Restoration Potential of the Maple River, An Abandoned Anabranch of the Lower Muskegon River

Abstract

This study examines the potential for restoration of the Maple River in western Michigan (Muskegon and Newaygo Counties). The Maple River is an abandoned anabranch channel of the Muskegon River. Historically the Muskegon split to form Maple Island but in the late 19th century flow was diverted down the northern channel of the Muskegon and the southern branch became what is now the Maple River. In the field I mapped the existing and underlying historic channel bottom size and shape. Then using HEC-RAS I developed a one-dimensional hydraulic model of the Maple River channel for both present and past condition. The model outputs were used to explore channel bankfull conveyance capacity and flooding thresholds. In addition I performed Weighted Useable Area (WUA) analysis to estimate potential increases in hydraulic habitat that restored connectivity with the Muskegon River might bring. Fishes in the Maple River were found to be less plentiful in diversity and evenness when compared to the Muskegon River. With the removal of nearly a meter of soft sediment the restored channel model provided more conveyance capacity than the existing channel model and contributed to an increase in hydraulic capacity for some of the life stages of the species of interest in this study. Hydraulic weighted useable area was predicted to increase for the eggs of chinook salmon, adult walleye, and both juvenile and adult steelhead under the restored channel model conditions. There is much more research necessary to weigh all the options for a restoration of the Maple River but there is evidence that hydraulic habitat may be improved for some fishes with the removal of the accumulated sediment throughout the Maple River channel.