Jefferson County, ID Water Table Trend
Jefferson County's groundwater trend, from USGS's own readings
Jefferson County's representative monitoring well shows depth to water declining at a typical pace for a declining county, a fitted trend of 2.1 ft per decade over 101 years of readings.
This is one representative well, not a county-wide survey, the same grain limit every page here discloses.
Jefferson County's source well, in detail
Depth to water at the last reading was 93.5 ft below land surface. Readings span 1922-06-30 to 2023-04-19, 152 measurements from USGS well USGS-435554112043301 (07n 37e 14cbc1), part of the National Water Information System. The qualifying bar and the OLS fit behind this trend are documented in the methodology guide.
How Jefferson County compares nationally
Jefferson County sits at rank 1188th 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. Jefferson County, Idaho is home to about 34,854 people. See the fastest-moving counties guide for how Jefferson County stacks up against the most extreme cases nationally.
If you own a well in Jefferson County
A dropping water table means a residential pump has to reach deeper and work harder, which shortens its life. In Jefferson County, that trend is real, not assumed: 2.1 ft per decade over 101 years.
Depth and quality are separate questions
This page answers a depth question, not a quality one. A well in Jefferson 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.