Lakewatch
Record dryness in the Mono Basin
by Greg Reis
Wait a minute, you think as you read the above headline--the last issue of the Mono Lake Newsletter featured record snowpack in this column. Just a few months later I'm reading about "record dryness?" What is going on?
As usual, California's weather is being predictably unpredictable. December and January brought record amounts of precipitation, and February and March set records for lack of precipitation. This dryness, coupled with relatively warm temperatures, caused an unprecedented drop in the Sierra snowpack between February 1 and April 1. Warm temperatures and dryness continued through April and May, although in May we did get some precipitation from thunderstorms that also sparked a few lightning fires. The fuel moisture level, an index of fire danger recently recorded near Topaz, California, was the lowest ever recorded for this time of year.
The April-September runoff forecast issued by the Los Angeles Department of Water and Power (DWP) is predicting 127,800 acre-feet of water to roar down the Mono Basin streams, which is 127% of average. Rush Creek runoff is expected to be 127% of average, Lee Vining Creek 126%, Parker Creek 125%, and Walker Creek 136%.
The unseasonably warm weather has caused an early snowmelt--Lee Vining Creek saw a peak of 414 cubic feet per second (cfs) on June 1, almost 100 cfs higher than the peak was expected to be! The streams are running high and Grant Lake Reservoir is spilling.
DWP has no plans to divert Lee Vining, Parker, or Walker creeks this year, and almost all of this year's runoff will flow past the Rush Creek aqueduct facilities as well. DWP is planning to export the 16,000 acre-feet allowed under the Water Board decision when Mono Lake stands higher than 6,380 feet above sea level. DWP began exporting 20-25 cfs through the Mono Craters tunnel on April 16. Diversions will stop temporarily during Rush Creek's peak, and then continue through next March.
Mono Lake, in early June, stood at an elevation of 6,381.8 feet above sea level. It is 2.3 feet higher than this time last year, and has risen 7.2 feet since the September 1994 Water Board Decision. Due to the recent dry weather, the lake now might not reach 6,383 feet above sea level, as was forecast in the last newsletter. But it is still likely to rise about a foot between now and next April.
January storm
The figures are finally in for January's monster storm. Lee Vining Creek peaked at 740 cfs! This is an 80-year flood, but without the flood control effect of upstream reservoirs, this flood would occur on average every 25 years. In other words, a flood that would naturally occur about three times in a person's life has become a once in a lifetime event.
Many floodplain surfaces in the Lee Vining Creek bottomlands were covered by floodwaters for the first time since a similar flood in 1967. This is the first time, however, that a flood of this magnitude occurred during the winter. The other creeks didn't peak nearly as high, but did rise significantly. And you can still see the effects of the flooding in many areas. The Parker Lake Road, washed out by South Parker Creek, wasn't repaired until just before fishing season in late April.
Changes will continue to occur. In fact, this spring's high flows on Lee Vining Creek have moved debris that the January flood pushed into the entrance of the A-2 channel. Now the A-2 channel has much more water entering it, estimated to be about 20% of the streamflow.
When you are in the Mono Basin this summer, take a look at the changes brought about by the winter of 1996-97. Walk along the Lee Vining Creek trail to see the channel changes in the bottomlands. Walk around the South Tufa Area and Navy Beach to see the results of the lake's rise.
There are many new dead end trails at South Tufa, and the lower hot spring at Navy Beach is now underwater. The island at Old Marina that hasn't been there since the early 1970s has reappeared. Take a look at the landbridge to Negit Island, now an island itself. Make your presence here a voice for continued protection of the Mono Basin. Come and see the lake at the highest it has been since 1974!
Greg Reis is the Committee's Information Specialist. Look for him out along the creeks, checking up on flows.
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