Walker
Lake Historic Water Levels graphic depicts the rapid decline
of Walker Lake following diversions of Walker River water for
upstream
agriculture. The current situation is that wet years
between
1995 and 1998 raised the water level of Walker lake by about 15
feet.
However, normal precipitation patterns returned causing Walker Lake to
once again fall 9 feet by the summer of 2001. Walker Lake,
once approximately 27 miles long, now is around 15 miles in length
requiring
the Walker River to flow an additional 12 miles to reach the declining
lake. Walker Lake needs at least 135,000 to 140,000 acre-feet of
river flows on average per year to stabilize around
elevation
3990.
Walker Lake Historic Volumes graphic depicts the loss of 7 million acre-feet of water once contained within Walker Lake. Following water diversions of Walker River water for upstream agriculture, too little water reached the lake. Evaporation from the lake's surface was not replenished by water from the Walker River causing a continual loss of water volume. The current situation is that wet years between 1995 and 1998 raised the volume of water in Walker lake somewhat. However, normal precipitation patterns returned causing Walker Lake to again approach the 2 million acre-foot volume. The smaller the volume of a "terminal" lake like Walker Lake, the higher the salinity of the water. The current salinity of Walker Lake is approaching lethal levels for Lahontan cutthroat trout (LCT) and tui chub, the prey-base for the LCT, cannot successfully reproduce. A volume of water needed for Walker Lake is between 3 to 4 million acre-feet to reduce salinity to healthy levels for the fish.
Walker Lake has seen dramatic increases in salinity as measured by total dissolved solids (TDS). This graphic shows the relationship between dropping water levels and rising salinity. While Walker Lake is still far fresher than seawater, it is rapidly reaching the tolerance limits of its native freshwater fish species. Lahontan cutthroat trout (LCT) barely survive at the present TDS levels and tui chub, the prey-base for LCT, are far less successful in reproduction. Once levels of TDS rise above 13,000 ppm (parts per million), tui chub may not be able to reproduce at all . For the LCT and the tui-chub to thrive in a healthier lake ecosystem, the TDS needs to be at or below 8,000 ppm. This can be acheived at a higher lake level (around 3990 feet elevation) with water volumes between 3 to 4 million acre-feet.
Acreage in agricultural production has increased dramatically from the 1950's. Agricultural irrigation is supported by direct diversion of surface water from the Walker River and , since the 1960's, "supplemental" groundwater through extensive pumping.
