Subbasin 02F, which consists mainly of the Neshaminy Creek and its tributaries, drains 232 square miles of west central and southern Bucks County and a portion of adjacent Montgomery County. A small portion of the Delaware River adjacent to the confluence of Neshaminy Creek between the villages of Croyden to Cornwells Heights is also included in the subbasin. Neshaminy Creek flows in a southeasterly direction for about 50 miles to its confluence with the Delaware River north of the City of Philadelphia. A total of 428 streams flow for 418 miles through the subbasin; however, the majority of the streams in the subbasin are small unnamed tributaries, only 17 of the streams have official names. The subbasin has three Mill Creeks and two Pine Creeks. Major tributaries are the North Branch, West Branch, and Little Neshaminy Creek. The subbasin is part of HUC Area 2040201, Neshaminy Creek, a Category I, FY99/2000 Priority watershed under the Unified Watershed Assessment.
Most of the subbasin lies within the Northern Piedmont Ecoregion (64). The upper two-thirds of the watershed is in the Triassic Lowlands (64a) subsection, which is comprised of gray arkose sandstone, red and brown sandstone, shale, and conglomerate of the Stockton Formation. The topography is flat to gently sloping (0 to 8 percent). Soils in this section are sandy and highly erodible. The Stockton Formation is the best source for water supply wells in the subbasin; however, yields vary greatly and some of the aquifer is under artesian pressure. Water is moderately hard and mineralized.
Interspersed through 64a is the Diabase and Conglomerate Uplands (64b), consisting mostly of gray or black argillite of the Lockatong Formation (Trap Rock) and diabase, which are quarried as building stone and aggregates. This area consists of a series of parallel northeast-southwest trending hills and ridges formed by diabase dikes and sheets which protrude through sedimentary rocks and rise above the Triassic Lowlands. The streams in this area flow through parallel, low relief valleys between low ridges. The Lockatong Formation is a tightly cemented rock that has low water well yields unless fractures are encountered. The highly erosion-resistant diabase rock of 64b forms a boulder-strewn terrain that is not conducive to farming. Much of this diabase portion of the subbasin is wooded or used for residential development. The argillite beds are fairly homogeneous with local thinner-bedded black shale. This section of the subbasin has primarily Group C and D soils which have low permeability and high runoff potential. Detention ponds are more feasible stormwater management practices rather than infiltration type systems in the Trap Rock areas.
Part of the lower portion of the watershed is within the Piedmont Uplands (64c), which is characterized by rounded hills and low ridges consisting mainly of gneiss and schist. A ridge along which the Neshaminy Creek makes a sharp 90-degree bend to the west marks the transition between the Piedmont Uplands and the Triassic Lowlands. The lower edge of the uplands is traversed by a narrow band of quartzite of the Chickies Formation, part of the Piedmont Lowlands (64d). The clay soils derived from these rocks have slow infiltration rates and a high potential for runoff.
The very lower portion of the basin adjacent to the Delaware River is in the Middle Atlantic Coastal Plain, Delaware River Terraces and Uplands (63a) consisting of unconsolidated sand and gravel. A relatively steep gradient known as the Fall Line marks the transition between the hillier Piedmont and the flat, sandy Coastal Plain. In this subbasin, the Fall Line is marked by a sharp 200-foot rise near the intersection of US Route 1 and Bristol Road near the Neshaminy Mall. The creek makes an abrupt 90-degree turn to the east as it flows from the Piedmont Lowlands into the coastal plain. Virtually none of the coastal plain remains in its natural state in this subbasin; the plain was either filled in or drained and converted into urban and suburban development.
Most of the subbasin contains clay soil formed from noncarbonate sedimentary rocks. These soils have high runoff potential due to slow infiltration rates and an impervious layer near the surface. The majority of streams in the subbasin exhibit extreme flow variability during the year. Streams are very flashy in nature and experience high runoff during rainfall and retain little rain for groundwater recharge and storage. Large commercial, industrial and housing development further limits rainfall infiltration. The coastal plain area along the Delaware River contains soils formed from unconsolidated water sorted materials, with substrata of sand, silt, and gravel. These soils have moderate to high infiltration rates. Groundwater is normally replenished by precipitation; however, groundwater in the coastal plain is also replenished by infiltration from the Delaware River.
The basin includes 26 municipalities in Bucks County, 13 of which are boroughs, and seven in Montgomery County, including two boroughs. The largest borough is Doylestown, the Bucks County seat. The location of the lower ¼ subbasin adjacent to the City of Philadelphia and major interstate highways such as the Pennsylvania Turnpike (I-476) and I-95 has encouraged development of high intensity residential villages and boroughs and large commercial and industrial tracts. Villages and boroughs have merged over the years and now little or no open space exists between them. Many houses in the older developments of the lower subbasin are very close to streams that have little natural riparian cover. This situation presents a high potential for flooding. The population of the subbasin was 256,000 in 1990 and is projected to increase significantly to 368,000 by 2040.
Some portions of the subbasin are still rural or semi-rural. Agriculture is a predominant but diminishing land use. Agriculture lands are being rapidly converting to residential and commercial developments. The majority of the remaining farmland is located north and west of the Boroughs of Newtown and Doylestown. Scattered forested tracts still remain in the upper half of the subbasin. Smaller woodlots are located in public parks and private lands. The headwaters of the West Branch, North Branch and the Little Neshaminy Creek are the most highly developed sections of the upper subbasin. The area surrounding the Borough of Doylestown is becoming developed into small, often upscale residential communities and commercial parks. Large estates with scattered small woodlots are located near the main stem east of Doylestown. Residential and commercial development is also expanding into the still largely rural North Branch watershed north and west of Doylestown.
Lake Luxembourg, Lake Galena, Pine Run Dam, and Churchville Reservoir are part of the Neshaminy Basin Flood Control System built in the 1970’s and funded through the Natural Resources Conservation Service (NRCS) under the Public Law (PL) 566 Program. Flood control is the primary purpose of the reservoirs, with recreation and water supply as secondary uses. Six other smaller impoundments are located in the subbasin. Lake Luxembourg watershed contains some of the last actively farmed land in lower Bucks County.
Most of the public water in the subbasin is supplied by wells. The Point Pleasant Diversion brings water from the Delaware River outside the subbasin into the Neshaminy Creek watershed, increasing the discharge of the North Branch Neshaminy Creek. Water from the Delaware River flows from a pumping station at Point Pleasant through a combined transmission main into Bradshaw Reservoir, then into the North Branch at PA Route 413 and then into Lake Galena. The Forest Park Water Treatment Plant draws water for municipal treatment from the North Branch two miles downstream of Lake Galena. This diversion and interbasin transfer increases the overall amount of water available for use in the Neshaminy Creek subbasin.
Local and county public parks: These parks are important because they provide valuable open space amid the rapidly expanding residential and commercial areas of the watershed. They also provide riparian buffers that protect the creek banks and help reduce flooding, stormwater runoff and erosion.
· Peace Valley County Park surrounds the 365-acre Lake Galena on the North Branch Neshaminy Creek. The Park encompasses 1,524 acres of mixed forest and open fields. The Peace Valley Nature Center, an environmental education center and outdoor classroom of the Central Bucks School District, is located on 20 acres of the northeast section of the lake and 300 acres of surrounding parkland.
· The 174-acre Lake Luxembourg impounds about 99% of the Core Creek basin and is the focal point of Core Creek Park, owned by the Bucks County Parks Department. The park, which is located between the boroughs of Langhorne and Newtown, is one of the most widely used in the county. The water and land based recreation (boating, fishing, trails, picnicking, recreational courts and areas, camping) attracts more than one million visitors each year. Core Creek Park provides valuable open space amid a rapidly expanding residential area.
· Lake Galena impounds 365 acres of the North Branch Neshaminy Creek. The lake is supplemented by water from the Delaware River Point Pleasant Diversion Project for the purpose of providing cooling water for the PECO Energy owned Limerick Nuclear Power Generating Station and augmenting public drinking water supplies. The water supply intake is downstream of the dam at the confluence of Pine Creek and North Branch Neshaminy Creek.
· Dark Hollow Park, southeast of Doylestown, which follows the Neshaminy Creek corridor for several miles.
· Churchville Park near Ironworks and Mill Creeks, Northampton Township, Bucks County.
· Playwicki Park on a bend in the Neshaminy Creek in Midletown Township, Bucks County, west of Langhorne.
· Kemper Park, along the Little Neshaminy Creek in Warminster Township, Bucks County
· Windlestrae Park on Little Neshaminy Creek, Montgomery Township, Montgomery County
Two state parks are located in the watershed:
· Neshaminy State Park, a 330-acre park on the Delaware River with a boat ramp/access to the Delaware River, a swimming pool and many other recreational opportunities.
· Tyler State Park, a 1,711-acre park near Newtown Borough, which has environmental education facilities in addition to other recreational opportunities.
Fisheries:
Watson Creek, Buckingham Township, Bucks County, a tributary to Mill Creek at Rushland, supports a wild brown trout population.
DEP Chapter 93 Exceptional Value (EV) and High-Quality (HQ) Stream Listings:
· No EV or HQ streams.
A variety of nonpoint and point source pollution sources affect the subbasin consistent with the variety of land uses. The conversion of farmland to residential development has lead to siltation problems from land construction and impairment by stream flow variability and stormwater runoff. Construction activities associated with rapid urbanization are major sources of high sediment loads. Soils are highly erodible, and disturbed areas contribute high sediment loads during storm events. In some cases, however, conversion from agriculture to suburban land use will likely reduce the siltation rates once construction is completed because raw soil is no longer exposed through regular plowing and planting. Erosion and stormwater runoff continue to carry sediments and nutrients to streams and lakes, especially Lakes Galena and Luxembourg.
Stormwater runoff is a severe problem especially in the highly urbanized lower subbasin. In September 1999 after the record rainfall from Hurricane Floyd, floodwaters reached the 100-year flood level at the USGS gauge at Langhorne, PA, causing millions of dollars of damage to hundreds of homes and businesses. In summer 2000, a localized storm that dropped 8 inches of rain in 3 hours over the lower Bucks County Townships of Upper and Lower Southampton brought Mill Creek (at Langhorne Terrace) over its banks, washing out roads, businesses and homes. Dozens of families were forced from their homes for more than a month and many businesses lost days or weeks of operation. Damages to roads, bridges and utilities disrupted services and access in many areas for several days. PHEMA was in the process of purchasing homes for removal and reestablishment of riparian buffers in the most severely affected areas. Streams in the subbasin also often become very turbid after minor rainstorms and may remain so for days after the storms. Stormwater impacts can be expected to increase due to the high amount of new development in the watershed.
Groundwater depletion is also a problem due to withdrawals through water wells that serve the numerous new housing, commercial, and industrial developments. Water withdrawn for home or commercial use is not always returned to the groundwater but instead enters the surface stream flow as discharges from sewage plants or runoff from paved roads and driveways. Runoff is rapid during storm events; rainwater has little time to infiltrate and replenish the groundwater system. Many of the agricultural lands of the 1960’s are now housing or commercial developments with lush fertilized lawns.
The watershed has a number of point source discharges, including 15 municipal sewage facilities that discharge into the main stem Neshaminy Creek, Little Neshaminy Creek and its unnamed tributaries, and Lahaska Creek. During low summer flow periods, these discharges may comprise the majority of flow to the receiving stream. Stream degradation associated with excess nutrients, phosphates, nitrates, sludge, fecal coliform bacteria, copper, chlorine, and bacteria from sewage treatment plants have been reported in Neshaminy Creek, Little Neshaminy Creek, West and North Branch Neshaminy Creeks, and Cooks Run. These discharges have significantly limited the diversity of aquatic life in several of these waterways.
Lake Luxembourg is impaired due to excessive nutrients and total dissolved solids (eutrophic). The lake has an impaired fishery due to poor habitat and competition with introduced fish species. Lake Galena is also impaired and in a eutrophic condition due to excess sediment and nutrient loadings.
Ninety-eight
percent of the subbasin was evaluated under the Department’s Unassessed Waters
Program in 1998. Fifty-eight percent of
the subbasin, 239 miles out of 410 miles assessed, was determined to be
impaired. The major impairment causes
were excessive nutrients, sediment, and water flow variability from a
combination of point sources including municipal sewage treatment plant discharges
and nonpoint sources such as runoff from agricultural land, stormwater and
urban development. The North Branch is
affected by runoff from agriculture.
DEP biologists use a combination of habitat and biological assessments as the primary mechanism to evaluate Pennsylvania streams under the Unassessed Waters Program. This method requires selecting stream sites that would reflect impacts from surrounding land uses that are representative of the stream segment being assessed. The biologist selects as many sites as necessary to establish an accurate assessment for a stream segment. The length of the stream segment assessed can vary between sites. Several factors are used to determine site location and how long a segment can be, including distinct changes in stream characteristics, surface geology, riparian land use, and the pollutant causing impairment. Habitat surveys and a biological assessment are conducted at each site. Biological surveys include kick screen sampling of benthic macroinvertebrates, which are identified to family in the field, and an evaluation of their tolerances to pollution. Benthic macroinvertebrates are the organisms, mainly aquatic insects, that live on the stream bottom. Since they are short-lived (most have a one-year life cycle) and relatively immobile, they reflect the chemical and physical characteristics of a stream and chronic pollution sources or stresses. Habitat assessments evaluate how deeply the stream substrate is embedded, degree of streambank erosion, condition of riparian vegetation, and amount of sedimentation.
Urbanization and paving can have a severe effect on stream aquatic life. Studies by the Maryland Department of Natural Resources showed that a reduction in stream aquatic species diversity may begin with as little as 2% impervious cover. Maryland streams with above 15% impervious cover were rated fair to poor for aquatic species. When the impervious cover reached 25%, species diversity was significantly reduced. Riparian vegetation removal and paving affect both stream water temperature and habitat for aquatic species. Organisms most affected include many species of reptiles and amphibians, brook trout, and stoneflies. Stormwater runoff from paved areas can also wash out oil and grease and other pollutants into streams. The paved areas also restrict replenishment of groundwater and contribute to flash flooding during storm events and extreme fluctuations in stream water levels. Extreme flow fluctuations cause difficulties in the attachment of bottom dwelling organisms to the stream substrate and also cause a scouring of the substrate. Retention of riparian vegetation in unnamed headwater tributaries, known as first order streams, which may comprise as much as 50% of the streams in a watershed, can be especially critical to the protection of organisms in the downstream watershed.
The latest PA Department of Environmental Protection 303d
and 305b lists includes unnamed tributaries, not just the named tributaries as
in previous lists. This listing may
help highlight the importance of protection of unnamed tributaries. The causes of impairment of many streams in
the Neshaminy Creek watershed are indicated as water flow variability or flow
alterations due to urbanization and new development. Most of the upper and middle main stem Neshaminy Creek and
several tributaries such as Mill Creek at Langhorne Terrace are
unimpaired. These streams or their
tributaries have retained a relatively high percentage of their riparian
vegetation.
Nonresidential development, which includes office, industrial, and commercial development, is booming in the subbasin. This type of development has a high potential for impact on surface and groundwater resources due to the massive site grading, removal of vegetation, and large areas of paving for parking lots. Local land use planning should encourage these developments to maintain open space, reduce unnecessary paving, improve land use standards, and better fit of the design to the landscape contours.
Lake Luxembourg:
A Clean Lakes Phase 1 Diagnostic/Feasibility Study of the Lake Luxembourg watershed conducted in 1990-93 resulted in the development of a lake and watershed restoration plan. Excess sediments and nutrients from agricultural sources adversely affect the lake. Over 90% of sediment and nutrient loadings to the lake are from surface runoff. The reservoir reached its 100-year sediment capacity in just 9 years. The lake is hypereutrophic, with very high lake Trophic Status Indices (TSIs) (ranging from 70 to 79). Algal blooms are a frequent occurrence. Lake light penetration (transparency) is low due to suspended silt and clay particles. The low transparency inhibits the growth of aquatic macrophytes in the lake. The summer oxygen depleted (anoxic) zone or thermocline begin at relatively shallow 4 meters depth. Total phosphorus (TP) concentrations ranged from 0.16-0.2 mg/l during normal conditions and much higher (0.72mg/l) during storm events. Water from a nearby well had low TP, but was very high in nitrogen, up to 30 mg/l. Nitrates varied with seasons, with the highest N values occurring in winter and spring. The lake is phosphorus limited due to a high nitrogen/phosphorus ratio. The fishery is impaired due a lack of cover and nursery areas for desirable fish and an overabundance of introduced gizzard shad and white perch.
Eight flood control dams were constructed along the Neshaminy Creek through the PL-566 program since congressional approval in 1967. Construction of the two remaining authorized dams was put on hold in 1989. The severe flooding that occurred in the watershed in 1996 led to the formation of the Neshaminy Creek Steering Committee and Technical Team to scientifically study additional flood control strategies for the watershed. In 1997, NRCS and the Technical Team began an updated watershed study for the lower Neshaminy Creek from Route 611 down to the Delaware River. The flooding which occurred during Hurricane Floyd in September 1999 further demonstrated the need for stormwater damage reduction. Four alternative flood control programs were selected for further study and public input: no action, nonstructural solutions, a dry dam in Dark Hollow Park, and a combination of dry dam and nonstructural solutions. A draft work plan was presented at public meetings in July 2000. The nonstructural alternative, in which buildings and businesses within the 100-year floodplain would be removed, elevated or flood-proofed depending on potential flood elevation, was determined to be the most cost-effective means of reducing flood damage. Landowner participation in the nonstructural alternatives is voluntary, however. Participation rates for such measures are normally in the 60 to 75% range.
DCNR Rivers Conservation Study:
Doylestown Township conducted a study of the Neshaminy Creek in their township and nearby areas of upper-middle watershed. Preservation of open space and protection of water quality, wildlife habitat and the scenic beauty of the area was determined to be of utmost concern for residents. Results of a visual analysis of the study area indicated that Neshaminy Creek from Chalfont Borough to Forest Park has been altered from its natural state due to residential, commercial and road development and poor land management. Inadequate sedimentation and erosion controls during construction have resulted in siltation and scouring of streambanks. Runoff from bridges has also impacted creek aesthetics. Stream corridors of other portions of the study area are variously affected by some urban, commercial and office development but generally retain much of their riparian buffers. Recommendations included better implementation of stormwater management plans to control erosion, stabilization of streambanks, and development a continuous recreational greenway park adjacent to Neshaminy Creek.
Increased development and paving has a high potential to decrease infiltration to groundwater and cause groundwater depletion. Expansion of impervious payment could also lead to additional reductions in the diversity of aquatic life. The supplemental NRCS PL-566 study indicated that future land use changes and stormwater management practices might slightly reduce future flood peaks. Developers, however, must comply with recently revised local stormwater ordinances adopted under the PA ACT 167 plans for the watershed for this decrease to occur. Acquisition and removal of some buildings in the flood plain and replacement with streamside riparian buffers should also help reduce flooding potential.
Pennsylvania Growing Greener Grants:
· $6,530 (FY2000) to North Branch Neshaminy Creek Watershed Association for organization of their group.
·
$10,965 (FY1999) to Horsham Township to pursue a
community educational outreach program that includes videotape, participation
by other townships and educators, and the design and construction of an
educational sign at the site of the Kohler Park streambank restoration (WRAP
project) on Park Creek. The sign will
educate the public about the value of the streambank restoration project in
protecting water quality and habitat.
·
$112,535 (FY1999) to the American Littoral Society to
develop a comprehensive watershed assessment followed by a water
quality-focused restoration plan for the Little Neshaminy Creek. The goals of the restoration plan will be to
attain designated stream uses and water quality standards, prevent future
stream degradation, and to serve as a model for other urban watersheds.
U.S. Environmental
Protection Agency (EPA) Clean Water Act Section 319 Projects:
· $145,225 in FY1995, $154,275 in 1996, $8,300 in 1997 to Bucks County Conservation District (CD) to implement recommendations of the Lake Luxembourg Phase II Clean Lakes study to control excess sediments and nutrients in Core Creek watershed.
· Funding of a nutrient management technician in the Bucks County CD office, started in 1993
Pennsylvania Watershed Restoration Assistance Program (WRAP):
· $15,000 (FY1999) to Horsham Township, Montgomery County, for a riparian buffer restoration project in Kohler Park adjacent to Park Creek. Streambank erosion will be reduced and native vegetation will be reestablished.
Natural Resources Conservation Service (NRCS):
· Environmental Quality Incentive Program (EQIP) agricultural best management projects to reduce erosion and sedimentation nutrient enrichment in the Neshaminy Creek watershed were begun in 1997
·
Public Law (PL-566) study of flood control measures
needed in Neshaminy Creek watershed.
Department of Conservation and Natural Resources (DCNR) Rivers Conservation Grants:
· $62,500 (2000) to the Delaware Riverkeeper Network to prepare a comprehensive rivers conservation plan for the upper and middle Neshaminy Creek.
· $43,000 (1997) to Doylestown Township to develop a greenway along Neshaminy Creek and its tributaries for recreation and flood protection, to establish river conservation environmental education programs, and to develop a new river conservation zoning ordinance and clean up the streams in the watershed.
· $17,000 (1995) to Doylestown Township to develop a comprehensive multiple municipal conservation plan for Neshaminy Creek watershed. An additional $4,000 was awarded to Doylestown Township in 1996 to complete their rivers conservation plan.
Public Participation/Outreach:
DEP’s website has a watershed notebook for each of its 104 State Water Plan watersheds. Each notebook provides a brief description of the watershed with supporting data and information on agency and citizen group activities. Each notebook is organized to allow networking by watershed groups and others by providing access to send and post information about projects and activities underway in the watershed. This WRAS is also posted in the watershed notebook to allow for public comment and update. The notebooks also link to the Department’s Watershed Idea Exchange, an open forum to discuss watershed issues.
A variety of federal and local agencies and staff from other Department programs reviewed or provided information for this WRAS. These included NRCS, the Bucks and Montgomery County Conservation Districts, and the DEP Southeast Regional Office. The public participation process has begun through distribution of this WRAS at various workshops and conferences and by the county conservation districts and DEP Regional Coordinators. Public input has been and will continue to be incorporated into expanding and fine tuning the WRAS for direction on use of 319 grant funds beyond FY2000.
The total needed dollars for addressing all nonpoint source problems in the watershed is undetermined at this time and will be so until stream assessments are conducted and necessary TMDLs are developed for the entire watershed. The TMDL for Lake Luxembourg was completed in 1999. The TMDL for Lake Galena is scheduled for completion in 2001. The TMDL for Neshaminy Creek is scheduled for completion in 2003. Existing programs addressing nonpoint source issues in the watershed will continue to move forward while TMDLs are developed.
Funding needs for restoration activities in the Core Creek watershed were estimated to be $1,492,520 in the 1993 Clean Lakes Study. Dredging and installation of agricultural best management practices (BMPs) comprised most of the budget. Implementation has begun using EPA 319 funds; the Bucks County Conservation District coordinates these projects.
Funding needs for the Lake Galena watershed identified in the 1995 Clean Lakes study focused on implementation of agricultural BMPs. Needs for agriculture conservation practices were estimated to be $768,915.
Funding sources available to support the development of site-specific implementation plans and remediation projects that address the sources of water quality impairment include the EPA Clean Water Act Section 319 grant program and the newer Pennsylvania funded Growing Greener program which target reductions in nonpoint source pollution. Pennsylvania has generally placed more emphasis on funding projects slated for implementation on water bodies where TMDLs have been completed or where water quality impairments have been documented.
Pennsylvania has developed a Unified Watershed Assessment to identify priority watersheds needing restoration. Pennsylvania has worked cooperatively with agencies, organizations and the public to define watershed restoration priorities. The Commonwealth initiated a public participation process for the unified assessment and procedures for setting watershed priorities. Pennsylvania’s assessment process was published in the Pennsylvania Bulletin, DEP Update publication and World Wide Web site. It was sent to the Department’s list of watershed groups, monitoring groups, and Nonpoint Source Program mailing list. Department staff engaged in a significant outreach effort which included 23 additional events to solicit public comment. The Department received 23 written comments from a variety of agencies, conservation districts and watershed groups. Pennsylvania is committed to expanding and improving this process in the future.
TMDLs identify the amount of a pollutant that a stream or lake can assimilate without violating its water quality standards. TMDLs are calculated to include a margin of safety to protect against a mathematical or data error. TMDLs are set for each pollutant causing impairment.
Sedimentation and excess nutrient loads cause impairment of Lake Luxembourg. Lake Luxembourg reached its 100-year sediment capacity in just nine years after filling. Agricultural practices and rapid urbanization combined with highly erodible soils contribute to high sediment loads to the lake during storm events. Reduced water depth, turbidity, and excess algae growths have interfered with the quality of aquatic and lakeside recreation, water supply and flood control uses of the lake.
Since Pennsylvania does not have water quality criteria for nutrients or sediment, Carlson’s Trophic Status Index (TSI) was used as the indicator of lake water quality to determine the necessary phosphorus (P) reduction targets for the TMDL. The relationship between the in-lake P concentration and TSI was used to estimate load reductions that will meet water quality objectives. Suspended solids reduction targets were set based on the life design of the lake and its sediment-filling rate. Estimated loadings were computed for each land use in the watershed, based on accepted land use runoff coefficients.
Additional information for pollutant loadings was obtained by monitoring some of the lake inlets during dry and storm events. The non-controllable load was estimated by using an all forest scenario to estimate what the natural conditions would be without the influence of man. A 20% change in P loading above the estimated natural condition was used to allow for a man-induced condition. Annual load reductions were computed and targets were set for 13 land use types in order to meet the P and sediment TMDLs. The highest load reductions for P were necessary in the commercial, row crops and nurseries land use categories. The highest load reductions for sediment were needed in the residential land use category; however, row crops, pasture/grass, nurseries, park, institutional, and commercial land uses were also targeted for reductions.
Remediation activities to reduce nutrient and sediment contributions as recommended in the 1994 Phase I Clean Lakes study are currently being implemented. The projects listed in the table below are agricultural best management practices (BMPs) designed to reduce sediment runoff and address a significant portion of the work needed to meet the objectives for agricultural land uses. Much more needs to be done to meet stream use criteria, especially in the developed areas of the watershed. Runoff from residential and commercial areas needs to be addressed along with agricultural land use categories targeted for load reductions. To support this effort, the public must be educated on ways to control nutrient and sediment runoff at their homes and businesses. Additional funding is needed for the completion of agricultural BMPs, water quality sampling, public education, and documentation of load reduction. These studies will help determine if the assumptions for phosphorus loading in the TMDL are correct and would also measure the performance efficiency of the various BMPs.
Completed Restoration Projects in Lake
Luxembourg Watershed
|
||
Practice
Installed/Task Completed
|
Number Installed
|
Approximate Cost |
|
Animal Waste Facilities |
1 |
$2,790 |
|
Barnyard Runoff Controls |
1 |
$11,240 |
|
Diversions |
7,875 ft. |
$12,980 |
|
Other Practices |
5 |
$12,450 |
|
Sediment Basins |
9 |
$112,705 |
|
Terraces |
22,935 ft. |
$31,990 |
|
Underground Outlets |
3 |
$8,000 |
|
Grass Waterways |
40,190 ft. |
$103,150 |
|
Total |
|
$297,000 |
Additional information and loadings calculations can be
found in the Final TMDL on the Department’s website at http://www.dep.state.pa.us/, choose
directLink, TMDL, Lake Luxembourg.
The assessment of the subbasin has been completed. Impaired waters have been placed on the 303d list. The watershed assessment underway in Little Neshaminy Creek watershed will provide management plans and prioritize restoration needs. The Act 67 stormwater plans should also be used to guide stormwater management. Restoration efforts have begun in several areas of the subbasin through grant to the Delaware Riverkeeper, several townships, and the conservation districts.
The highest restoration needs in this subbasin are the restoration of riparian buffers, streambank stabilization, and stormwater runoff controls. Restoration efforts should be directed towards these impaired stream and lake areas:
· Neshaminy Creek: 4.51 miles of lower main stem and 52.23 miles of unnamed tributaries: stormwater and agricultural best management practices (BMPs)
· West Branch Neshaminy Creek: 7.77 miles of main stem and 24.03 miles of unnamed tributaries: agricultural BMPs and better controls on land development
· North Branch Neshaminy Creek: 3.32 miles main stem and Pine Run at Chalfont, including Lake Galena: agricultural BMPs, repair of leaky septic systems, Canada goose controls, better controls on stream flow variability and stormwater runoff, riparian restoration and stabilization
· Cooks Run, entire basin: stormwater management BMPs
· Mill Creek at Tradesville, entire basin; better controls on residential development and surface mining
· Little Neshaminy Creek and its tributary Park Creek, entire basin: stormwater management
· Core Creek: entire basin including Lake Luxembourg, agricultural BMPs and better controls on stream flow variability
Implementation of BMPs for agricultural sources in the impaired areas should reduce nutrients and sediment loadings. Recommended agricultural BMPs include animal waste storage facilities, barnyard runoff controls, diversions, sediment basins, terraces, underground outlets, and grass waterways. Streambank stabilization and fencing should reduce phosphorus and sediment loads in the affected areas. Streambank fencing will keep livestock out of the streams and allow restoration of riparian zones to trap sediment and phosphorus, thus keeping these pollutants from reaching the stream. A reduction coefficient of 75% for nutrients and sediment is reasonable to expect with these BMPs. The 75% reduction in loading from BMP implementation is derived from empirical data from previous studies of BMP effectiveness reported in the literature and used by the Susquehanna River Basin Commission in their efforts to model pollutant reductions that may result from various load reduction strategies.
Better stormwater management and installation of BMPs to control runoff and increase infiltration should help reduce impairment from urban runoff; however, the high amount of paving in many portions of the subbasin may impede full restoration of water quality and aquatic habitat.
· State Water Plan, Subbasin 2, Central Delaware River. Department of Environmental Protection, July 1983
· USGS Topographic Maps
· 319 project proposals and summaries
· DEP: Watershed Notebooks, Unified Assessment Document, and information from databases.
· Map of Draft Level III and IV Ecoregions of Pennsylvania and the Blue Ridge Mountains, Ridge and Valley, and Central Appalachians of EPA Regions III
· Final Report, Phase I Clean Lakes Diagnostic Feasibility Study Lake Luxembourg, Bucks County, PA. Coastal Environmental Services, Inc., 1994.
· Final Report, Phase I Clean Lakes Diagnostic Feasibility Study of Lake Galena, Bucks County, PA, 1995. F. X. Browne, Inc.
· Delaware Riverkeeper web site information and fact sheets.
· From the Mountains to the Sea: The State of Maryland’s Freshwater Streams. Maryland Department of Natural Resources and U. S. Environmental Protection Agency. EPA Publication EPA/903/R-99/023. 1999.
· Final TMDL for Lake Luxembourg Watershed. DEP Bureau of Watershed Conservation. 1999.
Streams in
Subbasin 02F: 303d/305b Listings
|
Stream |
Stream Code |
Drainage basin (square
miles) |
Miles Impaired |
Miles Attained |
Impairment Causes/
Sources/ Comments |
|
2-Neshaminy Creek |
02484 |
232 |
4.51
main stem; and 52.23,
63
UNTs |
36.83
main stem; and 49.15, 86
UNTs |
Siltation
from land development; Siltation, nutrients & water/flow variability from
urban runoff/storm sewers & municipal point sources Siltation
& flow alterations from surface mining; Excessive
algal growth & siltation from agriculture |
|
02868 |
25.0 |
7.77,
main stem; and 24.03, 29
UNTs |
3.6, 3
UNTs |
Excessive
algal growth from AG and municipal Pt sources; Water/flow variability from
Land development |
|
|
3-North Branch Neshaminy
Creek |
02789 |
31.6 |
3.32
main stem |
7.59
main stem; 26.58, 53
UNTs |
Water/flow
variability from upstream impoundment |
|
4-Pine
Run at Chalfont & 20 UNTs |
02790 |
11.7 |
18.78 |
|
Siltation
& excessive algal growth from land development and upstream impoundment |
|
3-Cooks
Run & 4 UNTs |
02776 |
3.32 |
3.16 |
|
Nutrients
from Municipal point sources & urban runoff/storm sewers |
|
3-Mill
Creek at Tradesville |
02741 |
4.88 |
7.45
main stem & 12 UNTs; 6.21,
main stem & 15 UNTs |
|
Flow
alterations, siltation from surface mining Flow
alterations, siltation from small residential development |
|
3-Little Neshaminy Creek & 42 UNTs |
02638 |
43.0 |
50.76 15.78
main stem; 34.98, 42 UNTs |
|
Water/flow
variability & siltation from urban runoff/storm sewers; Fish
consumption advisory for PCB |
|
4-Park
Creek & 6 UNTs |
02661 |
11.8 |
6.19 6.84 main stem; 7
UNTs |
|
Nutrients,
Pathogens,
organic enrichment/ low DO; other from Municipal point sources; Water &
flow variability & nutrients from Urban runoff, storm sewers; Fish
consumption advisory for PCB |
|
02596 |
21.9 |
|
21.88 |
|
|
|
4-Lahaska
Creek & 4 UNTs |
02632 |
6.97 |
|
9.6 |
|
|
4-Watson
Creek & 5 UNTs |
4.26 |
|
6.19 |
|
|
|
4-Robin
Run & 7 UNTs |
02598 |
2.27 |
|
5.76 |
|
|
3-Newtown
Creek & 9 UNTs |
02561 |
6.29 |
|
9.12 |
|
|
3-Core
Creek & 12 UNTs |
02543 |
9.77 |
15.82 |
|
Flow
& thermal alterations & siltation from upstream impoundment and AG |
|
3-Mill
Creek at Langhorne Terrace & 8 UNTs |
02519 |
17.4 |
|
13.44 |
|
|
4-Ironworks
Creek & 5 UNTs |
02526 |
6.33 |
|
9.67 |
|
|
4-Pine
Run at Langhorne Terrace & 4 UNTs |
02520 |
2.66 |
|
4.16 |
|
Streams
are listed in order from upstream to downstream. A stream with the number 2 is a tributary to a number 1 stream,
3’s are tributaries to 2’s, etc.
Delaware River =1.
Totals
include unnamed tributaries (UNTs) and main stem as indicated. AG= agriculture
Lake Galena and Lake Luxembourg are on the Lake 303d list for impairment from excess nutrients and suspended solids from agriculture, urban runoff/storm sewers, and on-site wastewater.