Big McDonald Lake is a 935-acre mesotrophic (moderately fertile) lake located in north-central Otter Tail County approximately nine miles west of Perham, MN. Big McDonald Lake is located within the Otter Tail River Watershed. The immediate watershed is composed primarily of agricultural land interspersed with hardwood woodlots. Big McDonald Lake is connected to Schwartz Lake during high water years by a channel located along the southeast shoreline. An unnavigable outlet is located along the south shoreline of the lake and connects Big McDonald Lake with Round Lake. The maximum depth of Big McDonald Lake is 46 feet; however, 39 percent of the lake is less than 15 feet in depth. The secchi disk reading during the 2008 lake survey was 11.6 feet, which indicates good water clarity. Previous secchi disk readings have ranged from 9.0 to 13.9 feet. The north and west shorelines of Big McDonald Lake have been extensively developed. Homes, cottages and resorts compose the majority of the development. A DNR owned concrete public water access is located off of County Road 35 along the northwest shoreline of the lake. The shoal water substrates consist primarily of sand and gravel. Large stands of hardstem bulrush are located along the west, south, and east shorelines. Areas of common cattail and wild rice are also scattered along the southwest shoreline. Emergent aquatic plants such as bulrush, cattail, and wild rice provide valuable fish and wildlife habitat, and are critical for maintaining good water quality. Emergent plants provide spawning areas for fish such as northern pike, largemouth bass, and panfish. They also serve as important nursery areas for all species of fish. Because of their ecological value, emergent plants may not be removed without a DNR permit. To maintain the excellent water quality and angling that this lake has to offer, it is imperative to preserve the quality of the aquatic habitat. Big McDonald Lake can be ecologically classified as a bass-panfish-walleye type of lake and this is reflected in the assemblage of the fish community. Walleye, northern pike, largemouth bass, black crappie, and bluegill are the dominant game fish species present. Walleye is a primary management specie in this lake. The test-net catch rate of walleye was within the normal range for this class of lake. Walleye ranged in length from 9.7 to 24.4 inches with an average length and weight of 17.3 inches and 1.9 pounds. Walleye exhibit excellent growth rates with an average length of 15.6 inches at four years of age. Northern pike population characteristics have remained stable over the recent series of lake surveys. Northern pike abundance has remained at a moderate density since the 1986 survey and age data indicate that natural reproduction has continued to be consistently good. Northern pike ranged in length from 13.6 to 33.2 inches with an average length and weight of 17.5 inches and 1.1 pounds. Pike growth is slow with an average length of 16.9 inches at four years of age. The slow growth rates for pike may be attributed to the low abundance of yellow perch, a preferred forage fish. The bluegill test-net catch rate was within the normal range for this class of lake. Blulegill test-net catch rates have historically fluctuated. The bluegill population retained a good size distribution. Sixty percent of the bluegill sample was at least 7.0 inches in length. Bluegill attain an average length of 7.0 inches at seven years of age. Data from a spring electrofishing assessment indicate that a high-density largemouth bass population exists. Age data indicate that bass reproduction is consistently good. Although bass are abundant the average size is small and growth is slow. Bass ranged in length from 5.9 to 18.3 inches with an average length and weight of 10.1 inches and 0.6 pounds. Bass attain an average length of 12.5 inches at five years of age. Data from a spring trapnetting assessment indicated that black crappies are also abundant. Size structure is also good with 58 percent of the crappies measuring 10.0 inches or greater in length. The 2005 year class is strong and should provide consistently good crappie angling for several years. Crappies attain an average length of 9.1 inches at four years of age. Anglers can maintain the quality of fishing by practicing selective harvest. Selective harvest encourages the release of medium to large-size fish while allowing the harvest of the more abundant smaller fish for table fare. Releasing the medium to large fish will ensure that the lake will have enough spawning age fish on an annual basis and will provide anglers with more opportunities to catch large fish in the future.
Big McDonald Lake is over 1,000 acres in size, spring fed and has a water clarity of up to 25 feet - among the cleanest in Minnesota. Big McDonald Lake is one of the more popular lakes in the area for Walleye and Northern.