Boulder Lake (St. Louis County)

St. Louis County, Minnesota - DNR stocking history, depth and survey data

Minnesota · Minnesota Department of Natural Resources (DNR) · DOW 69037300

Boulder Lake (St. Louis County) has no DNR stocking rows in LakeFinder; this page carries its DNR depth, access and survey data.

• Boulder Lake (St. Louis County) shows no stocking records in Minnesota DNR LakeFinder as of September 2, 2026.
• Maximum depth 18 ft, mean depth 8 ft; surface area 3,260 acres, 3,207 littoral acres, 35.1 miles of shoreline, per the DNR lake survey.
• Average water clarity (Secchi depth) 5.5 ft.
• Fish species DNR lists here: black bullhead, black crappie, burbot, northern pike, pumpkinseed, rock bass, walleye, white sucker, yellow perch.
• 2 public accesses on the DNR list.
• Most recent DNR fish survey: October 8, 2025 (targeted survey).
• St. Louis County, nearest town Duluth; DNR lake number (DOW) 69037300.

Depth map

Bathymetric contours from the Minnesota DNR lake survey mapped 10/27/1965 (orig map); depths in feet. Simplified for the web; not for navigation.

Public accesses

DNR fish survey, 2025

Catch per net (CPUE) is the DNR survey's count per gill net or trap net set; higher means more of that species were sampled, not a fishing forecast. Top species per gear shown; where we have no verified common name for a DNR code, the code itself is shown.

Boulder is a 3,260-acre reservoir located 12 miles north of Duluth, MN, and can be publicly accessed at the terminus of Boulder Dam Road. Maximum depth is 18 feet and lies in the Cloquet River watershed and is located just upstream of Island Lake Reservoir, near headwater reaches of the Otter River watershed. Boulder is operated as a water storage reservoir by Minnesota Power and is subject to water-level manipulation. The reservoir was constructed in 1919 and overfilled several smaller natural lakes, including Boulder, Little Boulder, and Otter lakes. The 2024 Lake Management Plan (LMP) identifies Walleye as the primary management species. Walleye have not been stocked in Boulder since 1991 due to adequate natural reproduction. The LMP goals for Walleye are to maintain high gill net catch rates (greater than 9.5 fish per lift) with a balanced size structure, and the availability of some large Walleye exceeding 20 inches. Anglers can help achieve this goal through selective harvest and proper catch-and-release techniques. To help estimate spawning success and evaluate future year-class strength, a fall young-of-the-year (YOY) Walleye electrofishing assessment was conducted on Boulder in October 2025. This annual survey provides information on the abundance and average length of Walleye from the juvenile year classes. A total of 445 YOY Walleye averaging 5.5 inches were captured, resulting in a historical high catch rate of 358.7 fish per hour of electrofishing. Previous YOY catch rates have ranged from 13.6 to 325.3 per hour, with a long-term average of 136.8. The abundance of YOY Walleye captured suggests that the 2025 year-class may be very strong. A total of 12 age-1 Walleye averaging 8.7 inches were captured, yielding a catch rate of 9.7 per hour of electrofishing. Historical catch rates for age-1 Walleye have ranged from 5.2 to 72.5 per hour, with a long-term average of 23.6 per hour. The below-average catch rate of age-1 Walleye suggests the 2024 year class may be weaker than average. With three consecutive strong years of YOY catch rates, Walleye angling on Boulder is expected to remain strong in 2026 and beyond, offering anglers opportunities to catch good numbers of quality fish.

Minnesota DNR survey narrative, October 8, 2025.

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