This article was published on: 11/22/11 12:00 AM

Solutions for fish reintroduction

By Tom Davis, PE
Last modified: October 31. 2011 6:40AM PST

For more than 40 years, the Upper Deschutes habitat was closed to steelhead, spring Chinook and sockeye. The first adult salmon of one of the most ambitious reintroduction efforts in U.S. history are now returning to Pelton Round Butte Dam.

The relicensing agreement for the dam included a temperature-management and fish collection/passage structure. The total reintroduction cost is expected to exceed $300 million. The threats include low flows, water quality, passage and politics.

Recent OSU research on Whychus Creek concludes “an estimated four steelhead trout adults would be expected to return.” Low flows that are too warm and inadequate state flow targets mean low potential for steelhead, so the Crooked River watershed is exceptionally important.

The steelhead fry released were twice the number of Chinook fry released above the dam through 2009. The Chinook smolts that arrived in 2010 at the dam’s fish collection facility were five times the number of steelhead smolts and this may portend poor steelhead success. Hopefully the outmigration of steelhead will improve, since Chinook typically smolt in their first year, but steelhead can smolt in their first, second or third year.

The Crooked River below Prineville and many tributaries have flows that are too low and too warm. The good news is that the problems appear to have feasible solutions.

The total storage capacity of the U.S. Bureau of Reclamation’s Prineville Reservoir is 150,200 acre-feet, with 148,600 acre-feet of active/usable space. Of that, 70,282 acre-feet of Prineville Reservoir storage space is for irrigation and other storage accounts, with 82,000 acre-feet uncommitted.

This suggests that Crooked River flows can be adequate for Chinook, redbands and steelhead, without compromising irrigation or other needs. In drought years, some small, proportional reduction of flows for fish and irrigation may be needed. The actual flow augmentation releases would depend on credible flow targets and adaptive management decisions made as-needed by the responsible fish managers.

The Oregon Department of Fish and Wildlife recently analyzed a 2001 best-available-science study performed by a consultant for the USBR. Flow recommendations for steelhead spawning below Bowman Dam ranged from 140 to 160 cfs in the 2001 study.

The ODFW analysis emphasized flat-water boating and fishing in Prineville Reservoir. The impact of adequate flow releases on flat-water recreation during the infrequent low water years would usually be minor and mitigation is possible by extending/lowering the launch areas.

More than 100 large reservoirs and lakes exist in Oregon for such recreation. There are four large reservoirs and at least six large lakes within a one-hour radius of Redmond that provide flat-water recreation. Reintroducing ESA-listed steelhead into hundreds of miles of habitat is a rare opportunity and should be a high economic, biologic and ESA priority.

Flow augmentation for steelhead and Chinook will be needed for only three or four months during most years, and 70,000 acre-feet of reservoir space would accomplish that. The USBR supported “providing some of the now unallocated space in the reservoir for fish and wildlife.”

HR 2060 authorizes 17 cfs for downstream flows, which is way below best-available-science flows. It contains a “First Fill” provision so in the occasional dry years irrigation would get the water it would in a normal year and steelhead, Chinook and redbands would take the loss. The USBR testified that first fill presents an “increased possibility for conflict.”

Legislation should allocate 70,000 acre-feet of the available 82,000 acre-feet of unallocated Prineville Reservoir space to downstream flows and 5,100 acre-feet for City of Prineville mitigation. The full 70,000 acre-feet would seldom be needed. The flow release decisions must be by fish professionals and should vary by season, life stage, run characteristics and flows otherwise in the river. The flow objectives must be the 2001 best-available-science recommendations for steelhead and Chinook. For public transparency, these flows must be noted in the bill that eventually passes as objectives of the adaptive management process.

— Tom Davis, PE, is a volunteer with the Deschutes Reintroduction Network, an informal group working on fish reintroduction in the Upper Deschutes.

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