Water- and Bed-Sediment Quality of Seguchie Creek and Selected Wetlands Tributary to Mille Lacs Lake in Crow Wing County, Minnesota, October 2003 to October 2006

Abstract

Mille Lacs Lake and its tributaries, located in east-central Minnesota, are important resources to the public. In addition, many wetlands and lakes that feed Mille Lacs Lake are of high resource quality and vulnerable to degradation. Construction of a new four-lane expansion of U.S. Highway 169 has been planned along the western part of the drainage area of Mille Lacs Lake in Crow Wing County. Concerns exist that the proposed highway could affect the resource quality of surface waters tributary to Mille Lacs Lake. Baseline waterand bedsediment quality characteristics of surface waters tributary to Mille Lacs Lake were needed prior to the proposed highway construction. The U.S. Geological Survey, in cooperation with the Minnesota Department of Transportation, characterized the waterand bed-sediment quality at selected locations that the proposed route intersects from October 2003 to October 2006. Locations included Seguchie Creek upstream and downstream from the proposed route and three wetlands draining to Mille Lacs Lake. gaging station of 0.22 cubic meter per second was 5.6 percent gaging station of 0.21 cubic meter per second. Because of the large amount of storage immediately upstream from both intense precipitation. The ranges of most constituent concentrations in water were nearly identical between the two sampling sites on Seguchie Creek. No concentrations exceeded applicable waterquality standards set by the State of Minnesota. Dissolvedoxygen concentrations at the downstream gaging station were less than the daily minimum standard of 4.0 milligrams per liter for 6 of 26 measurements. Constituent loads in Seguchie Creek were greater at the downstream site than the upstream site for all measured, including dissolved chloride (1.7 percent), ammonia plus organic nitrogen (13 percent), total phosphorus (62 percent), and suspended sediment (11 percent) during the study. All constituents had seasonal peaks in spring and fall. The large loads during the fall resulted from unusually large precipitation and peaks at both sites to occur during October (2004 and 2005). metals and trace elements (arsenic, cadmium, chromium, lead, and zinc) exceeded the Interim Sediment Quality Guidelines (ISQG) set by the Canadian Council of Ministers of the Environment. Bed-sediment samples from the upstream site had more exceedances of ISQGs for metals and trace elements than did samples from the downstream site (seven and two exceedances, respectively). Bed-sediment samples from the downstream site had more exceedances of ISQGs (20 exceedances) for semivolatile organic compounds than did samples from the upstream site (8 exceedances), indicating different sources for organic compounds than for metals and trace elements. Concentrations of 11 semivolatile organic compounds exceeded ISQGs: ancenaphthene, acenaphthylene, anthracene, benzo[a]anthracene, benzo[a In bed-sediment samples collected from three wetlands, concentrations of all six metals exceeded ISQGs: arsenic, cadmium, chromium, copper, lead, and zinc. Concentrations of ranthene, phenanthrene, and pyrene. Results indicate that areas appearing relatively undisturbed and of high resource value can have degraded quality from previous unknown land use. Introduction Mille Lacs Lake and its tributaries, located in east-central Lacs Lake is the second largest inland lake in Minnesota by surface area (534 square kilometers (km2); Minnesota Department of Natural Resources, 2006). It is a popular recreation quality and an important resource for the Ojibwe Bands. The Ojibwe people, composed of the Mille Lacs, Fond du Lac, and Lacs Lake (Great Lakes Indian Fish and Wildlife Commission, 2004). Although large in surface area, Mille Lacs Lake is sensitive to eutrophication from increased nutrient loads (Heiskary and others, 1994) because of its relatively shallow Waterand Bed-Sediment Quality of Seguchie Creek and Selected Wetlands Tributary to Mille Lacs Lake in Crow Wing County, Minnesota, October 2003 to October 2006 By James D. Fallon and Christine S. Yaeger 2 Waterand Bed-Sediment Quality of Seguchie Creek and Selected Wetlands Tributary to Mille Lacs Lake