SEQUIM — Work could begin this week on creating as hospitable an environment as possible for hordes of pink salmon expected to return to the Dungeness River later this month.

A preseason prediction that 1.3 million pinks will return to the Dungeness this year may not come to pass, said Mike Gross, biologist with the state Department of Fish and Wildlife, who is based in Montesano.

That estimate was based on a run of 400,000 pinks in the Dungeness two years ago.

Pinks are on a two-year cycle, and the large run in 2013 led to the forecast “on paper” of about triple the number seen then, Gross said.

But even if they don’t reach that number, “we’re expecting a large return,” he said Friday, adding the run is expected to peak mid-month.

Hoping for 200,000

“The confidence is that there will be a lot of pinks coming in. Hopefully, we’ll hit at least 200,000,” he said.

And the Dungeness, a small river that runs low every year, is in poor shape for the spawning pinks.

“Low water is a concern in most of our rivers” because the Olympic Mountains snowpack that routinely feeds Peninsula rivers is at zero, but the Dungeness “is of particular concern,” Gross said.

On Thursday, the Dungeness was running at 108 cubic feet per second, lower than the Aug. 6 record low of 124 cfs, set in 1926. The average flow for the date is 283 cfs.

As stream flows decrease, temperatures are rising in Peninsula rivers.

Water temperature

The temperatures are higher than usual but are not too high for fish right now, Gross said.

“They are currently cool enough that we aren’t overly concerned for their survival, but we are watching carefully, and if temperatures spike, then we will need to take further action.”

Pacific salmon and trout show signs of physiological stress at water temperatures above 60 degrees Fahrenheit, with lethal effects possibly beginning at 70 to 72 degrees if additional conditions stress fish, Gross said.

The point at which returning adult salmon begin to have difficulties is 68 degrees, he said.

That’s “where we start to heighten our concern because it could escalate into something,” he said.

Spawning deaths can be seen if water temperatures rise to 70 to 72 degrees and other stressors are present, he said.

Daily high temperatures in excess of 60 degrees have already been observed in many Olympic Peninsula rivers and have occasionally reached 70 degrees in the lower Sol Duc and Dungeness rivers, said Barb Maynes, Olympic National Park spokeswoman, as the park announced closures of rivers to fishing starting Monday to buffer the impact on returning salmon.

Of greatest concern now is low stream flow.

Helping salmon

In the Dungeness, crews with both Fish and Wildlife and the Jamestown S’Klallam tribe are “working to concentrate flows so that fish have chutes to move into the next pool,” Gross said.

The crews have been testing ways to remove obstacles — both natural and man-made — and trying out some equipment, he said.

They plan to dig channels in shallow areas of the river.

“Work may start as early as next week,” Gross said.

The Dungeness already has some pinks, with a few already at the confluence of the Gray Wolf and Dungeness rivers.

“We’re expecting more,” Gross said.

“We want to do what we can to see that they get there.”