Sean C. Morgan
Green Peter Reservoir is as full as it will get this summer, while Foster will be among a small number of area lakes that will remain full later into the summer.
“Unless we get a lot more rain this summer, Green Peter is as full as it’s going to get,” said Scott Clemans, U.S. Army Corps of Engineers spokesman. The surface of the lake was 973 feet above sea level on Friday, 37 feet below where it ought to be, full pool at 1,010 feet.
Green Peter is used early in the year to augment river flows, Clemans said. “We have enough water to take care of our water supply mission.”
The Corps has enough water to fulfill its industrial, municipal and irrigation supply goals, he said. Officials think they’re probably OK with water quality and navigation “missions.”
They are communicating with environmental agencies about the situation, he said.
The main mission where Corps officials anticipate trouble “is obviously, of course, recreation,” Clemans said. Whitcomb Creek boat ramp is useful down to about 970 feet at Green Peter, just 3 feet lower than the pool on Friday.
Green Peter does have a low-pool ramp at Thistle Creek, and that will be useful deep into the summer, Clemans said.
The other mission in which the Corps will have an issue is flow and temperature control for endangered fish species in the South Santiam tributaries and main-stem Willamette, Clemans said. “There’s no way we’re going to have enough water to meet the recommendations in the Willamette biological opinion.”
The Corps is coordinating with the appropriate agencies and other users to figure out what flows it can put into each of the tributaries, Clemans said.
The entire Willamette system, including 13 dams and reservoirs, is about half full, Clemans said. The percentages vary widely across the system depending on the size and location of the reservoirs.
Dorena Reservoir is about 99 percent full, he said. That area had concentrated rain storms, and it is only about 6 inches below full pool.
Lookout Reservoir is artificially low right now for a spillway gate project. The Corps intended to draw it down early, so the agency has been using it first for water management purposes, allowing other reservoirs to hold more water longer.
Cougar and Detroit reservoirs are at 36 percent and 38 percent respectively. Many of the recreational facilities at Detroit have not even been in the water at all this summer, but most of them are located in the top fifth of the recreational pool.
When it is just a little low, those facilities are impacted, Clemans said.
Foster is full, but it is just 2 percent of the entire system, he said. Foster is a re-regulation dam for Green Peter. As Green Peter is used intermittently for peak power production, it sends pulses of water, up to 3,500 cubic feet per second, downstream. Foster smooths those pulses out downstream, keeping flows at about 800 cfs, and it is easier for the Corps to keep it full.
Paired with Lookout, Dexter Reservoir is in the same situation on the Willamette’s Middle Fork. That reservoir will maintain its pool, and so will Hills Creek, also located on the Middle Fork.
Fern Ridge Reservoir is primarily used for irrigation, and it requires fairly small releases, Clemans said. It’s in pretty good shape, down just a foot or two.
Clemans emphasized that the cause of the low water is not a lack of snowpack.
He said media outlets and people tend to focus on the lack of snowpack, but that has a small impact on the Willamette River projects. The Willamette reservoirs are filled by spring rain. The Corps starts filling the dams in February.
The snowpack helps keep them full longer into the summer. The snowpack’s impact is debated, but it ranges from 10 to 20 percent of the system, Clemans said. By the time snowpack starts melting, the reservoirs are already full.
In February, the area had 85 percent of normal precipitation, but it kept dropping all spring, Clemans said. In March, the area experienced just 70 percent of normal precipitation, and in April it received just 60 percent. Final numbers are not available yet for May, but Clemans suspects it may be just 50 percent.
The dams were built for flood control, Clemans said. From November through January, the Corps must hold levels low to handle potential flooding.
According to Corps measurements at Foster Dam, as of June 8, rainfall was just 13.36 inches this year. Last year by June 9, the Corps had recorded precipitation of 37.31.
Across the state, the U.S. Department of Agriculture Natural Resources Conservation Service reported on June 5 that record-low winter snowpack will lead to significantly low stream flows.
As of June 1, only one of 81 snow telemetry sites had any measurable snow, while normally, at least 10 still have snow.
Some mountain areas in western Oregon had snow on the ground for only a few weeks. Throughout the state, 60 percent of the snow measurement sites shows the lowest snowpack on record or were snow-free for the first time mid-winter.
In western Oregon, the snowpack peaked at 60 to 90 percent below normal amounts, while in the eastern part of the state, snowpack peaked at 30 to 80 percent below normal.
Stream flow from melting snow peaked in February, said Snow Survey Supervisor Scott Oviatt. “Snowmelt in February is months too early to synchronize crop planting and irrigating and too early for many of Oregon’s reservoirs to take advantage of the surge of moisture as they are designed for both flood control and late season irrigation.”
Most of Oregon is included in the moderate to severe drought category for this summer, and the southeastern third of Oregon is in the extreme drought category. On June 1, Gov. Kate Brown declared a drought state of emergency for Klamath, Lake, Malheur, Harney, Crook, Baker, Wheeler, Josephine, Jackson, Lane, Deschutes, Wasco, Grant, Morrow and Umatilla counties.
The dry weather has prompted the Oregon Department of Forestry to declare the start of fire season in its Central Oregon District on June 6. This is the same as 2014, but it is still about three weeks ahead of normal.
Fire officials had anticipated fire season starting in May, but cool weather and above normal rainfall delayed the onset of severe burning conditions.
Locally, at this point, fire officials expect the annual burn ban to begin on June 15 as usual, with fire season possibly starting a little early, in late June, depending on rain. It typically begins just before Independence Day.