Hydro operations use latest research to support fish recovery

With the benefit of ongoing research and the best available science, the federal agencies that manage the Federal Columbia River Power System (FCRPS) shall implement an expanded program of hydro actions to support recovery of Columbia River Basin salmon and steelhead.

Our approach responds to federal court decisions and specifies operations and improvements at each of the 14 federal dams that are uniquely designed to improve fish survival.

• For juvenile fish, we have adopted new, higher performance standards for fish survival through the dams - an average of 96 percent survival for spring chinook and steelhead and 93 percent survival for summer migrants. The plan includes assessing whether these standards are met and making changes as necessary to meet them.
• For adult fish, the plan includes actions and commitments to maintain current high survivals through the hydro system to meet adult performance standards.

The plan also includes assessments of in-river juvenile performance through the hydro system.

The action agencies are committed to achieving these performance standards based on the most current science and latest research on flows, spill and transport.

Spill amounts based on fish survival
Since the 1980s, the federal hydro operators have spilled water over the dams during the juvenile fish migration in the spring and summer to help fish in the river pass dams safely. We used research results to refine spill levels as more information became known; for example, some spill increases juvenile fish survival, but more spill is not necessarily better for the fish.

Using this information, we tailor operations at each dam to meet performance standards by increasing survival through the various migration paths (e.g. spillway, surface passage, bypass systems), and by addressing the timing of migration and the needs of the fish passing through the dams.

Structural improvements to help fish pass dams safely
We have made significant improvements to provide surface passage routes at the dams. Surface passage routes are considerably more efficient than traditional spill. More fish use surface passage per volume of flow, and more efficient spill generally reduces total dissolved gas in the river.

Surface passage routes also decrease the time smolts spend in dam forebays where they can be vulnerable to predators.

Federal engineers and biologists are developing new technologies to provide more surface-oriented passage for fish over the dams, such as spillway weirs installed at Lower Granite and Ice Harbor dams and the corner collector at Bonneville Dam.

We have recently made the following passage improvements at the dams to meet fish performance standards:

• Removable spillway weir (RSW) installed at Lower Monumental Dam (2008).
• Temporary spillway weirs installed at McNary Dam (2007), John Day Dam (2008), and Little Goose Dam (2009).
• Evaluation of other surface passage improvements at Bonneville first powerhouse (sluiceway modification beginning in 2009 and 2010) and second powerhouse (behavioral guidance device installation in 2008 to improve the performance of the corner collector).
• New spillwall at The Dalles Dam (2009-2010).

As of 2009, all eight federal dams on the lower Snake River and lower Columbia River have some form of surface passage installed.

Fish transportation plans based on survival research
There is a critical balance between leaving juvenile fish to migrate in the river versus transporting them around the dams.

For example, some stocks - such as chinook salmon - do better migrating in-river early in April. On the other hand, survival rates for Snake River steelhead are better with transport. In low flow years, when the rivers have less water, migration conditions in-river are poor, and fish do better when they are transported down river.

Research also shows a strong correlation between how soon fish arrive in the estuary after their trip down the river and their ability to survive as they enter the ocean, which affects the optimal timing and use of transportation.

We will maximize transportation during conditions when the best currently available scientific information shows higher adult returns expected for those fish compared to those that migrated in-river.

Depending on real time conditions and further research, we will further refine spill and transportation strategies to meet performance standards and increase overall fish survival.

Operating the FCRPS to provide flows and water quality
Each year, the action agencies coordinate water storage and releases from upstream reservoirs to augment flows downstream, with the goal of improving conditions for migration of juvenile salmon and steelhead. The BiOp approach designates specific water from storage reservoirs to be used for fish flows, as well as rules for water use.

• Dworshak Dam on the Clearwater River has a temperature control system that allows operators to release cold water from deep within the reservoir. This water helps keep downstream rivers cool, which can be a vital aid to salmon and other temperature-sensitive fish.
• Water from Canadian reservoirs provided through mutual agreements can be used under the plan, along with Montana operations designed to balance the needs of salmon with resident fish such as the endangered Kootenai white sturgeon and bull trout.
• Dry water year strategies are laid out, and additional studies of dry year operations will be implemented.

What's the status of fish passage today?
Over the last two decades, fish passage at the eight federal dams on the lower Columbia and Snake rivers has improved dramatically.

• Adult migration rates and travel time are similar to levels before the Columbia and Snake River dams were completed.

Juvenile survival is 95 to 98 percent for fish passing through the removable spillway weirs (fish slides) at Lower Granite and Ice Harbor dams and nearly 100 percent through the similar "corner collector" at Bonneville Dam.