Pennington County, SD Water Table Trend
Pennington County, SD: what the water table is actually doing
Pennington County's long-term well puts the trend at 5.6 ft per decade, declining faster than most declining counties, based on 663 measurements since 1966.
This is one representative well, not a county-wide survey, the same grain limit every page here discloses.
Pennington County's source well, in detail
Water in this well currently sits 110.4 ft above land surface (flowing/artesian), a flowing or artesian well rather than one pumped from below. Readings span 1966-01-04 to 2026-10-06, 663 measurements from USGS well USGS-440430103160202 (001n07e03cbaa2 Sioux Park Madison), part of the National Water Information System. The qualifying bar and the OLS fit behind this trend are documented in the methodology guide.
How Pennington County compares nationally
Pennington County sits at rank 1325th 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. Pennington County, South Dakota is home to about 115,979 people. See the fastest-moving counties guide for how Pennington County stacks up against the most extreme cases nationally.
If you own a well in Pennington County
A dropping water table means a residential pump has to reach deeper and work harder, which shortens its life. In Pennington County, that trend is real, not assumed: 5.6 ft per decade over 61 years.
Depth and quality are separate questions
This page answers a depth question, not a quality one. A well in Pennington 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.