Mercer County, IL Water Table Trend
Mercer County, IL: the closest actual trend
Warren County, IL, 25 miles from Mercer County, is the closest county with a qualifying well, and its water table is declining faster than most declining counties.
No well inside Mercer County clears this site's 15-year qualifying bar, so this is the closest real reading, not a measurement of Mercer County's own aquifer. Worth checking your own well's depth log against it rather than assuming it matches. See Warren County, IL's full page. See the no-data guide for why a county this close to a qualifying well still doesn't get its own number.
About Mercer County
Mercer County, Illinois covers 561 square miles and is home to about 15,292 people. USGS's National Groundwater Monitoring Network covers 1,449 of 3,222 US counties (45%) today; Mercer County isn't one of them yet, see the methodology guide for the exact qualifying bar.