St. Martin Parish, LA Water Table Trend
St. Martin Parish's groundwater trend, from USGS's own readings
St. Martin Parish's long-term well puts the trend at 0.5 ft per decade, declining, slower than most declining counties, based on 166 measurements since 1964.
This is one representative well, not a county-wide survey, the same grain limit every page here discloses.
St. Martin Parish's source well, in detail
Depth to water at the last reading was 21.1 ft below land surface. Readings span 1964-05-28 to 2026-09-10, 166 measurements from USGS well USGS-301308091521001 (Smn-103), part of the National Water Information System. The qualifying bar and the OLS fit behind this trend are documented in the methodology guide.
How St. Martin Parish compares nationally
St. Martin Parish sits at rank 970th 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. St. Martin Parish, Louisiana is home to about 51,218 people. See the fastest-moving counties guide for how St. Martin Parish stacks up against the most extreme cases nationally.
If you own a well in St. Martin Parish
A dropping water table means a residential pump has to reach deeper and work harder, which shortens its life. In St. Martin Parish, that trend is real, not assumed: 0.5 ft per decade over 62 years.
Depth and quality are separate questions
This page answers a depth question, not a quality one. A well in St. Martin Parish 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.