Sprague Lake water level study to begin

SPRAGUE--Over the past few years, water levels in Sprague Lake, which straddles the Lincoln and Adams County lines, have been slow to recede following storm events. To help identify flood risk solutions, the Department of Ecology is partnering with Washington Department of Fish and Wildlife to study water levels at the Sprague Lake outlet channel.

In 2017, high water levels combined with heavy rain and frozen ground caused significant flooding that damaged both public and private properties and city infrastructure.

“This study is the first step in discovering what’s contributing to high water levels in Sprague Lake,” said Brook Beeler, eastern region director for Ecology. “Once we better understand the contributing factors, we can move toward possible solutions and relief for property owners.”

The study will be conducted by private consulting firm Shannon & Wilson, Inc and is slated to be completed by June 30, 2023. It will include:

Developing and calibrating a hydraulic model to assess the existing conditions and constrictions from the Sprague Lake outlet into Cow Creek.

Analyzing flow constriction using a range of flow rates in the hydraulic model. This will determine if and where flow constrictions are present in the existing Cow Creek channel.

Analyzing alternative options including a bypass side-channel adjacent to Cow Creek to reduce lake water levels during high flow events. An investigation of permitting needs associated with alternatives will be included.

Assessing wind-driven lake levels to determine potential superelevation of the lake surface caused by wind.

“The Washington Department of Fish and Wildlife is also a landowner on Sprague Lake and is committed to trying to help find a solution to our mutual issue of flooding,” said Steve Pozzanghera, WDFW eastern region director.

Historically, Sprague Lake’s water levels have been managed by a water-control structure at the Cow Creek outlet. The channel, however, is slowly filling in with sediment and vegetation as it restores itself to a more natural wetland setting. Additionally, bridges and bedrock outcrops in Cow Creek will also be examined as possible contributors to the slow release of floodwaters.

“We’re eager to get started and looking forward to our community meeting to kick-off the work,” Beeler said. “The hydrology study is instrumental to determine the best path forward.”