TRAIL — A plan to draw Lost Creek lake about 30 feet lower than normal to help migrating Rogue River chinook salmon survive could lead to near-record low levels at Jackson County's largest reservoir this summer.
U.S. Army Corps of Engineers' hydrologists predict that the Stewart State Park boat ramps will be dry and unusable sometime in mid-August and the Labor Day water level could rival that of 1992's drought year that marks the nadir of lake levels since the reservoir first filled in 1978.
The ongoing drought's dwindling spring runoff into the reservoir is forecast to dip below 1,000 cubic feet per second within two weeks, a level normally not seen until September, water records indicate.
"It's significant," says Jim Buck, the Corps' Rogue Basin operations manager. "It's a real indicator of just how dry it is."
The Oregon Department of Fish and Wildlife on Tuesday unveiled its plans to spill 230,000 acre-feet of Lost Creek Lake water to help spring and fall chinook survive natural drought-triggered diseases in the Lower Rogue Canyon.
To stave off a deadly columnaris outbreak, the ODFW's goal is to keep Rogue flows below 70 degrees at Agness about 27 river miles east of Gold Beach. Higher flows tend to cool streams, but the dearth of natural stream flow this summer means stepped-up reservoir releases.
Based on a 1962 federal law authorizing the project, Lost Creek dam's two primary operating purposes are Rogue fisheries enhancement and flood control, meaning those needs trump secondary benefits such as reservoir recreation.
In drought years, that discrepancy can become magnified.
The three worst previous droughts in Lost Creek dam's history were 1992, '94 and 2001, and this year's impacts on lake levels will rival or surpass them, Corps records show.
The lake's normal low elevation is 1,812 feet above sea level, and the state park boat ramps are considered unusable 2 feet lower than that. However, the Taklelma Boat Ramp off Takelma Drive near the dam's northern edge will remain operable throughout the season.
By Labor Day, the lake elevation will be down to anywhere between 1,780 feet to 1,790 feet above sea level, according to the Corps' latest predictions.
The lowest Labor Day level on record is 1,782 feet above sea level in 1992, when the lake bottomed out later that fall at a record-low 1,763 feet above sea level, Corps records show.
This year's surface level was expected to bottom out at about 1,775 feet above sea level that is similar to the 2001 low, Corps hydrologist Alan Donner says.
"I don't think we'll get down to where we were in 1992," Donner says.
The main reason this year's surface levels will not set records is because the reservoir draw-down started with the lake 12 feet higher than in 1992, records show.