Altoona Lake

Altoona Lake grades an F: every scored parameter (clarity and phosphorus) rates poorly, placing it among the most stressed lakes monitored in Wisconsin. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.

At a TSI of 66, Altoona Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. A maximum depth of 25 ft puts Altoona Lake in the middle of Wisconsin's depth distribution. The lake's 720 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. Within the 3 graded lakes of Eau Claire County, Altoona Lake sits at rank 3, near the bottom of the county list.

An invasive species record — Chinese Mystery Snail — has been logged at Altoona Lake; Wisconsin DNR maintains the official infested-waters list. The fishery includes walleye among the lake's 4 documented species — a notable draw for Wisconsin anglers. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.