Mud

Temperature and dissolved oxygen measurements were collected from the deepest basin in Mud Lake on August 5th, 2025. This was done to evaluate the quantity and quality of cold, oxygenated water (i.e., oxythermal habitat) available to Cisco, also known as Tullibee, the most sensitive coldwater species present in this lake. Cisco require a layer of oxythermal habitat that contains water temperatures below 21.2 degrees C (70.2 degrees F) and dissolved oxygen concentrations above 3.0 mg/L. Based on data collected from the deepest basin (maximum sampled depth was 26.2 feet), the water temperature decreased to 21.2 degrees C (70.2 degrees F) at 12.4 feet and the dissolved oxygen concentration decreased to 3.0 mg/L at 12.7 feet at the time of sampling. This layer in the water column was 0.3 feet, indicating oxythermal habitat for Cisco was present but marginal. Further, the temperature at which dissolved oxygen decreased to 3.0 mg/L (i.e., TDO3, a single variable to characterize oxythermal habitat) was 20.6 degrees C (69.1 degrees F). TDO3 values cooler than 21.2 degrees C (70.2 degrees F) indicate that oxythermal conditions were marginal for Cisco at the time of the survey as the layer was confined to less than 3 feet of suitable habitat at the time of the survey. Data collected by the Minnesota Department of Natural Resources during the period of maximum oxythermal stress (July 26th to Aug 24th) in 2019 and 2023 also indicated suitable oxythermal habitat in all years surveyed, with the least favorable conditions recorded in 2025 when the suitable oxythermal habitat layer was 0.3 feet thick. When adequate oxythermal habitat is not available, Cisco are squeezed into unfavorable, warmer water conditions and experience higher levels of stress. In eight fisheries surveys during 1976-2019, Cisco catches were at least moderate in each survey.

Mud Lake is located approximately 11 miles W of Ely within the Superior National Forest. This scenic lake lies along a valley lined with steep hills and a mixed forest of large pines with a variety of deciduous trees also present. There is a concrete planked boat ramp located off the east side of the Mud Creek Road for public access. A navigable channel occurs going upstream approximately 1.2 miles along the creek to Mud Lake. There are two user developed campsites located on the lake for day or overnight use. Twelve species of fish were sampled during the 2019 survey of Mud Lake. Bluegill was the most common species sampled in the gill nets and the trap nets. Largemouth bass were sampled in good numbers during night electrofishing efforts. Large cisco or tullibee and northern pike were also sampled in the gill nets. Black crappie were sampled in low numbers from the trap nets. The remaining seven species were sampled in low relative abundances. Largemouth bass numbers sampled by electrofishing in 2019 were higher than in 1994 when the only other electrofishing sampling was done: 39 versus 25 bass/hour. The average largemouth sampled was 9.1 inches which is smaller than the 10.1 average size in 1994. The biggest largemouth sampled in 2019 was from the gill net catch and measured 19.9 inches long and was at least 17 years old. Bluegill numbers in 2019 were below the historical average for Mud Lake of 37.6/trap but well above average when compared to other similar lakes in the area. The average bluegill sampled was 5.7 inches which is nearly identical to the historical average length of 5.8 inches. Only one bluegill over 8 inches was sampled in 2019. Northern pike numbers in 2019 were slightly lower than the historical average of 4.0/gill net for Mud Lake but just above average compared to other similar area lakes. Pike average length was 23.9 inches which is larger than the historical average length of 20.9 inches. The largest pike sampled in 2019 measured 38.2 inches. Black crappie numbers in 2019 were close to the historical average for this lake and also when compared to other area lakes that are similar. The average crappie sampled was 9.2 inches which is larger than the historical average of 8.5 inches. The largest crappie sampled in 2019 was 11.4 inches.

Mud Lake is located approximately 11 miles west of Ely. It has a surface area of 165 acres and a maximum depth of 28 ft. Access is by boat up the creek from a concrete ramp off the Mud Creek Road. Bluegill numbers in 2012 (66.7/trap net) were higher than the long term average for all assessments on this lake. The average bluegill sampled was 5.5 inches long and about seven years old. The growth rate was slower compared to other lakes in this class. The largest bluegill sampled was 8.0 inches. Northern pike numbers in 2012 (6.7/gill net) were higher than the long term average for all assessments on this lake. The average pike sampled was 25.2 inches long and about 6 years old. The growth rate was similar compared to other lakes in this class. The largest pike sampled was 39 inches. Black crappie (1.8/trap net), largemouth bass, pumpkinseed, hybrid sunfish, rock bass, yellow perch, cisco, white sucker and golden shiner were also sampled. Crappie sizes averaged 7.6 inches and largemouth bass sizes averaged 13.6". The cisco present are of the larger variety often referred to as tullibee.

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

We don't have a confirmed public access point on record for Mud. Check the DNR LakeFinder page for current access details before you go.

Mud has a maximum depth of 27 feet, per Minnesota DNR data.

The most recent Minnesota DNR survey data for the main sport fish in Mud is from 2019.

No invasive species are on record for Mud in Minnesota DNR data. Always clean, drain, and dry your equipment to help keep it that way.