Abrahams Creek Hydrology and Water Quality Analysis
Abrahams Creek is a perennial stream—a waterway that flows continuously throughout the year—located in Pennsylvania. While the creek has experienced erosion in various sections and exhibits relatively poor water quality, particularly in its lower reaches, it is not officially classified as impaired by the Pennsylvania Department of Environmental Protection.
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Key Facts
- Water Status: Perennial stream, not officially impaired by the PA DEP.
- Daily Sediment Load: Approximately 13.7 million pounds.
- Primary Sediment Source: Transitional land (5.6 million lbs/day).
- pH Levels: Near neutral, ranging from 6.6 to 7.3.
- Average Precipitation: 41.63 inches per year (20-year average).
Water Flow and Discharge Dynamics
The discharge, or the volume of water moving through the channel, varies significantly by location and season. In the upper reaches, measurements from May 1970 showed a discharge of 2.2 cubic feet per second (cfs), which dropped to between 0.1 and 0.2 cfs by September of the same year.
Further downstream at West Wyoming, data from the 1960s indicated higher discharge values, ranging from 3.26 to 15.8 cfs. The creek also faces risks of extreme flow events. At US Route 11, there is a 1% probability of the peak annual discharge reaching 2,900 cfs, and a rare 0.2% chance of it hitting 5,050 cfs.
Peak Discharge Probabilities by Location
| Location | 10% Chance | 2% Chance | 1% Chance | 0.2% Chance |
|---|---|---|---|---|
| US Route 11 | 1,200 | 2,250 | 2,900 | 5,050 |
| 2,000ft Upstream of Rt 11 | 980 | 1,850 | 2,400 | 4,200 |
| Creek Mouth | 950 | 1,650 | 1,950 | 2,600 |
Sediment Contribution and Land Use
The creek carries a massive daily sediment load of 13,733,711 pounds, which translates to 1,267.75 pounds per acre per day. This sediment originates from a variety of land uses, with transitional land and agriculture being the primary contributors.
- Transitional Land: 5,597,060 lbs
- Cropland: 5,256,620 lbs
- Stream Banks: 1,741,891 lbs
- Hay and Pastures: 599,240 lbs
- Forested Land: 330,880 lbs
- Low-Intensity Development: 93,440 lbs
- Unpaved Roads: 63,620 lbs
- Coal Mines: 18,420 lbs
- High-Intensity Development: 3,980 lbs
- Wetlands: 360 lbs
- Turf Grass: 20 lbs
Chemical Composition and Water Quality
Data from the early 1970s provides a detailed look at the creek's chemistry near Dallas. The water temperature during this period ranged from 8 to 22 °C. The specific conductance—a measure of water's ability to conduct electricity, which indicates dissolved ion concentration—ranged from 83 to 185 micro-siemens per centimeter at 25 °C.
Dissolved Gases and Minerals
The creek maintains a near-neutral pH (6.6 to 7.3) and a water hardness range of 36 to 53 mg/L. Key chemical concentrations include:
- Dissolved Oxygen: 9.8 mg/L
- Carbon Dioxide: 2.5 to 5.8 mg/L
- Calcium: 11.00 to 15.00 mg/L
- Magnesium: 2.00 to 3.70 mg/L
- Sulfate: 14.0 to 22.0 mg/L
- Chloride: 8.3 to 17.0 mg/L
- Recoverable Iron: 160 micrograms/L
Climate and Runoff
Based on data as of 2007, the region experiences a 20-year average annual precipitation rate of 41.63 inches. However, only a small fraction of this becomes surface runoff, with a 20-year average annual runoff rate of 3.46 inches.
Frequently Asked Questions
Is Abrahams Creek considered an impaired waterway?
No, despite having relatively poor water quality in its lower reaches and experiencing erosion, the Pennsylvania Department of Environmental Protection does not consider it to be impaired.
What is the primary source of sediment in the creek?
The largest contributor of sediment is transitional land, providing 5,597,060 pounds per day, followed closely by cropland at 5,256,620 pounds per day.
How does the water flow change between seasons?
Using 1970 data from the upper reaches, discharge was measured at 2.2 cubic feet per second in May and decreased to 0.1–0.2 cubic feet per second by September.
What is the typical pH level of Abrahams Creek?
The pH of the creek is close to neutral, typically ranging between 6.6 and 7.3.
What are the peak discharge risks at US Route 11?
There is a 10% chance of reaching 1,200 cfs, a 2% chance of 2,250 cfs, a 1% chance of 2,900 cfs, and a 0.2% chance of reaching 5,050 cfs.