Johnson County, IL Water Table Trend
Johnson County, IL: the closest actual trend
The closest qualifying well to Johnson County is 27 miles away in Saline County, IL, where the trend runs holding roughly steady.
Johnson County itself has no monitoring well with enough history to call its own trend, so treat this as a regional estimate, not Johnson County's own number. If you own a well here, comparing your own depth log against this regional figure is worth doing before assuming either way. See Saline 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.
Johnson County, Illinois in brief
About 13,320 people live across Johnson County's 344 square miles, in Illinois. USGS's National Groundwater Monitoring Network covers 1,449 of 3,222 US counties (45%) today; Johnson County isn't one of them yet, see the methodology guide for the exact qualifying bar.