Stream Experience - St. Croix River, MN

My stream experience comes to you courtesy of the Saint Croix River in the Upper Midwest. The river is a National Wild and Scenic Riverway, bordering Minnesota and Wisconsin before flowing into the Mississippi River. The river is managed by the National Park Service, Minnesota and Wisconsin DNR, and the USFWS. The river is a 5/6th order stream, and averages 100 to 150 meters wide, with coarse gravel and cobble in swifter areas and shifting sand in slower reaches. A hydroelectric dam operates within the Scenic Riverway, and is required to maintain minimum flows, though enforcement and compliance have been spotty.

The stream supports 40 species of freshwater mussels, including two federally endangered species (L. higginsii and Q. fragosa), and more than 65 fish species, 10 of which are listed under species of special concern in the state of Minnesota. The river is heavily used for boating recreation (canoes and kayaks in the upper river, motorized boats in the lower), and fishing is excellent. Increasing urbanization and pressure to build large homes on river bluffs threaten the riverway and its watershed. Recently the Minnesota Pollution Control Agency listed the river as impaired by phosphorus.

I spent 3 full summers and part of another researching freshwater mussels on the St. Croix. The work involved excavating quadrats to assess long-term population changes in mussels, implementing a new sampling design to effectively estimate populations of rare and patchy species, and attempting to quantify microhabitat factors for endangered mussel species (sediment coarseness, shear stress, river velocity, organic sediment matter, etc). We also did some research with mussel host fish, and video documentation of nighttime mussel displays. I spent approximately 20 hours a week underwater, using SCUBA to accomplish our goals.

I learned a great deal about the river during my research, from seeing many fish and mussel species firsthand while diving, to learning about cooperative management strategies and difficulties.