A severe and largely unanticipated drop in lake levels at Lake Mary due to evaporation and other factors may push Mammoth into some outdoor watering restrictions as soon as this week.
A request to require commercial and residential water customers to cut watering hours down by three hours was expected to be approved by the Mammoth Community Water District Thursday night, right after the Mammoth Times went to press.
If passed, the restrictions could conserve about 10 percent of the 3.4 million gallons of water a day Mammoth Lakes customers currently use.
Instead of permitting irrigation from 5 p.m. to 10 a.m., the watering restriction will start at 8 p.m. (and end at 10 a.m.).
Although the district anticipated in April that some kind of water restrictions might be necessary after the extremely dry winter, the situation at Lake Mary so early in the season was not anticipated, the district said.
Mammoth Lakes gets much of its water much of the year from Lake Mary, where it has water rights to a certain amount of water.
Outdoor irrigation demands (the huge bulk of water used by Mammothites in the spring and summer is due to outdoor irrigation, not domestic use) often outstrip the water rights at some point and the district taps groundwater via its many wells.
For example, in the middle of October when tourists are gone and there is no outdoor irrigation, Mammoth residents use about 1 million gallons a day, as compared to the 3.8 million a day used during irrigation season.
The move to groundwater occurred this year at the beginning of August, according to operations superintendent Karl Schnadt.
“The primary concern that is occurring is the rapid decline in the level of Lake Mary this year, compared to prior dry years,” he wrote in an agenda document. “In previous discussions, I have been using 2007 as a comparable year in order to establish a prediction for our surface water supply for this year.
“In general usage and demand patterns have been comparable so far; however, the decline in Lake Mary’s level this year has not been following a comparable trend during the month of July.
“Treatment plant diversion was approximately the same this year as 2007. The problem lies in the extreme loss this year due to evaporation, seepage, and other natural lake system losses that have removed an excess of water that was expected to be available for future diversion. The loss trend is continuing into August.
“Barring a significant rainfall event,” Schnadt wrote, “we have effectively used up our surface water supply for now. Lake Mary has already reached the three-foot drawdown limit normally set for Sept. 15, and we need to maintain water in the lake for emergency usage.”
How to save water—and your lawn
Attend a water district workshop Aug. 23 from 11:30 p.m. to 1 p.m. at the water district. Call Betty at 760-934-2596 ext. 274 for more information.
Water less often, longer. This allows the plants to develop deep roots.
Set sprinkler to lower pressure. The water drops are bigger and don’t evaporate as quickly.
Cut lawn higher. Taller grasses use less water
Leave grass clippings on lawn. That traps moisture and cuts back on watering.