Lake Montello

Lake Montello earns a D — measurements through 2021 show persistent nutrient pressure that limits clarity through the summer. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

At a TSI of 51, Lake Montello reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 17 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. The lake's 341 acres and partial shoreline records put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Lake Montello ranks 12 of 13 in Marquette County — at the lower end of the locally monitored distribution.

Eurasian watermilfoil is established at Lake Montello, which can dampen recreational access and pressure the native plant community. The fishery is bass-led, with 3 documented species across the lake's records. A documented public access point at Lake Montello makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.