St. Johns County Lake Quality

St. Johns County holds 5 monitored lakes. With a sample that small the county-level summary describes those specific waters, not necessarily every water body in the county. 4 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. Most monitored lakes in St. Johns County are productive, shallow basins; each lake page shows its own phosphorus and chlorophyll-a readings beside the EPA condition class.

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. Lake South has the lowest nutrient and algae readings in the county.