Simpson County Lake Quality

Simpson County has 1 monitored lake — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. Every one of those lake carries recent nutrient and algae readings, so the county-level summary covers the full set rather than a monitored subset. For Simpson County the spread behind the average matters more than the average itself: a few nutrient-rich lakes among many clear ones produce the same figure as the inverse.

Most of the county's monitored lakes are shallow, under 50 feet, which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. West Fork Drakes Reservoir has the lowest nutrient and algae readings in the county.