Nevada warm springs 

Modeling Streams and 

Rivers 

Hydraulic models of streams and 

rivers can now be built at very fine 

scales – inches or feet – and then 

adapted to model the habitat of 

stream fishes. Researchers collect 

field data, construct habitat 

preference models that include 

water depth, water velocity, and 

other variables, and interweave 

these with the hydraulic models. 

The combined approaches are used 

to predict broad variations in fish 

habitat across a wide range of 

flows caused by upstream dam

operations, natural variability, 

climate change, and other factors. 

The WFRC has developed and 

applied these types of habitat 

models for analysis of juvenile 

Chinook salmon (Oncorhynchus 

tshawytscha) rearing in the Hanford 

Reach of the Columbia River and for 

adult chum salmon (O. keta) 

spawning below the Bonneville Dam

in the lower river. Plans are 

underway to develop a similar model 

for fish in the Yakima River Basin to 

help agencies evaluate a potential 

new reservoir that would increase 

irrigation reserves for southern 

Washington.

Warm Water Fish get Help

The Moapa dace (Moapa coriacea) 

is an endangered fish species that 

occurs only in warm springs and 

streams that feed into the Muddy 

River in southern Nevada near Las 

Vegas. These small, unique fish live 

in waters whose temperatures range

from 26 to 32o

 C (79-90o F) – such 

fish are called “thermal endemic” 

species, meaning that they require 

warm water to survive. The 

persistence of the Moapa dace has 

recently been jeopardized, 

however, by human activities. 

First, the headwaters of the Muddy

River were invaded by the nonnative blue tilapia which are 

known herbivores but switched to 

eating Moapa dace once all the 

aquatic vegetation was gone, 

eliminating them from 90% of 

their native range. Secondly, 

spring flow in the 10% of the 

habitat not invaded by blue tilapia 

is declining due to pumping of the 

nearby groundwater (the 

carbonated aquifer), the source of 

the spring flow. Reduction in 

Managing Water in the West: Developing New Tools for 

a Critical Resource 

Rapid population growth in the Western United States 

over the last century has placed increasing strains on 

our water supplies and aquatic ecosystems. 

Historically, water rights have been used to determine 

the allocation of water in the West, but rules and 

regulations related to endangered species now often 

drive how water is released from reservoirs in large 

rivers such as the lower Colorado and the Columbia. 

In numerous smaller watersheds, communities are 

trying to balance the water necessary for human use, 

irrigation, and the conservation of ecosystems. 

To assist managers in the face of increasing complexity

and uncertainty in water management decisionmaking, the Western Fisheries Research Center 

(WFRC) is involved in developing a new generation of 

integrative tools. Below are some examples of the types 

of tools that already exist within the WFRC. 

U.S. Department of the Interior WFRC Fact Sheet 

U.S. Geological Survey August 11, 2005 

 
 

spring flow is anticipated to lessen 

habitat quantity and quality 

through reduction of water volume 

and the extent of optimum thermal 

habitat. Biologists from the WFRC 

were contracted by the U.S. Fish 

and Wildlife Service to collect 

pertinent data and develop a model 

aimed at predicting the persistence 

of Moapa dace under various 

changing environmental 

conditions. The new generation 

model, along with field and

laboratory data, will include 

evaluations of habitat effects on 

movements, behavior, growth, and 

respiration of the fish, and will be a

useful tool to manage and protect 

Moapa dace. 

nd

Example of using hydrodynamic models and fisheries habitat data to illustrate changes in

habitat that could be expected under different water level elevations in a Columbia River 

reservoir. 

Columbia River, one of the last 

free-flowing segments of the 

river and the most important 

spawning habitat of fall Chinook

salmon, we have developed an 

internet mapping application that 

lets users select one or more

stream flows and then view

potential rearing habitat of subyearling Chinook salmon. In the 

John Day Reservoir of the 

Columbia River, we have 

developed an internet mapping 

tool that allows users to examine 

potential white sturgeon or 

Chinook salmon spawning 

habitat at a selected river 

discharge. Our next big

challenge is the development of 

an internet mapping tool that w

allow users to query and displa

important fish habitats 

throughout Puget Sound and 

identify gaps in the conservation 

of target species. Other areas we 

hope to develop are internet 

mapping applications for the 

Klamath Basin in southern 

Oregon and the Columbia River 

estuary. 

ill

y

What Comes Next? 

The USGS and the WFRC are 

beginning discussions with the 

Department of the Interior partners 

and other parties in the West to 

determine the need for new models 

and the types of tools that would be 

most useful. A series of workshops 

have begun across the region to 

obtain input from the Department of 

the Interior partners, identify

technical expertise within USGS, a

describe the types of models that 

would be most appropriate. The new 

generation of integrative tools will 

build on existing techniques to 

address the complex issues of 

changing stream flow, groundwater 

availability, climate conditions, and 

water quality, and allow managers to 

forecast the biological and habitat 

effects of these changes. 

For additional information, please contact: 

Lyman Thorsteinson, Center Director 

U.S. Geological Survey

Western Fisheries Research Center 

6505 NE 65th Street, Seattle, WA 98115 

(206) 526-6282 ext. 236 

 FAX (206) 526-6654 

Internet Tools 

The WFRC is developing a set of 

internet mapping applications that 

will allow scientists and the public to 

query and view important landscape 

features or species’ habitats of 

concern. In the Hanford Reach of the 

Satellite image of Puget Sound, WA.