Petersburg County Lake Quality

The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. The 18 monitored lakes in Petersburg County carry whatever clarity, phosphorus, and chlorophyll-a readings Alaska DEC has published, shown as reported.

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.