Streamwatch Project
East Branch of White Clay Creek: Site 18
Site 18 is located along Indian Run Road below the Avondale sewage treatment outfall and the tributary that Site 25 is on. Similar to sites upstream, pasture/hay fields are the predominant land cover. Cultivated crops and forest are also common features in the watershed. Human populations are at moderate densities compared to other study sites. Nitrate, sulfate, alkalinity and conductivity are all relatively high compared to other sites in the White Clay Creek watershed suggesting an impact from the treatment facility (Boyer 1997).
Total macroinvertebrate density ranged from 860 individuals/m2 to 35,900 individuals/m2. Oligochaetes and chironomid midges, taxa both tolerant to degradation, made up approximately 81% of the total numbers. The % EPT was relatively low (range of <1% to 7%), especially when compared to the reference Site 11 (29-83%). MAIS scores ranged from 3.0 (Poor) to 8.7 (Fair) and averaged 5.1 (Poor). 1994 and 2003 were the only years the site was considered Fair, in 2003 Total Richness and % EPT were high and in 1994 EPT Richness was high. Macroinvertebrate data from 1991 through 2008 suggest water quality at this location is variable and never above Fair.
| Location | |
|---|---|
| Site number | 18 |
| Description | Below the Avondale sewage treatment outfall along Indian Run Road |
| Lat Long (hr min sec) | 39°48.983’ N, -75°46.933’ W |
| Land Use | |
| Watershed area above site (km2) | 50 |
| Population density in 2000 (#/km2) | 151 |
| % Population increase from 1990 to 2000 | 33 |
| Percent pasture/hay | 54 |
| Percent cultivated crops | 17 |
| Percent forest | 15 |
| Chemistry* | |
| Nitrate (mg/L) | 4.76 |
| Ammonium (mg/L) | 0.05 |
| Total Dissolved Phosphorus (mg/L) | 0.051 |
| Soluble Reactive Phosphorus (mg/L) | 0.089 |
| Sulfate (mg/L) | 35.90 |
| Alkalinity (as mg/L CaCO3) | 108.77 |
| pH | 7.94 |
| Conductivity (μmhos) | 384 |
| Dissolved organic carbon (mg/L) | 2.63 |
| Macroinvertebrate Data | |
| years sampled | 1991-1999, 2003-2005, 2008 |
| MAIS score | 5.1 |
| water quality based on MAIS score | poor |
 Click on macroinvertebrate name to view a photo | |
| 1st most abundant macroinvertebrate | Chironomidae (midges) |
| 2nd most abundant macroinvertebrate | Oligochaeta (aquatic worms) |
| 3rd most abundant macroinvertebrate | Elmidae (riffle beetles) |
| 4th most abundant macroinvertebrate | Empididae (dance flies) |
| 5th most abundant macroinvertebrate | Simuliidae (black flies) |
*See Methods for number of years each chemistry variable was measured.