Dale Maffitt Reservoir
- +Two grade letters higher (F → A)
- ++7.6 ft water clarity
- +Lower phosphorus (20 vs 78.5 µg/L)

3 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Blue Heron Lake carries a Grade F (Algae-prone) water quality score. Within 30 miles, 3 lakes hold a higher grade. Dale Maffitt Reservoir (Dallas County, Grade A, 3.9 mi away) is the closest meaningful upgrade.
Only 3 lakes within a 30-mile radius score better than Blue Heron Lake's Grade F. The narrow set of options reflects either a fairly clean lake to begin with or a region without a wide range of cleaner alternatives — the trip-planning decision is more constrained than the headline "cleaner lakes nearby" suggests.
The closest cleaner alternative — Dale Maffitt Reservoir in Dallas County, Grade A — sits 3.9 miles from Blue Heron Lake. At that distance, the substitution cost is essentially zero: same drive time, same regional access, demonstrably cleaner water on the EPA indicators. For repeat visitors who care about clarity or phosphorus levels, swapping the routine to Dale Maffitt Reservoir is mostly a habit change rather than a logistics change.
Lakes are graded A to F on nutrients and algae — total phosphorus, total nitrogen, chlorophyll-a, and turbidity — measured against the EPA National Lakes Assessment 2022 condition classes for that lake's own ecoregion, so a lake is judged against the lakes it would naturally resemble. A higher letter reflects measurably lower nutrient and algae levels, not subjective beauty or access quality — a Grade A lake might have worse boat-launch facilities or shoreline access than a Grade C neighbor, so the ranking is one input alongside the rest of trip planning. The full grading formula is on our methodology page.
Rated lakes on LakeQuality have a letter from EPA Water Quality Portal samples — nutrients and algae measured against EPA National Lakes Assessment ecoregion classes. Secchi is shown, not scored. To suggest cleaner alternatives, we filter lakes within 30 miles to those with a strictly higher numeric score, then rank by grade improvement with a small proximity tiebreak. Cross-state and limited-data lakes are excluded so the list stays locally relevant.