Sunrise light on a grove of tufa towers emerging from the water of Mono Lake with soft green and dusty-red wild grasses in the foreground, Canada geese in the shallow water with reflections of the rocky towers, and desert hills in the distance.

March 1 Hydrology Update

Mono Lake
On April 1st, 2009 (the beginning of this Runoff Year), Mono Lake was at an elevation of 6382.5 feet. It dropped about a foot by the end of the calendar year, and in January and February it rose half a foot, for a net loss of 0.6 feet since last April 1st. The half-foot rise in January and February is the largest 2-month wintertime rise since a 0.6 foot rise in January and February 2006. Mono Lake usually rises 0.1 foot in March–if it does that this month, we should be looking at an April 1st level of about 6382.0 feet. Click here for more on Mono Lake’s levels.

Lee Vining Precipitation
Here in Lee Vining, from October through February we’ve received 11.72 inches of precipitation, which is 108% of the 10.9 inches we usually get by April 1st.

Lee Vining Snowfall
Here in Lee Vining, from October through February we’ve received 87.4 inches of snowfall, which is 134% of the 65.3 inches we usually get by April 1st. If it stopped snowing now it would be our 7th snowiest winter on record (since 1989), and we still have March to go, which can be a snowy month.

Mono Basin March 1st Snow Surveys
This past week, up in the headwaters of the Rush and Lee Vining Creek drainages from 9,150 to 10,750 feet, snow surveyors found 111% of average March 1st snow water content, and 94% of the April 1st average. This is the highest total of any watershed on the east side of the Sierra and an increase from 102% on February 1st  (which resulted in a 92% preliminary February runoff forecast). As yet no runoff forecast is available based on the March snow surveys, but if a 9% increase in snow water content translates into about a 9% increase in runoff, we should expect a 2010 Runoff Year very close to 100% of average (assuming the future is near average). Click here for more on water supply conditions.

Grant Lake Reservoir
The reservoir is dropping slowly (about 1000 acre-feet every 19 days) and will meet the State Water Resources Control Board’s target of 30-35,000 acre feet of storage on April 1st. This is the first time the target will have been met in a Normal or Dry-Normal year since 2002 (the wet year target of 40,000 acre-feet was met in 2006, and there are no dry year targets but the reservoir was also high in 2007–a dry year). This means good temperatures for fish this summer and a slight chance of spilling the reservoir if March and April turn out to be wet.