CONSERVATION CORNER

LONG-TERM DROUGHT

One way that water managers assess historic rainfall patterns to predict potential water availability in the future is to produce "cumulative departure from average precipitation curves". These are simple plots of annual rainfall, minus average annual rainfall, cumulatively added and plotted over time. Thus if any year has 20" of precipitation and average annual rainfall is 15", the departure from average for that year is 20" - 15" = +5". If the annual precipitation is 10", the departure from average would be 10" - 15" = -5". Then you simply add all of the years (cumulatively, one at a time, from year 1-???) and plot them to look for wet and dry periods. Here is a plot of precipitation data from CSDs rain gauge From 1955-1975, a series of predominantly dry years that lasted 20 years.

Thus, we know droughts lasting as long as 20 years have been recorded in Big Bear Valley. We are now in year 6 of the current drought and there is the potential that we could face 10 or more years of dry weather before this drought ends. It is essential that everyone in the community understands this and plans accordingly. Please use water efficiently. Water you waste today, may be water you need in the future. Your water provider knows many ways to conserve water. Call us if you need some help getting started.

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