Mazaska

Lake Mazaska is a 672-acre lake located northeast of Shieldsville in Rice County. There is a county-owned access located off Lake Mazaska Trail on the southwest shore and a state-owned access located off Highway 21 on the southeast shore. Lake Mazaska has a maximum depth of 50 feet, with approximately 50% of the lake less than 15 feet deep. Lake Mazaska is primarily managed for Bluegill and Black Crappie and secondarily for largemouth Bass, Northern Pike, and Walleye. The lake was designated as infested in 2010 after the discovery of Eurasian Water Milfoil and annual efforts have been made to keep Eurasian Water Milfoil and Curly-leaf Pondweed below nuisance levels. Lake Mazaska was surveyed the week of 21 July 2025 as part of a regular monitoring program conducted by the Minnesota DNR. This survey was intended to assess the fish community by deploying 8 gill nets and 12 trap nets, as well as recording water quality parameters. Daytime electrofishing was conducted to get a better understanding of the Largemouth bass population and size structure. The next standard survey for Lake Mazaska is scheduled for 2028. A total of 54 Bluegills were sampled with trap nets for a catch rate of 4.5/net. Lengths ranged from 3.4 to 8.7 inches with an average of 5.9 inches. Larger fish were sampled at a higher rate by gill nets with a total of 69 fish sampled for a catch rate of 8.6/net. Bluegills in gill nets ranged from 4.8 to 10.0 inches averaging 7.2 inches. Fish from both gears ranged from age-1 to age-12 with 8 year-classes present. Approximately 58% of the sample consisted of age-2 and age-3 fish. According to the 2022 creel survey, Bluegills were the most harvested fish from Lake Mazaska with an estimated 3,036 fish averaging 8.7 inches harvested during a 10-month period from December 2021 through September 2022. Based on the creel and survey data, the Bluegill population in Lake Mazaska was described as healthy and desirable to anglers. A reminder to anglers, Lake Mazaska has a 5 fish bag limit for sunfish in effect. Black Crappies were sampled in the gill nets at a rate of 3.3/net. Catch rates have diminished from 32.9 /gill net in 1995 to 3.3/ gill net in 2025. Lengths in 2025 ranged from 4.3 to 12.0 inches with an average of 7.2 inches. Fish from both gears were age-1 to age-6 with 5 year-classes present, suggesting consistent recruitment. According to a creel survey completed in 2022, Black and White Crappies were collectively the second most harvested species with an estimated 1,050 fish averaging 11.1 inches harvested during a 10-month period from December 2021 through September 2022. A spring boat electrofishing sample targeting Largemouth Bass was completed in 2025. A total of 41 Largemouth Bass were sampled. Lengths ranged from 3.0 to 17.8 inches with an average of 13.9 inches. The 2022 creel report offered some insight on the Largemouth Bass population in Lake Mazaska. An estimated 1,281 fish were caught during a 10-month period from December 2021 through September 2022. Estimated lengths of released fish ranged from 6.0 to 19.0 inches with an average of 15.0 inches. A total of 28 Northern Pike were sampled with gill nets for a catch rate of 3.5/net. Lengths ranged from 21.8 to 37.0 inches with an average of 27.0 inches. Approximately 82 percent of the fish sampled in gill nets exceeded the minimum size limit of 24 inches. The 2022 creel estimated only 58 Northern Pike averaging 25.5 inches were harvested during the study period. The 2 fish daily creel limit and 24-inch minimum size limit likely limited harvest as the average length of Northern Pike harvested during the 2016 creel survey was just over 21 inches. A total of 34 Walleyes were sampled with gill nets for a catch rate of 4.3/net. Lengths ranged from 15.6 to 25.7 inches with an average of 20.2 inches. Fish ranged from age-3 to age-13 with 7 year-classes present. Approximately 65% of the sample came from the 2022 (age-3) year class. On average, Walleye grew at a fast rate, reaching 15.0 inches by age-3. Results from the 2022 creel survey estimated only 122 Walleyes were harvested during the 10-month study period from December 2021 through September 2022. Anglers kept 68% of all Walleye caught during the 2022 creel study. Lake Mazaska has a unique opportunity for large White Bass that is not common in the Waterville management area. Five White Bass were sampled during the 2025 survey. Lengths ranged from 15.6 to 17.9 inches with an average of 16.8 inches. Fish ranged from age-3 to age-13 with 3 year-classes present. The presence of old fish suggests there are not many anglers targeting these fish. The 2022 creel supported this assumption with only an estimated 363 White Bass caught during the study period of which approximately 80% were released. A total of 10 Yellow Perch were sampled with gill nets for a catch rate of 1.3/net. Yellow Perch have been sampled in low numbers (2.0/gill net) in Lake Mazaska since 2002. Catch rates averaged 19.2/net prior to 2002. Lengths in 2025 ranged from 6.1 to 7.9 inches with an average of 6.8 inches. The 2022 creel survey showed that anglers caught Yellow Perch up to 9.0 inches, but no harvest of Yellow Perch was reported. Yellow Perch are an important prey species in Lake Mazaska and low abundance could impact predator species abundance and growth. Freshwater Drum were the most common fish sampled in gill nets in Lake Mazaska in 2025. A total of 72 fish averaging 16.5 inches were sampled for a catch rate of 9.0/net. Ninety-three percent of Freshwater Drum in the gill net sample exceeded quality length 15.0 inches. One 19.7 inch Freshwater Drum was aged to be 42 years old. By weight, Freshwater Drum accounted for approximately 60% of the trap net catch. Although undesirable to most anglers, Freshwater Drum are easily caught and provide a good fight and respectable table fare for the open-minded angler. Bullheads have historically been rare in Lake Mazaska. In 2025, the most common species was the Yellow Bullhead. A total of 35 Yellow Bullheads were sampled with gill nets for a catch rate of 4.4/net. Catch rates since 1984 have varied from 0.0/net in multiple samples to 9.1/net in 2022 with an average of 2.4/net. Given the stability of the lake, bullhead species will likely remain a small part of the fish community in Lake Mazaska. Four Common Carp were sampled in trap nets. These fish averaged 24.4 inches in length. Only twice since 1984 (1984 and 1986) has the catch exceeded 1.5/net. Although destructive, Common Carp remain rare in Lake Mazaska and do not appear to negatively impact the fishery. Other species sampled in 2025 include black Bullhead, Bowfin, Longnose Gar, Pumpkinseed, and White Crappie. Water quality parameter measurements included secchi depth, water temperature, and dissolved oxygen readings. At the time of this survey, secchi depth was 11.5 feet, indicating high water clarity. Water temperatures and dissolved oxygen readings throughout the water column ranged from 76.5 degrees Fahrenheit and 6.4ppm at the surface to 59.5 degrees Fahrenheit and 0.0 ppm at 40 feet. A thermocline was detected at a depth of approximately 17 feet. Lake Mazaska has an infested waters designation as Eurasian Watermilfoil has become established. It is important for all who use this waterbody to remember Clean In and Clean Out. CLEAN all visible aquatic plants, zebra mussels, and other prohibited invasive species from watercraft, trailers, and water-related equipment before leaving and entering any water access or shoreland. DRAIN water-related equipment (boat, ballast tanks, portable bait containers, and motor) and drain bilge, livewell and baitwell by removing drain plugs before leaving a water access or shoreline property. Keep drain plugs out and water-draining devices open while transporting watercraft. DISPOSE of unwanted bait, including minnows, leeches, and worms, in the trash. It is illegal to release bait into a waterbody or release aquatic animals from one waterbody to another. If you want to keep your bait, you must refill the bait container with bottled or tap water. Anglers can play an important role in maintaining or improving a fish population by practicing selective harvest. Selective harvest allows for the harvest of smaller fish for consumption, while encouraging the release of medium to large fish that may contribute to natural recruitment. This practice helps maintain balance in the fish community and provides anglers the opportunity to catch more and larger fish in the future. Additionally, smaller fish often taste better and have fewer contaminants than larger, older fish from the same water body. Shoreline property owners also play an important role in the overall health of an aquatic ecosystem, including the fish population. Natural shorelines, including vegetation, woody debris, and bottom substrates, provide valuable habitat for fish and wildlife, help maintain water quality, and reduce bank erosion. By leaving natural shorelines unaltered or restoring them to natural conditions, shoreline property owners are doing their part to maintain or improve a healthy ecosystem in the lake and protect the resource for future generations. -Tyler Fellows, fisheries specialist

Minnesota DNR Fisheries IBI program staff delineated the floating leaf and emergent aquatic vegetation of Mazaska lake 09/12/2023, following the protocols listed in the MN DNR Lake Plant Mapping Manual. There were a total of 46.7 acres of floating and emergent plants mapped. This consisted of 1.9 acres of emergent dominated plant communities and 44.8 acres of floating leaf plant communities. Waterlilies were surveyed along much of the shoreline. The following taxa were noted during the survey: arrowhead (Sagittaria spp.), bulrush (round-stem group) (Schoenoplectus spp.), cattail (Typha spp.), large-leaved pondweed (Potamogeton amplifolius), white waterlily (Nymphaea odorata), wild celery (Vallisneria americana), and yellow waterlily (Nuphar variegata). For more information see map and summary table below.

Minnesota DNR Fisheries IBI program staff delineated the floating leaf and emergent aquatic vegetation of Mazaska lake 09/12/2023, following the protocols listed in the MN DNR Lake Plant Mapping Manual. There were a total of 46.7 acres of floating and emergent plants mapped. This consisted of 1.9 acres of emergent dominated plant communities and 44.8 acres of floating leaf plant communities. Waterlilies were surveyed along much of the shoreline. The following taxa were noted during the survey: arrowhead (Sagittaria spp.), bulrush (round-stem group) (Schoenoplectus spp.), cattail (Typha spp.), large-leaved pondweed (Potamogeton amplifolius), white waterlily (Nymphaea odorata), wild celery (Vallisneria americana), and yellow waterlily (Nuphar variegata). For more information see map and summary table below.

Based on Minnesota DNR survey data, anglers target Northern Pike, Largemouth Bass, Walleye, White Crappie, and Hybrid Sunfish in Mazaska. See the full species list above for catch rates, size structure, and quality scores.

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

Mazaska has a maximum depth of 50 feet and a mean depth of 13 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Mazaska is from 2025.

Yes — Mazaska has confirmed Eurasian watermilfoil. Clean, drain, and dry your equipment to avoid spreading invasives to other waters.