Mill

Mill Lake is a 461-acre, moderately productive basin located eight miles southwest of Alexandria. Maximum depth of the lake is 40.0 feet. Average depth is estimated at 20.0 feet. Water clarity has increased markedly in response to establishment of zebra mussels. Water transparency at time of the June 2024 survey was measured at 21.0 feet. Mill Lake supports a diverse and robust aquatic plant community which provides important habitat for ambush feeders or vegetation-dependent gamefishes such as Northern Pike, Largemouth Bass, and Bluegill. Residential development is prominent with a few agricultural lots bordering the lake. A DNR public access site is located on the southeast shoreline, off MN-27. A standard fisheries survey was completed in 2024 to evaluate abundance and size distribution of gamefish populations. Survey methodology included a spring electrofishing survey, completed May 14, to effectively sample the Largemouth Bass population. The gill netting component of the standard survey was completed June 10-11. During the spring of 2022 a special regulation was implemented that reduced the daily sunfish limit from 20 down to 10. As an evaluation requirement of this special regulation, trap netting was conducted during the spring (May 14-15) when panfish are more susceptible to capture. These sampling practices will be standard protocol for future fisheries surveys on Mill Lake. Mill Lake historically supported a relatively stable Walleye population sustained through alternate year fingerling stockings. Since the discovery of zebra mussels in 2015 Walleye catch rates have declined to a near record low in 2024 (2.8 fish/gill net). Though not overly abundant, 64% of Walleyes observed were over 15.0 inches. It is apparent that survival of stocked Walleye fingerlings and Walleye abundance have diminished in response to competition and predation by a high-density population of small Northern Pike. These negative effects are likely compounded by the presence of zebra mussels. Northern Pike continue to be excessively abundant (20.3 fish/gill net). Average size of pike captures in 2024 remained modest at 18.4 inches. The largest pike measured 35.6 inches, though fish of this size are not common. Anglers are reminded that new pike zone regulations were implemented in 2018. Mill Lake is located in the North-Central Zone. Anglers can now keep up to 10 pike but not more than two can be over 26 inches in length. All pike between 22-26 inches must be immediately released. Anglers are encouraged to take advantage of these liberalized bag limits and harvest pike under 22 inches in length. Harvesting smaller pike will help shift the population back towards larger individuals and reduce the number of predators for young Walleye and other gamefish. Due to the lake's quality habitat attributes, Mill Lake supports a robust Largemouth Bass population. Growth rates are similar to the state-wide average with bass reaching 12.0 inches at age 4. Size structure of the electrofishing catch described a quality fishery. Sixty-two percent of the Largemouth Bass sampled were over 12.0 inches and the largest bass observed was 18.0 inches. Bluegill catch rates (69.7 fish/trap net) were high in 2024. Age distribution of Bluegill catches extended to age 9, but 63% of captures were age 5 or younger. Although the population is dominated by young fish, Mill Lake continues to boast a quality size structure for Bluegill and provides excellent angling opportunities. Sixty-four percent of Bluegill were over 7.0 inches in length and fish up to 9.6 inches were observed. Black Crappie catch rates were low and a majority of fish captured were age 4 and younger. Few crappies over 10.0 inches were observed during the 2024 spring survey. Black Crappie growth rates are moderate; average length of age 4 fish was over 9.5 inches. The largest Black Crappie in the sample was over 12.5 inches and the oldest crappie was 9 years old. Adult Yellow Perch numbers were low during the 2024 survey. Yellow Perch are preferred prey of Walleye, Northern Pike, and Largemouth Bass. Additional species sampled include Common Carp, hybrid sunfish, Pumpkinseed, and Brown and Yellow Bullhead. The next standard fisheries survey is tentatively scheduled for 2030. Zebra mussels were documented in Mill Lake in 2015, but no other invasive species have been documented. Anglers are reminded to drain boats and equipment prior to moving between bodies of water to minimize the risk of transferring aquatic invasive species to this or other lakes.

A targeted survey was completed in the spring of 2022 on Mill Lake to assess the Bluegill and Black Crappie populations. A special regulation that reduced the daily sunfish limit from 20 down to 10 was also implemented in the spring of 2022. The goal of this new regulation is to maintain or increase the average size of Bluegill. This survey will be used to help evaluate effects of the regulation on the Bluegill population. Bluegill catch rates were moderate, and many quality Bluegill were observed. Forty-three percent of the Bluegill were over 8 inches in length. Growth rates of Bluegill in Mill Lake are moderate and 7 year old Bluegill averaged 8 inches in length. The largest Bluegill observed in the survey was 9 inches. Black Crappie catch rates were low and a majority of fish captured were age 4 and younger. Approximately 42% of the fish were greater than 10 inches in length. Black Crappie growth rates are moderate; average length of age 4 fish was over 9 inches. The largest Black Crappie in the sample was over 11 inches and the oldest crappie was 7 years old. Quality fishing opportunities exist for multiple species in Mill Lake. Anglers are encouraged to practice selective harvest to help sustain the quality of the fishery. Selective harvest encourages the release of larger fish while promoting harvest of more abundant smaller fish. Releasing medium to large fish can help restore and maintain fish community balance, as well as increase opportunities to catch large fish. Zebra mussels were documented in Mill Lake in 2015, but no other invasive species have been found. Anglers are reminded to drain boats and equipment prior to moving between bodies of water to minimize the risk of transferring aquatic invasive species to this or other lakes.

This nearshore survey was conducted during summer 2018 to assess populations of non-game species and small game fish using backpack electrofishing and seining. Backpack electrofishing and/or seining were conducted at 10 stations, representing a variety of habitat types, along the shoreline of Mill Lake. The survey was conducted during the five-year sampling window for intensive monitoring efforts within the Long Prairie River watershed, and will be contributing to a watershed assessment process in coordination with Minnesota Pollution Control Agency. Fifteen species were collected during this survey. Two species (Banded Killifish and Iowa Darter) were considered "intolerant" and one species (Green Sunfish) was considered "tolerant" based on current tolerance classifications for Minnesota lakes. Nearshore catch data will be used along with gill and trap net catch data to develop an Index of Biotic Integrity (IBI) score, which is indicative of the health of Mill Lake.

Based on Minnesota DNR survey data, anglers target Muskellunge, Largemouth Bass, Bluegill, Black Crappie, and Northern Pike in Mill. See the full species list above for catch rates, size structure, and quality scores.

Minnesota DNR records list public access for Mill. Check the DNR LakeFinder page for the launch type and directions before you go.

Mill has a maximum depth of 40 feet and a mean depth of 20 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Mill is from 2024.

Yes — Mill has confirmed zebra mussel. Clean, drain, and dry your equipment to avoid spreading invasives to other waters.