Nevada County, CA Water Table Trend
Nevada County's groundwater trend, from USGS's own readings
Nevada County's long-term well puts the trend at 2.5 ft per decade, rising, getting shallower over time, based on 31 measurements since 1979.
This is one representative well, not a county-wide survey, the same grain limit every page here discloses.
Nevada County's source well, in detail
Depth to water at the last reading was 17.2 ft below land surface. Readings span 1979-03-12 to 2020-12-07, 31 measurements from USGS well USGS-390916121115901 (015n007e16g001m), part of the National Water Information System. The qualifying bar and the OLS fit behind this trend are documented in the methodology guide.
How Nevada County compares nationally
Nevada County sits at rank 109th of 1,449 ranked counties, ordered rising-to-declining, so a low number means a rising water table and a high one means fast decline. Nevada County, California is home to about 102,195 people. See the fastest-moving counties guide for how Nevada County stacks up against the most extreme cases nationally.
Depth and quality are separate questions
This page answers a depth question, not a quality one. A well in Nevada County can be stable in depth and still worth testing for quality, or declining and still test clean, the two are measured separately, and only a direct test settles the second one.