U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2008–3081

September 2008

White sturgeon.

Aerial view of The Dalles Dam looking east. Inset 

shows the east fish ladder.

Printed on recycled paper

White Sturgeon Passage at The Dalles Dam

Researchers at the USGS 

Western Fisheries Research 

Center’s Columbia River 

Research Laboratory, working 

with the U.S. Army Corps of 

Engineers, sought to better 

understand upstream and 

downstream passage of white 

sturgeon at dams. A study at 

The Dalles Dam provided the 

opportunity to compare two fish 

ladders; one that passes sturgeon 

upstream to one that does not, to 

determine if subtle differences 

in construction result in better 

passage of white sturgeon. 

Researchers conducted a study 

using a combination of acoustic 

and radio telemetry technologies 

to obtain information on juvenile 

and adult white sturgeon near 

The Dalles Dam, with the 

objectives of characterizing the 

distribution and movements of 

white sturgeon in the immediate 

vicinity of the dam and to determine

timing and routes of upstream 

and downstream passage.

White sturgeon Acipenser 

transmontanus are the largest freshwater 

fish in North America, and they are an 

important cultural, recreational, and 

commercial resource in the Columbia 

River Basin. Prior to the building of dams 

for hydroelectric power production and 

other uses, this species likely responded 

to seasonal changes in food and habitat 

availability by ranging extensively between

freshwater, estuarine, and marine

environments. Construction of the dams 

has largely blocked upstream sturgeon 

movements, although downstream passage 

still occurs. An exception to this is the 

east fish ladder at The Dalles Dam where 

significant numbers of white sturgeon 

have been counted passing upstream.

Columbia River Basin hydroelectric 

dams provide many benefits to society 

including electricity, navigation, water 

for irrigation, and recreation. However, 

they also impede migrations of fish. 

White sturgeon seldom ascend fish 

ladders at dams probably because fish 

passage facilities for upstream migrating 

fish were designed primarily for adult 

salmon and steelhead. The large body 

size and swimming capabilities of white 

sturgeon were not considered during the 

design of the fish ladders. Past studies 

have shown that white sturgeon do pass 

downstream through the dams, but the 

routes of passage through dams were 

never identified. Downstream passage by 

fish is possible only through operating 

turbines, open spill gates, the ice and 

trash sluiceway when it is operating or 

the navigation lock as vessels pass up or 

down stream. 

Upstream passage of white sturgeon 

does occur at some dams but the number 

of fish counted is typically quite low 

and at many ladders often no white 

sturgeon are counted. However, at The 

Dalles Dam, far greater numbers of white 

sturgeon are often seen. This dam has two 

fish ladders, and the east ladder nearly 

always allows a substantial number of 

white sturgeon to pass upstream. For 

example, in 1995 fish counters at the 

dam noted 943 white sturgeon passing 

upstream in the east fish ladder and 104 

in the north fish ladder. 

The researchers captured and tagged 

148 white sturgeon ranging in size from 

95 to 280 cm (37 to 110 in.) in length. 

Ninety fish were released downstream of 

the dam and 58 were released upstream. 
The researchers determined that 

some tagged white sturgeon entered and 

resided in both fish ladders, but only 

successfully passed upstream through 

the east ladder. They determined that 

although both ladders at this dam have 

overflow weirs with submerged orifices 

so fish can pass near the surface or along 

the bottom of the ladder, the east fish 

ladder is built slightly larger than the 

north fish ladder. In particular, the east 

ladder is wider by 1.82 m (6 ft) and the 

submerged orifices are twice the size of 

the orifices in the north ladder. 

The researchers also determined 

that white sturgeon passed downstream 

through open spillway gates. The 

researchers unexpectedly discovered 

that some fish that passed downstream 

through the spillway gates quickly 

returned back upstream by passing 

through the east ladder. Also, some fish 

that were tagged passed downstream 

through the Bonneville Reservoir and 

Bonneville Dam and were subsequently 

located in the Columbia River estuary.

Other Study Findings:

•	 White sturgeon resided within the 

ladders for periods ranging from 1 

minute to nearly 6 months.

•	 Upstream and downstream passage 

primarily occurred between April 

and September.

•	 Seventeen percent of the sturgeon 

tagged in the forebay moved 

downstream indicating that lower 

river fisheries benefit from fish 

produced in upstream areas. 

•	 During winter months, white 

sturgeon aggregated downstream 

of the dam as well as in the 

forebay. They dispersed as water 

temperatures rose during the spring.

Fish smaller than those tagged in 

this study pass downstream as well. 

Trash-racks on the turbine intakes prevent 

large fish from passing downstream 

through turbines, but smaller fish could 

pass through the turbines as well as pass 

over the spillways when the gates are open.

Sturgeons as a group of about 25 

species worldwide (the exact number 

depends on whether you count certain 

subspecies as one or two species), are 

considered to be among the world’s 

most endangered and threatened fishes. 

This research shows that fish ladders 

can be built to provide upstream passage 

for white sturgeon, and indicates that 

ladders can be built for other species 

as well. In the Columbia River Basin, 

further research is needed to understand 

how ongoing changes to operations at 

hydroelectric dams to benefit migrating 

salmonids may influence upstream or 

downstream passage by white sturgeon.

For additional information,

 please contact:

Michael J. Parsley

U.S. Geological Survey

Western Fisheries Research Center

Columbia River Research Laboratory

5501A Cook-Underwood Road, 

Cook, WA 98605; 

(509) 538-2299 ext. 247; 

FAX (509) 538-2843; 

mparsley@usgs.gov

http://wfrc.usgs.gov

Map showing dam locations.

Lower reach of the north fish ladder.

USGS staff surgically implanting a transmitter in a 

large white sturgeon.