Groundwater

Groundwater Levels Prove to be Falling

Why is it important?

When water resources are in short supply, groundwater levels fall. This occurs for two reasons when water shortages occur: groundwater is normally pumped to supplement surface water rights and less water is available to recharge underground reservoirs.

How are we doing?

The North Sierra has some monitored wells located in the Sierra Valley, where groundwater levels have been falling since 1998. In 1999, rainfall was ten inches below normal causing a decline in groundwater levels. However, rainfall from 2000-2003 has been more than ten inches above normal, yet groundwater levels continue to decline. This may be tied to increased agricultural acreage in the North Sierra.

In the North Central Sierra, groundwater levels are consistently measured only in the Lake Tahoe area. Rainfall levels have been at or below normal since 1999 causing groundwater levels to drop through 2003. Although, rising groundwater levels in 2003 occurred despite rainfall being six inches below normal that year.
Well monitoring is inconsistent in the South Central and East Sierra, although observed measurements follow the same trend as in the North and North Central Sierra.

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