Final Report 

Economic Values of National Park System Resources 

Within the Colorado River Watershed: Phase II 

August 2007 

Prepared for: 

National Park Service 

By, 

Dr. John Duffield, Chris Neher, and Dr. David Patterson 

Department of Mathematical Sciences 

The University of Montana 

Missoula, MT 59812 
2

Acknowledgements 

This report was prepared for the National Park Service Environmental Quality Division 

(cooperative agreement H1200040001, task J2380050112) with substantial assistance 

from Dr. Bruce Peacock and Heather Goeddeke. 

We would like to acknowledge the generous assistance of NPS staff in the Colorado 

River Basin parks including Kevin Schneider, Jim Holland, Linda Jalbert, Jan Balsom, 

Dave Roberts, Matt Malick, and Dave Wood in coordinating site visits and helping to 

identify relevant studies. David Harpman kindly shared his substantial bibliography on 

Colorado River Basin studies, as well as providing copies of his many papers and other 

relevant studies. Alan Kleinman helped educate us on irrigation economics and provided 

copies of recent studies. We are also indebted to George Oamek for providing copies of 

his own and related work in the basin. 

The final report benefited substantially from careful review and comments from Dr. John 

Loomis of Colorado State University. Additionally, helpful review comments were 

provided by Annie Kearns of Mojave National Preserve, Kevin Schneider of Glen 

Canyon NRA, and Dave Harpman, Mike Loring, Brooke Miller-Levy, Margot Selig, and 

Alan Kleinman of the Bureau of Reclamation. 
3

Table of Contents 

Acknowledgements............................................................................................................. 2 

Table of Contents................................................................................................................ 3 

Executive Summary............................................................................................................ 7 

1.0 Introduction................................................................................................................. 11 

2.0 Review of Economic Literature.................................................................................. 14 

2.1 Economics of Recreation ........................................................................................ 14 

2.1.1 Regional Economic Impacts ............................................................................ 15 

2.1.2 Direct Recreational Value Estimates ............................................................... 20 

2.1.3 Passive Value Estimates .................................................................................. 23 

2.1.4 Impact of Water Level on Recreation.............................................................. 29 

2.2 Other Colorado River Uses: Hydropower, Irrigation and Municipal ..................... 31 

3.0 Conduct Additional Analysis Using Existing Data .................................................... 38 

3.1 Analysis Using NPS Visitation and Reclamation Water Quantity Data................. 38 

3.1.1 Lake Powell Case Study .................................................................................. 38 

3.1.2 Lake Mead Case Study .................................................................................... 44 

3.1.3 Curecanti-Blue Mesa Reservoir Case Study.................................................... 54 

3.1.4 Grand Canyon NP - Colorado River through the Grand Canyon Case Study. 55 

3.1.5 Dinosaur NM – Green and Yampa Rivers Case Study.................................... 57 

3.1.6 Canyonlands NP – Colorado River through Cataract Canyon Case Study ..... 58 

3.1.7 Black Canyon of the Gunnison Case Study..................................................... 59 

3.2 Marginal Impacts of Water Levels on NPS Management Costs ............................ 60 

4.0 Comprehensive Estimates of Relevant Economic Values.......................................... 61 

4.1 Regional Economic Impact..................................................................................... 61 

4.2 Marginal Impacts of Water Level Changes ............................................................ 62 

4.3 Direct Recreational Value....................................................................................... 63 

4.4 Passive Use Value................................................................................................... 65 

4.5 Other Competing Water Uses ................................................................................. 65 

5.0 Summary of Uncertainty Analysis and Existing Data Gaps....................................... 67 

5.1 Regional Economic Analysis – Visitor Expenditure Data...................................... 67 

5.2 Direct Recreational Use Values.............................................................................. 68 

5.4 Passive Use Values ................................................................................................. 70 

5.5 Other Competing Water Uses ................................................................................. 70 

5.6 Summary................................................................................................................. 71 

References......................................................................................................................... 72 

Appendices........................................................................................................................ 80 

 
4

List of Tables 

Table 1. Is Sufficient Information Available Now to Produce the Necessary Analysis 

Tools for Phase III?................................................................................................... 10 

Table 2. NPS Colorado River Units and Associated Visitation Characteristics............... 14 

Table 3. MGM2 Estimated Regional Economic Impact of Visitor Spending, by Park 

Unit. (dollar figures are in millions of 2003 dollars, Jobs are number of full and part 

time jobs) .................................................................................................................. 17 

Table 4. Summary of Recent Estimates of Visitor Expenditures at Colorado River NPS 

Units.......................................................................................................................... 19 

Table 5. Summary of Literature and Estimates of Colorado River NPS Units Direct 

Recreational Value Estimates. .................................................................................. 23 

Table 6. Welsh et al. (1995) Estimates of Nonuse Values for Three Glen Canyon Flow 

Scenarios. (2005 dollars) .......................................................................................... 26 

Table 7. Empirical Estimates of Passive Use Values for Water-related Resources. ........ 28 

Table 8. Marginal NEV Estimates for Alternative Grand Canyon Float Colorado River 

Flow Levels............................................................................................................... 29 

Table 9. Booker and Colby (1995) Benefit Transfer for Flatwater Colorado River Basin 

Net Economic Value Estimates. ............................................................................... 30 

Table 10. Booker and Colby Estimated Marginal Recreational Net Economic Value per 

Acre Foot of Reservoir Storage. ............................................................................... 30 

Table 11. Annual Economic Hydropower Benefits of Colorado River System Dams..... 32 

Table 12. Comparison of Alternative Electric Generating Plant Operating Costs (2003$)

................................................................................................................................... 32 

Table 13. Marginal Per Acre Foot Values for Irrigated Agricultural Water Use in the 

Colorado River Basin................................................................................................ 33 

Table 14. Estimated Marginal Agricultural Water Values (1992 dollars)........................ 34 

Table 15. Estimated Municipal Water Benefits: Marginal 1992 Values.......................... 34 

Table 16. Hydropower Production at Basin Reservoirs During Sustained Drought (1992 

$) ............................................................................................................................... 36 

Table 17. Marginal Values for Other Uses ($/af) ............................................................. 37 

Table 18. Explanatory Model of Glen Canyon NRA Visitation as a Function of Lake 

Powell Water Volume and Air Temperature: Monthly 1996-2006 Data. ................ 42 

Table 19. Estimated Marginal Impact of Reservoir Elevation Changes, Lake Powell and 

Lake Mead. ............................................................................................................... 43 

Table 20. Lake Mead Visitation Lake Volume Model: Monthly Data, 1991-2006 ......... 47 

Table 21. Lake Mojave Visitation Lake Volume Model: Monthly Data, 1991-2006. ..... 49 

Table 22. Correlation between Lake Mead and Mojave Visitation: 1991-2007.............. 50 

Table 23. Implied Change in Visitation to Lakes Mead and Mojave from a One Foot 

Change in Lake Level, at Alternative Lake Levels................................................... 51 

Table 24. Explanatory Model of Echo Bay Resort Annual Receipts as a Function of 

Average Lake Mead Volume: 2001-2006................................................................. 53 

Table 25. Estimated Model Results and Changes in Concessionaire Receipts Associated 

with Lake Mead Volume Changes............................................................................ 54 

Table 26. Explanatory Model of June-October Cataract Canyon Float Visits as a Function 

of Flow Levels: 1999-2005 data ............................................................................... 59 
5

Table 27. Estimated Regional Economic Impact of Water-based Recreation Based on 

Available Data (Constant 2005 Dollars)................................................................... 62 

Table 28. Estimated Marginal Changes in Park visitation Associated with Marginal 

Changes in Water Levels. ......................................................................................... 63 

Table 29. Estimated Marginal Changes in Regional Economic Activity Associated with 

Marginal Changes in Water Levels........................................................................... 63 

Table 30. Summary of Direct Recreational Value Estimates for Water-Based 

Recreational visitation toColorado River NPS Units................................................ 64 

Table 31. Estimated Marginal Changes in Net Recreational Benefits Associated with 

Marginal Changes in Water Levels........................................................................... 64 

Table 32. Change in Net Benefits for Other Uses ($/af)................................................... 66 

Table 33. Summary of Available Regional Economic Impact Data for Colorado River 

NPS Units.................................................................................................................. 67 

Table 34. Summary of Uncertainty and Data Gaps Associated with Estimates of Changes 

in Visitation and Regional Economic Impacts with Marginal Changes in Water 

Levels........................................................................................................................ 68 

Table 35. Summary of Uncertainty and Data Gaps Associated with Estimates of Direct 

Recreational Values of Colorado River Basin NPS Units........................................ 69 

Table 36. Summary of Uncertainty and Data Gaps Associated with Estimates of Changes 

in Visitation and Direct Recreational Use Values with Marginal Changes in Water 

Levels........................................................................................................................ 69 

Table 37. Summary of Uncertainty and Data Gaps Associated with Direct Use Net 

Economic Values per Trip. ....................................................................................... 70 

Table 38. Is Sufficient Information Available Now to Produce the Necessary Analysis 

Tools for Phase III?................................................................................................... 71 

List of Figures 

Figure 1. Lake Mead Elevation: Interim Surplus Criteria Alternatives. (Source, Wheeler 

et al. 2002) ................................................................................................................ 12 

Figure 2. Lake Mead Pool Elevations, MSCP Scenarios. (Source Wheeler et al. 2002) 13 

Figure 3. Monthly Plot of Glen Canyon NRA Visitation and Lake Powell Volume: 1996-

2006........................................................................................................................... 40 

Figure 4. Plot of Summer Season Glen Canyon NRA Visitation and Lake Powel Volume: 

1996-2006. ................................................................................................................ 40 

Figure 5. Plot of Seasonal Glen Canyon NRA and Lake Powell Visitation and Water 

Volume Data: 1996-2006.......................................................................................... 41 

Figure 6. Plot of Wahweap Marina Annual Receipts and Average Lake Powell Levels. 43 

Figure 7. Plot of Wahweap Annual Receipts by Lake Powell Average Volume: 1995-

2005........................................................................................................................... 44 

Figure 8. Plot of Monthly Lake Mead Visitation and Lake Mead Reservoir Volume: 

1991-2006. ................................................................................................................ 45 
6

Figure 9. Plot of Annual Lake Mead NRA Visitation and Average Lake Levels. ........... 46 

Figure 10.Plot of Lake Mead NRA Summer Season Visitation by Average Summer Lake 

Mead Water Level: 1991-2006. ................................................................................ 46 

Figure 11. Plot of Monthly Lake Mojave Visitation and Lake Levels: 1991-2006.......... 48 

Figure 12. Plot of Annual Lake Mojave Visitation and Average Lake Level: 1991-2006.

................................................................................................................................... 48 

Figure 13. Comparison of Lake Mead and Lake Mojave Annual Visitation 1991-2006 50 

Figure 14. Comparison of Echo Bay Resort Annual Receipts and Lake Mead Average 

Annual Water Volume: 2001-2006........................................................................... 53 

Figure 15. Plot of Monthly Curecanti NRA Visitation and Blue Mesa Reservoir Average 

Storage: 1996-2005................................................................................................... 54 

Figure 16. Plot of Summer Season Curecanti NRA Visitation by Blue Mesa Reservoir 

Average Summer Storage. ........................................................................................ 55 

Figure 17. Bishop (1997) Relationship Between NEV and Flow Levels on Grand Canyon 

Float (source: Bishop, Figure 5-1)............................................................................ 57 

Figure 18. Plot of Cataract Canyon Float Visitation by Monthly Average Flow Levels: 

June through October, 1999-2005 Data.................................................................... 58 
7

Executive Summary 

This report presents the results of the Phase II investigations of the Economic Values of 

National Park System Resources along the Colorado River. 

For purposes of planning and participation in water resource allocation decisions, the 

National Park Service (NPS) needs to know the economic values of the resources it 

manages within park units along the Colorado River system (including major tributaries). 

At present, the NPS does not have recent or comprehensive values to represent their 

current water-related activities within these Colorado River park units. The purpose of 

this report is to synthesize economic estimates relevant to these resources in the Colorado 

River Basin, provide analysis of several existing data bases, and identify comprehensive 

estimates for all relevant resource uses in the basin. Uncertainty and data gaps are 

identified in these estimates to guide future research in Phase III of this study. 

The NPS Colorado River park units that have significant water-related visitor use include 

Canyonlands National Park, Curecanti National Recreation Area, Dinosaur National 

Monument, Glen Canyon National Recreation Area, Grand Canyon National Park, and 

Lake Mead National Recreation Area. These parks are nationally-important recreation 

and conservation resources, and in 2005 had a total of about 10.5 million recreational 

visits to reservoir and river sites. Other NPS Colorado River park units are Arches 

National Park, Black Canyon of Gunnison National Park, and Rocky Mountain National 

Park. 

Existing economic studies of NPS Colorado River park units and related economics 

literature can be grouped into four main areas: 1) estimates of visitor expenditures and 

associated regional economic impacts, 2) estimates of direct recreational use values (net 

economic benefits as measured by willingness to pay (WTP) over and above trip costs, 3) 

the influence of changing water levels (reservoir elevations and river flows) on 

participation (number of visitors), value per trip, and the regional economy, and 4) 

passive use values, which include the benefits individuals derive from simply knowing 

that a unique natural environment or species exists even if the individual does not visit or 

see the resource. These are sometimes called existence and bequest values. Additionally, 

this report summarizes the economic values associated with other uses of Colorado River 

water including hydroelectric generation, irrigation, and municipal uses. 

Table 1 provides a summary of the available information across these economic measures 

for each of the primary NPS Colorado River recreation resources including: the Yampa 

and Green River sections in Dinosaur National Monument; Blue Mesa, Morrow Point, 

and Crystal Reservoirs in Curecanti National Recreation Area; the Cataract Canyon 

section of the Colorado through Canyonlands National Park; Lake Powell and the 

Colorado River through Glen Canyon (between Glen Canyon Dam and Lee’s Ferry) in 

Glen Canyon National Recreation Area; the Colorado River through the Grand Canyon; 

and Lake Mead and Lake Mojave in Lake Mead National Recreation Area. 
8

With respect to regional economic impact estimates, the main limiting factor is whether 

relatively recent survey-based data is available on visitor expenditures. This data is used 

to derive regional economic impacts using input-output economic models, such as the 

county-level models available in the IMPLAN software. Only two NPS recreational 

resources in the Colorado River basin (Lake Powell and Lake Mojave) have survey-based 

expenditure data collected within the last ten years. Expenditure estimates and associated 

regional economic impact assessments are available for Glen Canyon day float use, and 

for both commercial and private boaters through the Grand Canyon, but this data is now 

over 20 years old. No survey-based estimates are available for half of the resources/units 

listed in Table 1. Estimates have been developed based on analyst and park manager 

judgment; however, where these judgmental estimates can be compared with surveybased estimates, the former appear to be overly conservative. 

With respect to net economic benefits derived from visitor use, relatively current 

estimates are available only for Lake Powell. A partial and quite dated (1978 survey year) 

study is available just for fishing use at Lake Mead, and a high quality study, now twenty 

years old (Bishop et al. 1987) was conducted as part of the Glen Canyon Environmental 

Studies for floating in Glen and Grand Canyon, and fishing in the Lee’s Ferry river 

section. An additional, even older study (Richards et al. 1985) also examined the latter 

use. Additionally, a 1986 survey of Blue Mesa Reservoir visitors (McKean et al. 1995) 

estimated per trip net economic values under several different travel cost parameter 

assumptions. No survey-based estimates of visitor WTP have been conducted for Lake 

Mead, Dinosaur, or Canyonlands park units. These uninvestigated sites support over 75 

percent of water-related visits to NPS Colorado River basin park units. 

The impacts of water levels on recreational values occur through two influences: water 

levels influence the quality of the recreational trip and accordingly the WTP per trip, and 

water levels affect visitor participation. Additionally, there are different measures of 

water for reservoirs (a stock amount, stable over a given period of time) and rivers (a 

flow amount of water passing a point per a period of time). For example, on river 

sections use drops to zero at very low (impassable or quite dangerous) flow levels and 

also to near zero in extreme floods. Participation and trip quality are generally optimized 

at intermediate flow levels. By contrast, use on some reservoirs increases continuously 

with reservoir elevations and is maximized at full pool. By identifying the relationship of 

participation and value to water levels, it is possible to estimate the marginal value of 

water associated with recreational use. This is typically in terms of dollars per acre-foot 

(af) of storage on reservoirs and dollars per cubic foot per second (cfs) or per acre-foot 

per year on rivers. 

Only one previous study was identified that empirically estimated marginal values for 

Colorado River park units. This was again the Bishop et al. 1987 study, which was 

limited to the influence of river flows through Glen and Grand Canyon on the value per 

trip. Because of considerable excess demand for floating trips in the Grand Canyon, 

participation is not correlated with river flows. This study is somewhat dated, as the 

survey was conducted over twenty years ago. Marginal recreation values were reported 
9

for Colorado River basin reservoirs in a 1995 study (Booker and Colby), but the 

estimates were based on the assumption that use would decline with the square of 

reservoir surface area. The authors, using data for 1980 to 1992 on visitation and 

reservoir elevations and surface area, were unable to estimate significant correlations. 

For purposes of this report, existing Bureau of Reclamation (Reclamation) and U.S. 

Geological Survey data on reservoir levels and NPS visitor data were used to estimate 

models that explain visitation as a function of water levels and other data. Statistically 

significant relationships and (generally) high proportions of the variation in monthly 

visitation were estimated for Lake Powell, Lake Mead, Lake Mojave, and for the Cataract 

section of the Colorado and Green Rivers in Canyonlands. No models could be estimated 

for the Dinosaur National Monument section of the Green and Yampa Rivers or the 

Grand Canyon due to excess demand and limits on participation. Additionally, no model 

was estimated for Curecanti due to a lack of time-series data on water-based recreational 

visitation to that park unit. 

Given the development of models of the influence of water levels on visitation, partial 

marginal recreation-related values could be developed only for park units with the 

existing expenditure and/or WTP estimates described earlier in this summary. Partial 

estimates of the net economic benefit per acre foot could be developed for this report 

only for Lake Powell and Lake Mojave. It needs to be emphasized that these are partial 

marginal estimates in that the variation in trip value with reservoir elevation has not been 

investigated at any of these parks. 

Similarly, meaningful regional economic impacts per acre foot could only be derived at 

park units that had both survey-based expenditure data and estimates of the influence of 

water levels on visitation. Such estimates could only be developed for Lake Powell and 

Lake Mojave. 

The last measure of the economic significance of NPS Colorado River park units is 

passive use value. Only one previous study, Welsh et al. 1995 was identified for these 

resources. This study was completed as part of the Glen Canyon Dam Operation EIS, and 

measured national and Western regional values for improved conditions to Grand Canyon 

endangered fish and associated river ecosystems through modified flow regimes. 

Estimated values were on the order of several billion dollars for the national sample. 

Similar studies have been undertaken for nine other Western river ecosystems, as 

described in the main report. Two such studies were identified that related to lake levels 

and lake water quality, at Mono Lake in California and Flathead Lake in Montana. The 

Mono Lake study (Loomis 1989) investigated the willingness of California residents to 

pay increased water bills to increase inflow (and reduce irrigation diversions) that would 

benefit the Mono Lake ecosystem, including bird life. The aggregate estimated value to 

eliminate diversions would be about $1.1 billion per year or $11,400 per acre foot in 

1990. The Welsh et al. (1995) and Loomis (1989)studies indicate that passive use values 

are potentially a large share of the value associated with NPS-related uses in the Colorado 

River basin. To summarize, to date only one such study exists. 
10

In addition to the data gaps discussed here and summarized in Table 1, there is additional 

uncertainty in the direct recreational use estimates in that the studies identified were all 

for single sites. Substitution among sites, for example in response to changing water 

levels, could also affect the estimates, and would require a regional recreational model to 

investigate. The estimated models that relate visitation to water levels are based on 

historical data. There is some uncertainty, which is difficult to quantify, associated with 

factors that were not quantified in the model and could change in the future. Additionally, 

the relationship between some types of use, particularly fishing, and the associated 

impact of water levels on fish habitat, fish populations and distribution, and angler catch 

rates are likely to be complex and not captured in the relatively simple models reported 

below. The survey data summarized below generally had acceptable response rates, 

which should minimize (but not eliminate) non-response bias. Many of the studies did not 

explicitly address this issue, which is an additional source of uncertainty. Finally, several 

of the survey-based studies reported are based on relatively small samples, as reflected in 

the size of the confidence intervals for the estimates, as reported below. 

A preliminary conclusion is that most (perhaps in excess of 80 percent) of the economic 

significance (whether in terms of regional economic impacts, visitor economic benefits, 

marginal values per acre foot, or passive use) of the water-related NPS uses in the 

Colorado River Basin park units cannot be measured reliably with existing studies and 

existing data sets. 

Table 1. Is Sufficient Information Available Now to Produce the Necessary Analysis Tools for Phase 

III? 

Park Unit 

Produce 

Regional 

Economic 

Impacts for 

Water-based 

Visitation? 

Estimate 

Marginal 

Impacts of 

Water level 

on Regional 

Economics? 

Produce 

Direct Use 

Total Value 

Estimates for 

Water-based 

Visitation? 

Estimate 

Marginal 

Impacts of 

Water level 

on NEV? 

Estimated 

Passive Use 

Values? 

Glen Canyon NRA

 Lake Powell YES YES YES PARTIAL NO 

Colo. River (Glen-Lee’s) DATED DATED DATED NO NO 

Lake Mead NRA

 Lake Mead NO NO NO NO NO 

 Lake Mojave YES YES NO NO NO 

Curecanti NRA PARTIAL NO NO NO NO 

Grand Canyon NP

 Grand Canyon Float YES YES DATED PARTIAL DATED 

Dinosaur NM

 Yampa & Green River NO NO NO NO NO 

Canyonlands NP

 Cataract Canyon NO NO NO NO NO 
11

1.0 Introduction 

This report presents the results of the Phase II investigations of the Economic Values of 

National Park System Resources along the Colorado River. 

For purposes of planning and participation in water resource allocation decisions, the 

National Park Service (NPS) needs to know the economic values of the resources it 

manages within park units along the Colorado River system (including major tributaries). 

At present, the NPS does not have recent or comprehensive values to represent their 

current water-related activities within these Colorado River park units. The purpose of 

this report is to synthesize economic estimates relevant to these resources in the Colorado 

River Basin, provide analysis of several existing data bases, and identify comprehensive 

estimates for all relevant resource uses in the basin. Uncertainty and data gaps are 

identified in these estimates to guide future research in Phase III of this study. 

The organization of this paper follows the task description outline of the Statement of 

Work. Task 1 is a synthesis of the existing literature of the relevant economic values of 

the National Park System resources along the Colorado River. This review of the 

literature is presented in Section 1, below. Task 2 calls for additional analyses of existing 

data that are relevant to the economic values of National Park System resources along the 

Colorado River. These analyses are presented in Section 2 of this paper. Section 3 of the 

paper addresses Task 3: identify comprehensive estimates of the relevant economic 

values from the existing literature where appropriate, and presenting marginal values of 

water flows, where feasible. Finally, Section 4 of this paper presents a discussion of the 

remaining data gaps and uncertainties in the comprehensive estimates. This discussion 

provides a guide to future research needs for Phase III of this study. 

The policy context for this report is that water planning and allocation decisions are made 

in the Colorado River Basin based in part on quantitative estimates of alternative policy 

impacts on river uses. For example, hydropower production and values, irrigation 

production and associated employment and output, and municipal uses are routinely 

quantified. However, to date the impacts on NPS resources, including recreation use and 

associated economic impacts, have generally not been quantified. An important exception 

is the Glen Canyon Dam EIS in which impacts of alternative flow regimes on recreational 

and passive use values (Bishop et al 1987; Welsh et al 1996) were quantified (as detailed 

below). As an example of a recent policy analysis, during the year 2000, the Secretary of 

the Interior, acting through the Bureau of Reclamation (Reclamation) considered 

alternative interim surplus criteria under which surplus water would be declared in the 

lower basin for a 15 year interim period to 2016. An EIS was prepared to evaluate the 

potential impacts of alternative criteria. Figure 1 (Fulp and Harkins 2001) shows, for 

example, the impacts on Lake Mead elevation by year across policy alternatives. As can 

be seen, the policies result in significantly different elevations, with a range, for example 

in year 2016, of about 30 feet (equivalent to roughly 3.3 million acre feet of storage) in 

the median projected elevation. In the surplus EIS (Reclamation 2000), the impacts, if 

any, of such an elevation change on recreational visits at Lake Mead, possible associated 
12

economic impacts on the regional economy, or any loss in recreational or passive use 

benefits were not quantified. 

Figure 1. Lake Mead Elevation: Interim Surplus Criteria Alternatives. (Source, Wheeler et al. 2002)

In part, the purpose of this report is to summarize existing information that can shed light 

on whether such impacts, at Lake Mead and other NPS Colorado River units, are in fact 

negligible or substantial when quantified in economic terms. 

It is useful to note that the hydrology computer model now being used by Reclamation is 

the RiverWare modeling platform (Fulp and Harkins, 2001). For basin-wide planning 

over decades (to inform water allocations as embodied in the river Operating Criteria), 

the time step of these analyses is monthly. Accordingly, in the following, where possible 

estimates have been based on monthly data (for example, NPS visitation and water 

elevations or water storage levels). Where marginal values are identified, these are 

generally in units related to acre feet (af) storage or cubic feet per second (cfs), to 

facilitate possible integration of NPS resource quantification into the Reclamation 

modeling framework. 

As further context, other recent studies by Reclamation based on the RiverWare platform 

include: California’s Quantification Settlement Agreement and Reclamation’s 

Inadvertent Overrun Policy; Multiple Species Conservation Program (MSCP), designed 

to conserve habitat and work toward the recovery of threatened and endangered species; 

the impact on water users of alternative approaches to supplying sustainable flows to 

restore biodiversity in the Colorado River Delta; and the operation of Flaming Gorge 
13

Dam (Wheeler, et al. 2002). Figure 2 from the MSCP illustrates the impacts of policy 

alternatives, again in terms of Lake Mead elevations. In this case, the range across 

policies (using scenario means) for much of the 50 year analysis period is on the order of 

50 feet elevation (or approximately 5 million acre feet). Most recently, the Reclamation 

modeling tool played a key role in negotiations among the seven Colorado River states to 

reach a consensus recommendation for managing the river under drought conditions 

(CADSWES, 2006). 

Figure 2. Lake Mead Pool Elevations, MSCP Scenarios. (Source Wheeler et al. 2002)
14

2.0 Review of Economic Literature 

2.1 Economics of Recreation 

The NPS units located along the Colorado River and its tributaries (shown in Table 2) 

accounted for nearly 20 million recreational visits in 2005. Of these, over 10 million 

visits were directly linked to water-based activities, and thus were dependent to some 

extent on water levels within the Colorado River system. Section 2.1, below, summarizes 

the economics literature relevant to recreational use of the Colorado River NPS units. 

Specifically, the literature review examines visitor expenditure estimates and related 

regional economic impacts, recreational use net benefit values, passive use values, and 

the impact of water levels on recreation. 

Table 2. NPS Colorado River Units and Associated Visitation Characteristics. 

Park Unit Waters Type of 

Water 

Total 2005 

Visitationa 

Colorado R. 

Water-related 

2005 visitationa 

Arches NP Borders Colorado R. River 781,670 negligible 

Black Canyon of 

Gunnison NP 

Gunnison R. River 180,814 46 

Canyonlands NP Colorado & Green R. River 393,381 11,508 

Curecanti NRA Blue Mesa, Morrow Point and 

Crystal Reservoirs 

Reservoir 882,768 882,768 

Dinosaur NM Green and Yampa R. River 360,584 12,802 

Glen Canyon 

NRA 

Lake Powell 

Colorado R. 

Reservoir 

River 

1,863,055 

45,671 

1,863,055 

45,671 

Grand Canyon NP Colorado R. River 4,401,522 22,000c 

Lake Mead NRA Lake Mead 

Colorado below Hoover Dam 

Lake Mojave 

Reservoir 

River 

Reservoir 

7,692,438 7,692,438 

Rocky Mountain 

NP 

Headwaters of Colorado R. River 2,798,368 negligible 

a Total 2005 recreational visitation from the NPS Public Use Statistics Office 

http://www2.nature.nps.gov/mpur/index.cfm

b

 The NRA units (Curecanti, Glen Canyon, and Lake Mead) are assumed to be entirely water-based 

recreation. 

c

 Total float use of Grand Canyon has been relatively stable at 20,000 to 24,000 visits in recent years 

(Grand Canyon NP Management Plan FEIS) 

Recreational visitation to NPS units within the Colorado River System are associated 

with significant economic values. These values are generally described within two 

distinct accounting frameworks: net economic value, and regional economic impact. The 

first measure of value, net economic value describes the value associated with park 

visitation in the context of a benefit/cost framework, including both use values and 

passive use values. The second framework, regional economic impact analysis, describes 
15

the impact of visitor spending on a defined local or regional economic area. The net 

economic value (benefit/cost) framework presents the overall value of recreational 

visitation to a resource within the context of the entire national economy. The second 

framework (regional economic impact analysis) provides a much narrower analysis, only 

examining the impact of visitor spending on a local economic area. 

2.1.1 Regional Economic Impacts 

Regional economic impact analysis narrowly examines the effect of visitor spending to a 

site or area (such as Grand Canyon NP) on the local economy surrounding the site. The 

inputs to a regional economic impact analysis focus on visitor spending, and the outputs 

are generally presented in terms of changes in personal income or employment. 

It should be noted that comparability between impact analyses, even for an identical site, 

is not assured. Each regional impact analysis defines a specific “impact area” (often a 

county, group of counties, or state) and only (or should only) counts expenditures made 

within that impact area by visitors coming from outside the impact area. Because 

definitions of the impact area and who constitute local or non-local visitors may vary 

across studies, care should be taken in comparing impact analyses for a specific site or 

park unit. 

It should be further noted that regional economic impact analysis describes impacts on 

one local area only, and ignores expenditure impacts to the remainder of the national 

economy. Specifically, this type of analysis ignores the offsetting loss in spending in 

other areas of the economy that result from visitor spending in a specific site or park 

locale. 

The economic impact of National Park System visitor spending on local economies has 

been previously investigated in a number of contexts. An example for the Colorado River 

is Douglas and Harpman (1995) who estimated the total expenditure by day use rafters, 

anglers, and commercial and private boaters in the Glen Canyon and Grand Canyon river 

corridor. In 2003, Hjerpe and Kim estimated the regional economic impact of Grand 

Canyon floater spending on the output of the local area economy. In addition to 

expenditures on commercial guides and outfitters, recreational visitors spend money on 

lodging, food, gasoline and other consumer items. These expenditures support retail and 

wholesale businesses and create induced spending throughout the regional economy. 

Douglas and Harpman defined their economic region as Coconino and Mohave Counties, 

and used an IMPLAN (Minnesota IMPLAN Group 2005) regional economic model to 

compute job creation. Loomis, Douglas, and Harpman (2005), updated the Douglas and 

Harpman 1995 estimates to 2004 dollars, and identified a total of $22 million in 

nonresident visitor expenditure in these two counties tied to Glen Canyon and Grand 

Canyon recreation. The estimated total number of jobs supported by this expenditure 

(based on the original study) is 586. This is consistent with more recent estimates by 

Douglas (2005) of 438 total jobs created by whitewater boating in the Grand Canyon.
16

Other studies of the regional economic impact of National Park System visitation include 

Neher and Duffield’s (2000) study of the economic impacts of flooding in Yosemite 

National Park, the economic impacts of the 1995-96 federal government shutdown on 

park visitation (Duffield et al. 1996), and the regional economic impacts of changing 

winter use management (for example, banning snowmobile use) in Yellowstone and 

Grand Teton National Parks (Duffield and Neher 2000). 

Visitors to NPS units spend dollars in the local area economies (both inside and outside 

the park boundaries) which stimulate local economic activity. In fact, these local 

economies can be in part dependent on local tourist-centered businesses and park 

management policies (Duffield et al. 1996; Duffield, Neher and Patterson 2006). 

Businesses provide eating, lodging and shopping opportunities for park visitors in 

gateway communities near the park boundaries. 

The spending of visitors to the Colorado River units provide significant economic 

stimulus to the generally relatively rural economies found along the Colorado River. 

Studies of the impacts of visitor spending focus on the relative magnitude and type of 

spending by park visitors. The largest consistent database of park visitor spending is 

found through the NPS Visitor Services Project.1

 This data in conjunction with 

supplemental park-specific visitation data has been used within the framework of the 

NPS-sponsored MGM2 economic impact model2 to estimate the local economic impact 

of recreational visitation to NPS units (Stynes and Probst, 2000). Table 3 summarizes the 

most current MGM2 estimated total regional economic impact on visitor spending, 

personal income and local area employment of recreational visitation to Colorado River 

NPS units. MGM2-estimated total visitor spending for the parks shown range from about 

6 million dollars at the Black Canyon of the Gunnison NP to nearly 300 million dollars at 

Grand Canyon NP. The quality of the data these estimates are based on varies across 

parks. An important difference is whether visitor expenditure estimates are based on 

recent visitor survey data at the parks or analyst judgment. Where recent Visitor Services 

Project survey data or other visitor survey data is not available, the MGM2 model 

substitutes either generic visitor spending data from similar park units or from 

communication with park managers. Other empirical issues in regional economic 

modeling include: the accuracy of the survey data, including possible non-response or 

sample selection bias, the disaggregation of the survey data into relevant IMPLAN 

sectors, and whether the survey accurately identifies the share of total visitor 

expenditures being spent in the local economy. There can also be issues with how well 

the off-the-shelf IMPLAN county-level or, especially, zip code-level models used in 

MGM2 or other modeling efforts accurately characterize the structure of the local 

economy. 

 

1

 The complete Visitor Services Project reports can be downloaded at http://www.psu.uidaho.edu/vsp.htm 2 http://web4.msue.msu.edu/mgm2/
17

Table 3. MGM2 Estimated Regional Economic Impact of Visitor Spending, by Park Unit. (dollar 

figures are in millions of 2003 dollars, Jobs are number of full and part time jobs) 

Park Unit Estimated 

Annual Direct 

Visitor 

Spending 

Estimated 

Indirect and 

Induced 

Spending 

Estimated 

Total 

Spending 

Impact 

Estimated 

Total Personal 

Income Impact 

Estimated 

Total Jobs 

Impact 

(full & 

part time 

jobs) 

Glen Canyon NRA $86.09 $38.80 $124.88 $45.27 2,668 

Lake Mead NRA $176.82 $55.82 $232.64 $81.89 6,052 

Curecanti NRA $28.28 $12.58 $40.86 $14.89 887 

Grand Canyon NP $298.43 $135.58 $434.01 $169.81 7,812 

Dinosaur NM $7.01 $2.27 $9.28 $3.18 237 

Canyonlands NP $12.90 $4.23 $17.13 $5.79 433 

Black Canyon NP $5.92 $1.95 $7.87 $2.66 199 

Arches NP $54.11 $17.81 $71.92 $24.65 1,756 

Rocky Mountain NP $153.66 $50.21 $203.87 $69.22 5,178 

Totals $823.22 $319.25 $1142.46 $417.36 25,222 

Source: MGM2 current impact estimates reported at http://web4.msue.msu.edu/mgm2/

The estimates of regional economic impacts for Grand Canyon NP presented in Table 3 

are also reported and expanded with significant detail in Stynes and Sun (2005). In 

addition to Grand Canyon NP, the Visitor Services Project has completed surveys for 

Glen Canyon NRA (1989), and Arches NP (2003). However, the 1989 Glen Canyon 

NRA study did not collect visitor expenditure data. 

Results of the MGM2 models using generic park expenditure and multiplier data have 

been used in a policy impact analysis for Curecanti NRA examining the use of personal 

watercrafts (Mactec Engineering and Consulting, Inc. et al. 2003). 

In addition to the MGM2-Visitor Services Project regional economic impact data, a 

handful of studies of Colorado River park units (primarily focusing on grand Canyon NP) 

have been completed in recent years. A recent study by the Arizona Hospitality Research 

and Resource Center (2005) provides an in-depth study of the regional economic impact 

associated with visitation to Grand Canyon NP. Bishop et al. (1987) developed estimates 

of river-based recreational visitor expenditures within Grand Canyon NP. As noted 

earlier, Douglas and Harpman (1994) and Harpman (1995) utilized and adapted the 

Bishop expenditure estimates to provide measures of regional economic impact 

associated with Colorado River recreational use between Glen Canyon Dam and Lake 

Mead. 

In a study of recreational use and impacts at Lake Mead, Graefe and Holland (1997) 

collected visitor expenditure data, both within the park unit and in nearby communities. 

The authors note that this data could be used to approximate regional economic impacts, 

but provide several limitations on the applicability of the data for such an analysis. 

Borden et al. (2003) conducted a survey of water-based recreationists below Hoover Dam 

though Lake Mojave. This study estimated the local regional economic impact of waterbased recreation to these river and reservoir sections. 
18

For Glen Canyon NRA two estimates pertaining to visitation impacts on regional 

economic activity were identified. As noted earlier, Douglas and Harpman (1995) 

included the stretch of the Colorado River between Glen Canyon Dam and Lee’s Ferry in 

their analysis of floater and angler impacts. Additionally, Douglas and Johnson (2004) 

report visitor expenditure data for users of Lake Powell, collected during a 1997 visitor 

survey. 

In 1998 Duffield and Neher conducted a 13-park survey of selected NPS units. The 

survey was designed as a visitor opinion survey of the Fee Demonstration Program. 

Included in this survey effort were surveys of visitors at Glen Canyon NRA and Grand 

Canyon NP. Since the primary purpose of the survey was to gather opinions on the Fee 

Demonstration Program, questions not specific to the program were limited in order to 

not unduly burden respondents. However, the surveys did include a limited number of 

questions on visitor expenditures and visitor net economic value per trip. 

A 2004 study of Blue Mesa Reservoir recreation for the Bureau of Reclamation (Munger 

and Vinton 2005) reported visitor expenditure data for the largest reservoir within the 

Curecanti unit. 

Sampling plans were developed for each park unit using maps of each park and 

the expertise of park managers. The final sample for the two Colorado River park units 

surveyed was 248 for Grand Canyon NP, and 150 for Glen Canyon NRA. Response rates 

for the two parks were 68% and 61%, respectively. 

A summary of the recent literature of studies of visitor expenditures at Colorado River 

NPS units, with an emphasis on water-based recreation is detailed in Table 4. The 

estimates presented in the table represent a broad range of methods, dates, and study 

purposes. They are presented in their original study year dollars and metric (e.g., per 

party or per person, per day or per visit) as well as in updated constant 2005 dollars per 

visit. 
19

Table 4. Summary of Recent Estimates of Visitor Expenditures at Colorado River NPS Units. 

Park Unit Studies Expenditure 

Estimates 

(study year $)

Expenditure 

Estimates (2005 $ 

per person visit) 

Notes and Limitations 

MGM2 $77 per party day 

(2003) 

$43 Key parameters based on park 

management judgment 

Douglas and 

Harpman (1994) 

$61 - $187 per 

person (1985) 

$111 - $340 River users between Lee’s 

Ferry and Glen Canyon Dam - 

Dated estimates based on 1985 

survey 

Douglas and 

Johnson (2004) 

$119.77 per person 

(1997) 

$146 Lake Powell visitor data 

Glen Canyon 

NRA 

Duffield and Neher 

(1998) 

$202 per party day 

(1998) 

$187 Somewhat dated 

MGM2 $100 per party day 

(2003) 

$56 Key parameters based on park 

management judgment 

Broden et al. 

(2003) 

$59.02 per person 

day (2003) 

$174 Lake Mead NRA water users 

below Hoover Dam (river and 

Lake Mojave) 

Lake Mead 

NRA 

Martin et al. 1982 $43.00 per angler $122 Only Lake Mead anglers 

MGM2 $75 per party day 

(2003) 

Curecanti NRA $42 Based on default parameters 

Munger and 

Vinton 2005 

$52 per party day 

(2005) 

$24 Summer estimate for primary 

site in the NPS unit 

MGM2, Visitor 

Services Project 

$1,388 per visit 

(2003) 

$1,471 Grand Canyon floaters 

Arizona 

Hospitality Study 

$1,131 per party 

(2005) 

$333 All Grand Canyon visitors 

Harpman (1995) $215-$510 per 

person (1995) 

$275 - $652 Grand Canyon Float below 

Diamond Creek – Based on 

Dated estimates from 1985 

user survey 

Douglas and 

Harpman (1994) 

$517 - $1427 per 

person (1985) 

$941 - $2,597 Grand Canyon Float below 

Lee’s Ferry - Dated estimates 

based on 1985 survey 

Grand Canyon 

NP 

Duffield and Neher 

(1998) 

$198 per party day 

(1998) 

$197 All Grand Canyon Visitors - 

Somewhat Dated 

Dinosaur NM MGM2 $58 per party day 

(2003) 

$32 Based on default parameters 

Canyonlands 

NP 

MGM2 $70 per party day 

(2003) 

$39 Based on default parameters 

Black Canyon 

NP 

MGM2 $75 per party day 

(2003) 

$42 Based on default parameters 

Arches NP MGM2, Visitor 

Services Project 

$172 per party day 

(2003) 

$89 All Arches Visitors 

Rocky 

Mountain NP 

MGM2 $132 per party day $74 Key parameters based on park 

management judgment 

Note: The expenditure estimates presented in the above table for a given park unit do not necessarily 

present strictly comparable measures of visitor spending per person visit. There may be differences in the 

definition of the local spending area, and which visitors are included in the estimates (local v. non-local). 
20

2.1.2 Direct Recreational Value Estimates 

To date the number of published estimates of the value of recreational visits to National 

Park System units is somewhat limited. Kaval and Loomis (2003) identified eleven 

studies that provided 49 activity-specific net economic value (NEV) estimates. The 

activities included sightseeing, boating, picnicking, hiking and wildlife viewing. 

Updating the Kaval and Loomis (2003) average estimates from 1996 dollars to 2005 

dollars indicates an average value per day across all 49 observations of $53.88. The 

updated average that Kaval and Loomis report for the Southwest Region national parks is 

$28.16. As noted earlier, studies of boating in Glen Canyon and Grand Canyon indicate 

net economic values on the order of several hundred dollars per trip and higher. A recent 

study, using a travel cost model, also provides estimates of values for a subset of seven 

National Parks along the Colorado River (Markowski et al. 2004). The results of this 

study, which are still preliminary, indicate that net economic benefits per trip may be 

higher than indicated by earlier work. Studies specific to Colorado River National Parks 

include Bishop (1987), Douglas and Harpman (2004), Douglas and Johnson (2004), 

Martin (1982), Duffield and Neher (1999), and Markowski et al. (2004). These are 

discussed further below and are summarized in Table 5. 

 To date there have been two major economic studies related to NPS-related uses in the 

Colorado River corridor, both in the context of the Glen Canyon studies. These studies 

had a fairly narrow geographic scope (just the river corridor through Glen Canyon and 

Grand Canyon). Both of these earlier studies focused on identifying marginal values, in 

the sense of measuring the change in value associated with moving from the base case or 

no action alternative in the EIS planning process for Glen Canyon Dam to some specific 

alternative. By having these marginal values, it was possible in the EIS process to 

compare the tradeoffs of alternative uses, including recreation and power generation 

values. 

The economic context of these studies is that historically the monthly allocation of flow 

releases at Glen Canyon was based on maximizing the value of power, subject to the 

constraints imposed by other purposes. In the early years of operation, the main 

constraints were providing sufficient available storage for flood control and river 

regulation. Typically this has meant that releases are higher in the months when power is 

most valuable, during the winter heating season and the summer cooling season. For 

example, given the markets for power in the Southwest in the mid-1990’s, releases were 

about 20 percent greater in a typical water year during the months of December, January 

and February and June, July and August, compared to the spring and fall months 

(Harpman 1999a). 

Hourly releases at Glen Canyon Dam historically were driven largely by hydropower 

economics. Prior to 1991, Glen Canyon was operated as a more or less unconstrained 

load following (or peaking) plant, with higher releases during the day and early evening 
21

when power demands (and values) were highest and lower releases during the night. This 

could mean a change from releases as high as 31,500 cfs (plant capacity prior to the late 

1980’s) during the day to as low as 1,000 to 3000 cfs (the historical minimum release in 

winter and summer, respectively). There were no constraints on how quickly these flow 

changes occurred (e.g., no constraint on ramp rates or allowable daily fluctuations). For 

the first several decades of Glen Canyon’s operations, this led to flow level fluctuations 

below the dam on many days on the order of 7 to 12 feet. 

The first Glen Canyon economic study focused on recreational use and was undertaken 

by Bishop et al. (1987). The second study focused on passive uses, and will be discussed 

in a following section. This study was conducted as part of the Glen Canyon 

Environmental Studies program during 1984 and 1985. The overall goal of the Bishop 

study was to evaluate the impacts of alternative flow release patterns from Glen Canyon 

Dam on white-water boating, day-use rafting, and fishing on the Colorado River below 

the dam. The 1987 study authors conducted a several phase investigation in order to 

address their goal. First, user surveys were conducted to identify the attributes of fishing 

and floating trips that provided value to users. A second, more comprehensive contingent 

valuation survey of river users addressed potential changes in resource values associated 

alternative flow release patterns. While Bishop et al. found no statistically significant 

relationship between flow levels and values associated with day-use floating below Glen 

Canyon Dam, they found a strong link between flows and both fishing and whitewater 

boating values. The study found that for whitewater rafters relatively constant flows 

between 20,000 and 25,000 cfs yielded the highest satisfaction and associated values. 

For anglers, a similarly constant flow regime in the 10,000 cfs range yielded improved 

recreational trip values over current flow regimes (Bishop et al. 1987, pp. 170-178). As 

an example of the range in values, the net economic value per trip (willingness to pay 

over and above trip costs) for commercial whitewater boaters was estimated at $127 per 

trip ($236 in 2005 dollars) at a 5,000 cfs flow level and rose to a maximum value of $888 

per trip ($1,653 in 2005 dollars) at higher flows. 

With respect to the significance of recreation use values in the Glen Canyon operations 

context, the influence of flows on recreational values is primarily through the effect on 

the quality of the trip. There is excess demand for river recreation below Lee’s Ferry (use 

is basically always at the permitted capacity in the main season). This limits the potential 

magnitude of changes in use values in response to changing flow regimes. By contrast, 

the nonuse value effects are quite large relative to the foregone power revenues for the 

alternatives examined, and have allocative significance, as noted below. 

For reservoir recreation within Colorado River Basin NPS units, Douglas and Johnson 

(2004) utilized 1997 survey responses for Lake Powell recreational visitors to estimate a 

travel cost model of WTP for trips to the reservoir. The authors estimated that per visit 

consumer surplus for Lake Powell visits ranged from $70.83 (based on a log-log model 

specification) to $159.36 (based on an inverse-price model specification). 

Douglas and Harpman (2004) report dichotomous choice contingent valuation results for 

the same 1997 survey data set as Douglas and Johnson (2004). The dichotomous choice 
22

question valued improvements in angler harvest, water quality (reduced beach closures 

relative to the 1991-1996 period), and archeological site protection and restoration. The 

payment vehicle was the season pass. A current trip valuation question was not included. 

For the authors’ preferred model, household benefits across the summer ranged from 

$396 (1997 dollars) to $1,100 per household per year. On a per visit basis, this implied a 

range in value of $8.63 to $38.92 per visit. It appears from the paper that this is just the 

incremental value of the improved trip. The value, particularly for the archeological site 

scenario, may include passive use, as well as recreational use value. In any case, these 

scenarios are bracketed by the angler harvest values (lowest) and the water quality 

improvement values (highest). 

Martin (1982) estimated NEV per trip for anglers at Lake Mead. A zonal travel cost 

model was estimated for this warm water fishery on data collected on anglers between 

July 1978 and June 1979. In this period, there were an estimated 1.3 million individual 

fishing days of use at Mead, mostly targeting striped and largemouth bass. Estimated 

mean net benefits per individual fishing day were $44.63 to $61.44, depending on the 

specification of the model. Martin et al. (1982) also report angler expenditure per day 

with a mean value of $43 and a median of $29 (1978-79 dollars). 

In 1998, visitors to two Colorado River NPS units (Glen Canyon NRA and Grand 

Canyon NP) were surveyed within the context of a study of visitor attitudes about the 

NPS Fee Demonstration Project. In addition to the survey questions related to the fee 

program, the surveys included a dichotomous choice WTP question designed to elicit 

per-trip NEV responses. These NEV responses were not part of the Fee Demonstration 

Program study objectives, and thus an analysis of the responses was not included within 

the study report (Duffield and Neher 1999). A subsequent analysis of these responses 

indicates that for park visitors who said that visiting the units was the primary purpose of 

their trip away from home, visitors to Glen Canyon NRA have a mean NEV per party trip 

of $383 ($460 in $2005). The 95% confidence interval for the Glen Canyon nonparametric NEV mean is $336 to $584 ($2005). Visitors to Grand Canyon NP had a 

mean NEV per party trip of $319 ($383 in $2005). The 95% confidence interval for the 

Glen Canyon non-parametric NEV mean is $295 to $470 ($2005). The estimated mean 

NEV per visit estimates for this study are Glen Canyon NRA ($109 with a 95% 

confidence interval of $80 to $138), and Grand Canyon NP ($142 with a 95% confidence 

interval of $109 to $174). 

A 1986 survey of visitors to Blue Mesa Reservoir (Curecanti) was undertaken by 

McKean, Johnson, and Walsh. The authors reported net economic value per trip 

estimates under several different sets of assumptions regarding construction of the travel 

cost parameters. The study found NEV per trip for the unit to range from $38 to $101 

(1986 dollars) for the Blue Mesa site. 
23

Table 5. Summary of Literature and Estimates of Colorado River NPS Units Direct Recreational 

Value Estimates. 

Study Description NEV Estimate NEV Estimate 

(2005 $ per visit) 

Bishop et al. 

(1987) 

Study of values of 

Grand Canyon - float boaters 

(CVM) 

$236-$1,653 per trip 

depending on river flow 

level (1985$) 

$430 - $3,000 

Hammer 

(2001) 

Study of Grand Canyon – Floaters 

(TCM) 

$134 per trip (private) 

$314 per trip (commercial) 

$157 (private) 

$368 (commercial) 

Martin (1982) Study of Lake Mead - Fishing 

Values (TCM) 

$44.63 to $61.44 per 

angler day (1978-9$) 

$643 - $887 

Douglas and 

Johnson (2004) 

Travel Cost study of 

Lake Powell – Recreationists 

(TCM) 

$70.84 - $159.35 per 

visit consumer 

surplus (1997 $) 

$86 - $194 

Duffield & 

Neher (1999)a

Visitor survey of Glen Canyon

NRA and Grand Canyon NP

Visitors. (CVM) 

Glen Canyon NRA - $384 

per party trip 

Grand Canyon NP - $319 

per party trip (1988$) 

Glen Canyon $109 

Grand Canyon $142 

Douglas and 

Harpman 

(2004) 

Survey of Glen Canyon - improved 

trip quality scenarios (angler 

harvest, water quality) 

$8.63 to $38.92 per visitb

(1997 $) 

$11 - $47 

McKean et al. 

(1995) 

Survey of Blue Mesa Reservoir

visitors (TCM) 

$37 to $101 per visit 

(1986$) 

$69 - $187 

a

 Consumer surplus estimates were derived in an analysis subsequent to the preparation of the primary 

report on visitor attitudes regarding park fee increases. 

b

 Not total value of current trip, but incremental values due to improvement. 

Just as there is an economic literature on instream flow values, there is a related literature 

on the effect of reservoir levels on recreation. Huszar et al. (1999) developed and 

estimated a joint model of fish catch and recreation demand, both of which depend on 

water levels, to assess the losses and gains from water level changes tied to events in the 

Humboldt River Basin of Northern Nevada. Additionally, Eiswerth and Englin, et al. 

(2000) estimated recreation values for preventing a decline in water levels at, and even 

the total loss of, a large western lake that is drying up. 

2.1.3 Passive Value Estimates 

Passive use values are an indication of the national significance of NPS resources. These 

values are associated with knowing that these resources are in a viable condition and with 

wanting future generations to also be able to enjoy this heritage. 

These motives for nonuse values were first described by Weisbrod (1964) and Krutilla 

(1967) as existence and bequest values. Existence values can derive from merely 

knowing that a given natural environment or population exists in a viable condition. For 
24

example, if there was a proposal to dam the Grand Canyon, many individuals could 

experience a real loss, even though they may have no expectation of ever personally 

visiting the river corridor through the Grand Canyon. Other individuals might similarly 

suffer a loss if the grizzly bear were to be made extinct in the Northern Rockies, even 

though those individuals may have no desire to directly encounter a grizzly. Bequest 

motives derive from ones’ desire to provide for future benefit to children and others in 

future generations. There may be many possible motives for nonuse values, and these 

motives may or may not be mutually exclusive. 

The methods used to estimate nonuse values are so-called stated preference methods 

(including contingent valuation and conjoint analysis (National Research Council 2005)). 

Individuals are asked in a survey to indicate directly the value they place on nonuse 

services or resources. These methods are generally accepted and applied in policy 

analysis, as evidenced by their endorsement as a recommended method in regulatory 

guidelines. These include the Department of the Interior regulations for implementing the 

Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (or 

CERCLA, at 43 CFR part 11) and in the U.S. Environmental Protection Agency’s 

Guidelines for Preparing Economic Analysis (2000). 

These methods have now been widely applied and reported in the published economics 

literature. When contingent valuation as a recommended approach was challenged in 

court (Ohio v. United States Department of Interior, 880 F.2d 432, 474 (D.C. Cir. 1989), 

the court affirmed its usefulness for natural resource damage assessment. Additionally, in 

the context of the development of related regulations for implementation of the Oil 

Pollution Act of 1990 by the National Oceanic and Atmospheric Administration 

(NOAA), the use of contingent valuation was reviewed by a panel which included several 

Nobel laureates in economics. The panel endorsed the use of contingent valuation in a 

litigation setting, subject to the caveat that studies meet certain recommended guidelines 

(Arrow et al 1993). 

The National Research Council (2005, at p. 6) offers the specific guidance that: 

“Economic valuation of changes in ecosystem services should be based on the 

comprehensive definition embodied in the TEV [total economic value] framework; both 

use and non-use values should be estimated.” 

Table 7 provides a summary of passive use studies relevant to water-related NPS 

resources including lakes and rivers (instream flows and endangered fisheries). These 

selected studies are generally in the Southwest or Intermountain West. All of the studies 

use stated preference methods, such as contingent valuation. Data is collected through 

surveys, generally of a resident population in a given geographic area. The choice of 

geographic area should correspond to the “market area” for the passive use service; that is 

to say, an area big enough to include most people expected to hold passive use values for 

the resource at issue. This area may be small for a county or city park of only local 

historical significance, but possibly national in scope for nationally significant resources 

such as the Grand Canyon or Yellowstone. A more complete characterization of the set of 

studies potentially relevant to passive use values for NPS resources is provided in 
25

Appendix B. This includes not only water resource-related river and lake studies, but also 

wetlands, riparian areas, and wilderness areas. 

Key characteristics of the studies summarized in Table 7 include: 1) the resource service 

being valued, generally a change such as increased lake elevations or populations of an 

endangered fish, 2) the payment mechanism (e.g. increase in monthly water bill, increase 

in annual taxes, a one time donation, etc.), 3) the population surveyed, 4) the estimated 

values. 

The only previous estimate of passive use values for Colorado River park units have all 

been for Grand Canyon National Park resources including visibility, river flow-related 

habitat, and wilderness. The first such studies were focused on visibility impacts of the 

Navajo Generating Station and include Schultz et al. (1980), Randall and Stoll (1983), 

Schultz (1983), and Hoehn (1991) as summarized in Appendix B. These and other studies 

eventually led the U.S. Environmental Protection Agency on October 3, 1991, to issue a 

regulation requiring the Navajo Generating Station coal-fired power plant to reduce 

sulfur emissions. In a 1990 study, the annual benefits of achieving 90% emission control 

was estimated to be between $130 and $150 million annually, compared to the estimated 

costs of this control of $89.6 million (1990 dollars). Deck (1997) describes both the 

benefit and cost studies that were the basis of this decision. 

The only passive use study relating to water resources is the Welsh et al. (1995) 

contingent valuation study undertaken as part of the Glen Canyon EIS process (Table 6). 

Harpman, Welsh, and Bishop (1995) describe the importance of nonuse economic values 

as a policy analysis tool, with specific reference to water-influenced resources in the 

Grand Canyon. 

In the Welsh et al (1995) study, contingent valuation methods were applied to estimate 

willingness to pay to improve native vegetation, native fishes, game fish (such as trout), 

river recreation, and cultural sites in Glen Canyon NRA downstream of Glen Canyon 

Dam and in Grand Canyon NP (Welsh et al. 1995). This study utilized a population 

survey of two groups, Western U.S. households within the marketing area for Glen 

Canyon power, and households in the entire U.S. Respondents were asked questions of 

their willingness to pay either increased electric power rates (Western U.S. sample) or 

higher taxes (national sample) to reduce flow fluctuations from Glen Canyon Dam to 

protect wildlife, beaches, and cultural sites. The study results (Table 6) show that the 

“steady flow” scenario that was presented as being most beneficial to resource protection 

also had the highest associated values. 
26

Table 6. Welsh et al. (1995) Estimates of Nonuse Values for Three Glen Canyon Flow Scenarios. 

(2005 dollars) 

National Sample Western US Sample 

Flow Scenario Per Household 

Annual Value 

(millions) Per Household 

Annual Value 

(millions) 

Moderate 

Fluctuations 

$17.74 2,791 $29.05 79 

Low Fluctuations $26.19 4,386 $28.25 80 

Steady Flow $26.91 4,474 $38.02 107 

While the nonuse study for the Colorado River corridor in Grand Canyon NP (Welsh et 

al. 1995) was completed too late to be fully utilized in the 1995 EIS (Reclamation 1995), 

the study findings did have an influence on the EIS outcome. The National Research 

Council panel that reviewed the Glen Canyon Environmental Studies commented 

favorably on this study. Their report stated: “The GCES nonuse value studies are one of 

the most comprehensive efforts to date to measure nonuse values and apply the results to 

policy decisions. ... While not completed in time to be reported in the final EIS, the 

nonuse value results are an important contribution of GCES and deserve full attention as 

decisions are made regarding dam operations.” (National Research Council, 1996, at p. 

135) 

The estimates of the Welsh (1995) contingent valuation study are conservative in that 

Welsh chose in his methodology to count only those “yes” respondents that also indicated 

they would “definitely yes” pay the stated amount. The use of only “definitely yes” 

responses has been shown in other CV validity studies to provide a valid estimate of 

actual willingness to pay. Champ et al. (1997) also found this result in assessing the 

nonuser social value of a program at Grand Canyon NP to remove compacted dirt roads 

on the North Rim of the Canyon to create a wilderness setting. A more recent study by 

Champ and her colleagues that is focused on riparian ecosystems (Duffield, Neher, 

Patterson, and Champ 2006) also found that CV responses with a self-rated high certainty 

of actual contribution corresponded well with actual levels of cash donations. The 

application in this case was to purchases of instream flow rights on dewatered Montana 

streams, primarily to benefit riparian ecosystems, fishery species of special concern, and 

other wild fish. 

As can be noted in Table 7, there have been considerably more studies related to river 

flows and related fisheries (8) than to lakes and reservoirs (2). 

A feature of this literature is that the range of values per household or respondent is quite 

large, and the range in aggregated values would be even greater. For example, the 

Duffield and Patterson study estimated a $2.24 payment per licensed angler, based on a 

one-time cash donation. By contrast, Hanemann, Loomis and Kanninen estimated $181 

per California household per year. To compare these, one would have to compute the 

one-time equivalent (present worth) for the California study, for example at 3% over the 

indefinite future, the implied value is $6,033 per household. (One could also correct for 

inflation to a common year purchasing power.) Additionally, the California number 

would be multiplied by the number of California households (about 11.5 million in 
27

2000), while the other estimate is aggregated over only several thousand resident 

Montana license holders. 

For the two lake studies, values range from about $45 per household for the preservation 

value of Flathead Lake in Montana, to about $5 per month (or $60 per year) for an 

increment of lake elevation at Mono Lake, California. 

Of the two, the Mono Lake study has the relevance as far as informing passive use value 

estimates for changing lake levels. Mono Lake is a hyper-saline lake just east of the 

Sierra Nevada Mountains in California. The saline water makes the lake unsuitable as a 

sport fishery but a very productive habitat for nesting gulls and migratory waterfowl. 

About 100,000 acre-feet of freshwater that would normally flow into Mono Lake is 

diverted each year by Los Angeles Department of Water and Power (Loomis 1989). 

Continuing of these diversions will reduce the lake level and likely eliminate the bird’s 

food supply. However, the lake is not well known or heavily visited. One of the survey 

populations was California households. Respondents were asked to indicate their 

willingness to pay for two different increments of lake level: the difference of a low 

ecologically damaging level and a level achieved by cutting diversions and half, and the 

improvement still further by cutting diversions entirely to achieve an optimal lake 

condition. Payments averaged about $5 in a 1986 survey for each increment, and in a retest, statistically similar results were found in a 1987 follow-up to the same respondents. 

Accordingly, in 1986 dollars, about $10 per household was the value per month placed on 

going from the present diversion of 100,000 AF per year to an optimal lake condition (or 

$120 per year). Aggregated over about 9.5 million California households in 1990, the 

total value is about $1.14 billion per year or $11,400 per acre foot. 
28

Table 7. Empirical Estimates of Passive Use Values for Water-related Resources. 

Authors Survey 

year 

Payment vehicle Resource Survey region Value Estimate Value (2005 $) 

(A) Lakes 

Sutherland and 

Walsh (1985) 

1981 Annual Payment 

into trust fund 

(per household) 

Flathead Lake 

and River 

Montana 

households 

$19.99 existence 

$26.48 bequest 

$36.38 existience 

$48.19 bequest 

Loomis (1989) 1986-7 Monthly water 

bill increase 

(per household) 

Mono Lake CA households 

and Mono L. 

visitors 

$4.12-$5.89 

(households) 

$9.97-$12.15 

(visitors) 

$6.51-$9.31 

(households) 

$15.75-$19.20 

(visitors) 

(B) Rivers 

Hanemann. 

Loomis & 

Kanninen 

(1991) 

1989 Annual 

household WTP 

(per household) 

San Joaquin 

Valey 

California $181 $259 

Duffield and 

Patterson 

(1991) 

1990 One-time 

donation to trust 

fund 

(per person) 

Instream flows 

in Montana 

trout streams 

Montana 

resident and 

nonresident 

fishing license 

holders 

$2.24-$4.64 

(residents) 

$12.60-$17.36 

(nonresidents) 

$3.20-$6.64 

(residents) 

$18.02-$24.82 

(nonresidents) 

Welsh et al. 

(1995) 

1994 Increased electric 

power rates or 

increased taxes 

(per household) 

Colorado R. 

riparian 

ecosystem 

Western U.S. 

households and 

all U.S. 

households 

$17.74-$26.91 

(U.S. sample) 

$29.05-$38.02 

(Western 

sample) 

$22.70-$34.44 

(U.S.) 

$37.18-$48.67 

(Western) 

Brown and 

Duffield 

(1995) 

1988 Annual WTP into 

trust fund 

(per household) 

Bitterroot, 

Bighole, Clark 

Fork, Gallatin 

and Smith 

Rivers 

Phone directory 

listings for 

major MT cities 

and Spokane 

WA 

$6.70 (one river) 

$12.43 (five 

rivers) 

$8.57 (one river) 

$15.91 (five rivers) 

Berrens, 

Ganderton and 

Silva (1996) 

1995 Annual donation 

to trust fund for 5 

years 

(per household) 

Middle Rio 

Grande, Gila, 

Pecos, Rio 

Grande, and 

San Juan 

Rivers 

New Mexico 

residents 

$28.73 - $89.68 $35.63 - $111.20 

Loomis (1996) 1994-5 Additional taxes 

for 10 years 

(per household) 

Elwah River 

system 

Challam Co. 

WA, rest of WA 

and rest of U.S. 

households 

Challam $59 

Rest of WA $73 

Rest of U.S. $68 

Challam $73 

Rest of WA $91 

Rest of U.S. $84 

Berrens et al. 

(1998) 

1995-6 Annual payment 

into trust fund 

(per household) 

Major rivers 

in NM 

NM residents $74 $89 

Berrens et al. 

(2000) 

1995-6 Annual payment 

into trust fund 

(per household) 

Gila, Pecos, 

Rio Grande, 

and San Juan 

Rivers 

NM residents $55 $62 

Duffield, 

Patterson, 

Neher & 

Champ (2006) 

2005 One-time 

donation to trust 

fund 

(per person) 

Small MT 

trout streams 

Resident and 

Nonresident MT 

fishing license 

holders 

$5.73 (residents) 

$31.07 

(nonresidents) 

$5.73 (residents) 

$31.07 

(nonresidents) 
29

2.1.4 Impact of Water Level on Recreation 

The Bishop et al. (1987) economic study, discussed above, is one of a number of such 

studies reported in the economics literature that relate changes in streamflow levels to use 

or nonuse values. Table 8 shows estimates of marginal values of flows at several 

alternative flow levels, based on the Bishop et al. (1987) and Boyle (1993) results. 

Studies such as those by Bishop et al. (1997) usually include recreation, but also may 

include other environmental services such as endangered species. For example, Brown 

(1991) lists nine studies of the value of instream flow for recreational activities including 

fishing, boating, and general shoreline activities. Ward, Roach, and Henderson (1996) 

examined the relationship between reservoir level and recreational levels at several Corps 

of Engineer Reservoirs in the Sacramento, California District. The authors’ travel cost 

modeling showed per acre foot values of reservoir water for recreation ranging from $6 at 

Pine Flat Reservoir to $600 at Success Lake. Duffield et al. (1992) estimated marginal 

WTP per acre foot for a range of flows at two sites, the Bitterroot River in Western 

Montana, and the Big Hole River in the headwaters of the Missouri River system. A 

related study in cooperation with the U.S.D.A. Rocky Mountain Experiment Station in 

Fort Collins estimated nonuse values for these same resources based on a random sample 

of regional households (Brown and Duffield, 1995). 

Table 8. Marginal NEV Estimates for Alternative Grand Canyon Float Colorado River Flow Levels. 

Flow Value per Trip Value per Day 

Commercial 

passengers 

Private boaters Commercial 

passengers 

Private boaters 

(A) Study year dollars 

5,000 cfs 127 111 21 7 

29,000-33,000 cfs 898 688 150 43 

45,000 cfs 732 376 122 24 

(B) 2005 dollars 

5,000 cfs 235 206 39 13 

29,000-33,000 cfs 1664 1276 277 80 

45,000 cfs 1357 697 226 44 

Source: Boyle et al. 1993; Bishop 1987. 

Little empirical study has been done regarding the relationship between reservoir and 

river levels within the Colorado River Basin and recreational visitation. Booker and 

Colby (1995) reported estimated annual net economic benefits of flatwater recreation 

within Colorado Basin reservoirs (Table 9). These estimates utilize a transfer of benefits 

from other recreation studies and a general weighting by type of recreational activity at 

each reservoir. 
30

Table 9. Booker and Colby (1995) Benefit Transfer for Flatwater Colorado River Basin Net 

Economic Value Estimates. 

Reservoir Visitation 

(million/year) Fishing 

($/day) 

Weight Other 

($/day) 

Weight Total 

($1992 

/day) 

Total 

($2005 

/day 

Flaming 

Gorge 

1.65 12.04 0.5 21.21 0.5 16.63 23.11 

Curecanti 

Unit 

0.78 29.22 0.4 21.21 0.6 24.41 33.93 

Navaho 0.59 29.22 0.4 21.21 0.6 24.41 33.93 

Powell 3.20 29.22 0.2 24.21 0.8 25.21 35.04 

Mead 6.76 30.17 0.2 36.16 0.8 34.96 48.59 

Mojave 2.05 30.17 0.2 36.16 0.8 34.96 48.59 

Havasu 1.99 30.17 0.2. 36.16 0.8 34.96 48.59 

Source: Booker and Colby 1995, Table 3, p. 884. 

Booker and Colby (1995) noted that within the Colorado River Basin use of reservoirs is 

assumed to be a declining function of reservoir area or volume. They found no 

significant relationship between Colorado River Basin visitation and reservoir water 

levels for the period 1980-92. Instead, they assumed that visitation at Colorado River 

Basin reservoirs declined as a function of the square root of the reservoir contents. They 

additionally assumed that per trip use benefits did not vary with reservoir levels. Ward 

and Fiore (1987) estimated changes in visitation across New Mexico reservoir sites as a 

function of the square root of reservoir area, but did not examine the effect of reservoir 

levels. Booker and Colby presented estimates of marginal recreational benefits 

associated with water levels at the Basin reservoirs (Table 10). 

Table 10. Booker and Colby Estimated Marginal Recreational Net Economic Value per Acre Foot of 

Reservoir Storage. 

Dam and Reservoir Total Recreation 

Benefits (million 1992$) 

Marginal Recreation 

Benefits (annual 

1992$ per acre foot) 

Marginal 

Recreation 

Benefits (annual 

2005$ per acre 

foot 

Flaming Gorge 23 8.7 12.09 

Curecanti Unit 17 19.5 27.11 

Navaho 12 10.0 13.90 

Glen Canyon Dam/Lake Powell 71 3.7 5.14 

Hoover Dam/Lake Mead 199 10.4 14.46 

Davis Dam/Lake Mojave 72 39.6 55.04 

Parker Dam/Lake Havasu 70 112.4 156.24 

Source: Booker and Colby (1995), Table 4, p. 885. 

While there is support for the ad hoc use of a certain functional relationship between 

water levels and visitation (as reported by Booker and Colby), estimating relationships 

based on observed data for each reservoir or river reach within the Colorado River Basin 

provides a stronger park-specific basis for predicting changes in park visitation as a 
31

function of fluctuating river and reservoir levels. In Section 3.1, existing datasets are 

used to estimate the impact of water levels on recreation for NPS Colorado River park 

units. 

Platt and Munger (1999) authored a report for the BOR reviewing a series of methods for 

evaluating the effect of changing reservoir water elevations on recreation use and value. 

In a follow-on BOR study, Platt (2001) presented a series of use estimation models 

developed to address recreational impacts from fluctuating water levels at two Kansas 

reservoirs. The analysis included models of both water-based recreational activities such 

as boating, fishing, and swimming, and water-associated activities such as picnicking at 

reservoir sites. 

2.2 Other Colorado River Uses: Hydropower, Irrigation and 

Municipal 

The Colorado River and its tributaries are the most significant source of freshwater in the 

arid Southwestern United States. The benefits of this resource include the provision of 

approximately 15 million acre feet of highly valued western water, supplying, among 

other uses, a good share of the agricultural production of California’s Imperial and 

Cochella valleys and municipal and industrial water to several of the West’s largest cities 

including Los Angeles, San Diego, Phoenix, and Las Vegas. Through the hydroelectric 

developments at numerous dams, including Glen Canyon and Hoover Dams, hundreds of 

millions of dollars worth of electric energy are provided annually. 

The most comprehensive estimates of the value of the various Colorado River resource 

uses are in Booker and Young (1991), Booker and Young (1994), Booker (1995) and 

Booker and Colby (1995). These studies identify the marginal values for major Colorado 

River uses and use them in several policy analysis (in the context of a river-reservoir 

simulation model developed for the studies) including the total cost due to a hypothetical 

500-year drought and the economic benefits of interstate transfers between irrigators and 

municipal users. Actual Reclamation depletion schedules for each use are the baseline for 

the analysis. A feature of this study is that values are estimated specific to each major 

facility and user group in the basin. 

Booker and Colby (1995) summarize the valuation parameters (economic benefit 

functions) used in the drought analysis. For example, hydropower value estimates are 

generated for each major hydropower unit in the basin (Table 11) and for marginal values 

per acre-feet. In the following discussion, the Booker and Colby (1995) estimates are 

updated to 2005 values based on existing data and other studies. 
32

Table 11. Annual Economic Hydropower Benefits of Colorado River System Dams. 

Dam and Reservoir Total Hydropower 

Benefits (million 

1992$) 

Marginal 

Hydropower Value 

1992$/acre foot 

Marginal 

Hydropower Value 

2005$/acre foota 

Flaming Gorge 18 19.8 22.57 

Curecanti Unit 109 45.2 51.53 

Navaho 24 17.0 19.38 

Glen Canyon Dam/Lake 

Powell 

223 26.3 29.98 

Hoover Dam/Lake Mead 201 23.6 26.90 

Davis Dam/Lake Mojave 46 5.8 6.61 

Parker Dam/Lake Havasu 23 3.3 3.76 

Source: Booker and Colby (1995) 

a 2005 adjusted values based on percent change in California statewide weighted average retail electricity 

prices between 1992 and 2005. www.energy.ca.gov/electricity

The economic value of water in hydroelectric power generation is based on the avoided 

cost of the next best alternative (Harpman 1995; 2005). Hydropower values reported are 

based on the cost saving of hydropower compared to alternative thermal energy 

production. Hydropower production in the lower basin during peak loading is constrained 

at the upper limit by plant capacities, and more generally by water available for 

discharge. The physical effect of marginal decreases in water flow is then dominantly a 

decrease in base load production. In Booker and Colby (1995) the marginal value of 

lower basin hydropower is conservatively valued at the avoided cost of base load 

production at thermal facilities. Upper Basin hydropower is modeled after the preferred 

alternative in the 1995 final Glen Canyon Dam operation record of decision, roughly 

valuing this hydropower at the average of peaking and baseload. The relative upper and 

lower basin values estimated were $52.40 and $46.90 dollars per megawatt hour 

($/MWhr), respectively. 

Table 12. Comparison of Alternative Electric Generating Plant Operating Costs (2003$) 

Plant Type Variable O&M ($/MWh) Average Fuel Cost ($/MWh) 

Coal 4.09 10.59 

NGCT 2.80 49.04 

NGCCCT 1.77 40.25 

Nuclear 0.44 4.53 

Hydropower 4.80 none 

Source: Harpman (2005) Table 2, p. 11. 

Note: NGCT=natural gas combustion turbine; NGCCCT=natural gas combined cycle combustion turbine. 

Given these values and based on the technical hydrological production relationship 

between hydraulic head (the difference of tailwater and reservoir elevations) , flows, and 

generation, one can generate schedules for each reservoir of the hydropower value at each 

facility as a function of alternative reservoir levels. These estimates are updated here with 

an electric price index, showing just a modest (about 14 percent) increase 1992 to 2005. 
33

An alternative and closely related approach is to use hourly spot market prices. Harpman 

(1999) provides an application in valuing the change in hydropower generation due to the 

flow restrictions introduced since 1995 at Glen Canyon Dam. Reclamation (2005) uses a 

similar model in evaluating a change in flows for endangered fisheries and the impact on 

hydroelectric generation values at Flaming Gorge. Actual recent historical spot market 

prices and projected prices over the period of analysis (based on Reclamation’s Aurora 

model) are reported in this the Flaming Gorge EIS as ranging from $60.00 $/MWhr in 

2002 to a low of $42.60 in 2004 and rising to $65.40 by 2012 (nominal dollars). These 

estimates are in the same range as the updated values estimated by Booker and Colby 

(1995). The actual yearly variation in spot market prices is strongly influenced by fuel 

prices and water availability in the major hydroelectric producing areas, including the 

Pacific Northwest. Variation by season tends to exceed variation across years. For 

example, summer peak prices may be higher than shoulder season (spring fall ) prices by 

a factor of three. 

Hydroelectric generation values are probably the best understood and most predictable of 

the various competing water uses in the Colorado River basin. 

Irrigation values are estimated in Booker and Colby (1995) for each major producing 

region, ranging from Western Colorado to the Central Arizona Project to California 

(Table 13). Additionally, municipal benefits are estimated for each major municipal user 

in the basin including Denver, Las Vegas, and Southern California (Municipal Water 

District or MWD) (Table 15). 

Table 13. Marginal Per Acre Foot Values for Irrigated Agricultural Water Use in the Colorado River 

Basin. 

Region Marginal Value 

at Full Usea

Elasticity of 

Demanda

Marginal value at 

25% reduction 

($/acre-foot)b 

Marginal Value 

at 50% reduction 

(%/acre-foot)b 

(A) 1992 dollars 

Western Colorado 12.20 -0.57 20.18 41.03 

Central Arizona Project 27.10 -2.44 30.49 36.00 

California 27.1 -0.52 47.08 102.55 

(B) 2005 dollars 

Western Colorado 17.32 -0.57 28.66 58.26 

Central Arizona Project 38.48 -2.44 43.30 51.12 

California 38.48 -0.52 66.85 94.93 

a

 from Booker and Colby (1995) 

b

 Derived 

c

 Based on crop price index for Imperial County (CA,AZ) and Mesa County (CO), derived from county 

level agricultural statistics. 
34

Table 14. Estimated Marginal Agricultural Water Values (1992 dollars) 

Agricultural Region Marginal 

Agricultural Value 

at Full Use 

(1992$/af) 

Marginal 

Agricultural Value 

at Full Use 

(2005$/af) 

Price Elasticity of Demand 

Western Colorado 12.2 17.32 -0.57 

Colorado Front Range 13.4 19.03 -0.45 

Wyoming 12.5 17.75 -0.65 

Utah 12.5 17.75 -0.65 

New Mexico 12.2 17.32 -0.57 

San Juan-Chama Export 12.2 17.32 -0.57 

Nevaho IIP 53.9 76.54 -14.77 

CAP 27.1 38.48 -2.44 

Colorado River Indian 

Tribe 

14.5 20.59 -1.79 

Yuma 20.0 28.40 -1.32 

California 27.2 38.62 -0.52 

Source: Booker and Colby 1995. 

Note: 2005 updated values based on average percent change in Imperial County, CA and Mesa County, CO 

crops between 1992 and current year. 

Table 15. Estimated Municipal Water Benefits: Marginal 1992 Values. 

Region Marginal Value at 

Full Use (1992$/af) 

Marginal Value at 

Full Use (2005$/af) 

Price Elasticity of Demand 

Denver 455.1 632 -0.45 

Central Utah Project 453.9 631 -0.45 

Albuquerque 479.8 667 -0.38 

Las Vegas 403.9 561 -0.44 

Central Arizona 362.9 504 -0.43 

MWD (South California) 343.9 478 -0.38 

Source: Booker and Colby 1995. 

Note: marginal 2005 values based on CPI-U change from 1992 to 2005. 

The methodologies for these estimates are widely used (Gibbons 1986; Young 2005). 

Irrigation water is valued as an input in the production of agricultural commodities. 

Accordingly, values will depend on the crop type and its production relationship to water, 

on crop prices, and other inputs such as climatic setting, soils, management, and 

irrigation technology. Booker and Colby (1995) summarize and interpret the literature 

based on linear programming models that assume irrigators optimize among these various 

inputs.. Municipal demand functions were estimated based on current average prices and 

estimated elasticity of demand. 

Booker and Colby’s estimates for irrigation are updated with a crop price index for 

Imperial County (California) and Mesa County (Colorado) using county specific crop 

mix and price changes for 1992 to 2005. For both these representative Lower and Upper 

Basin irrigation areas, the increase is about 42 percent. 
35

The updated (2005 dollars) irrigation marginal values in these tables are similar to values 

estimated in a recent Reclamation EIS (2000) on allocation of water supply and longterm contract execution for the Central Arizona Project. This EIS evaluates the effect of 

changing water allocations and prices between Indian and non-Indian irrigators 

necessitated in part by settlement of Indian water right claims. Reclamation (2005) 

identifies the variable net return (contribution to fixed costs) per acre foot for various 

crops for specific irrigation districts in the Central Arizona Project. For example, the 

maximum amount a farmer would pay for irrigation water per acre foot for grain in Pinal 

County is $41.13 – the level at which it is economic to either switch to groundwater or 

fallow the ground. Forage in Pinal County is $52.12 and cotton is $69.19. These 

estimates have conceptually the same basis as Booker and Colby’s and are in a similar 

range. 

With respect to municipal values, Gibbons (1986) observes that: “One implication of this 

analysis of municipal water values is clear: at the limit, as supply approaches zero, the 

marginal value approaches infinity. When water scarcity is so extreme that people are 

faced with shortages of drinking water, the marginal value of water is certain to be 

greater for this use than for any other water use...” (at p. 20). As an example, a 

transaction recently reported in the Water Strategist (April 2006) was for residential 

water in Pebble Beach, California at a price of $250,000 per acre foot. The equivalent 

acre foot per year value based on a capitalization rate of 6 percent is $15,000. At an 

average of 140 gallons per capita per day, this would imply a monthly utility bill of about 

$200. This is not unimaginable when homes in this area will be selling for many million 

of dollars. 

More specific to Colorado River basin municipal water values, recent water transactions 

between the San Diego County Water Authority and the Imperial Irrigation District (IID) 

are on the order of $375/acrefoot-year at present and escalation to around $600 nominal 

dollars/acre foot in fifteen years. Estimated costs of irrigation efficiency improvements in 

the IID are around $115 per acre foot. 

All of these estimates are for net benefits, not regional economic impacts. Other relevant 

benefits and costs in comparing among alternative uses include conveyance costs and 

salinity damages. Booker and Colby (1995) estimate conveyance costs at $10/af for 

Navajo Indian Irrigation Project users, $87 for CAP, $107 for MWD municipal users and 

$123 for CAP municipal users. Given the range of values for irrigation water, net benefits 

after conveyance are marginal for some regions. Salinity damages are also important in 

interpreting net benefits to irrigation. Damage estimates (in terms of dollars per unit of 

salinity (micrograms per liter) from Booker and Young (1991) are used. These 

parameters imply, for example, municipal damages on the order of $130/af. 

In Booker (1995), these parameters are modeled in the context of a 38 year drought 

sequence from Tarbolton (1995) representing one estimate of the worst extended drought 

(based on tree ring data) occurring during the last 500 years. Table 16 indicates the 

marginal value of instream flow for hydropower (in dollars per acre foot) for different 

years in this sequence. Most striking is that in a severe drought, upper basin reservoir 
36

production goes to zero (reservoirs are at or below minimal intake structures for the 

generation units, the head is zero) while production at lower basin reservoirs is not 

significantly impacted. This table illustrates that hydropower and recreation uses are in 

part complementary in that both benefit from higher reservoir elevations. 

Table 16. Hydropower Production at Basin Reservoirs During Sustained Drought (1992 $) 

Dam and Reservoir Marginal Value of Instream Flow for Hydropower ($/af) 

Base Period Year 16 Year 19 

(A) 1992 dollars per acre-foot 

Flaming Gorge 20.6 16.6 0 

Curecanti Unit 46.9 0 0 

Navaho 17.7 0 0 

Glen Canyon Dam/Lake Powell 27.1 20.9 0 

Hoover Dam/Lake Mead 24.7 24.0 23.0 

Davis Dam/Lake Mojave 5.9 5.9 5.9 

Parker Dam/Lake Havasu 3.4 3.4 3.4 

(B) 2005 dollars per acre-foot 

Flaming Gorge 23.48 18.92 0 

Curecanti Unit 53.47 0 0 

Navaho 20.18 0 0 

Glen Canyon Dam/Lake Powell 30.89 23.83 0 

Hoover Dam/Lake Mead 28.16 27.36 26.22 

Davis Dam/Lake Mojave 6.73 6.73 6.73 

Parker Dam/Lake Havasu 3.88 3.88 3.88 

Source: Booker and Colby 1995. 

Note: 2005 adjusted values based on percent change in California statewide weighted average retail 

electricity prices between 1992 and 2005. www.energy.ca.gov/electricity

There is a very extensive literature on hydropower, irrigation, and municipal uses. Other 

works specific to the Colorado River basin on irrigation economics include Oamek 

(1990), and Lee (1993). 

As noted, we update the Booker estimates with a crop price series and electric cost and 

price data. Electric utility costs were relatively stable through 2005 (except for the 

temporary spike in electric prices due to the West Coast power crisis). Table 17 

summarizes the range in Booker and Colby’s estimates, and, for comparison, shows more 

recent estimates for the Columbia River Basin based on a National Academy of Sciences 

study (NRC, 2004). Columbia River Basin hydropower estimates are relevant given the 

interconnected West Coast energy market, the homogeneity of baseload and peaking 

electric power technology, and a national market for fossil fuels. Irrigation estimates are 

relevant given national market for crops and produce. 
37

Table 17. Marginal Values for Other Uses ($/af) 

Competing Use Columbia River (1999 $) Booker Colorado 

River (1992 $) 

Booker Colorado 

River (2005 $) 

Agriculture 3 – 200 12 – 58a 17 – 82 

Minicipal 34 – 403 344 – 479 478 – 666 

Hydropower 4 – 62 3 – 45 3 - 51 

a Range includes full use and marginal change in drought. 

An important conclusion is that there is a considerable range in hydropower and 

irrigation benefits, depending on the specific characteristic of a facility and region. 

Municipal marginal values tend to be the highest. 

Other evidence of relative values can be observed in water market transactions, which in 

the Colorado River Basin are typically from the main consumptive user, irrigation, to the 

municipalities (Loomis 1992). Brown (2006) summarizes transactions in Western water 

markets 1990-2003. Median prices for leases (2003 dollars per acre-foot) by use are: $69 

bought for municipal use, $15 for irrigation, and $47 for environmental purposes. 

All of the above estimates relate to a benefit-cost accounting framework. The direct 

regional economic impacts related to hydropower production and municipal uses are 

likely to be negligible to non-existent in the local economies where the diversion takes 

place and the hydropower production occurs. Impacts on relative costs for end-consumers 

are likely to be negligible in the large economies where these are concentrated. The local 

regional economic impacts of changes in water allocations for irrigators are likely to be 

significant. These are being quantified by Reclamation in the context of the current 

shortage EIS (Alan Kleinman and Margo Selig, personal communication, 2006). 
38

3.0 Conduct Additional Analysis Using Existing Data 

As noted earlier, valuation associated with the relationship between water levels and 

recreational value has two primary components: 1) the impact of water levels on the 

number of trips taken to a site (the quantitative effect), and 2) the impact of water levels 

on the quality, and therefore value, of recreational experiences at a site (the qualitative 

effect) (Duffield et al. 1992). While the effect of varying water levels on the number of 

trips can be modeled from existing historical use and water level data, estimation of the 

impact of water levels on recreational value per trip generally requires specifically 

designed visitor valuation studies. 

The following sections present estimated models of the first type: impact of varying 

water levels on visitation levels for Colorado River NPS resources. 

 

3.1 Analysis Using NPS Visitation and Reclamation Water 

Quantity Data 

The degree to which changes in water levels impact changes in recreational visitation is 

reflected in estimated relationships between water levels and use levels. This section 

reports preliminary estimates of recreational use functions for the primary NPS managed 

water-based recreational resources along the Colorado River System. The relationship of 

recreational use to water levels is estimated where existing data was available, and 

qualitative descriptions of likely use relationships are presented where data is lacking. 

In order to estimate recreational use functions for water-based recreation associated with 

NPS units in the Colorado River Drainage two primary data series are necessary: data on 

recreational visitation and corresponding data on water levels or flows. Recreational 

visitation data for the following modeling came from NPS gathered data.3

 Water level 

data was drawn from Reclamation historical data4

, and USGS surface water data.5 

Use of aggregated visitation data in the following models supports only a limited 

interpretation of individual behavior and motivation. Other factors may in fact play a part 

in explaining decisions to participate in water-based recreation. As it becomes practicable 

or doable, other factors will be examined in future phases of this work. 

3.1.1 Lake Powell Case Study 

Water-based recreation within Glen Canyon NRA has two primary components: reservoir 

use above Glen Canyon Dam, and river use between the dam and Lee’s Ferry. A model 

of Glen Canyon NRA visitation was estimated based on monthly reservoir volume data. 

 

3

 NPS Visitation Statistics are available at http://www2.nature.nps.gov/mpur/index.cfm 4

 Bureau of Reclamation historical data can be accessed at http://www.usbr.gov/uc/crsp/GetSiteInfo 5

 USGS Water flow data is accessed at http://waterdata.usgs.gov/nwis
39

Figure 3 displays trends in monthly visitation and average lake volume over the period 

from 1996 through 2006. The variability across months in visitation shown in this plot 

reflects the very low levels of winter visitation to the NRA compared to summer and 

shoulder season visitation. Figure 4 shows only the relationship between lake levels and 

visitation for the heavy use summer (June-August) season. These plots suggest that 

declining lake levels are associated with reduced visitation. Figure 5 plots the 

relationship of seasonal visitation at Glen Canyon NRA to average seasonal lake storage 

levels. This plot suggests three distinct approximately linear relationships between 

visitation and water levels within the data. The uppermost line of data points represents 

summer season (June-August) visitation and lake levels. This data suggests a positive 

relationship between lake levels and visitation. The second line of data points is a 

combination of spring and fall season visitation and lake level data. Again the 

relationship suggests a slight positive relationship. The bottom line of data shows the 

winter season visitation and lake level points. In this season, the relationship is less 

clearly positive between the two variables. 

It is possible to model recreational use as a function of reservoir level or per acre feet of 

storage (or some other variable, such as surface area). We report some results below on a 

reservoir elevation basis, but most results are in terms of acre feet of stored volume, to 

facilitate direct comparison to competing and complementary uses including irrigation, 

hydropower, and municipal and industrial use. 

Table 18 reports the parameters for a linear regression model explaining Glen Canyon 

NRA monthly recreational visitation as a function of Lake Powell water storage, monthly 

indicator variables, and average high air temperature. The estimated adjusted r-square 

statistic shows that the model as specified explains approximately 98% of the variation in 

visitation through the inclusion of the explanatory variables. All of the variables have the 

expected sign. The key variables and coefficients for explaining the relationship between 

changing lake levels and changing visitation are the “Lake Powell Volume”, “summervolume interaction”, and “shoulder-volume interaction” variables. The interpretation of 

these coefficients is as follows. The coefficient on “Lake Powell Volume” (0.0000) 

indicates that during the off-season months (November-March) there is no estimated 

statistically significant relationship between water volume and visitation. This 

coefficient is the only non-significant coefficient of the water level variables, indicating 

that the relationship between use and water levels in the off-season is much weaker than 

in the shoulder or summer seasons. 
40

Plot of Monthly Lake Powell Volume and Glen Canyon NRA Visitation: 

1996-2006

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

123456789101112314151617181920212223425262728293031323334536373839404142434445647484950515253545556758596061626364656667869707172737475767778908182838485868788899019293949596979899100 101 12 103 104 105 106 107 108 109 110 1111231415161718192021 122 123 14 125 126 127 128 129 130 131 132

Monthly Data 1996-2006

Monthly Visitation

-

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

Lake Powell Volume (acre feet)

Powell Visitation

Volume

Figure 3. Monthly Plot of Glen Canyon NRA Visitation and Lake Powell Volume: 1996-2006. 

Plot of Summer Season Lake Powell Water Levels and Summer Season 

Visitation: 1996-2006

0

200000

400000

600000

800000

1000000

1200000

1400000

1 2 3 4 5 6 7 8 9 10 11 1996-2006

Average Summer Lake Volume

0

5000000

10000000

15000000

20000000

25000000

Total Summer Visitation

Summer Visitation

Summer Average Volume

Figure 4. Plot of Summer Season Glen Canyon NRA Visitation and Lake Powel Volume: 1996-2006. 
41

Plot of Seasonal Glen Canyon Visitation by Lake Powell Water Volume: 

1996-2006

0

200000

400000

600000

800000

1000000

1200000

1400000

7,500,000 9,500,000 11,500,000 13,500,000 15,500,000 17,500,000 19,500,000 21,500,000 23,500,000 25,500,000

Lake Powell Average Water Volume (acre feet)

Total Seasonal Visitation

Summer Season Data

Spring and Fall Data

Winter Season Data

Figure 5. Plot of Seasonal Glen Canyon NRA and Lake Powell Visitation and Water Volume Data: 

1996-2006. 

The other water level variables, “summer-volume interaction” representing levels in the 

June-August months, and “shoulder-volume interaction” representing levels in April and 

May and September and October, are highly statistically significant (at the 99% level of 

confidence). The “shoulder-volume interaction” coefficient indicates that during the four 

“shoulder season” months 1,000 acre feet of storage is associated with 4.1 visits per 

month (the coefficients 0.00405 times 1,000). The “summer interaction” coefficient 

shows that during the June through August period an additional 1,000 acre feet of Lake 

Powell storage is associated with an additional 9.2 recreational visitors per month. Table 

19 shows the marginal effects of volume on Glen Canyon NRA recreational visitation. 

Overall, the Powell/Glen Canyon model provides a statistically significant estimate of the 

marginal impact of varying lake levels on visits during two primary visitation seasons. 

As would be generally expected, the greatest impact is found in the summer months. The 

shoulder season showed the next largest marginal impact, and the off-season no 

significant marginal impact (Table 19). Within the range of data used in the explanatory 

model, it is predicted that an additional 1,000 acre feet of water in Lake Powell during the 

entire year would be associated with an increase in recreational visitation to Glen Canyon 

NRA of an estimated 44.0 visits. 

In addition to the variables reported in Table 18, additional variables were modeled 

including monthly regional gasoline prices, and indicator variables for critical lake levels 

which impact visitor use (such as the lake level at which Castle Rock Cut becomes 
42

passable and the level at which the Hite Marina access (now closed) was accessible). 

While models including only reservoir volume or only indicator variables for Castle Rock 

Cut were individually significant, models including both variables were not. The two 

models can be viewed as alternative ways of modeling use. The model presented in 

Table 18 describes marginal changes in visitation throughout the full range of observed 

lake levels, while a model including only the indicator variable for the lake level at which 

Castle Rock Cut is passable describes a step function showing only two water leveldependent levels of visitation, that above lake level 3620, and that below. The 

continuous model had more explanatory power. 

Table 18. Explanatory Model of Glen Canyon NRA Visitation as a Function of Lake Powell Water 

Volume and Air Temperature: Monthly 1996-2006 Data. 

Lake Powell Visitation-Water Volume Model: 

Monthly Data 1996-2006 

 

Regression Statistics 

Multiple R 0.992 

R Square 0.983 

Adjusted R Square 0.982 

Standard Error 16,416.17 

Observations 132 

 

ANOVA 

 df SS MS F Significance F 

Regression 11 1.91503E+12 1.74E+11 646.0113 3.584E-101 

Residual 120 32338889868 2.69E+08 

Total 131 1.94737E+12 

 

 Coefficients Standard Error t Stat P-value Lower 95% Upper 95% 

Intercept (63,642.959) 16112.45761 (3.95) 0.00 (95,544.48) (31,741.44) 

Volume 0.0000003 0.000485283 0.00 1.00 (0.000961) 0.000961 

april (19,506.720) 13950.69353 (1.40) 0.16 (47,128.10) 8,114.66 

may 19,516.654 16185.44679 1.21 0.23 (12,529.38) 51,562.69 

june 22,829.816 19146.27904 1.19 0.24 (15,078.46) 60,738.09 

july 47,217.525 20289.00488 2.33 0.02 7,046.74 87,388.32 

august 30,434.792 19186.35037 1.59 0.12 (7,552.82) 68,422.40 

september 13,254.564 16578.48033 0.80 0.43 (19,569.65) 46,078.78 

october (25,550.088) 14352.27159 (1.78) 0.08 (53,966.57) 2,866.39 

Summer interaction 0.00919 0.000744446 12.35 0.00 0.007717 0.010665 

Shoulder Interaction 0.00405 0.000696059 5.82 0.00 0.002674 0.005430 

Ave High Temp 2,195.989 298.7846071 7.35 0.00 1,604.42 2,787.56 

 Note: Dependent variable is monthly recreational visitation; summer interaction variable=(1,0) indicator 

variable for summer months (June, July, Aug) x volume; shoulder interaction variable=(1,0) indicator 

variable for shoulder months (April, May, Sept. Oct.) x volume. 
43

It is interesting to note that average high air temperature is a highly significant 

explanatory variable. When this variable is omitted, however, there is very little change 

in the volume-related variable coefficients. 

Table 19. Estimated Marginal Impact of Reservoir Elevation Changes, Lake Powell and Lake Mead. 

Season Months Marginal impact of 1000 acre feet change 

in volume (recreational visits per month) 

(A) Lake Powell 

Summer June-August 9.2 

Shoulder April, May, September, October 4.1 

Off-season November-March 0.0 

Analysis Based on Commercial Expenditure Data

A secondary analysis of the implied economic impact of varying Lake Powell water 

levels was done comparing annual gross receipts reported by the Wahweap Lodge and 

Marina to average annual Lake Powell Storage.6 Figure 6 shows the relationship over the 

1995-2005 period of Wahweap receipts and lake levels. This plot shows a strong 

relationship in recent years with receipts closely tracking trends in lake levels. 

Plot of Wahweap Marina Annual Receipts and Lake Powell Average Volume: 

1995-2005

30000000

35000000

40000000

45000000

50000000

55000000

1 2 3 4 5 6 7 8 9 10 11

Annual Data 1995-2005

Wahweap Marina Receipts

5000000

7000000

9000000

11000000

13000000

15000000

17000000

19000000

21000000

23000000

Average Lake Powell Volume

Wahweap Lake Powell

Figure 6. Plot of Wahweap Marina Annual Receipts and Average Lake Powell Levels. 

 

6

 Gross Receipt data from, Wahweap Lodge and Marina, Schedule G, Detail of Gross Receipts, Years 

1995-2005. 
44

Figure 7 shows a scatter plot of Wahweap gross receipts by Lake Powell average annual 

water volume. This plot shows a strong linear relationship throughout the past decade 

between water levels and economic activity at the Wahweap Lodge and Marina. A 

simple linear regression model of Wahweap receipts as a function of lake volume showed 

that changes in annual average lake volume explained about 93% of the variation in 

Wahweap receipts over the 1995-2005 period. Additionally, the highly significant 

coefficient on Lake Powell Volume indicates that on the margin a 1000 acre foot of 

storage in Lake Powell leads to an increase in Wahweap sales of $1,470. 

Plot of 1995-2005 Annual Waheap Marina Gross Receipts by Annual Average Lake Powell 

Storage

30000000

35000000

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50000000

55000000

60000000

65000000

5000000 7000000 9000000 11000000 13000000 15000000 17000000 19000000 21000000 23000000

Powell average storage (acre feet) 

Wahweap Annual Receipts (2005 $)

Figure 7. Plot of Wahweap Annual Receipts by Lake Powell Average Volume: 1995-2005. 

3.1.2 Lake Mead Case Study 

There are two reservoirs within the Lake Mead NRA: Lake Mead, and Lake Mojave. The 

following discussion presents an analysis for the two recreational resources separately and 

discussion of possible interactions between the two reservoirs and their recreational use. 
45

Lake Mead 

Plots of the relationship between recreational visitation for this park and Lake Mead 

water levels on a monthly, and annual basis are shown in Figure 8, and Figure 9, 

respectively. Although it is less clear than in the case for Lake Powell, the plots for Lake 

Mead show a general pattern of moderately declining visitation associated with declining 

lake levels. Figure 10 shows a scatter plot of summer season Lake Mead NRA visitation 

and average Lake Mead water elevation. Included in this plot is a fitted linear trendline 

showing a moderate positive relationship between summer lake levels and visitation. 

As was done in the case of Lake Powell, above, an explanatory model of the relationship 

between Lake Mead NRA visitation and Lake Mead volume (in acre feet) was also 

developed. The estimated regression model for this reservoir is presented in Table 20. 

The regression model results for the Lake Mead relationship show a model that explains 

63% of the variation in visitation as a function of the included explanatory variables. 

Additionally, all of the included explanatory variables are statistically significant at the 

99% level. Inclusion of interaction terms for the summer and shoulder seasons did not 

yield statistically significant results. Therefore, for the Lake Mead NRA model the 

modeled marginal effect of changes in lake volume is applicable to the entire year. This 

marginal impact of a change of 1,000 acre feet in lake volume is 9.5 visits per month or 

114 recreational visits per year. 

Lake Mead Monthly Visitation and Lake Levels: 1991-2006

-

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1234567810911121341516171819202122232452627282930313233343563738394041424344454674849505152535455565785960616263646566676890717273747576777879801828384858687888990912939495969798100 99101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195

Jan. 1991 through December 2006

Monthly Visitation

-

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

Lake Volume (Acre feet)

Mead Visitation Mead Volume

Figure 8. Plot of Monthly Lake Mead Visitation and Lake Mead Reservoir Volume: 1991-2006. 
46

Plot of Annual Lake Mead Visitation and Average Annual 

Lake Mead Water Volume: 1991-2006

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6500000

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7500000

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8500000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

1991-2006

Lake Mead Visitation

10000000

12000000

14000000

16000000

18000000

20000000

22000000

24000000

26000000

Average Annual Lake Volume

Sum of Mead Visitation

Average of Mead Volume

Figure 9. Plot of Annual Lake Mead NRA Visitation and Average Lake Levels. 

Plot of Lake Mead Summer Season Recreational Visitation 

and Average Summer Lake Mead Water Volume: 1991-

2006

12000000

14000000

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18000000

20000000

22000000

24000000

26000000

1700000 1900000 2100000 2300000 2500000 2700000 2900000

Lake Mead Summer Visitation

Lake Mead Average Summer Volume

Figure 10.Plot of Lake Mead NRA Summer Season Visitation by Average Summer Lake Mead 

Water Level: 1991-2006. 
47

Table 20. Lake Mead Visitation Lake Volume Model: Monthly Data, 1991-2006 

Variable Statistic Coefficient T-Statistic P-value 

Intercept 292,642 5.06 0.00*** 

Lake Mead Volume 0.00948 3.92 0.00*** 

April 207,866 7.99 0.00*** 

May 205,600 7.90 0.00*** 

June 298,799 11.48 0.00*** 

July 317,701 12.20 0.00*** 

August 243,444 9.34 0.00*** 

September 178,962 6.87 0.00*** 

October 124,973 4.80 0.00*** 

Trend -2867 -1.63 0.10 

Adjusted R-square 0.63 

*** significant at 99% level. 

As in the case of the Lake Powell modeling described previously, alternative model 

specifications were examined including additional indicator variables for time of year, 

and interaction terms between the indicator and water level variables. Additionally, 

indicator variables for critical lake levels affecting recreational use were also included. 

An indicator variable for lake elevation 1175, the level at which Pearce Bay Launch 

Ramp is closed, and for 1150, the level at which the Las Vegas Bay and Government 

Wash public launch ramps are closed were included in the modeling. While models 

including only reservoir volume or only an indicator variable for Lake elevation 1175 

were individually significant, models including both variables were not. The two models 

can be viewed as alternative ways of modeling use. The model presented in Table 20 

describes marginal changes in visitation throughout the full range of observed lake levels. 

A model was also estimated including only the indicator variable for the lake elevation of 

1175. This model describes a step function showing only two water level-dependent 

levels of visitation, that above lake level 1175, and that below. The later model did not 

provide a significantly better fit to the data than did the model using visitation as a 

continuous function of lake volume. 

Lake Mojave

Lake Mojave, which lies downstream of Lake Mead, and within the NRA also has 

significant recreational use levels. Lake Mojave is operated primarily as a re-regulation 

reservoir for Lake Mead releases. As a result, lake levels at Mojave tend to fluctuate less 

than at Lake Mead. Figure 11 and Figure 12 show plots of Lake Mojave monthly and 

annual visitation and lake levels. An estimated linear regression model explaining 

monthly visitation as a function of lake level and monthly indicator variables is shown in 

Table 21. The estimated model explains about 87% of the variation in Mojave visitation. 

The lake volume variable is statistically significant at the 99 percent level. Inclusion of 

interaction terms for the summer and shoulder seasons did not yield statistically 

significant results. Therefore, for the Lake Mojave model the modeled marginal effect of 

changes in lake volume is applicable to the entire year. This marginal impact of a change 

of 1,000 acre feet in lake volume is 75.2 visits per month or 902 recreational visits per 

year. 
48

Plot of Lake Mojave Monthly Visitation and Lake Volume: 

1991-2006

-

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

1234567810911121341516171819202122232452627282930313233343563738394041424344454674849505152535455565785960616263646566676890717273747576777879801828384858687888990912939495969798100 99101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195

Monthly data 1991-2006

Monthly Visitation

500,000

700,000

900,000

1,100,000

1,300,000

1,500,000

1,700,000

1,900,000

Average Lake Volume

Mojave

MOJAVE VOLUME

Figure 11. Plot of Monthly Lake Mojave Visitation and Lake Levels: 1991-2006. 

Plot of Annual Lake Mojave Visitation and Average Annual 

Lake Mojave Volume: 1991-2006

0

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Annual 1991-2006 Data

Total Annual Visitation

1540000

1560000

1580000

1600000

1620000

1640000

1660000

1680000

1700000

Total Sum of Mojave

Annual Average Lake Volume

Total Average of MOJAVE

Figure 12. Plot of Annual Lake Mojave Visitation and Average Lake Level: 1991-2006. 
49

Table 21. Lake Mojave Visitation Lake Volume Model: Monthly Data, 1991-2006. 

Variable Statistic Coefficient T-Statistic P-value 

Intercept -10,911 -0.23 0.79 

Lake Mojave Volume 0.0744 2.57 0.01*** 

April 64,310 8.33 0.00***

May 105,580 13.53 0.00*** 

June 146,021 18.73 0.00*** 

July 180,138 23.76 0.00*** 

August 170,298 22.52 0.00*** 

September 74,306 9.92 0.00*** 

October 35,603 4.46 0.00*** 

Trend -2682 -6.21 0.00*** 

 

Adjusted R-square 0.87 

*** significant at 99% level. 

Comparison of Lakes Mead and Mojave

Lakes Mead and Mojave comprise the two reservoirs of the Lake Mead NRA. As noted 

above, an examination of historical water volume and recreational use statistics for these 

two water bodies both show significant positive relationships; increased reservoir levels 

are associated with increased recreational visitation. A comparison of summer season 

visitation trends for the two reservoirs shows a relatively high level of correlation over 

the 1991 through 2006 seasons (Figure 13). Further examination of visitation for the 

entire year, however, shows no correlation between non-summer visitation and very weak 

correlation between year-round visitation levels to the two reservoirs (Table 22). 
50

Comparison of Lake Mead and Lake Mojave Annual Visitation: 1991-2006

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Annual Data 1991-2006

Lake Mead Visitation

1000000

1200000

1400000

1600000

1800000

2000000

2200000

Mead Annual Visitation

Lake Mojave Visitation

Mojave Annual Visitation

Figure 13. Comparison of Lake Mead and Lake Mojave Annual Visitation 1991-2006 

Table 22. Correlation between Lake Mead and Mojave Visitation: 1991-2007 

Statistic Result 

Correlation – summer months visitation 0.82 

Correlation – non-summer visitation -0.07 

Correlation – year-round visitation 0.34 

Year-to-year visitation changes

Number of years where Mead and Mojave visitation moves in 

the same direction 

8 out of 15 years 

Number of years where Mead and Mojave visitations move in 

opposite directions 

7 out of 15 years 

A comparison of the estimated marginal impact of an acre foot of reservoir storage shows 

water at Lake Mojave to have roughly eight times the impact on visitation as an acre foot 

at Lake Mead. This comparison, however, is to a degree an artifact of the differences in 

absolute size of the two reservoirs. When converted to a metric more directly 

experienced by reservoir users, changes in water elevation, the estimated marginal impact 

at Mojave of a one foot change in lake elevation is roughly 2 times that estimated for 

Lake Mead (Table 23). 
51

Table 23. Implied Change in Visitation to Lakes Mead and Mojave from a One Foot Change in Lake 

Level, at Alternative Lake Levels. 

Lake Level 

Change in Acre Ft. from 

one foot change in lake 

level 

Visitation/volume Model 

Coefficient on water 

volume 

Predicted change in visitation per 

month due to one foot change in 

lake level 

Lake Mead 

1115 97,000 0.0093 906 

1205 148,000 0.0093 1,382 

 

Lake Mojave 

644 27,700 0.0752 2,082 

630 24,900 0.0752 1,871 
52

Analysis Based on Concessionaire Annual Receipt Data

Another method which can be used to examine the relationship between lake levels and 

recreational visitation is to examine records of NPS concessionaire receipts, such as that 

earlier estimate for Wahweap Marina on Lake Powell. Since recreational visitors to the 

park units spend money on their trips, it would be expected that decreases in lake levels 

that lead to decreases in recreational visitation will also lead to decreases in 

concessionaire receipts. 

Data for Lake Mead NRA concessionaire annual receipts for the period 2001-2006 (Per. 

Comm. Leisa Cook, Lake Mead NRA) were examined in the context of annual average 

reservoir levels. The data used included total annual receipts for three Lake Mojave 

Concessionaires and eight Lake Mead concessionaires. While the majority of the 

concessionaire data showed no statistical relationship between inflation adjusted annual 

receipts and water volume, a strong relationship between annual receipts and annual 

average Lake Mead water volume was estimated for Echo Bay Resort on Lake Mead 

(Figure 14). An estimated explanatory regression model explaining Echo Bay annual 

receipts as a function of average lake volume showed a highly explanatory estimated 

model (adjusted R-square of 0.91) with a significant coefficient estimated for the water 

volume variable (significant at the 99% level of confidence (Table 24). The model 

suggests that within the range of the data (2001-2006) an increase of 1000 acre feet of 

water volume is associated with approximately 340 dollars of visitor spending at Echo 

Bay Resort. 

In addition to Echo Bay Resort, two additional concessionaires’ annual receipts data 

showed significant correlation with Lake Mead water volume in the estimated 2001-2006 

models. Table 25 shows the summary results for the estimated models along with 

estimated changes in annual receipts associated with an average one foot Lake Mead 

level change. A more comprehensive explanation of changes in concessions receipts 

would require information on changes in services and facilities and changes in prices. 

This data was not readily available. 

 
53

Comparison of Echo Bay Inflation Adjusted Annual 

Receipts and Lake Mead Annual Average Volume: 

2001-2006

10000000

12000000

14000000

16000000

18000000

20000000

22000000

2001 2002 2003 2004 2005 2006

Year

Lake Mead Average Volume

3,000,000

3,500,000

4,000,000

4,500,000

5,000,000

5,500,000

6,000,000

6,500,000

Echo Bay Annual Receipts (2006 

dollars)

Mead volume

Echo Bay

Figure 14. Comparison of Echo Bay Resort Annual Receipts and Lake Mead Average Annual Water 

Volume: 2001-2006. 

Table 24. Explanatory Model of Echo Bay Resort Annual Receipts as a Function of Average Lake 

Mead Volume: 2001-2006. 

Echo Bay Marina (Lake Mead) Annual Gross Receipts as a function 

of average Lake Mead Water Volume 

 

Regression Statistics 

Multiple R 0.964 

R Square 0.929 

Adjusted R Square 0.911 

Standard Error 261906.0932 

Observations 6 

 

ANOVA 

 df SS MS F Significance F 

Regression 1 3.5698E+12 3.57E+12 52.04257 0.0020 

Residual 4 2.7438E+11 6.86E+10 

Total 5 3.8442E+12 

 

 Coefficients Standard Error t Stat P-value Lower 95% Upper 95% 

Intercept (635,680.34) 783,987.67 (0.81) 0.46 (2,812,383.58) 1,541,022.90 

mead volume 0.338 0.047 7.214 0.002 0.208 0.468 
54

Table 25. Estimated Model Results and Changes in Concessionaire Receipts Associated with Lake 

Mead Volume Changes. 

Concessionaire Estimated Lake 

Mead Volume 

Coefficient 

P-statistic Model Adj. 

R-square 

Predicted change in 

Receipts from 1 Foot Lake 

level Changea

Echo Bay Resort 0.338 0.00 0.91 $33,800 

Lake Mead Ferry Service 0.106 0.00 0.84 $10,600 

Lake Mead Resort 0.048 0.12 0.36 $4,800 

a

 Based on 100,000 acre foot change at the 1115 foot water level for Lake Mead. At Lake Mead level 1115 

a change of 1 foot represents approximately 97,000 acre feet of volume. 

3.1.3 Curecanti-Blue Mesa Reservoir Case Study 

Curecanti NRA is comprised of three bodies of water, Crystal Reservoir, Morrow Point 

Reservoir, and Blue Mesa Reservoir. Blue Mesa, the largest of the three is the largest 

body of water in Colorado. The storage of water in Blue Mesa was examined in relation 

to visitation to Curecanti NRA. Figure 15 shows a plot of monthly recreational visitation 

to Curecanti NRA associated with alternative levels of water contained in Blue Mesa 

Reservoir. The plot shows a general trend of higher visitation levels being associated 

with higher volumes of water storage in Blue Mesa. 

Plot of Curecanti Monthly Recreational Visitation and Average Blue Mesa Reservoir Storage: 

1996-2005

0

50,000

100,000

150,000

200,000

250,000

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120

Monthly Data 1996-2005

Total Visitation

-

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

Blue Mesa Storage (acre feet)

Figure 15. Plot of Monthly Curecanti NRA Visitation and Blue Mesa Reservoir Average Storage: 

1996-2005. 
55

While the graphical relationship, shown in Figure 16, between summer Curecanti 

visitation and average Blue Mesa Reservoir storage suggests a positive relationship 

between water levels and visitation, there are a number of confounding factors in this 

relationship. While Blue Mesa is the largest reservoir in the Curecanti unit, comparing 

visitation to all three units to only Blue Mesa storage leads to the potential for significant 

measurement error. Additionally, not all Curecanti visitation is “water-based.” Munger 

and Vinton (2005) found that approximately 68% of use at Blue Mesa Reservoir during 

the summer of 2004 was related to water-based recreation. No time series exists showing 

the level of reservoir-based visitation to the Curecanti Unit on a monthly, seasonally, or 

even yearly basis. This type of data would be needed for any statistical modeling of the 

relationship between water levels and water-based recreation at the unit. 

Plot of Curecanti NRA Summer Visitation by Average Blue Mesa Reservoir 

Summer Storage

500000

550000

600000

650000

700000

750000

800000

850000

900000

300000 350000 400000 450000 500000 550000 600000 650000 700000 750000 800000

Average Blue Mesa Summer Storage Level

Total Curecanti NRA Recreational Summer Visitation

Figure 16. Plot of Summer Season Curecanti NRA Visitation by Blue Mesa Reservoir Average 

Summer Storage. 

3.1.4 Grand Canyon NP - Colorado River through the Grand Canyon 

Case Study 

The previous three sections have described the relationship between reservoir-based 

recreational visitation and water levels. Three additional NPS units within the Colorado 

River watershed have significant river-based recreational use. These waters are the 

Colorado River through Grand Canyon NP, the Cataract Canyon section of the Colorado 

River through Canyonlands NP, and the Green and Yampa Rivers through Dinosaur NM. 
56

The estimation of a relationship between water and recreational use on these river reaches 

is fundamentally the same as was done for reservoir recreation, with the exception being 

that water levels are measured as flows in cubic feet per second, rather than as a stock in 

acre-feet, or reservoir level. Additionally, the functional form is generally different. 

While lake and reservoir models may show recreation increasing with lake levels 

throughout the range of the data, existing literature shows quantity as a quadratic 

relationship with low use at both very low river flows and at very high flows and with use 

optimized at some middle level of flows. 

There is a second major difference between use levels on Lake Powell, Lake Mead, and 

Curecanti and on the three river sections. Use on the reservoirs is generally 

unconstrained by administrative maximum use levels. On two of the three river stretches 

(Grand Canyon NP and Dinosaur NM), however, use is limited and demand (at least 

during most of the year) significantly exceeds the supply of available floating 

opportunities. The administrative caps placed on the supply of recreational float days 

available masks any relationship between flow levels and use levels. 

In the case of the Colorado River through the Grand Canyon, supply of available float 

opportunities are notoriously constrained for non-commercial floaters. This group may 

sign up to float up to 10 years prior to their float. Clearly, in these cases water levels, 

unknowable that far in advance, are not significant in determining levels of demand. For 

commercial floaters, many recreationists also sign up for the trip one of two years in 

advance. Given the significantly constrained supply of Grand Canyon float permits 

relative to the demand for these permits, fluctuating flow levels have little impact on the 

quantity of river use.7

While flow fluctuations through the Grand Canyon may not significantly impact the 

number of river floaters, the quality of their floats are impacted (Bishop 1987). Figure 17 

shows the estimated relationship between flows on the Colorado River through the Grand 

Canyon and NEV (Surplus value) per trip. This relationship shows values increasing 

with flows to a point and then declining at extremely high flows. 

 

7 The 2005 Grand Canyon Management Plan FEIS noted this constraint in Chapter 3 (pp.198-99), 

“Multiple sources indicate that demand exceeds supply for both commercial and noncommercial trips in the 

Grand Canyon. Concessionaires report that they turn away prospective users because their trips are full, and 

some maintain informal waiting lists for those interested in future trips. Pricing also helps balance supply 

and demand for commercial permits, although concession contracts impose some constraints on trip prices 

(see Section 3.5 Socioeconomic Conditions for more information). On the noncommercial side, the long 

waitlist clearly indicates demand exceeds supply, but for several reasons, it does not provide an accurate or 

reliable indicator of exact demand:...” 
57

Figure 17. Bishop (1997) Relationship Between NEV and Flow Levels on Grand Canyon Float 

(source: Bishop, Figure 5-1). 

3.1.5 Dinosaur NM – Green and Yampa Rivers Case Study 

As was the case for the Colorado River float through Grand Canyon NP, use of the Green 

and Yampa River floats is also seriously constrained during the high-use May through 

September season. For the 2005 float season, NPS data shows that there were about 

4,800 applications received by the NPS for approximately 300 trip permits. 

Approximately 6% of trip requests were granted during the season. Even allowing for 

multiple applications per float group, these statistics indicate that demand on the Yampa 

is severely constrained during the entire float season. On the Green it is moderately 

constrained during much of the summer season.8

As was the case with the Colorado River through the Grand Canyon, the administrative 

constraints placed on Green and Yampa River use make estimation of statistical 

relationships between flows and use levels impossible. 

 

8

 The full river permit statistics for Dinosaur NM are available at 

http://www.nps.gov/dino/planyourvisit/upload/06-APP%20web%20stats04.doc
58

3.1.6 Canyonlands NP – Colorado River through Cataract Canyon 

Case Study 

One NPS-administered Colorado River float section that does not have use limits is the 

Colorado River through Canyonlands NP and Cataract Canyon. Table 26 shows the 

estimated model of Canyonlands NP river visitation as a function of river flows and other 

explanatory variables. The model was estimated on monthly June through October river 

visitation. The coefficients (all statistically significant at the 99% level of confidence or 

greater) show that and increase of 100 cfs in flow (at the maximum marginal rate) is 

associated with about 38 recreation visitors per summer month to float the river, or 190 

visitors over the 5 month high-use season. The June indicator variable shows that use in 

that month is on average 1583 visits lower than during the other months, all other 

variables held constant. The flow variable used was the sum of flows from the USGS 

monitoring stations on the Green River near Jensen, UT and the Colorado River near 

Cisco, UT. The flow variable was specified as a quadratic functional form, indicating 

that recreational use as a function of flows increases at a decreasing rate and levels off 

and decreases at very high water flows. This is consistent with the general findings in the 

literature. 

The quadratic specification of the Cataract Canyon float demand model allows direct 

calculation of the implied optimal flow level for maximizing float visitation. The implied 

optimal flow is calculated at approximately 21,000 cfs, all other variables held constant. 

Plot of June through October Cataract Canyon Float Visitors as a Function of Flow 

Levels:1999-2005

0

500

1000

1500

2000

2500

3000

0 5000 10000 15000 20000 25000 30000 35000 40000

Average Monthly Flow (CFS)

Monthly Float Visitors

Figure 18. Plot of Cataract Canyon Float Visitation by Monthly Average Flow Levels: June through 

October, 1999-2005 Data. 
59

Table 26. Explanatory Model of June-October Cataract Canyon Float Visits as a Function of Flow 

Levels: 1999-2005 data 

Cataract Canyon June through October 1999-2005 Visitation Model 

 

Regression Statistics 

Multiple R n/a 

R Square n/a 

Adjusted R Square n/a 

Standard Error 640.0093245 

Observations 34 

 

ANOVA 

 df SS MS F Significance F 

Regression 3 -5726416.9 -1908805. -4.6600342 n/a 

Residual 31 12697970 409611.93 

Total 34 6971553.059 

 

 Coefficients 

Standard 

Error t Stat P-value Lower 95% Upper 95% 

Intercept 0 n/a n/a n/a n/a n/a 

Flow 0.3775 0.024986916 15.109 0.000 0.32657 0.42849 

Flow sq 

 

(0.0000090) 9.44908E-07 (9.486) 0.000 (0.00001) 

 

(0.00001) 

June -1583.056855 367.6132586 (4.306) 0.000 (2,332.80946) 

 

(833.30425) 

 

Note: The model is estimated without an intercept, reflecting the implicit assumption that at zero flows the river floater use is also 

zero. 

3.1.7 Black Canyon of the Gunnison Case Study 

Black Canyon of the Gunnison NP reports a very low level of river use in its visitor 

statistics. Specifically, generally less than 100 visits per year are reported for floating the 

Gunnison River through the park. This is due to the extreme difficulty of the float 

through the Black Canyon. While river use in the park is likely correlated with river 

flows, the use level through the park is too low to estimate such a relationship with 

confidence. Additionally, marginal changes in use associated with increased flow levels 

would be extremely small in the context of total park visitation. The Gunnison Gorge 

section below the Black Canyon is a popular float section, and is administered by the 

BLM. 
60

3.2 Marginal Impacts of Water Levels on NPS Management Costs 

Access facilities at NPS-administered Colorado River reservoirs are designed when built 

for operations within a certain range of reservoir levels. The drawdown of reservoir 

levels below the design levels of these facilities necessitates either modifying the access 

areas, or closing them pending higher lake levels. Reservoir access points are discrete and 

limited in number. These characteristics do not lend themselves to modeling access 

management costs as a function of lake levels as was done in the case of recreational use. 

Rather, NPS is faced with management decisions specific to individual access facilities 

based on current and projected water levels. Decisions may be made to lengthen ramps, 

move facilities, of close facilities. These decisions are made based on weighing the 

benefits associated with maintaining access points as long as possible, against costs 

associated with access modification or relocation. 

At Glen Canyon NRA, the NPS reported spending approximately $8 million to provide 

continued lake access between 2002 and May 2005. The projects funded with these 

expenditures included extending boat launch ramps, ferry launch ramps, walkways and 

utilities, developing shuttle and low water parking areas, and funding an up-lake 

development concept plan.9

At Lake Mead NRA, the NPS spent $6 million over three years to extend and move 

launch ramp facilities. The NPS anticipated spending an additional $8 million for access 

as the lake approached 1095 feet. The costs of ramp extensions at Lake Mead are 

estimated at $1,520/ft (for a 160 foot wide ramp). Low water access impacts at Lake 

Mead include Las Vegas Bay Marina moving to Hemingway due to low water in 2004, 

and alternative ramps being required at Callville, Government Wash, Stewart Point, 

South Cove, Boulder Harbor, and Echo Bay. 

 

9

 NPS Briefing Statement, “Visitor Services- Low Water Facilities” Glen Canyon NRA, May 2005. 
61

4.0 Comprehensive Estimates of Relevant Economic 

Values 

4.1 Regional Economic Impact 

As noted previously, regional economic impact analysis narrowly examines the effect of 

visitor spending to a site or area (such as Grand Canyon NP) on the local economy 

surrounding the site. The inputs to a regional economic impact analysis focus on visitor 

spending, and the outputs are generally presented in terms of changes in personal income 

or employment. 

It should be noted that comparability between impact analyses, even for an identical site, 

is not assured. Each regional impact analysis defines a specific “impact area” (often a 

county, group of counties, or state) and only (or should only) counts expenditures made 

within that impact area by visitors coming from outside the impact area. Because 

definitions of the impact area and who constitute local or non-local visitors may vary 

across studies, care should be taken in comparing impact analyses for a specific site or 

park unit. 

It should be further noted that regional economic impact analysis describes impacts on 

one local area only, and ignores expenditure impacts to the remainder of the national 

economy. Specifically, this type of analysis ignores the offsetting loss in spending in 

other areas of the economy that result from visitor spending in a specific site or park 

locale. The following impact estimates provide a “first blush” view of data and 

estimates currently available. Estimates may not be strictly comparable between park 

units due to different treatments in the studies in defining local and non-local spending, 

and in defining the area of impact. Rather the following data is presented as an indication 

of the estimates and data developed to date for the CRW units. 

Table 27 shows a summary of estimates of regional economic impacts associated with 

recreational visitation to the Colorado River NPS units. While estimates are presented 

for all Colorado River Basin Units with significant water-based recreational visitation, 

the estimates vary in quality. Four of the five lowest estimates of per visitor trip 

spending ($43 at Lake Powell, $56 at Lake Mead, $32 at Dinosaur and $39 at 

Canyonlands) have been derived from 2003 MGM2 published estimates. These estimates 

are all parkwide estimates and are not based on recent visitor survey data. In the case of 

Dinosaur and Canyonlands, the MGM2 estimates of per visitor spending may not be 

representative of the river recreational visitors to the parks. A general trend is that 

estimates of per visitor spending based on visitor surveys are significantly larger than are 

the primarily default MGM2 estimates. 
62

Table 27. Estimated Regional Economic Impact of Water-based Recreation Based on Available Data 

(Constant 2005 Dollars). 

Park Unit Estimated 

Direct 

Spending per 

Visitor Trip 

Estimated 

Indirect and 

Induced 

Spending 

Multipliera

Estimated 

Total 

Spending 

Impact per 

Visitor 

(2005$) 

Water-based 

Visitation 

(000’s) 

2005 Total 

Direct, Indirect 

and Induced 

Spending 

(million 2005$) 

Glen Canyon NRA

 Lake Powell 

 Colo. River (Glen-Lee’s)

43c – 187d 

111e – 340e 

1.45 62 – 271 

161 – 493 

1,392 

179 

86 – 377 

29 – 88 

Lake Mead NRA

 Lake Mead 

 Lake Mojave 

56c 

174f 

1.32 74 

230 

6,287 

1,533 

465 

353 

Curecanti NRA 24c 1.44 35 Uncertain -- 

Grand Canyon NP

 Grand Canyon Float 1,471e 1.45 2,118 22 46 

Dinosaur NM

 Yampa & Green Riverb 32c 1.32 42 13 0.6 

Canyonlands NP

 Cataract Canyonb 39c 1.33 52 12 0.6 

Black Canyon NP 

Arches NP 

Rocky Mountain NP 

Minimal water-based use 

a

 Multipliers are based on MGM2 model estimated expenditure multipliers 

b

 Expenditure estimates for Canyonlands and Dinosaur are for all visitors and may not represent spending 

by river-recreationists who make up a small part of total visitation. 

c

 Munger and Vinton (2005). 

d

 Duffield and Neher (1999) 

e

 Stynes and Sun (2005) 

f

 Borden et al. (2003) 

4.2 Marginal Impacts of Water Level Changes 

The derivation of the marginal effects of water level changes on park visitation are 

presented in the preceding Sections 3.1.1 – 3.1.7. A summary of these estimated 

marginal effects are shown in Table 28. There were three park units (four specific 

waters) where it was possible to estimate the marginal relationship between water levels 

and visitation. The marginal impact of a change of 1000 acre-feet of storage (in the case 

of the reservoirs) and 100 cfs average flow (in the case of river recreation) are shown in 

the table. 
63

Table 28. Estimated Marginal Changes in Park visitation Associated with Marginal Changes in 

Water Levels. 

Park Unit Marginal Water 

Change 

Marginal change in visitation 

Glen Canyon NRA 1000 af 44 

Lake Mead NRA – Lake Mead 1000 af 114

Lake Mead NRA – Lake Mojave 1000 af 902 

Curecanti NRA No estimated model due to lack of water-based visitation data 

Grand Canyon NP No estimated model due to constrained supply of river permits 

Dinosaur NM No estimated model due to constrained supply of river permits 

Canyonlands NP 100 cfs 190 

Black Canyon NP No estimated model due to very low river use 

Table 29 presents the resulting estimated changes in spending in the regional economy 

associated with the marginal impacts on visitation shown in Table 28. 

Table 29. Estimated Marginal Changes in Regional Economic Activity Associated with Marginal 

Changes in Water Levels. 

Park Unit Marginal Water 

Change 

Marginal change in 

total spending 

Marginal change 

per acre-foot 

(2005$) 

Glen Canyon NRA 1000 af $2,700 - $11,900 $2.70 - $11.90 

Lake Mead NRA – Lake Mead 1000 af $8,400 $8.40 

Lake Mead NRA – Lake Mojave 1000 af $207,500 $207.50 

Curecanti NRA No estimated model due to lack of water-based visitation data 

Grand Canyon NP No estimated model due to constrained supply of river permits 

Dinosaur NM No estimated model due to constrained supply of river permits 

Canyonlands NP 1000 af (June – 

October) 

 $322 $0.32 

Black Canyon NP No estimated model due to very low river use 

4.3 Direct Recreational Value 

Table 30 summarizes the best available estimates of total direct recreational value 

estimates for water-based recreation within the Colorado River NPS units. Where 

uncertainty regarding the magnitude of a consumer surplus estimate exists, that is noted 

and a range of values is presented. 
64

Table 30. Summary of Direct Recreational Value Estimates for Water-Based Recreational visitation 

toColorado River NPS Units. 

Park Unit Resource Visitation (2005) 

(000’s) 

NEV per 

visit 

Total annual NEV 

(million 2005 $) 

Glen Canyon 

NRA 

Lake Powell 

Colorado R. – Lee’s to Glen 

1,392 

179 

86c – 109c 

n/aa

112 – 270 

n/a 

Lake Mead NRA Lake Mead 

Lake Mojave 

6,287 

1,533 

643– 887b

n/a 

4,042 – 5,577 

n/a 

Curecanti NRA Blue Mesa Reservoir 

Morrow Point Reservoir 

Crystal Reservoir 

531 69 – 187e 36 - 99 

Grand Canyon NP Colorado R. 22 430d – 

3000d 

1 - 66 

Dinosaur NM Yampa River & Green River 13 n/a n/a 

Canyonlands NP Colorado R. – Cataract Canyon 12 n/a n/a 

Black Canyon NP 

Arches NP 

Rocky Mountain 

NP 

Minimal water-based recreation 

a

 n/a indicates no site-specific estimate exists. 

b

 based only on angler values (Martin 1982) 

c

 Douglas and Johnson (2004); Duffield and Neher (1999). See Table 5 for details of sources. 

d

 Bishop et al. 1987. 

e McKean et al. 1995. 

Table 31 shows available estimates of the marginal change in direct use net economic 

value associated with water-based recreation within NPS units resulting from changes in 

reservoir or river levels. 

Table 31. Estimated Marginal Changes in Net Recreational Benefits Associated with Marginal 

Changes in Water Levels. 

Park Unit Marginal Water 

Change 

Marginal change in 

Net Benefits 

(2005 $) 

Marginal change in 

Net Benefits per acrefoot (2005 $) 

Glen Canyon NRA 1000 af 3,800 – 4,800 3.80 – 4.80 

Lake Mead NRA – Lake Mead 1000 af 73,300 – 101,100 73.30 – 101.10 

Lake Mead NRA – Lake Mojave 1000 af N/A N/A 

Curecanti NRA No estimated model due to lack of water-based visitation data 

Grand Canyon NP 1000 af 243a 0.24 

Dinosaur NM No estimated model due to constrained supply of river permits 

Canyonlands NP 1000 af n/a n/a 

Black Canyon NP No estimated model due to very low river use 

Note: Lake Mead estimates are based only on angler survey responses. a

 based on the maximum marginal flow value from Bishop (1987), Figure 8-3. 

In addition to the estimated marginal impacts of water level changes on visitation shown 

in Table 31, marginal impacts of water level changes on the value of individual trips can 

also be modeled. This marginal effect can only be modeled through a site-specific user 

survey. To date estimates for this marginal effect of flows within the Colorado River 
65

NPS units have been completed only for the Grand Canyon float reach of the river 

through Grand Canyon NP (Bishop et al. 1987). Lacking more site specific data on this 

marginal effect, no best estimate of marginal effects on value per trip are presented. 

4.4 Passive Use Value 

As summarized in Table 7, two passive use value studies of lakes and reservoirs and nine 

passive use value studies were identified as being potentially relevant to NPS resources in 

the Colorado River Basin. 

With respect to the literature on rivers, only one set of passive use estimates is available 

for Colorado River park units, and that is the Welsh et al 1995 study of river flows in the 

Grand Canyon. This resource is sufficiently unique that it would be difficult to justify 

extending this estimate to other Colorado River sites. While the river-related literature is 

more extensive than the lake and reservoir literature, the available estimates are still 

relatively thin given the great variety in resources and services evaluated. Accordingly, 

the only useable estimate is for the Colorado River through the Grand Canyon, and no 

other sections. 

With respect to lakes, there are only two studies, one of Flathead Lake in Montana and 

the other for Mono Lake in California. Both these studies are rather dated (1981 and 

1986-1987 survey years). Additionally, these lakes are quite different in market setting, 

attributes, and national prominence compared to, for example, Lake Powell and Lake 

Mead. Accordingly, there is insufficient economics literature to undertake a benefit 

transfer estimate for Colorado River NPS lake and reservoir resources. 

4.5 Other Competing Water Uses 

Other uses are valued in the range summarized in Table 32. These values necessarily 

range across facility, region, and user population for hydropower, irrigation, and 

municipal users, respectively. These values are relatively well understood, and are 

generally computed specific to the policy issue at hand in water resource planning and 

related NEPA process publications in the Colorado River Basin. 

Some related values, such as salinity damage estimates, are quite complex but have been 

well investigated relative, for example, to NPS resource recreation and passive use 

values. 
66

Table 32. Change in Net Benefits for Other Uses ($/af) 

Competing Use Columbia River (1999 $) Booker Colorado 

River (1992 $) 

Booker Colorado 

River (2005 $) 

Agriculture 3 – 200 12 – 58a 17 – 82 

Minicipal 34 – 403 344 – 479 478 – 666 

Hydropower 4 – 62 3 – 45 3 - 51 

a Range includes full use and marginal change in drought. 
67

5.0 Summary of Uncertainty Analysis and Existing Data 

Gaps 

5.1 Regional Economic Analysis – Visitor Expenditure Data 

Table 33 presents a more general summary of the availability of estimates and data 

associated with regional economic analyses of the visitor expenditure impacts for the nine 

Colorado River System NPS units. Specifically, whether estimates exist specific to 

differing water segments (river v. reservoir, for example) While three of the units (Grand 

Canyon NP, Arches NP and Curecanti NRA) have relatively up-to-date visitor data, these 

are generally parkwide estimates which obscure significant differences between waterbased visitation and general visitation. Some units have specific water-based visitor data 

that is current and high quality (Lake Powell and Lake Mojave). Other units have waterbased visitor expenditure data that is relatively dated (the Colorado River sections 

between Glen Canyon Dam and Lake Mead). Still others have no visitor expenditure 

data specific to water based recreation at the park units (Dinosaur NM, Canyonlands NP). 

Table 33. Summary of Available Regional Economic Impact Data for Colorado River NPS Units. 

Park Unit Regional Impact Analyses Expenditure 

Estimate Available? 

Data gaps 

Glen Canyon NRA Lake Powell 

Colorado R. – Lee’s to Glen 

Yes 

Yes 

Limited Samples 

Dated 

Lake Mead NRA Lake Mead 

Lake Mojave 

Colorado R. above Mojave 

Limited 

Yes 

Yes 

No estimates 

-- 

-- 

Curecanti NRA Blue Mesa Reservoir 

Morrow Point Reservoir 

Crystal Reservoir 

Yes 

No 

No 

Water based est. 

No estimates 

No estimates 

Grand Canyon NP Colorado R. – Lees to Diamond 

Colorado R. – Diamond to L. Mead 

Yes – Dated 

Yes – Dated 

20 years old 

20 years old 

Dinosaur NM Yampa River 

Green River 

No 

No 

No estimates 

No estimates 

Canyonlands NP Colorado R. – Cataract Canyon No No estimates 

Black Canyon NP Gunnison River No No estimates 

Arches NP 

Rocky Mountain NP Not Applicable 
68

Table 34. Summary of Uncertainty and Data Gaps Associated with Estimates of Changes in 

Visitation and Regional Economic Impacts with Marginal Changes in Water Levels. 

Park Unit Resource Marginal Impacts 

on Visitation 

Estimate 

Available? 

Regional 

Economic 

Impact 

Estimate 

Available? 

Marginal Regional 

Economic Impact Estimate 

Available? 

Glen 

Canyon 

NRA 

Lake Powell 

Colorado R. – Lee’s to Glen 

Yes 

Yes – combined with 

Powell 

Yes 

Yes 

Yes 

Yes 

Lake Mead 

NRA 

Lake Mead 

Lake Mojave 

Yes 

Yes 

No 

Yes 

No 

Yes 

Curecanti 

NRA 

Blue Mesa Reservoir 

Morrow Point Reservoir 

Crystal Reservoir 

No 

No 

No 

Yes-limited 

No 

No 

No 

No 

No 

Grand 

Canyon NP 

Colorado R. – Lees to Diamond 

Colorado R. – Diamond to L. Mead 

Constrained use 

Constrained use 

Yes-dated 

Yes-dated 

n/a 

n/a 

Dinosaur 

NM 

Yampa River 

Green River 

Constrained use 

Constrained use 

No No 

Canyonlands 

NP 

Colorado R. – Cataract Canyon Yes No No 

Black 

Canyon NP 

Gunnison River Low use

Arches NP 

Rocky 

Mountain 

NP 

Not Applicable 

5.2 Direct Recreational Use Values 

Table 35 summarizes the existing uncertainty and data gaps associated with estimation of 

direct recreational values of water-based recreation within the Colorado River NPS units. 
69

Table 35. Summary of Uncertainty and Data Gaps Associated with Estimates of Direct Recreational 

Values of Colorado River Basin NPS Units. 

Park Unit Resource Park-specific NEV per trip Estimate 

Available? 

Glen Canyon NRA Lake Powell 

Colorado R. – Lee’s to Glen 

Yes 

Yes – 20 years old 

Lake Mead NRA Lake Mead 

Lake Mojave 

Yes – limited to fishing & 28 years old 

No 

Curecanti NRA Blue Mesa Reservoir 

Morrow Point Reservoir 

Crystal Reservoir 

Yes - dated 

No 

No 

Grand Canyon NP Colorado R. – Lees to Diamond 

Colorado R. – Diamond to L. Mead 

Yes – 20 years old 

No 

Dinosaur NM Yampa River 

Green River 

No 

No 

Canyonlands NP Colorado R. – Cataract Canyon No 

Black Canyon NP Gunnison River Low use 

Arches NP 

Rocky Mountain NP 

Not Applicable 

Table 36. Summary of Uncertainty and Data Gaps Associated with Estimates of Changes in 

Visitation and Direct Recreational Use Values with Marginal Changes in Water Levels. 

Park Unit Resource Marginal Impacts 

on Visitation 

Estimate 

Available? 

NEV per Trip 

Estimate Available? 

Marginal NEV Value 

Estimate Available? 

Glen Canyon 

NRA 

Lake Powell 

Colorado R. – Lee’s to Glen 

Yes 

Yes – combined with 

Powell 

Yes 

Yes 20 years old 

Yes 

Yes- dated 

Lake Mead 

NRA 

Lake Mead 

Lake Mojave 

Yes 

Yes 

Yes – limited to fishing 

and 28 yeas old 

No 

Partial 

No 

Curecanti 

NRA 

Blue Mesa Reservoir 

Morrow Point Reservoir 

Crystal Reservoir 

No 

No 

No 

Yes - dated 

No 

No 

No 

No 

No 

Grand 

Canyon NP 

Colorado R. – Lees to Diamond 

Colorado R. – Diamond to L. Mead 

Constrained use 

Constrained use 

Yes-20-years old 

No 

n/a 

n/a 

Dinosaur NM Yampa River 

Green River 

Constrained use 

Constrained use 

No 

No 

No 

No 

Canyonlands 

NP 

Colorado R. – Cataract Canyon Yes No No 

Black Canyon 

NP 

Gunnison River Low use

Arches NP 

Rocky 

Mountain NP 

Not Applicable 
70

Table 37. Summary of Uncertainty and Data Gaps Associated with Direct Use Net Economic Values 

per Trip. 

Park Unit Resource Marginal Impacts 

on NEV 

Visitation level 

Values? 

Marginal 

Impacts on 

NEV Value per 

Trip Values? 

Combined 

Visitation and 

Marginal Impact on 

Value per Trip 

Values? 

Glen Canyon 

NRA 

Lake Powell 

Colorado R. – Lee’s to Glen 

Yes 

Yes- 20 years old 

No 

Yes 20 years old 

Partial 

Yes- 20 years old 

Lake Mead 

NRA 

Lake Mead 

Lake Mojave 

Partial 

No 

No 

No 

No 

No 

Curecanti 

NRA 

Blue Mesa Reservoir 

Morrow Point Reservoir 

Crystal Reservoir 

No 

No 

No 

No 

No 

No 

No 

No 

No 

Grand 

Canyon NP 

Colorado R. – Lees to Diamond 

Colorado R. – Diamond to L. Mead 

n/a 

n/a 

Yes-20-years old 

No 

Partial 

No 

Dinosaur NM Yampa River 

Green River 

No 

No 

No 

No 

No 

No 

Canyonlands 

NP 

Colorado R. – Cataract Canyon No No No 

Black Canyon 

NP 

Gunnison River Low use

Arches NP 

Rocky 

Mountain NP 

Not Applicable 

5.4 Passive Use Values 

The available literature most relevant to Colorado River park unit water resources was 

summarized above in Table 7 and in Appendix B. This literature is too limited to support 

a benefit transfer. Nonetheless, the literature, particularly the Mono Lake study (Loomis 

1989) and the Welsh et al (1995) study of the Grand Canyon suggest that significant 

passive use values may be associated with fluctuations and absolute levels of NPS lakes 

and reservoirs, perhaps especially Lake Powell and Lake Mead. There may also be 

significant values associated with river flows and the health of riparian ecosystems in the 

free-flowing Colorado River sections. This is a very significant data gap – monetarily 

perhaps the most important – in the set of comprehensive value estimates for Colorado 

River park units. 

5.5 Other Competing Water Uses 

Relatively speaking, data gaps and uncertainty are not significant for other uses. The 

range in values is based in differences across locations and facilities, and is relatively 

well understood. 
71

5.6 Summary 

Table 38 presents a summary of the availability of existing data and estimates needed for 

a comprehensive analysis of the impacts of water levels within the rivers and reservoirs 

of the Colorado River Basin NPS units on regional economic activity, direct use net 

economic value and passive use value. While data and estimates are available for a 

number of the cells in parks and tasks in the table, many cells show missing, dated, or 

only partial data. 

Table 38. Is Sufficient Information Available Now to Produce the Necessary Analysis Tools for 

Phase III? 

Park Unit Produce 

Regional 

Economic 

Impacts for 

Water-based 

Visitation? 

Estimate 

Marginal 

Impacts of 

Water level 

on Regional 

Economics? 

Produce 

Direct Use 

Total Value 

Estimates for 

Water-based 

Visitation? 

Estimate 

Marginal 

Impacts of 

Water level 

on NEV? 

Estimated 

Passive Use 

Values? 

Glen Canyon NRA

 Lake Powell 

 Colo. River (Glen-Lee’s)

YES 

DATED 

YES 

DATED 

YES 

DATED 

PARTIAL 

NO 

NO 

NO 

Lake Mead NRA

 Lake Mead 

 Lake Mojave 

NO 

YES 

NO 

YES 

NO 

NO 

NO 

NO 

NO 

NO 

Curecanti NRA PARTIAL NO NO NO NO 

Grand Canyon NP

 Grand Canyon Float YES YES DATED PARTIAL DATED 

Dinosaur NM

 Yampa & Green Riverb NO NO NO NO NO 

Canyonlands NP

 Cataract Canyonb NO NO NO NO NO 

Black Canyon NP 

Arches NP 

Rocky Mountain NP 

Minimal water-based use 
72

References 

Arizona Hospitality Research and Resource Center. 2005. Grand Canyon National Park: 

Northern Arizona Tourism Study. Northern Arizona University, Flagstaff, Arizona. 

Arrow, K., R. Solow, P. Portney, E. Leamer, R. Radner, and H. Schuman. 1983. Report of the 

NOAA Panel on Contingent Valuation. 

Berrens, Robert P., Alok K. Bohara, Hank Jenkins-Smith, Carol L. Silva, Philip Ganderton, and 

David Brookshire. 1998. “A Joint Investigation of Public Support and Public Values: 

Case of Instream Flows in New Mexico.” Ecological Economics. 27: 189-203. 

Berrens, R.P., A.K. Bohara, C.L. Silva, D. Brookshire, and M. McKee. 2000. “Contingent 

Values for New Mexico Instream Flows: With Tests of Scope, Group-size Reminder and 

Temporal Reliability.” Journal of Environmental Management. 58: 73-90. 

Berrens, Robert P., Philip Ganderton, and Carol L. Silva. 1996. “Valuing the Protection of 

Minimum Instream Flows in New Mexico.” Journal of Agricultural and Resource 

Economics. 21(2): 294-309. 

Bishop, R., K. Boyle, and K. Welsh. 1987. “Glen Canyon Dam Releases and Downstream 

Recreation: an Analysis of User Preferences and Economic Values.” Glen Canyon 

Environmental Studies Report No. 27/87. Bureau of Reclamation, Washington, D.C. 

Bishop, R., K. Boyle, and M. Welsh. 1993. “The Role of Question Order and Respondent 

Experience in Contingent-valuation Studies.” .” Journal of Environmental Economics 

and Management. 25(1):S80-S99. 

Booker, J. 1995. Hydrologic and Economic Impacts of Drought under Alternative Policy 

Responses. Water Resources Bulletin Vol. 31(5). 

Booker, J and B. Colby. 1995. Competing Water Uses in the Southwestern United States: 

Valuing Drought Damages. Water Resources Bulletin. 31(5):877-888. 

Booker, J. and R. Young. 1991. 

Booker, J. and R. Young. 1994. Modeling Intrastate and Interstate Markets for Colorado River 

Water Resources. Journal of Environmental Economics and Management 26(1):66-87. 

Borden, G., R. Fletcher, J. Lopez, and R. Grumbles. 2003. Water User Profile and Estimated 

Contributions to the Laughlin and Bullhead City Regional Economy. Nevada 

Cooperative Extension Center for Economic Development, University of Nevada, Reno, 

and University of Arizona Cooperative Extension. 
73

Brown, T. 2004. “The Marginal Economic Value of Streamflow from National Forests.” 

Discussion Paper DP-04-01, RMRS-4851. USDA Forest Service, Rocky Mountain 

Research Station. Ft. Collins, CO. 

Brown, T. and J. Duffield. 1995. “Testing Part-Whole Valuation Effects in Contingent Valuation 

of Instream Flow Protection.” Water Resources Research 31(9): 2341-2351 (September). 

CADSWES - Center for Advanced Decision Support for Water and Environmental Systems 

cadswes.colorado.edu

Champ, P., R. Bishop, T. Brown, and D. McCollum. 1997. “Using Donation Mechanisms to 

Value Nonuse Benefits from Public Goods.” Journal of Environmental Economics and 

Management. 33(2):151-162. 

Dawdy, David R. 1991. “Hydrology of Glen Canyon and Grand Canyon,” in Colorado River 

Ecology and Dam Management: Proceedings of a Symposium May 24-25, 1990. Santa 

Fe, New Mexico. Washington, D.C. National Academy Press. 

Deck, Leland. 1997. “Visibility at the Grand Canyon and the Navajo Generating Station.” In 

Richard D. Morgenstern, ed. Economic Analysis at EPA: Assessing Regulatory Impact,

pp. 267-301, Washington, D.C.: Resources for the Future. 

Douglas, A.J., 2005. Colorado River environmental and recreational values below Glen Canyon 

Dam: Fort Collins, Colo., U.S. Geological Survey. 

Douglas, A.J., and Harpman, D.A., 1995. Estimating recreation employment effects with 

IMPLAN for the Glen Canyon Dam region: Journal of Environmental Management 

44:233-247. 

Douglas, A.J., and D.A. Harpman. 2004. “Lake Powell Management Alternatives and 

Values:CVM Estimates of Recreation.” Water International 29 No. 3 (September, 

2004):375-383. 

Douglas, Aaron J. and Richard L. Johnson. Empirical Evidence for Large Nonmarket Values for 

Water Resources: TCM Benefit Estimates for Lake Powell. International Journal for 

Water Resources. 2 No. 4 (**** 2004):229-246 

Duffield, J. 1992. “An Economic Analysis of Wolf Recovery in Yellowstone: Park Visitor 

Attitudes and Values.” In John D. Varley and Wayne G. Brewster, Ed. Wolves for 

Yellowstone? A Report to the U.S. Congress Vol. IV. Research & Analysis, pp. 2-31 to 

2-87. National Park Service, Yellowstone National Park, July 1992. 

Duffield, J. and C. Neher. 1996. “Economic Analysis of Wolf Recovery in Yellowstone National 

Park”. Transactions 61st. North American Wildlife and Wilderness Conference. Pp. 285-

292. 
74

Duffield, J. and C. Neher. 2000. “Winter 1998-99 Visitor Survey Yellowstone N.P., Grand Teton 

N.P., and the Greater Yellowstone Area.” National Park Service, Yellowstone National 

Park, May 2000. 

Duffield, J. C. Neher, and T. Brown. 1992. “Recreation Benefits of Instream Flow: Application 

to Montana’s Big Hole and Bitterroot Rivers” Water Resources Research 28(9): 2169-

2181. 

Duffield J. and T. Brown. 1995. "Testing Part-Whole Valuation Effects in Contingent Valuation 

of Instream Flow Protection". Water Resources Research 31 (9):2341-2351 

Duffield, J., J. Carrey, C. Neher, T. Power, and R. Walsh. 1996. “The Economic Impacts of the 

1995-96 Shutdown of the National Park System: Macro Study.” Report for the National 

Park Service, Washington, D.C. 

Duffield , J. 1991."Total Valuation of Wildlife and Fishery Resources: Applications in the 

Northern Rockies", pp. 97-114 in Claire Payne, J.M. Bowker and Patrick C. Reed, eds. 

The Economic Value of Wilderness Proceedings of the Conference, Jackson, Wyoming, 

May 9-11, 1991. Asheville: Southeastern Forest Experiment Station. 

Duffiled, J., C. Neher, J. Boyer, and J. Carey. 1997. Economic Assessment of the Highwater 97A 

Incident: Yosemite National Park. Report for the National Park Service. 

Duffield, J., C. Neher, and D. Patterson. 2006. Integrating Landscape Scale Economic and 

Ecological Models in the Greater Yellowstone Area: Application to Wolf Recovery. 

Forthcoming, Proceedings of the 8th Biennial Scientific Conference on the Greater 

Yellowstone Ecosystem. 

Duffield, J., C. Neher, D. Patterson, and P. Champ. 2006. “Do Fishermen Lie: Measuring 

Hypothetical Bias across Response Formats”. Pp 86-114 in Klaus Moeltner, comp. 

Benefits and Costs of Resource Policies Affecting Public and Private Lands. Proceedings 

from the W1133 Annual Meeting, San Antonio, Texas, February 22-25, 2006. Nineteenth 

Interim Report. University of Nevada, Reno, Department of Resource Economics. 

http://www.ag.unr.edu/moeltner/w1133_s_antonio/w1133%20San%20Antonio%20Proce

edings.pdf 

Duffield, J., C. Neher, D. Patterson, and P. Champ. 2005. “Replication of a Cash and Contingent 

Valuation Experiment.” Proceedings from 2005 Western Regional Research Project W1133: Benefits and Costs in Natural Resource Planning, Salt Lake City, UT. 

Duffield, J., D. Patterson, and C. Neher. 1999. Evaluation of the National Park Service Fee 

Demonstration Program: 1998 Visitor Surveys. National Park Service, Washington DC. 

Eiswerth, M. E., J. Englin, et al. (2000). “The value of water levels in water-based recreation: A 

pooled revealed preference/contingent behavior model.” Water Resources Research

36(4): 1079-1086 
75

Fulp, Terrance, and Jane Harkins (2001), Policy Analysis Using RiverWare: Colorado River 

Interim Surplus Guidelines, Proceedings of ASCE World Water & Environmental 

Resource Congress, Orlando, FL. 

Gibbons, D. 1986. The Economic Value of Water, Resources for the Future, Washington DC. 

Graefe, A., and J. Holland. 1997. An Analysis of Recreational Use and Associated Impacts at 

Lake Mead National Recreation Area: a Social and Environmental Perspective. National 

Park Service, Lake Mead National Recreation Area. 

Griffen, R. 1998. “The Fundamental Principles of Cost-benefit Analysis.” Water Resources 

Research. 34(8)2063-2071. 

Hanemann, Michael, John Loomis, and Barbara Kanninen. 1991. “Statistical Efficiency of 

Double-Bounded Dichotomous Choice Contingent Valuation.” American Journal of 

Agricultural Economics. November. 

Harpman, D. A. 1999a. “Assessing the Short-Run Economic Cost of Environmental Constraints 

on Hydropower Operations at Glen Canyon Dam.” Land Economics 75(3):390-401 

(August). 

Harpman, D. A. 1999b. “The Economic Cost of the 1996 Controlled Flood.” In The Controlled 

Flood in Grand Canyon. Geophysical Monograph 110. Edited by Robert H. Webb, John 

C. Schmidt, G. Richard Marzolf, and Richard Valdez. Washington, D.C: Amercian 

Geophysical Union. 

Harpman, D. A. and L. M. Jalbert. 1997. Impacts of the Glen Canyon Dam Beach/Habitat 

Building Flow on Recreation and Hydropower. July 14. Draft paper. 

Harpman, D.A., M.P. Welsh, R.C. Bishop. 1995 “Non-use Economic Value: Emerging Policy 

Analysis Tool.” Rivers 4(4):280-291. 

Herriges, J.A. and C. L. Kling. 1999. Valuing Recreation and the Environment. Northhampton: 

Edward Elgar, 290 pp. 

Hjerpe, E., and Y. Kim. 2003. “Regional economic Impacts of Grand Canyon River Runners.” 

Northern Arizona University, School of Forestry. 35 pp. 

Hoehn, John P. 1991. “Valuing the Multidimentsional Impacts of Environmental Policy: Theory 

and Methods.” American Journal of Agricultural Economics. May. 

Hoehn, J., and A. Randall. 1989. “Too Many Proposals Pass the Benefit Cost Test.” American 

Economic Review. Pp.544-551. 
76

Holmes, T.P. and W.L. Adamowicz. 2003. “Attribute-Based Methods”. Pp 171-220 in P.Champ, 

K.J. Boyle, and T.C. Brown, eds. A Primer on Nonmarket Valuation. Boston: Kluwer. 

Huszar, Eric, W. Douglass Shaw, Jeff Englin, and Noelwah R. Netusil. 1999. “Recreational 

Damages from Reservoir Storage Level Changes” Water Resources Research 35, 11: 

3489-3494. 

Ingram, H., A. Tarlock, and C. Oggins. 1991. “The law and politics of the operation of Glen 

Canyon Dam.” IN: Colorado River ecology and dam management. Washington, DC: 

National Academy Press. pp. 10-27. 

Kaval, Pam, and John Loomis. 2003.Updated Outdoor Recreation Use Values with Emphasis on 

National Park Recreation. Fort Collins: Department of Agricultural and Resource 

Economics, Colorado State University. 

Krutilla, J. 1967. “Conservation Reconsidered.” American Economic Review. 

Lee, D., R. Howitt, and M. Marino. 1993. A Stochastic Model of River Water Quality: 

Application to Salinity in the Colorado River. Water Resources Research 29(12):3917-

3924. 

Leggett, Christopher G., Naomi S. Kleckner, Kevin J. Boyle, John W. Duffield, and Robert 

Cameron Mitchell. 2003.“Social Desirability Bias in Contingent Valuation Surveys”. 

Land Economics 79(4):561-575 (November). 

Loomis, J. 1992. The 1991 State of California Water Bank: Water Marketing take a Quantum 

Leap. Rivers 3, 129-140. 

Loomis, John B. 1989. “Test-Retest Reliability of the Contingent Valuation Method: A 

Comparison of General Population and Visitor Responses.” American Journal of 

Agricultural Economics. 71(1): 76-84. February. 

Loomis, John B. 1996. “Measuring the Economic Benefits of Removing Dams and Restoring the 

Elwha River: Results of a Contingent Valuation Survey.” Water Resources Research. 

32(2): 441-447. February. 

Loomis, J., A. Douglas, and D. Harpman. 2005. “Recreation Use Values and Nonuse Values of 

Glen and Grand Canyons.” IN The State of the Colorado River Ecosystem in the Grand 

Canyon, USGS Circular 1282. U.S. Geological Survey, Edited by Gloss, S., J. Lovich 

and T. Melis. 

McKean, J., D. Johnson, and R. Walsh. 1995. “Valuing Time in Travel Cost Demand Analysis: 

An Empirical Investigation.” Land Economics V71.No.1. 

Martin, William C., F.H. Bollman, and R. Gum. The Economic Value of the Lake Mead Fishery 

with Special Attention to the Largemouth Bass Fishery.” Final report to the Nevada 
77

Department of Wildlife, the Arizona Game and Fish Department and the Water and 

Power Resources Service. Contract No. 14-06-300-2719. Sacramento, California: Jones 

& Stokes Associates, Inc., October 15, 1980. 

Minnesota Implan Group. 2005. www.implan.com. 

Munger, D., and R. Vinton. 2005. “Blue Mesa Reservoir Economic and Recreation Study: Data 

Collection and Survey Analysis.” U.S. Department of the Interior, Bureau of 

Reclamation. Technical Services Center, Economics Group. Denver, CO. 29 pp. 

National Academy of Sciences, 1999. Downstream: Adaptive Management of Glen Canyon Dam 

and the Colorado River Ecosystem. National Academy Press, Washington D.C. 230 pgs. 

National Park Service. 2004. “Economic Impact Analysis of the Temporary Winter Use Plan for 

Yellowstone and Grand Teton National Parks and John D. Rockefeller, Jr., Memorial 

Parkway.” Fort Collins, CO: National Park Service Environmental Quality Division, 

August. 

National Research Council. 1996. River Resource Management in the Grand Canyon. National 

Academy Press, Washington, D.C. 

National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental 

Decision Making. National Academy Press, Washington, D.C. 

Neher, C.J. and J.W. Duffield. 2000. "Economic Analysis of National Park issues: An 

Assessment of the Impacts of the 1997 Floods in Yosemite Park". Park Science

20(1):21-23 (Spring 2000). 

Oamek, G. 1990. Economic and Environmental Impacts of Interstate Water Transfers in the 

Colorado River Basin. Monograph 90-M3, Center for Agricultural and Rural 

Development, Iowa State University, Ames, Iowa. 

Parsons, George. 2003. “The Travel Cost Model”. Pp. 269-330, in P.Champ, K.J. Boyle, and 

T.C. Brown, eds. A Primer on Nonmarket Valuation. Boston: Kluwer 

Platt, J. and D. Munger. 1999, Impact of Fluctuating Reservoir Elevation on Recreation Use and 

Value. Bureau of Reclamation, Technical Service Center. Denver, Co. 

Platt, J. 2001. Reservoir Recreation Use Estimation Modeling with Water Level Fluctuation. 

Bureau of Reclamation, Technical Service Center. Denver, Co. 

Power Resources Committee. 1995. Power System Impacts of Potential Changes in Glen Canyon 

Power Plant Operations, Phase III Final Report. 305 pp. Stone Webster Manage. 

Consult., Inc., Denver, CO (NTIS No. PB96-114004). 
78

Randall, A. and J. Stoll. 1983. “Existence Value in a Total Valuation Framework.” IN Managing 

Air Quality and Scenic Resources at National Parks and Wilderness Areas. (Rowe and 

Chestnut, Eds. 1983). 

Schulze, W., D. Brookshire, et al. 1983. “The Economic Benefits of Preserving Visibility in the 

National Parklands of the Southwest.” Natural Resource Journal Vol. 23, 149-165 

Stockton, C.W. and G.C. Jacoby. 1976. “Long Term Surface Water Supply and Stream Flow 

Trends in the Upper Colorado River Basin.” Lake Power Research Project Bulletin No. 

18 (University of California at Los Angeles: Institute of Geophysics and Planetary 

Physics). 

Stynes, D., D. Propst, , W. Chang, and Y. Sun. 2000. “Estimating regional economic impacts of 

park visitor spending: Money Generation Model Version 2 (MGM2).” East Lansing, MI: 

Department of Park, Recreation and Tourism Resources, Michigan State University 

Sutherland, Ronald J. and Richard G. Walsh. 1985. “Effect of Distance on the Preservation 

Value of Water Quality.” Land Economics. 61(3): 281-291. August. 

Tarboton, D. 1995. Hydrologic Scenarios for Severe Sustained Drought in the Southwestern 

United States. Water Resources Bulletin 31(5):803-813. 

U.S. Department of the Interior, Bureau of Reclamation. 1995. Operation of Glen Canyon Dam 

Final Environmental Impact Statement. Bureau of Reclamation, Salt Lake City, UT. 

U.S. Department of the Interior, Bureau of Reclamation. 1999. Glen Canyon Dam Modifications 

to Control Downstream Temperatures—Plan and Draft Environmental Assessment. 

Bureau of Reclamation, Salt Lake City, UT. 

U.S. Department of the Interior, Bureau of Reclamation. 2000. Colorado River Interim Surplus 

Criteria Final Environmental Impact Statement. Bureau of Reclamation, Henderson, NV. 

U.S. Department of the Interior, Bureau of Reclamation. 1996. Glen Canyon Dam Beach/Habitat 

Building Test Flow: Final Environmental Assessment and Finding of No Significant 

Impact. Bureau of Reclamation, Salt Lake City, UT. 

U.S. Department of the Interior, Bureau of Reclamation. 2004. 2005 Colorado River Annual 

Operating Plan. http://www.usbr.gov/lc/

U.S. Department of the Interior, Bureau of Reclamation. 2005a. Law of the River at 

http://www.usbr.gov/lc/region/pao/lawofrvr.html. 

U.S. Department of the Interior, Bureau of Reclamation. 2005b. Draft 2006 Colorado River 

Annual Operating Plan. http://www.usbr.gov/lc/riverops.html. 
79

U.S. Environmental Protection Agency (U.S. EPA). 2000. Guidelines for Preparing Economic 

Analyses. EPA 240-R-00-003. 

U.S. Water Resources Council. 1983. “Economic and Environmental Principles for Water and 

Related Land Resource Implementation Studies.” U.S. Govt. printing Office, 

Washington, D.C. 

Ward, F., and J. Fiore. 1987. Managing Recreational Water Resources to Increase Economic 

Benefits to Anglers in the Arid Southwest. New Mexico Agricultural Experiment Station 

Research Report 609, New Mexico State University, Las Cruces, New Mexico. 

Ward, F., B. Roach, and J. Henderson. 1996. “The Economic Value of Water in Recreation: 

Evidence from the California Drought.” Water Resources Research Vol. 32, No. 4, pp. 

1075-1081. 

Weisbrod, B. 1964. “Collective Consumption Services of Individual Consumption Goods.” 

Quarterly Journal of Economics. 78 pp. 471-477. 

Welsh, M., R. Bishop, M. Phillips, and R. Baumgartner. 1995. “Glen Canyon Dam, Colorado 

River Storage Project, Arizona—Nonuse Value Study Final Report.” Madison, WI. 

Wheeler, K., T. Magee, T. Fulp, and E. Zagona. 2002. Alternative Policies on the Colorado 

River. University of Colorado, Center for Advanced Decision Support for Water and 

Environmental Systems. Report for the U.S. Bureau of Reclamation. 

White, P.J., Douglas W. Smith, Michael Jimenez, Terry McEneaney, John W. Duffield, and 

Glenn Plumb. 2005.“Yellowstone After Wolves: Environmental Impact Statement 

Predictions and Ten-Year Appraisals”. Yellowstone Science 13(1):34-41 (Winter 

2005). 

Young, R. 2005. Determining the economic value of water: concepts and methods 

Resources for the Future, Washington DC.

 
80

Appendices