Streamwatch Project
East Branch of White Clay Creek: Site 12
Site 12 land use is very similar to Site 11: mostly pasture/hay fields, with some cultivated crops and intact forest. Although phosphorus levels were similar between Sites 12 and 11, nitrate, alkalinity and conductivity were higher at Site 12. Known potential pollution (e.g., fertilizers, pesticides and sedimentation) sources upstream of this location consist of a golf course, mushroom houses, and agriculture and livestock farming.
Total macroinvertebrate density ranged from 9100 individuals/m2 to 44,700 individuals/m2. Chironomid midges, a pollution-tolerant group, on average made up half of the total numbers. Total Richness was lower (11 taxa/200 individuals) compared to Site 11 (16 taxa/200 individuals), considered the best site. EPT Richness (4 taxa/200 individuals) was also not abundant at this site. % EPT averaged 22%, much lower than the upstream location (Site 11), which averaged 55%. MAIS score study average was 7.5, which rates this site as Fair. Eight of the 10 years rated this site as Fair: in 2004 and 2005 Site 12 was rated Poor. The long-term trend for water quality at this site appears to be unchanged since the study started.
| Location | |
|---|---|
| Site number | 12 |
| Description | At Rosazza Orchards off of Glen Willow Rd north of Avondale |
| Lat Long (hr min sec) | 39°50.146’ N, -75°46.915’ W |
| Land Use | |
| Watershed area above site (km2) | 28 |
| Population density in 2000 (#/km2) | 76 |
| % Population increase from 1990 to 2000 | 35 |
| Percent pasture/hay | 64 |
| Percent cultivated crops | 16 |
| Percent forest | 15 |
| Chemistry* | |
| Nitrate (mg/L) | 4.64 |
| Ammonium (mg/L) | 0.05 |
| Total Dissolved Phosphorus (mg/L) | 0.021 |
| Soluble Reactive Phosphorus (mg/L) | 0.038 |
| Sulfate (mg/L) | 27.25 |
| Alkalinity (as mg/L CaCO3) | 91.36 |
| pH | 7.93 |
| Conductivity (μmhos) | 318 |
| Dissolved organic carbon (mg/L) | 1.91 |
| Macroinvertebrate Data | |
| years sampled | 1991-1999, 2003-2005, 2008 |
| MAIS score | 7.5 |
| water quality based on MAIS score | Fair |
 Click on macroinvertebrate name to view a photo | |
| 1st most abundant macroinvertebrate | Chironomidae (midges) |
| 2nd most abundant macroinvertebrate | Oligochaeta (aquatic earthworms) |
| 3rd most abundant macroinvertebrate | Hydropsychidae (common netspinner caddisflies) |
| 4th most abundant macroinvertebrate | Elmidae (riffle beetles) |
| 5th most abundant macroinvertebrate | Ephemerellidae (spiny crawler mayflies) |
*See Methods for number of years each chemistry variable was measured.