Lewis and Clark County, MT Water Table Trend
Lewis and Clark County, MT: what the water table is actually doing
Lewis and Clark County's long-term well puts the trend at 2 ft per decade, declining at a typical pace for a declining county, based on 455 measurements since 1976.
This is one representative well, not a county-wide survey, the same grain limit every page here discloses.
Lewis and Clark County's source well, in detail
Depth to water at the last reading was 28.8 ft below land surface. Readings span 1976-11-14 to 2019-03-08, 455 measurements from USGS well USGS-463906112043901 (10n04w02cbaa01), part of the National Water Information System. The qualifying bar and the OLS fit behind this trend are documented in the methodology guide.
How Lewis and Clark County compares nationally
Lewis and Clark County sits at rank 1178th 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. Lewis and Clark County, Montana is home to about 75,129 people. See the fastest-moving counties guide for how Lewis and Clark County stacks up against the most extreme cases nationally.
If you own a well in Lewis and Clark County
A dropping water table means a residential pump has to reach deeper and work harder, which shortens its life. In Lewis and Clark County, that trend is real, not assumed: 2 ft per decade over 42 years.
Depth and quality are separate questions
This page answers a depth question, not a quality one. A well in Lewis and Clark 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.