The Neshaminy Creek watershed occupies an area of 233 square miles; 86% is in central and lower Bucks County and 14% is in Montgomery County. The stream flows approximately 50 miles in a southeasterly direction to its confluence with the Delaware River. Ten impoundments along the Neshaminy and its tributaries provide public water, recreation and flood protection.
The topography of the watershed is predominately rolling hills and steep sided stream valleys. The northern portion of the watershed lies in the uplands of the Piedmont Province while the southern portion lies in the lowlands of the Coastal Plain. These two geologic regions are separated by a dramatic Fall Line, which rises sharply up 200 feet and is easily seen from the Neshaminy Mall area.
Groundwater in both the Piedmont and Coastal Plain is replenished by precipitation being absorbed into the soil and underlying strata. Precipitation is supplemented in the Coastal Plain however, by infiltration of water from the Delaware River. This area forms the most extensive aquifer in the lower Delaware River Valley.
Riverkeeper Monitoring Sites Riverkeeper has three volunteer monitoring sites on the Neshaminy Creek, two on the North Branch and one on the Main Stem, near the head of tide. Tests are performed twice a month for basic water quality parameters. Volunteers also record stream conditions, sightings of flora and fauna and any observations of pollution or other threats. This information is recorded in Riverkeeper's database and is distributed to environmental protection agencies responsible for stream protection and is available to residents and all decision makers. The goal of Riverkeeper is to ensure that the Delaware River and every tributary stream of the watershed is actively protected by local residents. To that end, Riverkeeper, in cooperation with local grass-roots organizations with similar goals, encourages citizens to get involved in municipal land use decision-making, sponsors stream watch training workshops, and assists local groups to actively work on local stream protection projects.
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VITAL STATISTICS Length: 50 creek miles
Watershed Area: 233 square miles
Headwaters:
West Branch: Lansdale/Hatfield area
North Branch: Northeast of Doylestown
Significant Tributaries and Sub-Watersheds, north to south:
Land Use: Some portions of the upper watershed are still rural or semi-rural in nature. Agriculture is still a predominant, but diminishing, land use in those areas. Very few, small and scattered forested areas still exist. The headwaters of the West Branch, the Little Neshaminy and the southern portion of the watershed are highly developed. There is a continuing increase in the amount of development in the watershed (Impairment Survey, p2).
Municipalities:
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PA DER WATER QUALITY ASSESSMENT IN BRIEF
The entire Neshaminy Creek Watershed has been identified as having a documented nutrient-related use impairment problem. Phosphorous and nitrates are elevated throughout most of the watershed: nitrite and nitrate levels in the West Branch nearly exceeded Chapter 93 water quality criteria on more than one occasion (Impairment Survey, ii).
Ammonia concentrations exceeded Chapter 93 criteria on more than one occasion in the West Branch near its confluence with the North Branch, in the headwaters of the North Branch, in Little Neshaminy, and in Neshaminy Creek below the confluence of the North and West Branches (Impairment Survey, ii).
The minimum Chapter 93 dissolved oxygen criteria was violated at stations on Little Neshaminy, West Branch and the North Branch. On the average, the entire watershed was co-limited by nitrogen and phosphorous (Impairment Survey, ii).
Non-point Source Assessment: Non-point sources, particularly agriculture, appeared to exert a considerable impact of water quality in the Neshaminy Creek Watershed, and in particular, on the North Branch. There was significant evidence that an erosion and sedimentation problem existed in the watershed. Neshaminy Creek is highly impacted by stormwater. Following minor rainstorms, the streams were very turbid and remained that way for days following the storms. Stormwater impacts can be expected to increase due to the tremendous amount of development in the watershed (Impairment, p37).
Agricultural dominated landscapes of the 1960's are now multi-density housing projects with lush green fertilized lawn runoff entering a reduced base flow stream system. Recommended action..."Non-point source controls consistent with Chapter 95 are needed" (PA DER Water Quality Assessment, p88).
Lake Galena is listed by PA DER as "Threatened and Impaired" due to excessive algal growth, low oxygen levels and siltation (PA DER Water Quality Assessment, p88).
Point Source Assessment: The stream has a large number of point source discharges. including about 15 municipal sewage facilities. During low flows, stream flow probably consists mostly of discharges. The stream has a long, well-documented history of nutrient enrichment throughout the basin, including point and non-point sources from urban runoff and agriculture. References to dense growths of aquatic vegetation, organic sediment build-up (DER Neshaminy Creek file summary).
Aquatic biology investigation on an unnamed tributary in Bensalem Township to "assess stream impacts off a continuing horse manure runoff problem at Philadelphia Park." Recommended action..."utilize Clean Streams Law to bring about enforcement of BMP's for runoff from confined animal facility" (DER file summary).
PA DER Permitted Discharges:*
| PA DER Permitted Discharges:* | Permit # | Receiving Water |
| Philadelphia Suburban Water Co. | PA0011274 | Neshaminy Creek |
| Warminster Township STP | Little Neshaminy Creek | |
| Buckingham Township STP | Lahaska Creek | |
| Doylestown Harvey Ave./ Green St. STP | trib to Little Neshaminy | |
| Chalfont/New Britain STP | Neshaminy Creek | |
| Bucks County Water and Sewer STP | Neshaminy Creek | |
| U.S. Naval Warfare Center STP | trib to Little Neshaminy |
* Source: Bucks County Health Department. Other dischargers may exist.
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RIVERKEEPER DATA SUMMARY
Neshaminy Creek Coastal Plain Monitoring Station: Adjacent to State Road bridge, Bensalem.
Parameter Range Mean pH: 6.5 - 7.5 7.3 Nitrates: 0.20 - 0.88 mg/L 0.77 mg/L Phosphate: 0.1 - 0.8 mg/L 0.3 mg/L Dissolved Oxygen (DO): 5.5 - 11.7 mg/L 8.7 mg/L DO Saturation: 67.0 - 91.0% 82.2% (sampling period: February, 1993 - August, 1993)
pH
The pH of natural waters is an important general water quality indicator because pH is a major factor affecting most chemical and biological reactions. The pH observed in water is determined by a number of complex interactions and provides an overall measure of the intensity of the various acid/base interactions which are occurring. For example, the geology of an area, including soil type, and the increasingly acidic precipitation (acid rain) can have a significant affect on the pH reading. The pH of normal rainwater (containing no pollutants) is about 5.6. As the rainwater travels over and through rocks and soil, chemical reactions with minerals affect the pH and buffering capacity of the water.
The pH scale ranges from 1 to 14 standard units. A pH of 7 indicates neutral conditions, while waters with a pH less than 7 are acidic and those with pH values greater than 7 are basic. Since pH is expressed on a logarithmic scale, each 1 unit change in pH represents a ten-fold increase or decrease in hydrogen ion concentrations. Therefore, a pH of 6 would be 10 times more acidic than a pH of 7 and 100 times more acidic than a pH of 8.
pH readings at Neshaminy Creek varied through-out this monitoring period. The average reading, however, indicates relatively neutral conditions.
Nitrate (NO3-N)
Nitrate is the principal form of nitrogen in most surface waters, but high concentrations of nitrate (>4 ppm) may reflect unsanitary conditions because of human and animal wastes are major sources of nitrate.
Nitrate readings at Neshaminy Creek are within an acceptable water quality range and are the lowest of any neighboring streams monitored by Riverkeeper volunteers during this sampling period.
Phosphate (PO4)
Phosphorous is a natural and essential nutrient and is often the factor limiting additional growth of aquatic organisms. However, excessive phosphorous concentrations can be detrimental to surface water quality. Typical external sources of phosphorus are fertilizer, septic leachate, sewage effluent, detergents and soaps, and particulate materials transported by stormwater.
Phosphate readings at Neshaminy Creek varied considerably over the sampling period. They were, however, within acceptable water quality range and similar to neighboring stream monitored by Riverkeeper volunteers.
Dissolved Oxygen
The dissolved oxygen (DO) concentration of a river is an important indicator of the overall "health" of the system. Oxygen is essential for the survival of fish and many other aquatic organisms. The amount of oxygen which can dissolve in water is subject to fluctuation in temperature, photosynthetic activity, and stream flow (low flow and high temperatures are a common cause of low oxygen readings during the summer months). Respiration processes, oxidation of inorganic wastes, and the decomposition of organic matter deplete oxygen, while photosynthesis and re-aeration by contact with the atmosphere increase oxygen concentrations in water. Most desirable aquatic organisms require a DO concentration of 4.0 ppm or greater for long-term survival.
The "mean" dissolved oxygen reading maybe misleading because data was only collected at this site over a seven month period, without the full impact of seasonal temperature changes accounted for.
Dissolved Oxygen Saturation
Dissolved oxygen can also be expressed in percent of saturation. The amount of oxygen that can dissolve in water decreases with increasing temperature and dissolved solids concentration. For this reason alone, dissolved oxygen concentrations in surface waters usually increase significantly during the winter months. By eliminating the seasonal variations caused by temperature, dissolved oxygen saturation can provide a better comparison of dissolved oxygen in water between sampling dates than dissolved oxygen concentrations.
Rivers with dissolve oxygen saturations of 90% or greater are considered healthy. Unless the waters are supersaturated due to cultural eutrophication (enrichment of surface water as a result of human impacts). Rivers below 90% saturation may have large amounts of oxygen demand materials (organic waste).
Neshaminy Creek's dissolve oxygen saturation readings were high compared to neighboring sites. However, data was only collected for seven months, not showing the full impact of seasonal temperature and flow changes. This may have contributed to artificially high readings.
Observations and Comments
Volunteers observe wildlife, weather conditions and general water and habitat conditions. Volunteers saw Mallards with ducklings and cloudy water. The volunteers have confirmed what you already know -- Neshaminy Creek has its problems, but is still a viable ecosystem worth protecting and restoring. It supports wildlife and offers tranquility and recreation. Neshaminy Creek needs continued monitoring so that field tested stream conditions can be used as input to devise strategies for improving water quality and streamside habitat. Continued monitoring is also important to ensure that problems are identified early and corrected before additional degradation occurs.
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For Additional Information:
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Sources: