Updated Aug 2026
Delaware Lake Water Quality
51 lakes across 3 counties, 2 with a recent water-quality reading.
Lake Map
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New water-quality readings for Delaware lakes as DNREC publishes them. Unsubscribe anytime.
Where to stay near Delaware's major lakes
Cabins, resorts, and vacation rentals around Big Round Pond and the other major Delaware lakes pinned on the map. Live availability and prices.
Top-rated places to stay near Big Round Pond
Prices for Oct 9–11, 4 adults. Change dates on the map below.
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Delaware fishing & travel
EPA-Impaired Lakes in Delaware
View all 23 impaired lakes →23 of 51 Delaware lakes (45%) are officially listed as impaired under Clean Water Act §303(d) in the most recent EPA ATTAINS reporting cycle. 23 have an approved Total Maximum Daily Load (TMDL) restoration plan.
Delaware Fishing & Recreation
Licenses, regulations, records, and where to fish across Delaware.
Counties
All 3 Delaware counties, ranked by average lake water quality. Compare them against every county nationwide in the county rankings, browse the full directory of lakes, or pick a different state.
Delaware lists 51 lakes across 3 counties, 2 of them with a recent clarity, phosphorus or algae reading. The rest are here because they are real named lakes, listed for their size, depth and location.
Big Round Pond is the largest lake in this index at about 477 acres, one of 0 here that clear 500 acres. The rest run smaller, and small and shallow is where nutrient loading shows up first, because there is less water to dilute it and the bottom sediment stays within reach of the sun.
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of lakes that fit, with the water quality behind each one.
Source: EPA National Aquatic Resource Surveys and the EPA Water Quality Portal.
More on lake water quality
A data snapshot of the lakes we track: the clearest and the greenest states, and where the water is improving.
How nutrient and algae readings are read against EPA ecoregion condition classes, what each class means in the water, and why a clean reading is not a clearance.
The clearest lakes in America, ranked by measured Secchi depth in feet from EPA monitoring data — and why the famously clear lakes are missing.