Upper Klamath River Basin Forecasts Active

Located in southern Oregon and northern California, there are approximately 240,000 acres of irrigable agriculture land and National Wildlife Refuge land in the Upper Klamath Basin. Water delivered to most of these lands comes from Upper Klamath Lake.

During the spring and summer, water managers must balance the amount of water:

• passed over the Link River Dam for threatened Chinook and coho salmon in the lower Klamath River
• delivered from the lake through the A-Canal for crop irrigation and wildlife refuge habitat
• retained in the lake to protect water quality and habitat for two endangered sucker species.

Accurate forecasts of spring and summer streamflow are essential to optimally manage limited water for these multiple purposes. Determining water availability in the Upper Klamath Basin has always had a degree of uncertainty as a result of the complex hydrology and geology in the region and limited streamflow data. To improve streamflow forecasting, the USGS now models snowpack, evapotranspiration, solar radiation, surface-water, and groundwater processes on a daily time step.

Specific objectives of the study include:

1. Develop a physically-based hydrologic model encompassing the Upper Klamath Lake drainage area.
2. Calibrate and validate the hydrologic model using measured streamflow, snowpack, lake stage, evapotranspiration, and solar radiation data.
3. Assess the skill of the model to forecast total April-July inflows to the Upper Klamath Lake.