Since 1969, the U.S. Geological Survey and the
Chester County Water Resources
Authority
have conducted a cooperative program to evaluate stream ecology and water-quality conditions using
benthic macroinvertebrates and stream-water chemistry. The Stream Conditions of Chester County Program
has sampled streams every fall for over 30 years. The initial goals of the program
were to evaluate stream-water quality and to further the understanding of changes in the stream ecosystem
in response to urbanization. The current goals of the program are to use the data to
monitor current conditions and determine trends. Data from the program have been used to help
support Chester County Landscapes by providing information on biological diversity and
water-quality conditions. Without monitoring it is impossible to determine if changes in land use or
environmental policies and regulation are having a positive affect on water quality.
Benthic macroinvertebrates are macroscopic animals that inhabit the bottoms of aquatic habitats.
Freshwater forms include aquatic insects and other invertebrates including clams, crustaceans, snails,
and worms. Factors such as streamflow, food availability, habitat, temperature, and water quality
determine the makeup of the macroinvertebrate community. By sampling in similar habitats with similar
physical conditions, water quality becomes the determining factor controlling community structure.
Changes in abundance, diversity, species richness, and presence or absence of pollution tolerant or
intolerant species can be measured and related to water quality. Trends in water quality can be
determined by sampling at a single location over several years and observing changes to the community
structure.
Benthic macroinvertebrates are well suited as water-quality indicators because of their biology and
availability. They are present in most aquatic systems and are relatively easy to collect. They are
indicators of overall water quality and can be used to identify specific types and sources of degraded
water quality. Benthic macroinvertebrates have limited mobility and cannot avoid poor water-quality
conditions. They are sensitive to a wide range of environmental impacts including chemical and physical
impairments.
Biological samples collected for the Stream Conditions of Chester County Biological Monitoring Network
consist of benthic macroinvertebrates collected from a riffle area of the stream. A riffle habitat is used
because macroinvertebrate diversity and abundance is usually highest there.
Sample collection and identification methods remained consistent from 1970 through 1997.
Benthic macroinvertebrates were collected by taking 10 rocks (45-90 millimeters in diameter) at random.
Water-quality conditions were determined by analysis of the community structure and
calculation of Brillouin's Diversity Index. In this index, diversity is high if
a community contains many organisms that are evenly distributed; diversity is low if there are few
organisms that are unevenly distributed. Brillouin's diversity index values greater than 3.0 are associated
with waters receiving little or no organic wastes. Values between 1.0 and 3.0 are associated with
waters receiving moderate organic wastes, and values below 1.0 are associated with waters receiving
heavy organic wastes.
A new sampling protocol for the Stream Conditions of Chester County Biological Monitoring Network was
established in 1998 to update the program and meet the county's current needs. The new sampling protocols
are based on Rapid Bioassessment Protocols (RBP) established by the U.S. Environmental Protection Agency.
Samples are collected from areas of various velocities from within a riffle.
Water-quality conditions are determined by analysis of the community structure and calculation of
various metrics including total individuals, taxa richness, Brillouin's Diversity Index, Hilsonhoff
Biotic Index, EPT taxa richness, percent EPT taxa, and percent dominate taxa. This sampling method
will allow the county to compare results with those from the Pennsylvania
Department of Environmental Protection, universities, local watershed associations, and other federal
agencies that are using RBP's.
Sampling locations were adjusted in 1998 to relocate the sampling sites to better meet the county's
needs. Twenty-seven sites are samples each year. Eighteen sites are fixed integrator or reference
sites (see table below). These fixed integrator sites are sampled every year. Nine sites are selected each
year to assess the water quality in areas of interest to the county. The realignment of sampling sites
provides better spatial coverage while increasing flexibility. The increased flexibility allows for
the placement of sites to study the effects on water-quality of specific events such as road
construction or residential and business developments. This makes the program capable of both short-term
and long-term evaluation of stream-water quality.
The Stream Conditions of Chester County Program has determined that the quality of Chester County
streams has greatly improved since 1970. Current benthic macroinvertebrate communities are more
diverse and contain more pollution sensitive species compared to communities sampled at the beginning
of the program. Forty-five of forty-six sites analyzed between 1970 and 1986 had a statistically
significant increase in diversity.
| SITE NUMBER | USGS STATION NUMBER | SITE NAME | YEARS SAMPLED |
|---|---|---|---|
| SCHUYLKILL RIVER WATERSHED | |||
| 5 | 01472190 | Pickering Creek near Phoenixville | 1970-2003 |
| 10 | 01472080 | Pigeon Creek near Slonaker | 1970-2003 |
| 15 | 01472157 | French Creek near Phoenixville | 1970-2003 |
| 52 | 01473169 | Valley Creek at PA Turnpike bridge near Valley Forge | 1998-2003 |
| 1 | 01472190 | Pickering Creek near Eagle | 1970-1996, 2002 |
| 3 | 01472080 | Pickering Creek near Merlin | 1970-1996, 2002 |
| 12 | 01472157 | South Branch French Creek at Coventryville | 1970-1997, 2002 |
| 13 | 01473169 | French Creek near Coventryville | 1970-1997, 2002 |
| DELAWARE RIVER WATERSHED | |||
| 24 | 01476835 | East Branch Chester Creek at Westtown | 1970-2003 |
| 53 | 01475850 | Crum Creek at Newtown Square | 1998-2003 |
| 81 | 01476450 | Ridley Creek at PA Rt 3 near Willistown | 2000-2003 |
| BRANDYWINE CREEK WATERSHED | |||
| 42 | 01480653 | East Branch Brandywine Creek at Glenmoore | 1973-2003 |
| 46 | 01480629 | Buck Run at Doe Run | 1973-2003 |
54 | 01480870 |
East Branch Brandywine Creek below Downingtown |
1998-2003 | |
| 56 | 01480617 | West Branch Brandywine Creek at Modena | 1998-2003 |
| 57 | 01480300 | West Branch Brandywine Creek near Honey Brook | 1998-2003 |
| 36 | 01480700 | East Branch Brandywine Creek near Downingtown | 2003 |
| 38 | 01480640 | West Branch Brandywine Creek at Wawaset | 2003 |
| 39 | 01480950 | East Branch Brandywine Creek at Wawaset | 2003 |
| 48 | 01480648 | East Branch Brandywine Creek near Cupola | 2003 |
| 69 | 01480636 | Broad Run at Romansville | 1999, 2001-2002 |
| 70 | 01480638 | Broad Run at Northbrook | 1999, 2001-2002 |
| 76 | 0148063750 | Broad Run at Marshallton | 2001-2002 |
| 77 | 01480743 | Beaver Creek at Reeceville | 2001 |
| 78 | 01480745 | Beaver Creek at Guthriesville | 2001 |
| 79 | 01480750 | Beaver Creek at Bondsville | 2001 |
| 80 | 01480660 | East Branch Brandywine Creek at Lyndell | 2003 |
| 85 | 01480658 | Indian Run near Glenmoore | 2003 |
| 86 | 01480675 | Marsh Creek near Glenmoore | 2003 |
| 87 | 01480800 | East Branch Brandywine Creek at Downingtown | 2003 |
| CHRISTIANA RIVER WATERSHED | |||
| 26 | 01479800 | East Branch Red Clay Creek near Five Points | 1970-2003 |
| 28 | 01478120 | East Branch White Clay Creek at Avondale | 1970-2003 |
| 55 | 01479700 | West Branch Red Clay Creek near Kennett Square | 1998-2003 |
| 58 | 01478230 | Middle Branch White Clay Creek nr Avondale | 1998-2003 |
| 82 | 01479800 | Trout Run at Avondale | 2002 |
| 83 | 01478120 | East Br. White Clay Creek nr Stricklersville | 2002 |
| BIG ELK CREEK WATERSHED | |||
| 59 | 01494953 | Big Elk Creek at Maple Grove | 1998-2003 |
| SUSQUEHANNA RIVER WATERSHED | |||
| 60 | 01578347 | East Branch Octoraro Creek near Steelville | 1998-2003 |
Hardy, M.A., Wetzel, K.L., and Moore C.R., 1995, Land use, organochlorine compound concentrations,
and trends in benthic invertebrate communities in selected stream basins in Chester County, Pennsylvania:
U.S. Geological Survey Water-Resources Investigations Report 94-4060, 78 p.
[ abstract ]
Lium, B.W., 1976, Limnological data for the major streams in Chester County, Pennsylvania:
U.S. Geological Survey Open-File Report, 219 p.
Lium, B.W., 1977, Limnological studies of the major streams in Chester County, Pennsylvania:
U.S. Geological Survey Open-File Report 77-462, 37 p.
[ abstract ]
Moore, C.R., 1987, Determination of benthic-invertebrate indices and water-quality trends of
selected streams in Chester County, Pennsylvania:
U.S. Geological Survey Water-Resources Investigations Report 85-4177, 62 p.
[ abstract ]
Moore, C.R., 1989, Physical, chemical, and biological data for selected streams in
Chester County, Pennsylvania, 1969-80:
U.S. Geological Survey Open-File Report 85-686, 289 p.
[ abstract ]
Reif, A.G., 2000, Physical, chemical, and biological data for selected streams in
Chester County, Pennsylvania, 1981-94:
U.S. Geological Survey Open-File Report 99-216, 607 p.
[ Very large PDF file ]
Reif, A.G., 2000, Physical, chemical, and biological data for selected streams in
Chester County, Pennsylvania, 1995-97: U.S. Geological Survey Open-File report 00-238, 147 p.
[ PDF file ]
Reif, A.G., 2002, Assessment of stream conditions and trends in biological and water-chemistry data
from selected streams in Chester County, Pennsylvania, 1981-97:
U.S. Geological Survey Water-Resources Investigations Report 02-4242, 77 p.
[ PDF file ]
Reif, A.G., 2002, Assessment of stream quality using biological indicies at selected sites in the
Schuylkill River Basin,
Chester County, Pennsylvania, 1981-97: U.S. Geological Survey Fact Sheet FS-114-02, 4 p.
[ PDF file ]
Reif, A.G., 2002, Assessment of stream quality using biological indicies at selected sites in the
Big Elk and Octoraro
Creek Basins, Chester County, Pennsylvania, 1981-97: U.S. Geological Survey Fact Sheet FS-115-02, 4 p.
[ PDF file ]
Reif, A.G., 2002, Assessment of stream quality using biological indicies at selected sites in the
Delaware River Basin,
Chester County, Pennsylvania, 1981-97: U.S. Geological Survey Fact Sheet FS-116-02, 4 p.
[ PDF file ]
Reif, A.G., 2002, Assessment of stream quality using biological indicies at selected sites in the
Brandywine Creek Basin,
Chester County, Pennsylvania, 1981-97: U.S. Geological Survey Fact Sheet FS-117-02, 4 p.
[ PDF file ]
Reif, A.G., 2002, Assessment of stream quality using biological indicies at selected sites in the
Red Clay and White Clay Creek Basins,
Chester County, Pennsylvania, 1981-97: U.S. Geological Survey Fact Sheet FS-118-02, 4 p.
[ PDF file ]
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