Santa Clara County Lake Quality

Santa Clara County has 13 monitored lakes — 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. 2 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. The county's readings sit in the middle of the California range, with one or two lakes pulling the average up or down depending on year.

The county's lakes lean shallow, which makes the readings sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest measured lake is Almaden Reservoir.