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October 22, 2016
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Muddy Waters; Fish sing the blues

Visible in the foreground is a slug of sediment-laden water as it enters a clear body of water.
Photo courtesy Wayne County (PA) Conservation District

As hard surfaces are constructed and take the place of our natural infiltrating wetlands, forests and other habitats, stormwater runoff increases even during small rain events, scouring stream banks and increasing erosion and sedimentation, often undermining the trees, and unfortunately disconnecting many streams from their floodplain as the stream becomes entrenched. Scientists have shown that streams’ aquatic life diversity begins to suffer and decline when a watershed becomes more developed and exceeds an impervious surface area of 10%. As a stream loses its floodplain, whether due to entrenchment, harmful development or fill, this in turn makes flows even greater, exacerbating erosion and flooding downstream.

The Clean Water Act requires that states keep sediment pollution out of streams. For example, in Pennsylvania, sediment is largely regulated through its Chapter 102 Erosion and Sediment Control regulations. In a nutshell, these laws require that when earth disturbance occurs on land, the construction contractor must develop and use best management practices (BMPs) to minimize the potential for accelerated stream erosion and sedimentation and to manage post-construction stormwater runoff so that the sediment stays on the construction site and does not end up traveling, during rain events, into local streams and water bodies or offsite onto neighboring properties. BMPs include things like installing black fabric silt fences and compost filter socks that one often sees along perimeters of earth disturbance, hay bales to help reinforce these fabrics especially on steeper slopes, and straw mulch that is required to cover raw earth during construction activities. These practices are designed to minimize the amount of disturbed soil at one time, minimize soil compaction, remove sediment from onsite runoff before rainwater leaves the site and generally slow down runoff.

There are also additional BMP protections for high-quality and exceptional-value streams in PA, including preservation of 150-foot natural forest buffers along these streams. The crux of the matter here though can be enforcement and compliance; these BMPs must be maintained and inspected over time to ensure they are not being compromised and are functioning properly. This is where citizen monitors have played an essential role in reporting potential pollution problems to county conservation districts, especially recently on large gas transmission pipeline projects in the Delaware River Basin (DRB).

Citizen watchdogs can make a difference