Big Portage Lake is a 918 acre lake located near Backus, Minnesota. Big Portage Lake has 7.22 miles of shoreline and a maximum depth of 23 feet. The lake has extensive vegetation with 98 percent of the lake area less than 15 feet deep. The Minnesota Department of Natural Resources has classified Minnesota's lakes into 43 different lake classes based on physical, chemical, and other characteristics. Big Portage Lake is in Lake Class 39. Lakes in this lake class are generally shallow, regularly shaped lakes. There is a public access on the east shore off of State Highway 87.
Big Portage Lake offers opportunities for anglers seeking a variety of fish species. Northern pike are abundant with quality size fish present. The average length of pike sampled in 2012 was 19 inches with fish up to 35 inches captured. Bluegill abundance is average compared to similar lakes in the area. A few fish over 8 inches in length were sampled in 2012 but the majority were between 5 and 7.5 inches. Walleye numbers are below average with larger fish present. The average length of walleye sampled was 18 inches and fish up to 26 inches were sampled. Historically black crappie abundance has been low, but the 2012 sample saw better numbers than previous years. Fish up to 13 inches long were caught. Because the lake has extensive areas of shallow water with an abundance of vegetation, largemouth bass have been difficult to sample. The same probably could be said for bluegill and black crappie. There was only one largemouth bass caught in the 2012 sampling, it was 16 inches long. Historically, largemouth bass have been sampled up to 19 inches in length. Yellow perch numbers are similar to other Lake Class 39 lakes with fish up to 10 inches in length present. Other species sampled were bowfin (dogfish), black bullhead, brown bullhead, yellow bullhead, pumpkinseed sunfish, rock bass, and white sucker.
People can have significant impacts on lakes and the fish populations they support. Harvest, lakeshore development, removal of shoreline vegetation, and introductions of invasive species can all adversely affect fish populations. Currently no aquatic invasive species (AIS) have been identified in Big Portage Lake. AIS are moved from infested to non-infested waters by anglers, boaters, and lake shore owners and can adversely impact lakes and fish populations. To avoid spreading AIS, lake users are required to remove all aquatic plants or animals from their watercraft and drain all water from their boat before leaving the access. If you suspect an infestation of an invasive species in this lake, save a specimen and report it to a local natural resource office. Additional information on all of these topics can be found on the DNR website (www.dnr.state.mn.us) or by contacting the Walker Area Fisheries office.