) acrossall counties.We the vehicleoperatingcostsfor a givenyear by the round-trip therefore report only seasonalCS. distanceto a centralpoint in the countyof origin.We haveno In the "baseline"case,total WTP is about $470,000per data that would allowaccurateconstructionof the opportunity season($472,428).Thiscanbe interpretedasthetotalseasonal cost of time [e.g., McKean et al., 1995], and so our welfare WTP rather than go without Rye Patch.This value is quite low

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comparedto many other estimatesof aggregateusevalue.We suspectthis is becausethere are very small populationswho currentlyuse the reservoirand becausethere are fairly high travel costsassociatedwith long distanceswhich reduce the consumer'ssurplus. Becausewe have an annual time series,the water level varies

at our singlesite over each year. We are therefore able to calculatea welfare measurefor a changein a site characteristic, which typicallycannot be done with a single-sitemodel. This representsanother advantageof our model comparedto individualand single-sitemodels:With the exceptionof crosssectionaldata pooled acrossall sitesor use of a multiple-site countmodel [Shonkwiler,1999],one cannotinvestigatewelfare changesfor changesin site characteristics usingthe countdata

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regionis sparselypopulated,and the estimatereflectsonly use values for anglers;other recreational values or values that might be linked to preservationor existencemotives are not part of our analysis.If mine dewateringcontinues,asexpected, for the next 20-30 years,the presentvalue of the annualWTP shouldbe calculated;thiswould yield a much larger value for enhanced

water levels at the reservoir.

Even at discount rates

ashigh as 10%, whichare muchhigherthan is currentlybeing recommendedfor policyanalysisby the Federal government, the gains are in the millions of dollars.Large values are not unreasonable; Loomis [1996]findstotal presentvalue benefits for removinga dam to increaseflowsfor salmonto be in the billionsof dollars.He usesthe contingentvaluationtechnique and thusobtainstotal (useand nonuse)values. model. The resultspresentedin this paper haveimportantimplicaFirst, we try to calculatethe welfare measure due to the tionsfor water managementin the Humboldt River Basin.The draining of the reservoirin 1992. Ideally, one would want to estimatedannualWTP to preventthe completeeliminationof calculate the exact loss in welfare which resulted from the 1992 anglingat Rye Patchprovidessomeinsightinto the discounted drawdown,and thiswouldtake subsequent fishstockingefforts damagesfrom future drawdownsthat may occur once the into consideration.Following the fish kills in 1992, a major open-pitgold minesceasedischargingwater into tributariesof stockingeffort did take place. Accordingto the Nevada De- the Humboldt.Our estimateis probablylow comparedto some partment of Wildlife, in 1993 about 97,000 larger fish were "true" numberbecausethe populationof recreatorswill likely stockedat Rye Patch and about 1 million fry fishwere added grow over time, and our model does not forecastor predict in May of that year. The best calculationof welfare impacts how potentialusers(thosewho are not in the market now but would match effort to the loss in stocked fish or stocked mass. could be under some other set of conditions)behavein reModeling exact links between water levels, stockingefforts, sponseto qualitychanges(one needsa modifieddemandstrucand eventualcatch is not possiblehere, as no suchbiological ture to allow for potentialusers'behaviorto be modeled;see model is available and we have no good data separatingfry Shonkwilerand Shaw [1996] or Shaw and Ozog [1999], who from adult fish stocked. allowfor total participationto be influencedby changesin site Instead, we develop a scenariothat examinesthe welfare conditions). Qualitative changesin sport fishingat Rye Patch are likely gain that would have occurredhad the 1992 drawdownnever occurred.To simulate this, we simply replace the minimum sincethe NevadaDepartmentof Wildlife (NDOW) hasmade water level of zero for 1992 with the minimum water storage stockingRye Patch to ensurehigh-qualitysport fishinga top level averagedfor the entire period (1980-1996), which is priority.As a final caveat,as mentionedin section3, we have about45,000acre-feet(222,120m3).For all thesecalculationsa few potential sourcesof measurementerror and potential the 1992 dummyvariable and nonlinearpoundsparameters, bias that may influencethe accuracyof the welfare measures. which are not significantlydifferent from zero in estimation, However,thesemaybe smallin comparisonto the usualerrors are treated as zeros. When the minimum for 1992 is increased that researchersmake in aggregatingto the populationfrom fromnearzeroto approximately 45,000acre-feet (222,120 m3), individual-specificmodels. One advantageof the aggregate the mean expectedcatchrisesslightly,aswould be expectedif count model usedhere over more detailedindividual-specific water level increasesresult in larger catches.Expectedtrips recreationmodelsis that the inclusionof the populationsize also increase,and the seasonalconsumer'ssurplusfor the variabledirectlyin the model allowsdirect estimationof poppopulation of recreatorsvisiting Rye Patch increasesfrom ulation participationand measuresof welfare. $472,428millionto $491,028for a smallgainof about$20,000 ($18,599).In otherwords,giventhe assumptions of our model, if the recreators had faced a minimum of 45,000 acre-feet

(222,120m3) of waterin 1992insteadof a minimumof zero,

7.

Summary and Conclusions

Agriculture and miningare of tremendousimportanceto the

they would have been willing to pay approximately$20,000 economyof the HumboldtRiverBasin,but recreationalsohas more that season to obtain

this increase.

value, and both agricultureand mining activitiesaffect water-

These types of calculationscan be undertaken for any changein water levels. For example,we estimate that the populationof recreatorscurrently(up to 1996) visitingRye Patchwouldhavebeenwillingto payapproximately $80,000to

based recreation

recreate

to allow

in the basin. Federal

trustees

of water

re-

sourcesmight at some point be legally expectedto manage water resourceson behalf of the public, consistentwith the publictrust doctrine.The time seriescountyrecreationmodel increase the amount of water in the reservoir from actual levels presentedin thispaper allowsusto estimatethe effect of water corresponding to the 1986-1995 droughtto about 90,000acre- levelson demand,aswell as somepossibleeffectson expected feet (111,060)eachyear.This largervalueis to be expectedif catch.We noted in section6 that much more work bringing additional waterin RyePatchisa "good"thingfor anglers who togetherfisheriesbiologistsand economistsneedsto be done there.

better

calculation

events such as the reservoir

of welfare drawdown

losses due to actual we considered.

The approachtaken here is important,as it allowsfor some quantificationof potentiallossesfrom drainingRye Patchand The total annual value estimatedfor the "population"of hasimplicationsfor future losseswhen the open-pitgoldmines recreatorsin Nevadashouldbe consideredcarefully.The study stoppumpingand discharginginto tributariesof the Humboldt 6.

Discussion

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restoringthe Elwha River: Resultsof a contingentvaluationsurvey, River. Thoughthe physicalimpactsfrom miningare daunting Water Resour. Res., 332, 441-447, 1996. in their magnitude,no suchestimatesof economiclosseswere Loomis, J., and M. Creel, Recreation benefits of increased flows in attemptedin the environmentalimpactstatements constructed California'sSan Joaquin and StanislausRivers, Rivers,3, 13-20, 1992. for the mining operations.However, the future is highlyuncertain,andviewingour estimatesasmuchmore thanballpark McKean,J. R., D. M. Johnson,andR. G. Walsh,Valuingtime in travel cost demand analysis:An empirical investigation,Land Econ., 71, figureswould not be appropriateat this time. 96-105, 1995.

Acknowledgments. Our thanks go to Daniel Hellerstein and StevenYen for helpfulsuggestions aboutestimatingcountmodelswith aggregatedata. We alsothank Gardner Brown for pointingus toward the interestingwater and propertyrightsissuesand BennyHodgesfor informationon the Humboldt River. Researchis supportedby a WatershedsProgram grant from the National ScienceFoundationand EnvironmentalProtectionAgencyand alsopartiallysupportedby the Nevada ExperimentStationvia USDA W-133 and Hatch grants.We are solelyresponsiblefor the ideashere aswell aspossibleerrorsthat may remain.

References Bishop,R., C. Brown, M. Welsh, K. Boyle, Grand Canyonrecreation and Glen Canyon Dam operations:An economicevaluation, in WesternRegionalResearchProjectInterim Report,vol. 2, edited by K. Boyle,pp. 407-434, Univ. of Maine, Orono, 1989. Cameron,T. A., W. D. Shaw,S. Ragland,J. M. Callaway,and S. Keefe, Using actual and contingentbehaviordata with differinglevelsof aggregationto model recreation demand,J. Agric. Resour.Econ., 21(1), 130-149, 1996. Cooper, J., and J. Loomis, Pooled time-seriescross-sectional travel costmodels:Testingwhetherrecreationbehavioris stableovertime, Leisure Sci., 12, 161-171, 1990.

Morey, E., and D. Waldman, Measurement error in recreation demand models:The joint estimationof participation,site choice,and site characteristics, J. Environ.Econ. Manage.,35, 262-276, 1998. NationalAudubonSocietyversusSuperiorCourt of Alpine City, State of Utah, no. 33Ca13d 419, 1983.

NevadaDivisionof Water Resources,Mine pumpagewithin the Humboldt River Basin,memorandum,CarsonCity, March 3, 1998. Peterson,G., D. Stynes,and J. R. Arnold, The stabilityof a recreation demand model over time, J. Leisure Res., 17, 121-132, 1985.

Shaw,W. D., andP. Feather,Possibilities for includingthe opportunity cost of time in recreationdemand systems,Land Econ., in press, 1999.

Shaw,W. D., and M. T. Ozog, Modeling overnighttrip choice:An applicationof the repeatednestedmultinomiallogit model,Environ. Resour.Econ.,13(4), 397-414, 1999. Shonkwiler,J. S., Recreationdemandsystemsfor multiple site count datatravelcostmodels,in UsingRevealedPreference Modelsto Value RecreationalResources,Cambridge:New Horizons Ser. Environ. Econ., edited by J. Herriges and C. Kling, pp. 253-269, E. Elgar, Northampton,Mass., 1999. Shonkwiler, J. S., and W. D. Shaw, Hurdle count data models in

recreation demand analysis,J. Agric. Resour.Econ., 21, 210-219, 1996.

U.S. Department of the Interior, Final environmentalassessment and findingof no significantimpact:Rye PatchDam modificationsafety of dams program, report, Bur. of Relam. Mid-Pac. Reg., Sacra-

Cordell, H. K., and J. C. Bergstrom,Comparisonof recreationuse mento, Calif., Oct. 1992. values among alternative reservoir water management scenarios, Ward, F., R. Cole, R. Deitner, and K. Green-Hammond,Limiting Water Resour. Res., 29, 247-258, 1993. environmentalprogramcontradictions:A demandsystemsapplicaEnglin, J., D. Lambert, and W. D. Shaw,A Structuralequationsaption to fisherymanagement, Am. J. Agric.Econ., 79, 803-813, 1997. proach to modeling consumptiverecreation demand,J. Environ. White, H., Maximum likelihood estimationof misspecifiedmodels, Econ. Manage.,33, 33-43, 1997. Econometrica, 50, 1-25, 1982. Fadali, E., and W. D. Shaw, Can recreation valuesfor a lake constitute

a market for banked agriculturalwater?, Contemp.Econ. Policy, XV/(October), 433-441, 1998. Hellerstein,D., Using count data modelsin travel costwith aggregate data,Am. J. Agric.Econ.,73(3), 860-866, 1991. Hellerstein, D., Intertemporal data and travel cost analysis,Environ. Resour.Econ.,3(2), 193-204,1993. Jakus,P., P. Dowell, and M. Murray, The effect of fluctuatingwater levelson reservoirfishing,discussion paper, Dep. of Agric. Econ., Univ. of Tenn., Knoxville, 1999.

Loomis,J. B., Measuringthe economicbenefitsof removingdamsand

J. Englin, E. Huszar, and W. D. Shaw, Department of Applied Economics andStatistics, Universityof Nevada,Mail Stop204,Reno,NV 89557-0105.([email protected];[email protected]; wdshaw@ unr.edu) N. Netusil, Department of Economics,Reed College, 3203 SE WoodstockBlvd.,Portland,OR 97202-8199.([email protected])

(ReceivedJuly 13, 1998;revisedJuly 19, 1999; acceptedJuly21, 1999.)