A series of storms pulsating through Southern Oregon this week are forecast to recharge Lost Creek Lake with the 30 feet of extra storage space spilled last summer to help chinook salmon migrate up the Rogue River despite severe drought conditions.
New National Weather Service forecasts show a rise in runoff into Lost Creek Lake, which, when matched with continued low outflows to the Rogue, will allow the reservoir to catch up to its normal December target level Dec. 19.
Previous forecasts called for more snow and less runoff, but a rise in the freezing levels this weekend means more rain, less snow and a bump-up of runoff into the Rogue Basin's largest reservoir, authorities say.
"I'm planning on seeing the flows pick up this weekend," says hydrologist Alan Donner, the Corps' Rogue Basin regulator. "If these flows come out as forecast, it looks like we will catch up."
But catching up at Lost Creek Lake doesn't mean an end to the region's drought or a greater risk of future flooding in the Rogue Basin this winter.
Seeing the reservoir's surface level at 1,812 feet above sea level means it recouped the 65,000 acre-feet of so-called "carryover" storage spilled in July and August, putting reservoir levels at their target for the first time in nearly a year.
"It's more important to be at 1,812 (feet) now than building a snowpack," says Pete Samarin, an Oregon Department of Fish and Wildlife biologist who pushed for the extra releases last summer. "We've got months to do that. We have weeks to get to 1,812."
When Lost Creek Lake fills, 180,000 acre-feet of stored water is set aside for downstream fisheries enhancement. ODFW, the Corps and others judiciously plot out a release schedule that increases outflows when needed and pares them back when they're not, so as to get the biggest water bang for their buck each summer.
Last summer, historically low tributary levels and at times triple-digit air temperatures meant the Rogue potentially could flow so low and warm that an outbreak of natural but deadly diseases among salmon was possible. But digging into that carryover storage averted those die-offs.
The reservoir's level, however, bottomed out Oct. 27 at 1,782 feet above sea level, a full 30 feet lower than normal heading into the flood-control season.
The hope was that being miserly with storing water during any December storms could pay the reservoir back that water so it could start the normal filling schedule Jan. 1, thus giving it the best chance of filling as scheduled by May 1.
"My thought is to do everything in our power to get to 1,812 by the end of the month," Samarin says.
But it's not like the agencies were gambling with the kids' lunch money.
In the previous three drought years when the Corps dipped into Lost Creek Lake's carryover to save Rogue salmon — 1992, 1994 and 2001 — December rains made up for the loss and the reservoir filled as scheduled the following May, Corps records show.
"Three years isn't a big sample size," Donner says. "But I think I had fairly good confidence."
At Applegate Lake, the surface level of 1,887.5 feet above sea level Thursday already was a sliver above its target level for that day, records show. That reservoir, however, plays a much lesser role in chinook survival in the mainstem Rogue than Lost Creek Lake.
While Lost Creek Lake is primarily rain-fed, the snow-fed trio of Hyatt, Howard Prairie and Emigrant reservoirs are not recharging as quickly.
The three irrigation reservoirs were sitting Thursday at about 14,000 acre-feet, instead of the normal amount of 25,000 to 30,000 acre-feet of storage in mid-December.
"Right now we're a little behind the eight-ball," says Manager Jim Pendleton of the Talent Irrigation District, which is the largest of the districts fed by those reservoirs. "I don't know if we have enough snow in the watershed to help us out, but we can capture that rain runoff. Everything helps."