Clearwater Lake, also known as Tadpole Lake, is located about eleven miles north of Grand Rapids, MN and within the Mississippi River Watershed. The small lake is 68 acres with 1.5 miles of shoreline and a maximum depth of 38 feet. There are two inlets, Clearwater Creek from Wabana Lake and Hanson Creek from the Hanson Lake chain, and one outlet, Clearwater Creek, to the Prairie River. It is likely the outlet connectivity to Prairie River that facilitates seasonal fish passage while a low head dam at Wabana Lake acts like a fish barrier and beaver dams along Hanson Creek likely prevent fish passage. Access is gained from Clearwater Creek at the County Road 60 crossing.
Northern pike were the most numerous fish sampled in gill nets at a rate of 10.5/net, exceeding the expected range for lakes similar to Clearwater Lake. The catch was similar to the previous assessment in 1965 (7.5/gill net). Lengths ranged from 13.1 to 30 inches with a mean length of 17.2. Size structure was poor, similar to the previous assessment, with one fish sampled exceeding 20 inches. Scale and bone analysis identified ages 1 through 4 and 6 present in the sample suggesting relatively consistent recruitment. Ages 1 and 2 comprised 70% of the sample suggesting the population is dominated by small, young individuals. Averaged growth was similar to the statewide average. Neascus was observed on all sampled northern pike.
Walleye were captured at a rate of 2.5/gill net, within the expected range, while there are no records of them ever being stocked. Walleye were not observed in the initial assessment. Lengths ranged from 18.4 to 20 inches, and scale and bone analysis determined the ages were from 5 to 7. Growth was similar to the statewide average with walleye averaging 17.7 inches by age-5. The modest walleye population is likely a product of connectivity to Prairie River. One of the five sampled walleye had a possible fin punch from an upstream fish passage project at CoRd 49, however the mark was inconclusive. Neascus was observed on four of the five sampled walleye.
Bluegill were sampled at a rate of 3.0/gill net and 1.0/trap net. Size structure was poor and likely of little interest to anglers. Bluegill had a mean length of 4.5 inches in the gill net sample and 5.3 inches in the trap net sample. Pumpkinseed were the most numerous species sampled in trap nets, at a rate of 2.0/trap net near the expected range. These fish were small with lengths from 3.3 to 4.3 inches.
Other species sampled included brown bullhead, golden redhorse, green sunfish, rock bass, and white sucker.