Cleaner Lakes Than Jamestown Reservoir

Reading the cohort

Within 30 miles of Jamestown Reservoir, 5 water bodies score higher than its Grade D on the same EPA water-quality metrics. That density of cleaner options is itself a signal — when several nearby lakes score better on the same indicators, the issues at Jamestown Reservoir are typically lake-specific (depth, watershed inflow, stratification pattern) rather than regional. The choice for a swim, paddle, or fishing trip is genuinely between meaningfully different water bodies, not between marginal differences in the same dataset.

Spiritwood Lake (Stutsman County, Grade A) is the closest cleaner option at 11.5 miles from Jamestown Reservoir — close enough to be a genuine substitute for most users, far enough that it isn't the same neighborhood lake. Worth the trip if water quality is the primary driver; less obvious if Jamestown Reservoir is on the way to other plans.

The EPA water-quality grading combines clarity (Secchi depth), phosphorus, and chlorophyll-a measurements from state environmental sampling. A higher letter grade reflects measurably cleaner water on those indicators, 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. See the methodology page for the full grading formula.

How this list is built

Every lake on LakeQuality has a calculated grade from EPA Water Quality Portal samples — secchi depth, total phosphorus, and chlorophyll-a measured against Metropolitan Council thresholds. 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.