So far we have had a pretty wet summer. I am sure that is not news to you. The river levels are well above average all along the Huron. Generally this is a good thing, as it keeps the tributaries flowing, provides new habitat for critters to populate or feed at, and allows more of the river to be floated by us all.
Sometimes these higher flows can be bad. The current is more rapid making it difficult for fish and other wildlife to move against it to find food or shelter. Strong currents can also be dangerous for paddlers.
In some places, our actions as humans, interacting with and changing the structure of our environment, exacerbates the consequences of heavy rains, which are occurring more frequently due to climate change. In natural environments, heavy rains slowly collect (after saturating the soil) and flood lowlands and eventually the river after a long period (days, even). In built up environments with lots of hard, impervious surfaces, and straightened channels or underground pipes, the rain does not even have a chance to soak into the ground, let alone move out into a flood plain. The result can be a rapid rise in water level and velocity that can be destructive or even deadly to wildlife and humans alike. A good example of a built-up area like this is Allens Creek in Ann Arbor. Over 90% of the stream in this tributary watershed is piped underground, and over 40% of the land cover in the watershed is impervious.
During a 3-inch rain storm on June 14, the top video here was recorded at the outfall of Allens Creek to the Huron River, just downstream of Argo Dam. The flow out of Allens Creek exceeded 1,000 cubic feet per second (cfs) on two separate occasions during the storm, and hit a peak flow of 1,350 cfs. The flow returned to its usual trickle within a matter of hours. The second/bottom video shows what it looked like the next day.
Nothing could survive, human or otherwise, in a concentrated flow with such a velocity. The flow is strong enough to send logs and boulders downstream and scour the river bed of any finer materials or living plants. Note how the downstream river condition following the blast looks more like a Rocky Mountain gorge river than the Midwestern meander the Huron usually is. Such “flashy” flows are not natural, and HRWC is working with partner municipalities to change the way stormwater is managed. New approaches utilize green infrastructure to capture and infiltrate rains into the groundwater before they hit the pipes or streams. Other, larger storage projects, like the one under Pioneer High School in Ann Arbor or in Mary Beth Doyle Park are being installed to hold storm flows back. It all makes a difference, but more is needed to overcome past actions and return our streams and the river to a more natural state.