Delaware Lake Water Quality

Delaware has 3 graded lakes in our dataset, sampled across 2 counties, drawing on monitoring by the Delaware Department of Natural Resources and Environmental Control plus federal and volunteer measurements. A-grade lakes are scarce in Delaware: about 0% of the dataset. Most lakes here sit in C or D — productive, often shallow, frequently algal in late summer.

Trophically, oligotrophic lakes — cold, clear, low-nutrient — dominate the state's graded inventory. These are the deep glacial basins that buffer against nutrient inputs by sheer volume, and they hold most of Delaware's A-grade waters. a leading county ranks highest on average county grade (—). a struggling county sits lowest. With only 2 counties in the state, the cross-county spread is narrower than the within-county spread for most lakes.