Portage Canal Analysis

Biological Analyses of the Portage Canal

By Luke Treutel – Graduate Student – The University of Wisconsin-Madison

Completed with assistance from the City of Portage and the Wisconsin Department of Natural Resources

1 INTRODUCTION

Listed on the National Register of Historic Places, the Portage Canal is a significant historic landmark which has played a major role in shaping the City of Portage into what it is today. Completed in 1851, it allowed transit of ships between the Wisconsin and Fox Rivers. It was open to navigation until 1959, and has since changed ownership from the federal government to the State of Wisconsin. In 1981, Governor Dreyfus made the Wisconsin Department of Natural Resources (WDNR) responsible for managing the canal

Due to runoff and industrial discharges, the habitat and water quality of the canal have been significantly degraded over time. The canal has four distinct segments, as seen in figure 1. Although they share some characteristics, the segments differ from one another in many ways. As a result, each segment needs to be evaluated and addressed

to Adams St. It is characterized by vertical concrete and wooden walls, and brown, turbid water. Its depth ranges from about 1 m to 2.5 m. There is an abundance of macrophytes including Eurasian Milfoil and curlytail pondweed in addition to floating duckweed and cladophora algae. Invasive bighead carp are commonly observed as well. There is little to no shade cover, and almost no structure on the mucky substrate (streambed).

Segment 2

Segment 2 runs from Adams St. to the Canadian Pacific Railway bridge, and is roughly 2/3rds of a mile long. This segment is relatively shallow throughout (<1 m), and is similar to an emergent wetland ecosystem. There is a significant amount of invasive reed canary grass in the channel, which is able to colonize due to the depth and slow flow. There is some sand and rocky substrate, and a more diverse macrophyte community. The riparian zone is well-vegetated, creating shade cover for nearly the entire segment. Although segment 2 is narrower than the others, it has the highest meander.

Segment