Thunderstorms a blessings to Mono Basin
In spring of this year, the Los Angeles Department of Water and Power (LADWP) runoff forecast predicted snowmelt runoff at 48 percent of average; drier than the last two years. Given this diminished runoff, the LADWP also predicted that Mono Lake’s waterline would drop from an elevation of 6,380.6 feet as of April, to 6,379 feet by December.
According to the Mono Lake Committee (MLC), this would be the lowest level since March, 1996.
But the MLC recently reported that while the Lake’s water level dropped .7 feet in July and August of last year, this year it only dropped .33 feet. The water level was at 6,379.78 feet above sea level as of August 20, owing to a wet summer that produced a welcome inch and a half of rain to supply the Lake and its tributary streams with much needed water.
MLC Information & Restoration Specialist Greg Reis noted that thunderstorms have “extended the late July streamflows into mid-August, buying about 3-4 weeks of extra time at or above the late July flows.” This means that late July and early August flows might end up higher than last year—something no one could have anticipated at the beginning of the summer.
Reis pointed to Walker Creek as the most dramatic example of this effect. Last year the Creek water flow was down to 1 cubic feet per second on August 8, and flowed at 1-2 cfs the remainder of the year. This year, because of the rain, as of August 21 the Creek has remained at or above 3 cfs.
Elsewhere, rainwater kept streams at a higher level for longer, as in the case of Rush Creek. Between Silver Lake and the Grant Lake Reservoir, Rush Creek reached 12 cfs before the rain, and only recently declined to that same level.
However, Reis noted that “this is [still] a very low summer flow … It is less than half the flow at the same times last year.” Reis said that apart from 2001, the Creek’s water flow has not been this low in August in at least 30 years.
And while Mono Lake didn’t drop below a threshold that would require the LADWP to reduce water exports from the Mono Basin from 16,000 to 4,500 acre-feet per year, MLC Communications Coordinator Elin Ljung said that “it’s likely that by April 1, 2015, Mono Lake will be below that threshold.”
The good news: even with the three year drought, Ljung said it’s unlikely the Lake’s level will drop enough to expose the land bridge to Negit Island, allowing coyotes to access California Gull nests. Ljung said the water level would have to drop another four feet, to a level it hasn’t reached since 1994, to do this. Such a dramatic decline is unlikely in the next few years. “It would be really awful to see it go that low,” she said.
