Virginia Lake Water Quality

152 of the 390 Virginia lakes in this index carry a recent clarity, phosphorus or algae reading, spread over 99 counties. Those readings come from the Virginia Department of Environmental Quality, alongside federal programs and volunteer monitoring networks. The rest are listed for their size, depth and location, with no recent nutrient or algae sampling behind them. Low nutrient and algae readings are common among measured Virginia lakes, mostly the cold, deep, kettle-formed lakes in the north of the state, which buffer themselves against nutrient inputs.

By surface area the largest lake here is Dam Lake, at about 20,400 acres, and 16 of the lakes in this index cover more than 500 acres. Size is worth knowing before you go: a large deep basin buffers nutrient inputs by sheer volume, while a shallow one warms quickly and can turn over its whole water column in a single summer storm. The measured lakes lean eutrophic, with enough nutrient input to support an active algal community and the trade-offs in clarity and dissolved oxygen that come with it. The county with the lowest nutrient and algae readings on average is Russell. The gap between counties is large enough that a single figure for Virginia lake water quality hides real local variation.