Streamwatch Project
East Branch of White Clay Creek: Site 11
Site 11 is located upstream of Spencer Rd at the Stroud Water Research Center, Avondale, PA. This is considered the study reference site because it was awarded Exceptional Value status by the PA Department of Environmental Protection in 1984.
The stream at this location has an intact riparian forest, low human density and most fields in pasture/hay. Measurements of nitrogen (ammonium and nitrate) and phosphorus (soluble reactive and total phosphorus) were relatively low suggesting minimal impacts from agriculture or residential septic tanks. There are no known point sources upstream of this location.
Densities at this location were generally the highest observed in the study and averaged 17,000 individuals/m2. Density was highly variable among years and ranged from a low of 2400 individuals/m2 in 1994 to a high of 43,200 individuals/m2 in 1999. Even though density varied % EPT was notably high most years and ranged from 29% to 83% during the 14 year study. Half of the Total Richness (16 taxa/200 individuals) on average was composed of EPT taxa, a group of taxa considered sensitive to degradation. Site 11 was the only location to be categorized as good water quality based on the MAIS score. The MIAS score averaged 13.2 and ranged from 10.8 (fair) to 15.2 (good). Density and metric scores suggest that the macroinvertebrate community at this site was relatively stable during the study.
| Location | |
|---|---|
| Site number | 11 |
| Description | Upstream of Spencer Rd at the Stroud Water Research Center, Avondale |
| Lat Long (hr min sec) | 39°51.579’ N, -75°47.059’ W |
| Land Use | |
| Watershed area above site (km2) | 7 |
| Population density in 2000 (#/km2) | 33 |
| % Population increase from 1990 to 2000 | 13 |
| Percent pasture/hay | 62 |
| Percent cultivated crops | 18 |
| Percent forest | 17 |
| Chemistry* | |
| Nitrate (mg/L) | 3.76 |
| Ammonium (mg/L) | 0.01 |
| Total Dissolved Phosphorus (mg/L) | 0.027 |
| Soluble Reactive Phosphorus (mg/L) | 0.045 |
| Sulfate (mg/L) | 18.0 |
| Alkalinity (as mg/L CaCO3) | 58.38 |
| pH | 7.73 |
| Conductivity (μmhos) | 200 |
| Dissolved organic carbon (mg/L) | 1.55 |
| Macroinvertebrate Data | |
| years sampled | 1991-2001, 2003-2005 |
| MAIS score | 13.2 |
| water quality based on MAIS score | good |
 Click on macroinvertebrate name to view a photo | |
| 1st most abundant macroinvertebrate | Ephemerellidae (spiny crawler mayflies) |
| 2nd most abundant macroinvertebrate | Chironomidae (midges) |
| 3rd most abundant macroinvertebrate | Hydropsychidae (common netspinner caddisflies) |
| 4th most abundant macroinvertebrate | Elmidae (riffle beetles) |
| 5th most abundant macroinvertebrate | Simuliidae (black flies) |
*See Methods for number of years each chemistry variable was measured.