The ongoing effort to explore the benefits of surface passage for juvenile fish at federal dams takes two steps forward this spring with the operation of new "spillway weirs" at both John Day Dam on the lower Columbia River and the lower Snake River's Lower Monumental Dam.

A 120-foot high, 80-foot wide, 2 million-pound removal spillway weir was towed upriver this winter and put in place at Lower Monumental. With the juvenile salmon outmigration, as well as the spill season, soon to begin, the new device will be tested using balloon tagged fish, according to Marvin Shutters of the U.S. Army Corps of Engineers' Walla Walla District. The tests are intended to gauge direct mortality for fish passing through the RSW.

Spill for fish passage is scheduled to begin April 3 at the dam. Spillway weirs are fitted into a dam's existing spillway bay to allow juvenile salmon and steelhead to pass the dam near the water surface. Fish passage and initial biological testing will be conducted throughout the spring and summer.

A prototype spillway weir was installed at Lower Granite Dam on the lower Snake River in 2001. A second weir was installed during February 2005 at Ice Harbor Dam on the lower Snake River. Testing at Lower Granite and Ice Harbor noted averages of 96-98 percent survival for fish passing via the fish slides.

The policy emphasis for operation of federal Columbia River Power System projects includes increasing survival rates of Columbia basin salmon and steelhead listed under the Endangered Species by, in part, enhancing fish passage efficiency -- passage through non-turbine routes -- for juvenile salmon. Providing a surface flow route of passage in-concert with adequate attraction flows, is one accepted means of increasing FPE and has proven to attract more fish per unit of water than costly traditional spill.

Two "top" spillway weirs are now on their way to John Day. The weirs, new vertical spillway gates and installation cranes will barge up the Columbia River starting late Saturday. The Corps will install the weirs and gates on March 24 in spillway bays 15 and 16.

Balloon tag testing will be carried out there April 1-4, according to Mike Langeslay, Anadromous Fish Evaluation Program project coordinator for the Corps' Portland District.

Advanced American Construction Inc. of Portland, Ore., built the weirs and gates at a cost of $1.4 million apiece. In all, the Corps expects to spend about $8.5 million during fiscal year 2008 to build, install the devices, monitor and evaluate their performance, and study other configuration options.

"To help determine the best locations for placing the weirs on the dam's spillway and the optimal flow patterns to attract fish to the weirs' entrances, we used research data from two prototype weirs installed at McNary Dam in 2007," said Bob Wertheimer, Portland District fisheries biologist. "While we made adjustments to weir design for John Day Dam, the application of lessons learned and the information and advances of our salmon recovery efforts up and down the river are saving time and money."

Results from last year's McNary research showed significant steelhead losses last year through one of the TSW spillbays, about 7 percent mortality. The higher-than-expected losses were attributed to "edge effects" – a slack water below the dam that developed between the powerhouse and the TSW. It created a place for predatory pikeminnow to gather and wait for young steelhead to emerge from the turbulent spill water.

The John Day TSWs will be placed in two spillways farther from the powerhouse than was originally planned in hope of avoiding the occurrence that happened at McNary. The McNary TSWs will also be tested in different spillbays this year.

The weirs are about 25 feet high and 54 feet wide and weigh about 50 tons. The structure can fit into any one of John Day's spillway bays to create surface spill. The crest of each weir is shaped to create an overflow trajectory that contacts the spillway at a relatively shallow angle.

Juvenile salmon and steelhead using this surface overflow route can pass the dam near the water's surface under lower accelerations and lower pressures than passing through normal spill. This is anticipated to provide a more efficient and less stressful route while reducing migration delays at the dam.

For more information on fish recovery in the Columbia River Basin, visit www.salmonrecovery.gov