Nevada Water Science Center
Walker Lake is one of the few perennial, natural terminal lakes in the Great Basin. Terminal lakes are surface-water drainage in topographically closed basins. Under natural conditions, evaporation from the lake surface typically is the primary component of basin outflow. Due to high evaporation rates in the Great Basin, the water-levels and salinity of terminal lakes are extremely sensitive to changes in streamflow. Most streamflow in the Walker River Basin originates as snowmelt from the Sierra Nevada. Prior to the late 1800s, most of the water flowed into Walker Lake. Since then, agricultural diversions have increased to the point that, except during flood flows, most streamflow is consumed by agriculture. Between 1882 and 2010, upstream diversions caused Walker Lake to decline almost 160 feet and the total dissolved solids (TDS) concentrations increased from 2,500 mg/L to 18,000 mg/L. Compared to the Great Salt Lake, Walker Lake is relatively fresh and supports a diverse ecosystem including the threatened Lahontan cutthroat trout (LCT). The LCT has adapted to the high TDS of terminal basins. However, increasing TDS concentrations threaten its survival.
The ecosystems and recreational uses of Walker Lake and other terminal lakes in the Great Basin have become at-risk due to consumptive water use. The goal of section 2507 of Public Law 107-171 is to provide water to selected at-risk terminal lakes in Nevada in order to sustain their ecosystems. This study will provide scientifically sound data to parties in the Walker River Basin so they can evaluate alternatives for supplementing flow to Walker Lake.
The first part of this study began in 2004 and focused on the lower Walker River basin downstream from Wabuska. This effort concluded in 2009 and produced an improved understanding of the hydrology and refined water budgets of the lower basin. The second part of this study began in 2010, will conclude in 2014, and focuses on the Walker River basin upstream from Wabuska. Like the first part, the main products will be an improved hydrologic understanding and refine water budgets of the upper basin.