CONSERVATION CORNER

AQUIFER RECHARGE:
A VITAL LINK IN THE VALLEY'S GROUND WATER CYCLE!

Now that we are getting rain and snow in the Big Bear Valley, some of us are wondering whether our aquifers are being recharged! Here are the basics on how recharge works. First, we must have precipitation, which has been in short supply in recent years. Then, the amount of water that is potentially available for recharge is what is left over after you subtract water lost due to evaporation, runoff, plants, water that is retained in the soil and matrix above the aquifers, and others. By the time you account for all of the water that is lost, often less than half (possibly as little as 10-20%) of the original precipitation remains to percolate downward towards the aquifers. Since many of these losses are similar in magnitude in both wet and dry winters, below average winter precipitation may not exceed the cumulative water losses, resulting in very little water available for ground water recharge.

One way to visualize whether or not we are getting recharge is to watch the lake level. In general, if lake level is rising or water is spilling over the dam's spillway, the aquifers will usually get recharge. If the lake level remains stationary or declines during the winter, recharge will most likely be minimal. When we do get recharge, it is often not detectable in monitoring wells until at least March or April. In some portions of the valley, it may be 6 months or longer until recharge can be detected. So with all of the above in mind, cross your fingers and hope we get a wet winter and by the middle of next summer we will have an idea about this winter's recharge.

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