Sentinel Lake Assessment Report Elk Lake (15-0010) Clearwater County, Minnesota

The Minnesota Pollution Control Agency (MPCA) is working in partnership with the Minnesota Department of Natural Resources (MDNR) on the Sustaining Lakes in a Changing Environment (SLICE) Sentinel Lakes Program. The focus of this interdisciplinary effort is to improve understanding of how major drivers of change such as development, agriculture, climate change, and invasive species can affect lake habitats and fish populations, and to develop a long-term strategy to collect the necessary information to detect undesirable changes in Minnesota lakes (Valley, 2009). To increase our ability to predict the consequences of land cover and climate change on lake habitats, SLICE utilizes intensive lake monitoring strategies on a wide range of representative Minnesota lakes. This includes analyzing relevant land cover and land use, identifying climate stressors, and monitoring the effects on the lake's habitat and biological communities. The Sentinel Lakes Program has selected 24 lakes for long-term intensive lake monitoring (Figure 1). The "Deep" lakes typically stratify during the summer months only. "Shallow" lakes are defined as mixing continuously throughout the summer. "Cold Water" lakes are defined as lakes that harbor either cisco, lake whitefish, or lake trout and are the focus of research funded by the Environmental Trust Fund (ETF). "Super Sentinel" lakes also harbor cold-water fish populations and research on these lakes is also funded by the ETF. Elk Lake was selected to represent a deep, mesotrophic lake in the Northern Lakes and Forests (NLF) ecoregion. With the exception of a group campsite and a paved nature trail, there is no development on Elk Lake. Additionally, Elk Lake was selected as a "Super Sentinel" lake where intensive habitat monitoring and mechanistic forecast models are being built by the U.S. Geological Survey (USGS) to predict future consequences of climate change on water quality and fish habitat. Elk Lake is a 109 hectare (271 acre lake) and is located within Itasca State Park in Clearwater County. It represents the headwaters of the Mississippi River (Headwaters-Lake Winnibigoshish) major watershed. Elk Lake has a maximum depth of 28.4 meters (93 feet) and a mean depth of 6.6 meters (21.8 feet). The lake is 24 percent littoral with one public access on the northern shore. The total contributing watershed for Elk Lake is 802 hectares (1,984 acres).