2024 Snake River and Columbia River Mainstem Juvenile and Adults

Population Exposure Alerts is a web-based reporting tool that presents current and future water quality conditions, and it extends our real-time monitoring of juvenile and adult passage to assess if river conditions reach critical levels during the migration season. This tool presents observed exposure and our water quality forecasts with fish passage forecasts to predict the cumulative exposure of juvenile and adult salmon to TDG and temperature conditions.

The tool supports RPA 15, 53, and 54 to assess the impact of passage conditions on juvenile and adult salmon migration and the effects of operations for juveniles on adult upstream migration.

Update Population Exposure Critical Values

Notes:

1. Percent of the run exposed may be less. Due to lack of corresponding water data, less than 95% of the fish population is analyzed for exposure conditions. For example, forebay temperature monitoring ends at many locations before the end of adult migration.
2. Juvenile passage based on PIT Tag data. Adult passage based on Visual Counts.
3. Click the Percent Exposed value to view the Exposure Index results in detail, including data graph. Exposure Index Methods.
4. Percent Exposed in red indicates that more than 10 % of run is exposed to the critical conditions.
5. Observed PIT Tag, Adult Passage and River Environment from Columbia River DART database. Forecasted Juvenile Passage, Adult Passage and River Conditions from Inseason Forecasts. Exposure Index calculations from Columbia Basin Performance Measures.
6. At this time, there are no CBR Inseason Forecasts for adult steelhead.
7. Forecasted Adult Chinook for Lower Snake River dams (Ice Harbor to Lower Granite) are a subpopulation of the whole population forecasted at the Columbia River mainstem dams.
8. At this time, there are no juvenile PTAGIS PIT Tag detectors installed at The Dalles Dam (TDA).
9. View DART Lower Granite PIT Tag Summary with Migration Timing for Juvenile Chinook component stocks and Juvenile Steelhead component stocks.
10. References
    • https://www.nwd.usace.army.mil/CRWM/Water-Quality/
    • https://www.epa.gov/columbiariver/tmdl-temperature-columbia-and-lower-snake-rivers
    • http://www.nwd-wc.usace.army.mil/tmt/wq/studies/wq_plan/wq2014.pdf STATE temps. pg 30

Critical temperature thresholds for adult salmonids in the Columbia River

Apart from the impact of high temperatures that may lead to metabolic stress (Brett 1995) or disease (McCullough 1999), temperatures have an impact on travel rates (Bjornn and Reiser 1991). There are two components to this. First, bioenergetic efficiency allows fish to swim most rapidly in optimal temperature waters (Hinch and Rand 2000). E. g., Columbia River Chinook and Fraser River sockeye swim most rapidly near 16°C (Lee et al. 2003; Salinger and Anderson 2006). Second, sufficiently high temperatures delay migration, e.g. Chinook are known to slow their migration above 20°C (Goniea et al. 2006), and several species completely cease migration above 21°C including Chinook, steelhead and sockeye (McCullough 1999; Quinn et al. 1997) .

Although individual tolerances to temperature are determined partly on acclimation temperatures, diel variation, spatial variability and fish size, temperatures above 21°C are widely regarded as detrimental to migration. The U.S. Environmental Protection Agency recommends using a metric called the “7 day average of daily maximums” (a.k.a 7DADM) which “can be used to protect against acute effects, such as lethality and migration blockage conditions” (EPA 2003). This is 20°C for salmon/trout migration.

Finally, extreme temperatures lead directly to mortality. These thresholds are near 24°C and 25°C for steelhead and Chinook respectively.

References