Visit this page often for regular updates about events, ongoing research and programs, and other topics of interest at our Clackamas hydroelectric project.
Studying Smolts at Oak Grove Fork
March 6, 2019
For 88 years, spring Chinook were absent from the lower Oak Grove Fork – extremely low flows in the summer caused by historic dam diversions meant that fish couldn’t enter this Clackamas tributary.
In 2013, that all changed. Thanks to several major habitat and flow projects, spring Chinook are now returning to Oak Grove Fork, where PGE biologists monitor their populations.
How does the study work?
- Every other year, biologists snorkel the lower Oak Grove Fork, swimming upstream to observe and record numbers of spring Chinook. This survey provides information on the various life stages of fish present in the stream.
- A rotary screw trap is installed each year in the same location. The trap collects a sample of out-migrating juvenile fish; this data is compared to samples from previous years, allowing us to evaluate the effect of recent changes.
- Improvements to the lower Oak Grove Fork include habitat alterations (large wood installation, gravel augmentation, and restoration of side channels) as well as enhanced flows from Lake Harriet Dam.
What have we learned?
- Early indications suggest that fish populations have responded quickly and positively to the habitat changes in the lower Oak Grove Fork.
- ODFW spawning data obtained in 2018 suggest that this area is responsible for 7.5 percent of all spring Chinook redds in the Clackamas basin.
- Collection of fry, smolts and other juveniles at the screw trap indicates that successful spawning is taking place in the area.
- Despite their extended absence from 1924 to 2012, spring Chinook now represent the second most abundant fish species produced in the lower Oak Grove Fork.
Spring outmigrant sampling will continue for three more seasons, followed by a five year break, then another five years of sampling.
Tracking Fish on their Journeys Upstream
Dec. 7, 2018
In 2013, PGE began a multi-year evaluation of upstream fish passage through the Clackamas Hydroproject and into the upper basin. This ongoing study allows our biologists to monitor the migration of winter steelhead, spring Chinook, coho, and Pacific lamprey, helping us understand how our facilities and dams may be affecting fish behavior.
An adult fish is implanted with a tracking device.
How does the study work?
Each year, biologists collect a small percentage of adult fish at the North Fork Sorting Facility and carefully implant radio transmitters into the animals’ throats. The fish are released below the Project so that their movement can be monitored through our facilities and beyond.
Radio tags emit continuous signals which are detected when fish pass by a receiver. We have 29 receivers in fixed locations throughout the hydroproject and the upper basin, and we also track fish manually by foot, vehicle, and even helicopter. Using multiple tracking methods allows our biologists to access remote locations and gather a more complete picture of where, when, and how fish move throughout the river.
PGE biologist Maggie David uses a radio antenna to track fish by foot.
What have we learned?
The study has helped us understand how long it takes fish to navigate various stretches of the river and our fish ladders. Additionally, the study has shown that our improvements to fish passage infrastructure have shortened the amount of time fish spend traveling through our project, enabling them to reach historic spawning grounds in the upper river earlier.
Fish also have a higher chance of survival, likely caused by a reduction in stress during their migration through our sorting facility. In fact, we’ve seen an 80 percent reduction in pre-spawning mortality for Chinook!
PGE staff monitor fish movement upstream by helicopter.
Restoring 30 Miles of Streamside Habitat through the Shade our Streams Program
Nov. 2, 2018
30 miles of streamside habitat in the Clackamas basin have been restored thanks to the Shade our Streams program, powered by a partnership between PGE and the Clackamas River Basin Council (CRBC).
Staff from PGE, CRBC, and the Oregon Department of Environmental Quality (DEQ) recently toured several of these sites, witnessing their amazing transformation.
At each site, invasive species like Japanese knotweed and reed canarygrass were removed, beneficial native plants were installed, and in some areas, logs and boulders were placed instream to enhance aquatic habitat. Healthy riparian areas like these reduce erosion, enhance water quality, and support fish and wildlife.
During the tour, a pair of coho salmon even showed up to express their gratitude!
Oak Grove Fork Gravel Augmentation
Aug. 14, 2018
It’s raining gravel at Oak Grove Fork!
Every year, PGE deposits 500 tons of gravel into Oak Grove Fork, allowing the rocks to slowly move downstream and improve the ecosystem below Lake Harriet dam. Gravel provides necessary habitat for macroinvertebrates as well as spawning grounds for the salmon that eat them.
When dams on the Clackamas were constructed decades ago, they cut off the flow of gravel, logs, and other debris, resulting in a river that lacked necessary components of habitat for fish and insects. Today, the annual gravel augmentation restores this essential biological process that was interrupted for so long.
Habitat Improvements on the Clackamas River Featured in Northwest Steelheader Magazine
Aug. 8, 2018
PGE’s Clackamas River downstream fish-passage efforts were recently featured in the summer issue of Northwest Steelheader magazine, put out by the Association of Northwest Steelheaders.
The article, written by Ian Fergusson, is the second in a series discussing fish passage in the Willamette Basin. PGE biologist Garth Wyatt provided quotes and information for the article.
Note: Part 1 of the series can be found on page 8 of the spring issue.