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Applegate water release might be repeated

I read your wet-October story and was intrigued by the water-release plan drafted by state biologists to draw Applegate Dam down during the chinook salmon spawning. My question is, did it work?

— M.F., Medford

It was not only successful, M.F., but the Oregon Department of Fish and Wildlife might ask the U.S. Army Corps of Engineers to do it again, because when it comes to rain this fall, the Siskiyou Mountains continue to have too much of a good thing.

It's become known as "The Pulse," and it was crafted by state biologists and federal hydrologists to draw Applegate Lake down to its normal flood-control level by Nov. 15, but without threatening eggs nests, called redds, from wild fall chinook salmon now spawning in the Applegate River.

Record October inflows to Applegate Lake saw the lake's elevation at 1,916.3 feet above sea level. The U.S. Army Corps of Engineers typically draws the lake down to at least the 1,889-foot elevation at or near Nov. 15 to create storage capacity for any fall or early-winter flooding.

Simply cranking up the outflows a few hundred cubic feet per second until Nov. 15  was not an option, because wild chinook are spawning in the river. Raising the flows for a sustained period would cause the salmon to spread out their redds, and those along the river's edge during the higher flows would dry up and die when the flows dropped. 

ODFW biologist Pete Samarin came up with an outside-the-box idea of ramping up outflows from 350 cfs last Friday morning to 1,550 cfs in two-hour increments of 200 cfs, then holding them there until Sunday before walking the flows down again to 350 cfs by early Monday.

The idea was that the pulse would seem to the chinook like a freshet, so they would delay spawning and hang out until the water dropped again to resume spawning.

An ODFW monitoring crew floated the river Tuesday and discovered it had apparently worked.

"There was no real evidence that the brief higher water caused fish to move and spawn where the redds would dry up," says Dan VanDyke, ODFW's Rogue District fish biologist.

The problem, however, is that last weekend's rains increased inflows to where the lake elevation Wednesday was a foot higher — and counting — than when The Pulse began, because inflows continue to be higher than outflows.

The Corps and ODFW on Wednesday discussed engineering The Pulse II for three days next week. Talk now is it will include slightly higher flows and end higher than 350 cfs, but those flow targets have yet to be set, says Jim Buck, the Corps' operations manager for the Rogue River Basin.

The Corps also is willing to back off a bit on the 1,889-foot elevation target for Nov. 15, perhaps fudging that elevation to somewhere around the 1,896-foot level to reduce the amount of water needed to be sloughed from the reservoir by Nov. 15, Buck says.

Stay tuned.

— Send questions to “Since You Asked,” Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to youasked@mailtribune.com. To see a collection of columns, go to mailtribune.com/youasked. We’re sorry, but the volume of questions received prevents us from answering all of them.