Ann Lake is located in Sherburne County, five miles west of Zimmerman. The lake has a surface area of 184 acres and a maximum depth of 26 feet. The watershed is small and dominated by forest and the lake is lightly developed. The lake has excellent water quality and a diverse aquatic plant community. Northern pike, largemouth bass, and bluegill are present. A public access is located on the northwest corner of the lake. A state forest campground and beach are located on the west side of the lake. Ann Lake was surveyed in June 2011.
Northern pike abundance was lower than the last survey in 2001, but still high and above the expected range for lakes similar to Ann. The average size was 21.5 inches and 2.5 pounds. The largest northern pike caught was 29.5 inches long. Northern pike growth was similar to other lakes statewide. Northern pike grew to 20 inches in five years. The percentage of northern pike longer than 24 inches was 22%.
Largemouth bass were sampled by daytime electrofishing in May 2011. The catch rate was low, but most bass were larger than 15 inches. The average size was 16 inches and the largest bass caught was 18.5 inches. Electrofishing was not possible in the shallow, heavily vegetated, south basin, likely reducing the number caught.
The number of bluegill was lower than in 2001, but still very high and well above the expected range for lakes similar to Ann. The average length was 5.5 inches and the largest bluegill was 8 inches. Bluegill grew slowly, reaching 6 inches in 7 years.
Few yellow perch were caught in 2011 and no black crappie. Past survey catches have also been low for both species. Other species captured during the survey included: hybrid sunfish, pumpkinseed, and yellow bullhead.