1
ADale Maffitt Reservoir
Dallas County, Iowa · 21.8 mi from Beaver Lake
- +Two grade letters higher (F → A)
- ++7.9 ft water clarity
- +Lower phosphorus (20 vs 105 µg/L)
Cleaner Lakes Than Beaver Lake
3 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Beaver 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, 21.8 mi away) is the closest meaningful upgrade.
Reviewed by LakeQuality Editorial Team · Updated
2
DSpringbrook Lake
Guthrie County, Iowa · 21.3 mi from Beaver Lake
- +Higher grade (F → D)
- ++1.1 ft water clarity
- +Lower phosphorus (59 vs 105 µg/L)
3
DNodaway Lake
Adair County, Iowa · 22.4 mi from Beaver Lake
- +Higher grade (F → D)
- +Lower phosphorus (57 vs 105 µg/L)
Reading the cohort
Within 30 miles of Beaver Lake, 3 lakes score higher on EPA water-quality metrics than its Grade F. The short list means the alternatives are real upgrades but not interchangeable — each carries its own access, size, and species mix worth checking before substituting it into a weekend plan.
The nearest cleaner alternative — Dale Maffitt Reservoir in Dallas County — sits 21.8 miles from Beaver Lake, putting it firmly in "destination trip" rather than "neighborhood swap" range. The water-quality gap has to be the deciding factor; for a casual outing, Beaver Lake is the practical choice and the cleaner options are reserved for purpose-specific visits.
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.
How this list is built
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.