Hartley

Hartley Lake is a 288-acre, moderately deep lake with about 4.7 miles of shoreline. The water is brown-green and bog-stained with a clarity of about 8 feet. In midsummer, oxygen drops sharply below about 18 feet, restricting fish to shallower waters. There's a public concrete boat ramp on the east end near the outlet dam. Fish populations are maintained by natural reproduction, and the lake is not stocked. Statewide fishing seasons and limits apply. The most recent lake management plan was revised in 2020 and listed Northern Pike and Largemouth Bass as primary species with Bluegill and Black Crappie as secondary species. The current assessment was a Standard Lake Survey conducted from June 30 through July 3, 2025. Sampling included standard gill nets and trap nets to assess the status of the fish community. Hartley Lake continues to produce a quality pike fishery. Northern Pike were common in the 2025 gill nets, with a good size distribution from 16 to nearly 39 inches and an average length near 25 inches. The lake produced many fish in the 22-26-inch slot, which must be released when caught by anglers under current zone regulations. Pike showed consistent recruitment across multiple year-classes, making them the lake's main sportfish. Anglers can help maintain size quality by only harvesting pike under 22 inches. Panfish were relatively abundant compared to similar lakes, but generally small. Bluegills were common, but growth was slow, and few reached quality-size (6 inches), making this lake better for catching and harvesting numbers rather than quality sunfish. Black crappies were also abundant with catch rates above average for similar lakes, but most fish were under 10 inches. Tullibee and Yellow Perch are important prey species and were present at moderate levels. Small perch sizes likely limit the angling potential, however. Walleye were present but angling opportunities in Hartley are limited. Walleye remained scarce in 2025, likely due to high pike competition and limited perch. Overall conditions for Walleye are poor in Hartley Lake. Bass electrofishing was not completed but Largemouth Bass were sampled in gill nets with fish up to 16.8 inches present. Overall, Hartley Lake offers strong northern pike fishing, plenty of panfish action for anglers targeting numbers, and occasional Walleye. It's a classic northern lake with healthy predator-prey dynamics, rewarding anglers who enjoy active fishing rather than trophy-size catches.

Hartley Lake is an ecological class 23 lake located 15 miles northwest of Nashwauk, MN, in the Mississippi River Watershed. The lake is 281 acres and has a maximum depth of 49 feet. The nearshore fish species sampling began on 17 June 2025. Area Fisheries staff conducted a standard survey setting 6 gill nets and 9 trap nets on 30 June 2025. The nearshore catches will be used with the data from the standard survey to calculate a fish-based Index of Biotic Integrity (IBI) score which is indicative of lake health. The surveys will assist the watershed assessment process in coordination with MN Pollution Control Agency. Nearshore sampling included 10 sites (100 feet long) evenly spaced around the lake, sampling a variety of habitat types. Each site is sampled by backpack electrofishing and seining with a 15-ft or 50-ft 1/8th inch mesh seine, depending on habitat condition. Shoreline seining was conducted at 8 sites using the 15-ft seine and 11 sites with the 50-ft seine. Backpack electrofishing was completed at all 10 sites. Nearshore sampling captured 20 different species: 14 species by seining and 15 species by backpack electrofishing. Nearshore sampling captured all but two species observed in the gill nets and trap nets (Tullibee and Walleye). The species can be found in the gear-specific catch tables in this report.

Hartley Lake is a 281-acre lake located 15 miles northwest of Nashwauk, MN. A county owned cement access is located off Hartley Lake Road (off 53) on the west-central shore with parking for four rigs. Hartley Lake has a maximum depth of 49 feet and 35% of the lake is 15 feet or less. The lake has moderately soft water and fertility. The water color is light green, resulting in visibility to 13 feet in mid-summer. The depth of water at which oxygen levels limit fish presence was between 15 and 18 ft. in the summer of 2019. Hartley Lake has two inlets and one outlet. One small inlet that drains a wetland on the southwest shore and one larger inlet on the north-central shore that is the West Fork of the Prairie River. The West Fork of the Prairie River is the outlet and is located on the east-central shore. The water control structure (i.e. dam), was modified in 2011 by adding a series of seven rock weirs and by cutting notches in the existing metal sheet piling, allowing fish movement upstream and downstream. Other similar area lakes include Bello, Loon, Ruby, Three Island, and Thistledew. The 2019 survey was the ninth survey of the fish community since 1954. Surveys occur to monitor the fish community for changes in species composition, abundance, size structure and growth. Gamefish species that are best suited for the lake are Northern Pike, Largemouth Bass, Bluegill, and Black Crappie. No special regulations are present. The 2012 management plan indicated Northern Pike and Largemouth Bass were primary management species, while Black Crappie and Walleye were secondary management species. The Northern Pike population had a high catch rate, above average size distribution, and average growth. The gill net catch in 2019 was the highest observed. Higher catches are undesirable, as they typically indicate higher density populations with poor size structure and slow growth. Lengths of pike ranged from 14 to 34 inches, with an average of 21 inches. Size structure was above average, as 42% of pike exceeded 21 inches and 9% exceeded 28 inches. Pike were aged from 2 to 11 years old. Growth was average, resulting in pike taking five years to exceed 21 inches. Due to the lake's small size, anglers are encouraged to release pike exceeding 26 inches and harvest up to 10 less than 22 inches to help improve size structure. Spearers are encouraged to harvest smaller pike also. The Largemouth Bass population had an above average catch rate, with average size distribution and growth in the 2003 electrofishing survey. Only seven Largemouth Bass were sampled in 2019, and ranged from 7 to 15 inches. Electrofishing did not occur in 2019 due to staff reductions and weather; however, the 2003 electrofishing catch rate was nearly twice the long-term average of Grand Rapids Area electrofishing surveys. Lengths in 2003 ranged from 6 to 19 inches, with an average of 12 inches. Due to the lake's small size, anglers are encouraged to release bass exceeding 15 inches to help maintain or improve size structure. The Black Crappie population had above average catch rates and size distribution, and below average growth. The trap net catch in 2019 was higher than the lake average, while the gill net catch was similar. Lengths ranged from 4 to 12 inches, with average lengths of 8.4 and 9.2 inches in the gill nets and trap nets. Size structure was above average, as 77% of crappie exceeded 8 inches and 42% exceeded 10 inches. Typical of most crappie populations, there were two primary year classes in each of the past two surveys. Age 8 fish were most common in 2019. Growth was below average, resulting in crappie taking seven years to exceed 8 inches. The Walleye population had a low catch rate, above average size distribution, and average growth. The gill net catch in 2019 was the highest observed. Ten Walleye were sampled in 2019, which is more than the total number of Walleye sampled in all previous surveys of six. Despite stocking Walleye 21 times from the 1940s through the 2010s, gill net catch rates have never exceeded 0.3/net. Stocking was discontinued after 2011. Statewide Walleye stocking guidelines recommend discontinuing stocking if stocking fails to produce a viable fishery supporting a catch rate of 2.0/gill net. The dam removal in 2011 had a greater positive influence on the Walleye population than 65 years of stocking, likely due to better access to suitable spawning locations and river connectivity. The Bluegill population had an average catch rate, size distribution and growth. The trap net catch in 2019 was similar to the lake average. Lengths ranged from 3 to 9 inches, with an average of 6.6 inches. Size structure was average, as 71% of Bluegill sampled exceeded 6 inches and 13% exceeded 8 inches. Growth was only evaluated in 2004, and was similar to the statewide average at that time. Recruitment appeared to be consistent. Bluegill took six years to exceed 6 inches. Due to the lake's small size, anglers are encouraged to release Bluegill exceeding 8 inches to help maintain or improve size structure. The Smallmouth Bass population had a low catch rate, average size distribution, and below average growth in the 2003 electrofishing survey. Only two Smallmouth Bass were sampled in 2019, while only eight have ever been sampled with nets. Five were sampled electrofishing in 2003. The 2003 catch rate was one quarter the average catch rate for Grand Rapids area lakes. A 13 and 17-inch fish were sampled in 2019, while lengths ranged from 14 to 16 inches in the 2003 electrofishing survey. Electrofishing was not conducted in 2019. Only three Yellow Perch and no Tullibee (Cisco) were sampled in 2019 indicating a low number of prey are available to support gamefish populations. The number of perch sampled the past two surveys were by far the lowest number sampled in all surveys. Although higher Walleye numbers resulting from dam modification are viewed by anglers as a positive, prey consumption rates are also likely higher. Tullibee were sampled in seven of nine surveys. Other species sampled included Bowfin (Dogfish), Brown Bullhead, Golden Shiner, Pumpkinseed Sunfish, Rock Bass, Shorthead Redhorse, White Sucker and Yellow Bullhead. In order to maintain or improve fish and wildlife populations, water quality and habitat must be protected. People often associate water quality problems with large-scale agricultural, forestry, urban development or industrial practices in the watershed. In reality, the impact of land use decisions on one lake lot may be relatively small, yet the cumulative impact of those decisions on many lake lots can result in a significant decline in water quality and habitat. For example, removing shoreline and aquatic vegetation, fertilizing lawns, mowing to the water's edge, installing beach sand blankets, failing septic systems and uncontrolled run-off, all contribute excess nutrients and sediment which degrade water quality and habitat. Understanding these cumulative impacts and taking steps to avoid or minimize them will help to insure our quality fisheries can be enjoyed by future generations. Anglers and boaters are reminded to help slow the spread of invasive species by removing all aquatic plants from boats, trailers, and equipment. All drain plugs must be removed and live and bait wells must be drained before leaving the access. Anglers and boaters are encouraged to power wash and thoroughly dry all equipment prior to use in another water body.

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

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

Hartley has a maximum depth of 49 feet and a mean depth of 21 feet, per Minnesota DNR data.

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

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