Record rise in Mono Lake expected

by Greg Reis

Alot of snow was melting around Mono Lake in April, but Mono Lake rose less than a tenth of a foot that month, to 6380.07 feet above sea level on May 1. Why didn’t Mono Lake rise faster?

April consistently has the least variation in Mono Lake levels of any month. If no big storms occur and streamflows are near historical averages, Mono Lake tends to rise a tiny bit, because inflow only slightly exceeds evaporation. May is also a low-variation month, and a rise exceeding 0.36 feet will set a new record (since 1989).

June through August, in an Extremewet year-type like this, is when most of the rise in Mono Lake will occur. In fact, if you add up the record monthly rises between April and September, a total rise of 4.3 feet is along the lines of what we will see this summer. This is about a foot higher than the 3.2-foot April–September rise in 2017, which beat the previous record 2.7-foot rise in 1983. Multiple monthly records could be broken this year, and with a strong El Niño likely to bring warmer winter temperatures, there is a good chance for the runoff year record rise of 3.56 feet set in 2017 to be broken next April 1.

In August Mono Lake will be the highest it has been in more than a decade and about a foot shy of the highest levels reached since the State Water Board’s 1994 decision to protect Mono Lake. It is urgent that stream diversions are paused as soon as possible in order to be reached, however, an early peak could be captured by the reservoir and a cool summer could result in a lower peak but extend high flows well into August. High August flows, if combined with a wet 2024 winter, could make it challenging to lower Grant enough for construction before October 1 to maintain low fall and winter flows that benefit Rush Creek fish. In anticipation of these possible wet-year challenges, DWP has requested from the State Water Board a one-year delay in construction. 

Mono Lake’s record monthly rises since 1941

April

August

September feet (1983) feet (1983) preserve these gains, allowing the lake to rise to the 6392-foot Public Trust lake level as quickly as possible.

Greg Reis is the Committee’s Information & Restoration Specialist. At a Living Lakes conference in South Africa he realized that migrating birds stay in the same spot relative to the sun, and the Earth tilts under the migrating birds.