Connoquenessing Creek Watershed Conservation Plan - Western ...

Connoquenessing Creek Watershed Conservation PlanChapter 3. Water Resourcesmodify the physical characteristics of the stream. Streams may be channelized to purposefully drainwetlands, improve navigation, control flooding or divert the flow to a reservoir for agricultural use orconstruction of a road, dam, bridge, or other structure. The negative consequences of streamchannelization include aquatic and terrestrial habitat alteration, wetland loss, streambank destabilization,erosion, and sedimentation. In urban areas, the city of Butler for example, where the floodplains havealready been developed, streams may be channelized to increase the volume of water it is capable ofholding to aid in flood control. However, when the stream channel is straightened, the velocity of thewater flowing within it greatly increases, scouring the stream bed and eroding streambanks. The sedimentis carried downstream to deposit and accumulate once the flow slows down sufficiently, which then canlead to increased flooding in downstream areas, causing the opposite effect for which it was originallyintended.Not all streams flow year-round. Because surface water flowing in streams is primarily contributedto from groundwater, it is important to understand the relative position of the stream bottom with respectto the water table in order to define a perennial, intermittent, or ephemeral stream.Although not all streams flow year-round, all streams within Pennsylvania are protected under thePennsylvania Clean Streams Law of 1931, which gave the state of Pennsylvania the power to enactlegislation and regulations pertaining to the protection of streams.According to the Pennsylvania Code (1997), an intermittentstream is a “body of water flowing in a channel or bed composed ofsubstrates primarily associated with flowing water, which duringperiods of the year is below the local water table and obtains its flowfrom both surface runoff and groundwater discharges.” Streams that donot flow year-round are intermittent streams.An ephemeral stream is a “water conveyance which lackssubstrates associated with flowing waters and flows only in directresponse to precipitation in the immediate watershed or in response tomelting snowpack and which is always above the local water table.”A perennial stream is a “body of water flowing in a channel orbed composed primarily of substrates associated with flowing waterand is capable, in the absence of pollution or other manmade streamdisturbances, of supporting a benthic macroinvertebrate communitycomposed of two or more recognizable taxonomic groups of organismsDry phase of an intermittentstreamwhich are large enough to be seen by the unaided eye and live at least part of their life cycles within orupon available substrates in a body of water or water transport system.” Perennial streams flow yearround,because they are always below the water table.Point discharge limits (as described later in this chapter) are estimated at the point where the streamsupports a benthic macroinvertebrate community characterizing a “perennial stream.” In the past, miningoperations in Pennsylvania could get streams to be reclassified as intermittent or ephemeral,classifications requiring no special protections under state mining regulations. However, DEP has recentlybegun shifting its policy to require detailed biological assessments before approving such operations.Under this new policy, non-permanent intermittent and ephemeral streams are receiving similar protectionas permanent, perennial streams before mining can proceed.Protection of intermittent and ephemeral streams is also included for logging and other earth-movingactivities, although permitted activities may differ from those involving perennial streams. In cases where3-5