Watershed Conservation Plan - Destination Erie

5.10.3 Nonpoint Source Pollution
A major source of contaminants to streams in the study area is nonpoint-source pollution (NPSP), which
is not as readily controlled as point-source pollution. NPSP differs from point source pollution in not being
"easily traced back to a particular location" and originating from "everyday land use activities such as
agriculture, residential development, construction and forestry" (PADEP 2000). In rural areas of the
Pennsylvania Lake Erie watershed, increased NPSP is associated with physical disturbance in the riparian
zone of small streams and close proximity to highways, which increase streams< exposure to contaminants
from automobiles and road de-icing materials (Welte and Campbell 2003). In urban areas near the City of
Erie, Campbell et al. (2002) identified four principal NPSP problems: (1) runoff from streets and other
impervious surfaces (e.g., parking lots), (2) stream-side trash dumps and fills, (3) degraded wetlands and
riparian areas, and (4) stream bank erosion exacerbated by excessive flows during major storms.
Weber and Campbell (2005) note that degradation of the bottom substrate of streams due to deposition
of silt or scouring flows, which exposes bare bedrock, is common in both urban and rural streams in the study
area. Absence of cobble/boulder material and predominance of scoured bedrock were considered primary
factors contributing to degraded conditions near the mouths of Sixteenmile, Sevenmile, Fourmile, and Elk
Creeks in a recent assessment study by Campbell (2005). Reduction of forest cover, draining or filling
wetlands, and development activities that increase impervious cover contribute to substrate degradation in
streams by increasing runoff/sediment loading to streams and thereby decreasing the stability of stream
channels and banks (PADEP 2000).
Sediment particles entering streams from eroding stream banks and exposed agricultural soils are often
associated with nutrients (including phosphorus and nitrogen compounds) that may contribute to excessive
plant growth in receiving waters (Prepas and Charette 2003; see discussion regarding eutrophication in 5.1
Lake Erie). As stated above, considerable effort is being focused in the Great Lakes Basin on reducing
phosphorus-loading from NPSP (USEPA 2006 a, 2006b). Particulate materials entering streams from streets
and parking lots in our urban areas are often associated with heavy metals and polycyclic aromatic
hydrocarbons (PAHs), which subsequently accumulate in stream and lake sediments (Diz and Johnson 2002;
PADEP 2006a).
Elevated concentrations of at least one dissolved metal (iron) in streams are correlated with major runoff
events. Loeffelman et al. (1985) note that elevated iron concentrations in West Virginia tributaries of the Ohio
River were correlated with stream flow and suspended solids concentration. Graphical analyses of STORET
Legacy data for Twelvemile and Conneaut Creeks (Figure 5.15) indicate "excursions" of iron in these streams
appear to correspond closely with periods of increased flow. It should be noted that the high flow rates
measured in Conneaut Creek are at least two orders of magnitude higher than the maximum flow rates
observed in Twelvemile Creek (se Figure 5.15), and that this corresponds to more than doubling the
maximum iron concentrations. Based upon Loeffelman et al