Ada County, ID Water Table Trend
Is the water table dropping in Ada County, ID?
Over 48 years of USGS readings, the well tracking Ada County's aquifer is rising, getting shallower over time: 1.2 ft per decade.
This is one representative well, not a county-wide survey, the same grain limit every page here discloses.
Ada County's source well, in detail
Depth to water at the last reading was 691.1 ft below land surface. Readings span 1976-04-14 to 2023-11-07, 38 measurements from USGS well USGS-431402116173701 (02s 01e 23add1), part of the National Water Information System. The qualifying bar and the OLS fit behind this trend are documented in the methodology guide.
How Ada County compares nationally
Ada County sits at rank 216th 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. Ada County, Idaho is home to about 535,799 people. See the fastest-moving counties guide for how Ada 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 Ada 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.