Portland District


District Fish Program

We rely on varied operational approaches, including spill, turbine improvements, surface passage, bypass and fish transportation systems, to address the impacts on fish populations from hydroelectric projects (along with habitat, hatcheries and harvest--commonly referred to as the four H’s) for an effective fish restoration strategy.

The Corps has monitored pinniped predation on adult salmonids and sturgeon at Bonneville Dam since 2002. Working with NOAA, CRITFC, and the states of Oregon and Washington, the Corps also began active non-lethal hazing from the dam in 2006 while the states began boat based non-lethal hazing. In 2008, the states began a removal program for specific California sea lions and the Corps' monitoring program supports these efforts and the continuation of non-lethal hazing efforts.

Improving Passage

Bonneville Power Administration, in partnership with the Corps of Engineers and NOAA Fisheries, produced this video to explain recent improvements we're making for fish passage.

Draft Reports: Open Review Period

No draft reports are currently available for review.


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The District transports between 15-22 million fish each year, depending upon run-off and amount of spill.

The Corps began a maximum collection and transport operation using specially-designed trucks and barges to collect Snake River steelhead and late migrating spring/summer Chinook salmon during late spring.

The Corps began barging as an emergency measure in 1977 in the record drought year as a way to move large numbers of fish. In 1978 the Corps modified two barges and started the program, in earnest, in 1981. By 1983 two more barges were built, giving the Corps the ability to barge every day out of Lower Granite Dam.

The transport systems recirculate water, add oxygen and have refrigeration systems that allow us to heat or chill the water. If the water temperature is 65 degrees at Lower Granite Dam and it’s 62 degrees at Bonneville Dam, then over the course of the trip we will slowly drop the temperature to 62 degrees before we release them.

Transporting helps increase fish survivability by putting them on a more natural calendar and helps them bypass potential predators.

Transporting fish gets them back toward their biological clock for the appropriate timing when they should be entering the ocean which enables them to have a better transition to salt water, and hence survival.

Transport is not the total answer to long-term fish population restoration, but it is one tool in our toolbox. There is a time and place for transport, and as we incorporate new technologies like the spillway weirs, we’re reconfiguring the project to accommodate them. We also are building new juvenile facilities and incorporating flexibility into our systems so we can operate the dams to maximize adult fish returns.
The Corps has been concerned with fish restoration efforts since 1888, when it warned Congress of an enormous reduction in the numbers of spawning fish in the Columbia River due primarily to harvesters, over-fishing and habitat destruction.

In 1929, regional Corps officials advised that future Corps-built dams provide for the passage upstream of fish, especially salmon migrating to breeding places. In 1934, the Corps assembled teams of internal and outside experts to design fish passage systems for Bonneville Dam.

The Corps applied the lessons learned and decades of research into constructing the dams on the lower Snake River from 1968 to 1975.
Juvenile fish bypass systems, which have operated at the dams for decades, guide fish away from turbines by means of submerged fish screens installed in front of turbines. As the fish migrate downriver, they follow currents and may be attracted by the current created by an operating turbine.

As the fish follow the current towards the turbines, screens guide fish up and into a collection channel in the dam. Fish are then routed either out a bypass outfall or to a raceway for transportation by truck or barge downstream. Estimates of how many fish are guided into mechanical screen bypass systems at dams vary by location (dam, turbine), time (season, day, time of day), species/run, river flow, and powerplant operations.
Regardless of hydrosystem operations, fish, sea lions and birds, especially Caspian terns and cormorants, take a large toll on juvenile fish. Several federal agencies were involved in redistributing a Caspian tern colony in the Columbia River estuary, downriver to an island nearer the ocean. The terns, which had consumed 15 million salmonids in 1999, consumed about three million salmon and steelhead in 2004.

Also, a relatively small but stable population of Caspian tern (about 1,000 birds) on Crescent Island above McNary Dam consumed an estimated one million smolts in 2004, including about 35 percent of the Snake River steelhead smolts.

In addition, double-crested cormorants, have increased their take of fish. Their numbers grew from 100 birds in the estuary in 1989 to 18,000 in 2004 when they also consumed an estimated 6.4 million salmonids leading Federal agencies to evaluate alternatives to address this situation.

The Corps has pioneered research for the past 50-years seeking solutions to improve fish survival through the hydrosystem. This effort integrates the technical expertise of biologists and engineers that lead to novel fish passage operations and structural improvements at the dams.

While the Corps continues the spread the risk approach to fish operations, we will continue exploring the development of future spillway weirs and other innovative fish passage options, and pioneering research to ensure the long-term restoration of salmon.
Spill is widely recognized as one of the highest survival routes for juvenile fish passage. Water is poured through spillway openings rather than being routed through turbines to generate power or being used for other purposes. Spill has to be carefully managed to avoid gas supersaturation that can be harmful to fish. The Federal agencies responsible for fish restoration recommended using an “adaptive management” approach starting with a spring spill operation that maximizes in-river passage for Snake River spring/summer Chinook until April 20- May 1.
The District is pioneering research into surface passage systems that use emerging technologies like spillway weirs to improve fish passage over spillways. In the spring, most juvenile salmon tend to stay in the upper 10 to 20 feet of the water as they migrate downstream to the ocean. Fish migrating during the summer stay deeper.

When approaching dams, juvenile fish dive 50-60 feet to locate fish passage routes such as a spillway opening or juvenile fish screening system. At 1.7 million pounds, 10 stories high and 70-feet long, spillway weirs act as giant fish slides, allowing juvenile fish to pass near the water surface under lower accelerations. It uses less water, which benefits hydropower production, and less spill also reduces the dissolved gas levels in water, which can be harmful to fish.

The first spillway weir was installed at Lower Granite Dam in 2001, and a second was placed at Ice Harbor Dam in 2005. The next two spillway weirs were installed at McNary dam in 2007. In 2008, another spillway weir was installed into Lower Monumental Dam, and in 2009, Little Goose dam had a spillway weir installed. This allowed a surface passage route to be available for downstream migrating fish at each of the NWW FCRPS hydroelectric projects.
Fish research is aided by the use of Passive Integrated Transponder, or PIT tags, that are inserted into juvenile fish and read as they pass detectors at the dams. As the tag is read, data about that particular fish is fed into computers that allows tracking of migrating PIT-tagged fish through the river system. That helps researchers determine, for example, which watershed is most successful in returning salmon after smolt release. As for adults, in 2004, improvements were made to provide swim thru antennas for detecting adults as they pass through fish ladders. These electromagnetic field PIT-tag detectors not only enabled researchers to track the progress of individual juvenile fish migrating through the dams downstream, but also tracked them as adults returning to spawning grounds. Adult PIT-tag detectors are in operation Bonneville, McNary, Ice Harbor and Lower Granite dams.

Fish Counts

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Day, night, and winter fish counts from 15 Corps fishladders are reported on these pages.

Day fish counts (4 a.m. - 8 p.m. PST each day from April 1 through Oct. 31 each year) are taken by fish counters looking directly into the fishladders. They count the fish passing by 50 minutes each hour.

To account for the fish that pass by during the breaks they take (160 minutes of break), we add the counts made during the day's counting periods (800 minutes of counting), multiply the total by 1.2, round to the nearest whole fish, and present that number as our estimate of the day count in each ladder.

The fish counters are currently taking separate counts of adult chinook, jack chinook, clipped steelhead, unclipped steelhead, adult coho, jack coho, sockeye, chum, pink, shad, and lamprey. We add the adult chinook and jack chinook day estimates together to get All chinook, clipped steelhead and unclipped steelhead day estimates together to get All steelhead, and adult coho and jack coho day estimates together to get "All" coho. When night (8 p.m. - 4 a.m. PST each day) or winter (Nov. 1 through March 31) fish counts are taken, the fish counters use video, recording and reading the entire 60 minutes of each hour, so no estimation is necessary.

The counting schedules we maintain, which fish species are counted, how the counts are reported, and the methods for expansion or estimations we use are determined by the Fish Passage and Operations Management committee, who are NOAA, CRITFC, ODFW, WDFW, IDFW, BPA, and COE biologists.

April 1 was the start of the 2011 fish passage season. The fish counters returned to work and resumed counting. They count fish from 5 a.m. to 9 p.m. (DST) each day, and will count until Oct. 31.

Fish counting at the dams was started as each dam was put into service:

  • at Bonneville in 1938,
  • at McNary in 1954,
  • at The Dalles in 1957,
  • at Ice Harbor 1962,
  • at John Day in 1968,
  • at Lower Monumental in 1969,
  • at Little Goose in 1970,
  • and at Lower Granite in 1975.

Portland District publishes the fish counts taken at the dams in annual fish passage reports, as daily, monthly, and yearly count totals of fish migrating upstream through the fishladders at each dam.

The fishladders assist native populations of returning anadromous chinook, steelhead, sockeye, and coho salmon and lamprey. Chinook (Oncorhynchus tshawytscha), coho (O. kisutch), sockeye (O. nerka), and steelhead (O. mykiss) have been counted steadily.

Pink (O. gorbuscha) and chum (O. keta) are rarely seen above Bonneville. Few are seen at Bonneville each year. No persistent populations of pink are known to exist in the Columbia Basin. A persistent population of chum is known to exist in the Columbia Basin at the Grays River, Hardy Creek, and Hamilton Springs. The Grays River is well below Bonneville Dam. Hardy Creek and Hamilton Springs are only a few kilometers below Bonneville Dam.

The counters have fairly steadily counted two other returning anadromous fish; American shad (Alosa sapidissima) and Pacific lamprey (Lampetra tridentata).

Cutthroat trout (especially anadromous cutthroat trout), which often need to be handled to be identified correctly, are rarely seen by the fish counters.

Bull trout (Salvelinus confluentus) and white sturgeon (Acipenser transmontanus, a diadromous fish) are also counted in the notes the fish counters take. River-resident species of fish, were counted from 1939 through 1969, but are no longer counted.

Since 1980:
Jack size chinook (12 inches to under 22 inches) and jack size coho (12 inches to under 18 inches) are counted separately from adult size chinook (22 inches and up) and adult size coho (18 inches and up).

Since 1981:
Fish counts from each fishladder (first 2 queries below) go back to 1981. In Portland District annual fish passage reports fishladder counts are combined to get the counts for each dam (Bonneville, The Dalles, John Day, McNary, Ice Harbor, and Lower Monumental each have 2 fishladders). These dam by dam counts (3rd, 4th, and 5th queries below) go back to 1938. Individual fishladder records from before 1981 are either archived (the counts from the fishladders at Bonneville, The Dalles, and John Day are archived) or may be in storage at the other dams, unavailable, or lost.

Since 1981, at Bonneville:
The upper section of the Cascades Island fishladder (before 1981 this fishladder was the Washington shore fishladder at Bonneville) is closed to fish passage and upstream migrating fish are rerouted to the Washington shore fishladder. It is occasionally reopened when the Washington shore fishladder is out of service or the channel to the Washington shore fishladder is blocked.

Since 1994:
Clipped and unclipped steelhead are counted separately.

Since June 1, 2010 at Bonneville:
Lamprey passage systems are in use seasonally. These provide lamprey with alternate routes to take around sections of the Bradford Island and Washington shore fishladders. In the Cascades Island fishladder entrance area, a third LPS leads to a trap. Biologists take the trapped lamprey to sites upriver of Bonneville.

On the advice of the Fish Passage Operations and Management committee, made up of NOAA, CRITFC, ODFW, WDFW, IDFW, BPA, and COE biologists, Portland District has stopped shad counting at The Dalles, beginning in 2011.