Olson

Olson Lake is a small, 34-acre lake located in Cook County, Minnesota. It has been managed exclusively for stream trout since it was reclaimed in 1961. Currently, Olson Lake is stocked annually with 1,500 Arlee-strain rainbow trout fingerlings during the fall. The 2018 lake management plan established a long-range goal to maintain a minimum rainbow trout trap net catch of 0.75 fish/net, with some fish over 14 inches present. In 2025, a standard survey was conducted on Olson Lake using standard gillnets and trap nets to assess the current fish community. Catch rates of rainbow trout were low in both gill nets (1.5 fish/net) and trap nets (0.25 fish/net) in the 2025 survey and lower than previous catch rates observed in 2008 when brook trout were stocked. Only five rainbow trout were caught and ranged from 13.0 to 19.3 inches, with only one fish exceeding 14.0 inches. Age analysis found two- and three-year-old fish, from the 2023 and 2022 stocked year classes. Age two rainbow trout averaged 12.8 inches and the only three-year-old fish caught was remarkably 19.3 inches. Trap nets did not find any numbers or sizes of minnows and may indicate a lack of forage within the lake. Anglers looking to target rainbow trout in Olson Lake will have their best luck during the fall and winter months when fish are more readily available from stocking. A water temperature and dissolved oxygen profile taken in late July found unsuitable conditions for rainbow trout. Surface waters to depths of 6.0 ft were too warm (> 70°F) while depths from 6.0 to 14.0 ft were depleted of oxygen (< 3.0 mg/L). A temperature and oxygen profile taken in September found somewhat improved temperature conditions, but still limiting in oxygen conditions. Habitat for stream trout in Olson Lake has been frequently marginal, with the potential for winter kills in years with harsh winters. Aging data suggests poor survivorship of stocked rainbow trout and Olson Lake is being considered as a candidate lake for transitioning towards panfish management. Minnesota Lakes within Cook County continue to be susceptible to aquatic invasive species introductions. Invasive species have the potential to significantly alter fish communities and overall lake health. Anglers should clean watercraft and fishing gear, drain all water, and dispose of unused bait in the trash to prevent accidental introductions.

Olson Lake was rehabilitated for stream trout management in 1961, and has been managed as a designated stream trout lake since that time. Management goals for the lake, from the current (2018) lake management plan, are to maintain a minimum Rainbow Trout trap net catch of 0.75 fish/set, with some fish over 14 inches present. This was not a scheduled survey under the 2018 plan. Because the winter of 2017-18 had been harsh and long, we conducted winter dissolved oxygen testing on Olson Lake, where at least one past partial winterkill was suspected to have occurred. When the results of that testing suggested a winterkill was a possibility in 2018, this follow-up targeted survey was done to determine whether there had been any over-winter survival of stocked trout, and to collect some additional information on late-summer temperature-oxygen conditions. Winter testing on 12 April at three sites found dissolved oxygen levels of less than 2 ppm just under the ice at all locations, with oxygen levels under 1 ppm at greater depths. Although other signs of winterkill were not observed (no dead fish, no hydrogen sulfide smell), it seemed that at least a partial winterkill could have been possible. Follow-up testing on 22 August, using a single over-night graduated-mesh monofilament gill net set, captured two Rainbow Trout that had been stocked in the fall of 2017. Netting results gave no indication of abundance; they merely confirmed some over-winter survival. They did not rule out a partial winterkill. The temperature-oxygen profile measured on 22 August found conditions suitable for Rainbow Trout (water temperature 5 ppm) from the surface to a depth of 10 ft. At the testing site waters were stratified, but dissolved oxygen in colder waters below the surface layer was too low to support trout (or fish of any kind). Surface water temperatures may already have begun to cool going into the fall, but it seemed likely that even earlier in the summer, some waters suitable for Rainbow Trout would have been present.

Olson Lake is a designated stream trout lake located near Two Island Lake, approximately 14 miles from the City of Grand Marais. The lake can be accessed from a brushy spur trail off a rough logging road that begins at the USFS Two Island Lake Campground. In the winter, the logging road is part of the Gunflint snowmobile trail system. High clearance vehicles or foot travel are recommended for reaching Olson Lake during the open-water season. Olson Lake has been stocked with Brook Trout and Rainbow Trout at various times since 1962. In 2007, management was shifted from Brook Trout to Rainbow Trout with the hope that Rainbow Trout would perform better under the less-than-ideal water quality conditions observed in this lake. The 2017 targeted survey of Olson Lake was the first completed since annual Rainbow Trout stocking was initiated in 2009. Currently, the lake is stocked annually with 1,500 fingerling Rainbow Trout in the fall. The long-term goal for Rainbow Trout management in Olson Lake is to maintain a population with a minimum catch in fall trap net sets of 0.75 fish/net, with some fish over 14 inches. Inclement weather encountered during the 2017 survey of Olson Lake resulted in one gill net and five 0.75-inch-mesh trap nets being set for 48 hours before being pulled. Therefore, we could not directly evaluate the trap net catch goal set for the population from these results. The size goal set for Olson Lake was apparently met in 2017. A total of ten Rainbow Trout were taken in trap net sets in 2017, with those fish ranging in length from 6.1 to 15.2 inches. Two Rainbow Trout, 12.4 and 13.7 inches long, were taken in the gill net set. Two fish from the fall 2017 fingerling stocking (stocked about a month prior to the survey) were included in the 2017 catch; the rest were apparently two-year-old (nearly three) survivors of the 2015 fingerling stocking. Those fish ranged in length from 12.0 to 15.2 inches at capture. Rainbow Trout growth may have been somewhat slower than average; fish reached a mean length of 10.1 inches by the end of their second year, compared to an average of 11.6 inches in other Rainbow Trout lakes in the Grand Marais area. As of 2017, no aquatic invasive species (AIS) had been documented in Olson Lake. Anglers and boaters are reminded to review the recommended actions for cleaning watercraft and gear before and after accessing a waterbody, and to adhere to all Minnesota AIS laws to protect Minnesota lakes and rivers from additional infestations.

Based on Minnesota DNR survey data, anglers target Brook Trout, Rainbow Trout, and Walleye in Olson. See the full species list above for catch rates, size structure, and quality scores.

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

Olson has a maximum depth of 18 feet and a mean depth of 5.9 feet, per Minnesota DNR data.

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

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