De Witt County, IL Water Table Trend
De Witt County's groundwater trend, from USGS's own readings
Over 40 years of USGS readings, the well tracking De Witt County's aquifer is declining, slower than most declining counties: 0.9 ft per decade.
This is one representative well, not a county-wide survey, the same grain limit every page here discloses.
De Witt County's source well, in detail
Depth to water at the last reading was 62.7 ft below land surface. Readings span 1985-09-20 to 2025-06-17, 24 measurements from USGS well USGS-400805088531501 (19n3e-5.3e), part of the National Water Information System. The qualifying bar and the OLS fit behind this trend are documented in the methodology guide.
How De Witt County compares nationally
De Witt County sits at rank 1073rd 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. De Witt County, Illinois is home to about 15,319 people. See the fastest-moving counties guide for how De Witt County stacks up against the most extreme cases nationally.
If you own a well in De Witt County
A dropping water table means a residential pump has to reach deeper and work harder, which shortens its life. In De Witt County, that trend is real, not assumed: 0.9 ft per decade over 40 years.
Depth and quality are separate questions
This page answers a depth question, not a quality one. A well in De Witt 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.