Mesotrophic Lakes in Montana

Mesotrophic lakes are the productive middle of the trophic scale — TSI between 40 and 50. Clear enough to be inviting, productive enough to support a strong fishery, with moderate phosphorus and a modest algal community that does not dominate the optical signal. 14 lakes in Montana sit in the mesotrophic band. About 0% are deep (50+ ft); the rest are shallower basins where watershed management keeps nutrients from pushing the system into eutrophy.

Mesotrophic lakes sit in the middle of the phosphorus and chlorophyll-a range: productive but still clear, with readings that rarely reach the EPA's poorest condition class.