“When I bought this house 20 years ago, you could hop across the creek out back. Now it’s a so deep and wide that I can’t even wade across it.”
If I had a dollar for every time I’d heard that on a landowner assistance site visit…
But why does this happen, and why is it happening now, all throughout Cuyahoga County and in many of our neighboring communities in northeast Ohio?
To find out, we need to go back to what northeast Ohio was like before people settled here. The landscape then was almost entirely forested. They say a squirrel could walk from one end of the state to the other without ever touching the ground. If you, like me, have been out for a walk in the woods when it starts to rain, then you know that you don’t get very wet – not at first anyway. The rain is intercepted by the tree canopy. As it rains more and more, it slowly works its way down through the forest canopy, down through the leaves and branches of the understory trees and shrubs, eventually making its way to the forest floor. As the storm continues, the rain is absorbed by the composting leaves and smaller plants on the forest floor and is infiltrated into the soil. If it is a big enough storm, finally some of this rain runs off the forest floor and makes its way to the nearest stream, which gradually rises, crests, and gradually recedes. If it’s a really big storm, the stream will spread out onto its floodplain, where it stores the extra water and dissipates energy. This is the setting in which are local streams and rivers formed and found equilibrium.
How is our landscape different now? We’ve built roads, rooftops and parking lots to accommodate our society. And while those are all things that we need, all those new hard or impervious surfaces do have an impact on how water flows across the landscape. For instance, let’s contrast our walk in the woods with a walk through the parking lot at a large-scale grocery store. If it starts raining when you’re in the parking lot, you feel it right away. And if it’s a stronger rainstorm, you feel it not just on your head or shoulders, but sloshing around your ankles too. And instead of being intercepted by the forest canopy and slowly infiltrating into the soil, it runs off to the nearest storm drain, which in most cases leads directly to the nearest creek or river. This was the state of the art for municipal engineering during the time that most of northeast Ohio’s cities and suburbs were being developed – get the water off the landscape as quickly as possible.
So, we’re getting more water into our local stream system, and getting it their faster than it did under the natural conditions under which our local streams formed. This “more water getting there faster” situation creates a flashy stream system that leads to the erosion of the stream’s bed and banks, and flooding. The more the stream erodes and downcuts, the larger the stream channel gets, and the more rain it takes for the stream to spread out onto its floodplain – meaning that more of the water and energy (moving water = energy) is concentrated in the stream channel, causing even more downcutting and erosion – a vicious cycle that threatens nearby infrastructure and degrades aquatic habitat. All of which leads us to the kind of situation where a bubbling backyard brook can turn into an impassable chasm over the course of a decade or two.
This is further exacerbated by the effects of climate change in northeast Ohio, which has already altered our weather patterns in such a way that we are seeing more frequent, intense storms, which generate even more runoff.
So what are we doing about it?
Most larger land developments (greater than 1 acre) in northeast Ohio since the early 2000’s have been required to install stormwater management measures that capture, store and slowly release runoff into the stream system. Think of the detention basins and retention ponds in newer housing developments or commercial areas. Even if these aren’t 100% effective, they at least provide a base-level of protection against excess runoff for our local stream systems.
The problem is that most of northeast Ohio was built before the early 2000’s, leaving us with a lot of legacy impervious surfaces that are not being treated. In order to address the runoff from these impervious surfaces, we have to retrofit the built landscape to better mimic how water flows through the natural landscape.
If you take a look around our web site, almost everything Cuyahoga SWCD does and advocates for leads to better runoff management. From large-scale projects to restore streams, reconnect floodplains and directly treat stormwater from large impervious surfaces, to site-scale actions such as installing rain barrels and rain gardens, restoring soil health for improved infiltration and planting trees to restore our urban forest canopy, there are many steps that each of us can take to make a difference for the health of our local streams.
Blog Author: Jared Bartley, Rocky River Watershed Program Manager