Sean C. Morgan
Of The New Era
Rain over the last couple of weeks has filled Green Peter Reservoir and improved the outlook for the summer.
“We are really pleased,” said Heidi Helwig, U.S. Army Corps of Engineers public affairs specialist. But “there are so many variables. We are pleased with the way things are going right now.”
At the end of March, Corps officials stated that most of the 13 reservoirs in the Willamette Valley water system would be low this summer due to an unusually dry winter that had left the Valley about 30 percent behind normal rainfall and the snowpack extremely low.
But 4.28 inches of rain that has fallen thus far in April has raised hopes that the situation may be less dire than it was a month ago.
The question now, Helwig said, is whether the rain will continue and how the Corps will need to manage the system as a whole.
The Willamette system includes 13 projects. Four of those reached normal levels or better during recent rains. They included Cottage Grove, Dorena, Blue River and Green Peter.
As of April 13, Green Peter was at 998.4 feet, just 11.6 feet below its full pool. Green Peter was 4.2 percent above the Corps’ rule curve, the level where the reservoir was supposed to be on that date.
Green Peter had 2,630 cubic feet per second inflowing and 50 cfs flowing out.
Foster was at 613.8 feet. Full pool on Foster is 637 feet. It had an inflow of 1,770 and an outflow of 2,360 and was 5.5 percent below its rule curve.
Foster Lake is usually drawn down to help with fish passage then brought up to full pool by Memorial Day weekend.
February and March were the driest on record, Helwig said. Those two months play a large role in filling the lakes.
April rain did “an amazing job,” Helwig said. How long it will stay that way is hard to say.
The snow pack is not key to the Willamette projects, Helwig said. The system is rain-driven.
The Natural Resources Conservation Service reported that snow water on April 13 was 39 percent of average.
Hills Creek, Lookout Point, Cougar and Detroit remained below their rule curve elevations for this time of year, the service reported. In general, rains have continued to be weaker in the southern part of the basin and the large reservoirs.
At this point, forecasts suggest that most reservoirs may not fill this year, but expectations for good recreation at many Corps lakes have improved.
Green Peter is one of the first lakes to be tapped to help provide sufficient flows for fish on the Willamette system during the summer.