Where are the Fish? How could we have more?

 

Prior to the construction of the three dams of the Pelton-Round Butte (PRB) Hydroelectric Complex starting in the mid-1950s, the Crooked River was one of the longest salmon and steelhead rivers in Oregon.  The Metolius River produced large numbers of sockeye.  But dam construction by Portland General Electric (PGE) stopped access by fish to those tributaries at what is now Lake Billy Chinook, and those runs of fish became extinct.  Which is what happens to anadromous fish when there is no fish passage.  

PGE initially tried to provide fish passage when the dams were constructed, but was stymied by the inability of migratory fish to survive the downstream migratory trip through Lake Billy Chinook.  A problem which may persist today.

In 2007 PGE, the Confederated Tribes of the Warm Springs Reservation, and the Oregon Department of Fish and Wildlife (ODFW) began planting juvenile hatchery steelhead and salmon above Lake Billy Chinook (LBC) in Whychus and McKay creeks (tributaries to the Crooked and Middle Deschutes rivers respectively) in the hope that those fish would mature and migrate downstream to and through LBC to Round Butte Dam.  

Once in LBC, it was hoped that fish would make the miles long swim to the newly constructed Selective Water Withdrawal Tower near the reservoir’s terminus, attracted to the Tower’s fish trap by the currents it was to generate.  Once at the tower, fish would be collected and then hauled by truck around the three dams of the Pelton-Round Butte Hydroelectric Complex to be dropped into the lower Deschutes River, there to swim to the ocean. Upon their return, the idea was to trap them again, load them (again) into trucks, and haul them around the three dams -- this time in an upstream direction back to Lake Billy Chinook.  From there they were to migrate to where they had been planted a couple of years prior, spawn naturally, and produce the next generation of anadromous fish.  At least that was the plan. 

That plan was to be pursued so as to ensure “harvestable numbers of salmon and steelhead” would populate the Crooked and Middle Deschutes rivers.

So where are we at today, twelve years later?  The following graph shows the trends in fish reintroduction success:

 
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One thing is certain, these adult return rates do not suggest a harvestable bounty.  They don’t even approach a number required to become a self-sustaining population.  This despite millions of juveniles having been planted in the tributaries over the past twelve years.  Based on the trend lines, this situation is not progressing or improving. But what might it take to change these trends?  How many millions more juvenile fish will it take?

The reasons for the inability to make fish reintroduction successful are likely many, and probably in some cases, immutable.

Let’s start with the fact that Chinook salmon and steelhead were never naturally adapted to standing water.  They spawn, grow to out-migration size as smolts, out-migrate to the ocean, and then return migrate as sexually mature adults to their natal waters, all in moving water.  Lake Billy Chinook is not a moving body of water for nearly the entirety of its 47 square miles. 

For decades this has been a problem for migratory fish in the Columbia Basin and despite the expenditure of billions of dollars on technology to aid Columbia River migratory fish, only two things seem to have actually provided any benefit to those fish: fish ladders and springtime spill at Columbia River dams to provide adequate current for out-migrating anadromous fish.

Despite the best attempt to use the tower to create fish-attracting currents in Lake Billy Chinook, the currents only extend less than a mile out from the dam.  The remainder of the greater than six-mile distance to the moving water of the Crooked River is still without observable current on the surface, where migratory fish swim. The same is true for the reservoir arm that extends up to the Metolius River, a ten-mile plus distance that is also without surface currents.

Still-water absorbs heat from the sun as days lengthen in the spring. The combination of sunlight, heat, and nutrient-rich water creates massive blooms of phytoplankton (often toxic blue-green algae, for which health advisories are posted on the reservoir).  The algae might not be toxic to fish, but the pH of 9.5 of surface water (which occurs often during algal blooms), is a by-product of algae metabolism, and is detrimental to fish survival according to fish researchers.

The obvious solution here would be to allow fish to avoid the gauntlet of the reservoir.  The dam operators are already trucking juvenile fish up to the areas where they are planted.  They then truck captured out-migrating fish downstream from the LBC forebay around the three dams.  Later, they truck returning adults back upriver around the dams.  It is no great reach to just truck the fish around the reservoir as well, in both directions.  At the very least this idea should be tested to see if it would improve fish reintroduction success, as opposed simply to doubling down on a failing and expensive scheme.

Photo by Brian O’Keefe

Photo by Brian O’Keefe