Deschutes Basin Studies

Good science is at the heart of our fisheries and water quality program. 

Our biologists and technicians work with partner organizations and expert consultants to gather and analyze the data needed to make the best management decisions possible in support of healthy, wild salmon, steelhead and other species in the Deschutes Basin above and below our project.

Reintroduction studies

The following studies evaluate all aspects of the reintroduction program from rearing in the streams, downstream smolt migration, survival through the reservoir and in the lower Deschutes river and finally their return as adults.

These studies are conducted by fisheries biologists with Portland General Electric and the Confederated Tribes of the Warm Springs Reservation of Oregon.

Juvenile Rearing

Salmonid Rearing, Juvenile Densities, and Habitat: Study by PGE and CTWS

During the late summer to early fall, researchers use Mark-Recapture electrofishing to sample the juvenile redband/steelhead trout population and estimate the population sizes in Whychus, McKay and Ochoco creeks.

Juvenile Chinook salmon are also captured. Electrofishing results are also reported in the PGE Native Fish Monitoring Report.

In the Metolius River, Lake Creek and Whychus Creek, we conduct snorkeling surveys in spring, summer and fall to estimate spring Chinook parr densities and measure growth throughout the year.

Juvenile Migration

Juvenile Migration: Study by PGE and CTWS

We operate downstream migrant traps, called rotary screw traps, in the tributaries that feed Lake Billy Chinook, including the Metolius and Crooked rivers, Ochoco, McKay and Whychus creeks.

These traps capture downstream migrating salmon and steelhead smolts. By releasing captured fish above the traps we can calculate capture efficiencies for the population, allowing us to estimate the number of migrating smolts.

PIT tags help us collect additional information about smolt behavior. In these reports you’ll find information on tributary smolt population estimates, travel times through the reservoir, growth, percentage of smolts captured at the SWW, and survival to the mouth of the Deschutes River and Bonneville Dam.

Reservoir Survival

Reservoir Survival, Predation, Fishery and Disease: Study by PGE and CTWS

Several of our one-time or recurring studies help us evaluate factors that may affect the survival of salmon and steelhead smolts migrating into and through Lake Billy Chinook.

Our reservoir survival studies use radio and PIT-tags to estimate survival (based on collection efficiency) from tributary smolt traps and release locations to the Selective Water Withdrawal (SWW).

Studies looking at smallmouth bass diet and populations sizes in LBC were conducted in 2009 and 2014, and a bull trout diet study was conducted 2011-2013.

Both these studies were designed to help estimate the impact of predation on salmon and steelhead smolts. A recurring creel survey also looks at the number of salmon and steelhead smolts captured by anglers.

Lastly, Oregon Department of Fish and Wildlife pathologists examine fish captured throughout the Deschutes Basin, including at the SWW, to identify any health issues.

Adult Migration

Adult Migration, Survival, and Spawning: Study by PGE and CTWS

As adult Chinook salmon, sockeye salmon, and summer steelhead return to the Pelton Fish Trap, located below the Re-Regulating Dam (river mile 100), we identify reintroduction fish – fish that reared in upstream tributaries – by a jaw clip we gave them as smolts, when they were captured at the SWW for downstream transport.

These fish are transported above the project and released into Lake Billy Chinook to spawn in the Metolius, Deschutes and Crooked Rivers.

A sub-sample of adults receive a radio tag, allowing biologist to track their movements through Lake Billy Chinook and their chosen tributary. Each radio tag emits a unique signal we can detect using hand-held, helicopter, truck and boat mounted antennas.

In these annual reports you will find adult return numbers, timing, movement data and spawning locations.

Water Quality

PGE and the CTWS monitor water quality as part of their responsibility to be good stewards of the river and surrounding environment. We work closely with water quality regulators for the State of Oregon and the Tribes to understand and mitigate the impact of our project while helping to improve conditions for fish and other aquatic life.

Water Quality Study

Water Quality Study (2015-2019) by PGE and CTWS

We completed data collection for this multi-year study in early fall, 2016 and will use it to evaluate changes in water quality markers from multiple sites on the Deschutes system, above and below the Pelton Round Butte Hydroelectric Project, comparing the data with conditions measured before the Selective Water Withdrawal system became operational.

We are also using this data to create parameters we can use with computerized models developed by the U.S. Environmental Protection Agency (EPA), which will allow us to evaluate the effect of project management and environmental factors on water quality, temperature and algae growth.

A final report will be available in summer, 2019, but preliminary findings may be posted from time to time when meaningful information becomes available.

Upper Basin Studies

A key component of our stewardship efforts on at the Pelton Round Butte Project is focused on reintroduction of salmon and steelhead runs in the upper Deschutes River basin.

As part of that work we learn from research conducted by our partners into the health and condition of other fish species in the upper basin to better understand the entire system and the impact of our project.

Deschutes River Sockeye Development Project

Study by CTWS

Using seine nets, researchers catch thousands of kokanee each summer in the upper end of the Metolius Arm of Lake Billy Chinook. Captured fish are tagged with 2” fluorescent plastic tag and released.

Kokanee then continue upstream into the Metolius River to spawn where crews survey most of the river and record the number of fish observed with and without tags. That information is used to estimate how many kokanee left Lake Billy Chinook to spawn.

During the spring, the CTWS operates a rotary screw trap in Lake Creek below the outlet of Suttle Lake to capture and estimate how many kokanee are leaving the lake.

Some of the fish are implanted with PIT-tags so they can be detected moving downstream by PIT-tag antennas. In the summer and winter, CTWS researchers survey 41 transects in Lake Billy Chinook using boat mounted hydroacoustics, a high powered fish finder, to estimate the number of fish by size class.

Effects of a modified flow regime on the fish populations of the Crooked River below Bowman Dam

Study by Oregon Department of Fish and Wildlife

ODFW crews use drift boat mounted electrofishing gear to sample the Crooked River redband trout and mountain whitefish populations periodically between Big Bend and Cobble Rock campgrounds (2.6 mile reach).

Captured fish are weighed, measured, and marked before release. The reach is sampled again the following day and the number of marked and unmarked fish captured is recorded.

This information allows a population estimate to be calculated, expressed as the number of fish per mile. In this report, population estimates for redband trout from 2006 to 2016, are compared to the Bowman Dam discharge to better understand how dam operations (flows) may impact fish populations in the Crooked River.

The report also includes redband and whitefish population estimates for 1989, 1993 to 1995, 2001, 2003 and 2006 to 2016.

Crooked River Redband Trout

Study by Cramer Fish Sciences

Researchers conducted backpack and drift boat electrofishing to collect redband trout in the Crooked River below Bowman Dam. They were able to capture various sizes of fish using the two methods.

Fin-clips were taken from some larger fish for genetic analysis to determine if they were native Crooked redband or steelhead from Round Butte Hatchery stocked for the reintroduction effort.

In this report you will find information on the life history of Crooked River redband, estimated number of fish in the Crooked River below Bowman Dam, the habitat conditions and results of genetic analysis.

Lower Deschutes River Fish Studies

One of the goals of restoring a more natural temperature regime downstream of the Pelton Round Butte Project was to improve conditions for fall Chinook and redband trout.

ODFW and CTWS have been closely monitoring these populations in the lower Deschutes River.

Redband Trout in the Lower Deschutes River

Growth, Condition and Age Structure of Redband Trout in the Lower Deschutes River, Ore.:
Study by Oregon Department Of Fish and Wildlife

ODFW personnel sample the redband trout population in four sampling reaches in the lower Deschutes River between Trout Creek (river mile 87) and Beaver Tail Boat Ramp (river mile 31).

Fish are captured using a drift boat mounted electrofishing unit. Sampling occurs within reaches historically sampled by ODFW to compare changes over time, specifically changes after the Selective Water Withdrawal system became operational in 2009.

Data on fish survival, condition, age, length, weight, sex, and stomach contents is summarized in these reports.

Deschutes River Fall Chinook Monitoring and Research

Study by CTWS

To monitor the wild fall Chinook population in the lower Deschutes River, biologists using seine nets capture and PIT-tag migrating smolts as they head toward the ocean.

Lengths and weights are taken and information from the PIT-tags is used to track the smolts’ migration down the Deschutes and Columbia Rivers, as well as their return as adults one to five years later.

To estimate the number of adult salmon returning crews float the lower Deschutes River between the Re-regulating Dam and Sherars Falls to count post spawn adults (carcass surveys), and count the number of spawning redds (nests) by helicopter.