Colusa County, CA Water Table Trend
Colusa County's groundwater trend, from USGS's own readings
Over 26 years of USGS readings, the well tracking Colusa County's aquifer is holding roughly steady: 0.2 ft per decade.
This is one representative well, not a county-wide survey, the same grain limit every page here discloses.
Colusa County's source well, in detail
Depth to water at the last reading was 1.4 ft below land surface. Readings span 1997-08-05 to 2023-08-02, 15 measurements from USGS well USGS-391653122101401 (017n003w35m001m), part of the National Water Information System. The qualifying bar and the OLS fit behind this trend are documented in the methodology guide.
How Colusa County compares nationally
Colusa County sits at rank 493rd 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. Colusa County, California is home to about 22,074 people. See the fastest-moving counties guide for how Colusa 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 Colusa 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.