A Final Word

Wayne Groesbeck, Founder, Vice Chair
Muskegon River Watershed Assembly

The removal of small dams on the tributary streams of the Muskegon River will always be a primary focus of the Muskegon River Watershed Assembly.

People have often asked me “What’s so bad about dams?” Years ago, a visiting lecturer at Ferris State University explained the impact of dams in terms of the hands of a clock moving from midnight to noon, an analogy which I have since found useful.

Think of a river at its origin. It may be the outlet of a lake, surface water from runoff, or groundwater from a spring. In either case, it will be cool, narrow, shallow, and briskly flowing. It may be heavily shaded by vegetation. It will run over obstacles, mixing with air and gaining dissolved oxygen. It will support
living things that need those conditions. Call the water source midnight, and the stream it creates 4 AM.

In its midsection, the river will carry more water because tributaries having their own water sources will contribute to its volume. More water will widen, deepen, and slow the river. Its greater surface will be exposed to more warming sunlight, but its temperature will be moderated by the cool water contribution of its tributaries. It will flow around obstacles rather than splashing over them, but again, the oxygenated water from those tributaries will moderate the dissolved oxygen loss. Organisms needing a bit more warmth, a bit less oxygen, and greater water depth will live in the river’s middle reaches. Call the river’s junction with its first tributary 4 AM, and its junction with its last tributary 8 AM.

The river in its lower reaches will form a delta as it approaches its destination. It has achieved its maximum volume of water, is broadly exposed to sunlight, and becomes slower and warmer. Much of its dissolved oxygen escapes. The sediment the swifter part of the river has been carrying along settles out, causing the river to become shallower and wider. Living things which require warm, slow moving water and little oxygen will live in the delta. Eventually, the river empties into an ocean (The Muskegon River empties into Lake Michigan, which eventually empties into the North Atlantic via the St. Lawrence River). This is a broadly descriptive narrative; a specific river may vary somewhat. Call the beginning of the delta 8 AM, and the river’s mouth 12 noon.

Returning to dams, think of the dam as restarting the river at midnight; the spillway of the dam becomes the river’s new source. However, the fact that the dam holds back the river’s flow will create an artificial lake, called an impoundment, to form behind the dam. The water from the impoundment will not be as cool, as swift, or as oxygenated as the river’s natural source. Instead, it will have less volume, be warmer, slower, and contain less oxygen, more like the river’s delta. The progression of living things will be interrupted, and the river will be impaired this way from the dam to the river’s mouth, Depending on the dam’s location, our clock will jump from from, say, 6 AM to 10 AM, with the gradual changes that period entails missing from our morning. On the Muskegon River, Dead Stream Swamp, Rogers Pond, Croton Pond, and Hardy Pond are all impoundments.

These impoundments make our tributaries that much more valuable as a means of maintaining our river’s health as a “cool water system” supporting both cold and warm water life. Free flowing tributaries help restore some of the unity the main stem of the river loses, being chopped up into sections, or “fragmented.” By MRWA’s best calculation, there are 86 tributary dams in our watershed, the great majority of which have not served a purpose since generators replaced water wheels as a source of energy. This is why the MRWA constantly scans for opportunities to remove small dams, as we and our partners did in the village of Hersey. We want our “whole morning” back.