The Problem
Past stormwater practices neither treated stormwater nor did they address the volume of water running off the land into our creeks. As the percentage of developed land in our watersheds has gone up, stormwater runoff has contributed to a decline in water quality in our streams, adding pollution, changing flow rates, causing erosion, reducing the capacity of streams to handle pollution and harming creek habitats. In the Dysart Run watershed, the erosion has gotten so bad as to threaten houses. A tributary of Blacklick Creek, Dysart Run is approximately 5 mi. long and drains a 4.2 mi2 watershed. Nearly 25% of the watershed is covered with hard surfaces. Research has indicated that when the percentage of hard surfaces in a watershed rises above 10 percent, the stream in that watershed begins to become unhealthy. Investigations done by Ohio State University students indicated that the stream was not in hydrogeomorphic equilibrium. In 2000, Ohio EPA sampling indicated that the stream was not in attainment of water quality standards.
This project involved doing a hydrological and hydraulic study (H & H study) of the watershed to determine what options were available to restore a more natural hydrology to the stream. An instream project was also planned for the headwaters of the stream to improve water quality and potentially reduce peak stormwater flows slightly. We had hoped to find that there were enough stormwater basins in the Dysart Run watershed that could be retrofitted to reduce the stormwater flows in the stream. Unfortunately, we learned that there was too much developed land in the watershed with no stormwater controls at all to allow us to make a significant difference in stormwater flows by retrofitting stormwater basins. Moreover, most of the existing basins were too small to be retrofitted. Normally stream restoration efforts involve bringing out heavy construction equipment to move earth, as well as installation of large rock berms to prevent erosion. The only equipment needed for the inserts is the mesh material, some stakes and anchors, a circular saw and 2-3 people to perform the installation. 20 inserts can be installed along a half mile of stream for about $10,000. This cost also includes invasive removal and buffer plantings
The inserts are like leaky beaver dams, aproximately one foot high, made from cut-to-size pieces of recycled, fibrous, plastic material that are stacked in the stream. Stacks of this material are secured into the streambed by steel stakes and an anchor. They reduce erosion by taking power out of the stream, slowing it down and redirecting flow. They can be installed in such a way as to move the primary flow away from eroding banks. Their benefits extend beyond erosion protection and can include improving water quality, adding stream habitat, sustaining flow during dry weather and enhancing pools and riffles.
We do
not generally think of a stream as having "skin". However, the vegetation along the banks of a stream
serves as its skin. This buffer zone protects the stream from pollution, much as our skin protects our bodies from bacteria and other things that could do us harm. These buffers ought to contain a variety of vegetation: trees, shrubs and non-woody, native perennial plants. In addition to protecting streams from pollution and removing pollution from their water,
vegetated buffers stabilize banks, keep the creek cool, reduce algae growth, and provide food and shelter for aquatic organisms. They are more effective when they are free from invasive plants that take over stream corridors, excluding other plants and providing limited benefits to the stream. Try as we might we have yet to invent something that can do as good of a job protecting streams from pollution and erosion than native trees and plants. For this reason we incorporated invasive removal and native plantings along the edges of the stream where we installed our inserts.
Now that installation is complete we will track changes in the stream and the inserts, addressing problems that may arise. The Ohio EPA will also monitor the aquatic life in the stream, which is how stream health is assessed in Ohio. In a pilot insert project we saw an increase in number of species of fish and aquatic insects that are sensitive to pollution present in the stream, indicating an improvement in stream health.
This project was financed through a grant from the Ohio Environmental Protection Agency and the United States Environmental Protection Agency, under the provisions of Section 319(h) of the Clean Water Act.
Dysart Run Photo Gallery