Water Quality Monitoring And Assessment Section (DSB)
Division of Water Quality Assessment And Standards
Bureau of Water Supply and Wastewater Management
Department of Environmental Protection
June 2000
Revised July 2001
GENERAL WATERSHED DESCRIPTION
Unnamed Tributary Chester Creek (00595) is located in Thornbury Township, Delaware County. This basin has a drainage area of 1.2 square miles and contains 2.5 stream miles. The candidate stream is currently designated Trout Stocking (TSF). In response to a petition submitted by Frank Akutowicz, this watershed was evaluated for a possible redesignation to Exceptional Value Waters (EV). This evaluation is based on field surveys conducted in July 1998 and April 1999.
This watershed contains no major population centers. The large majority is owned by the Glen Mills School and is mostly undeveloped land. The school is currently building a golf course that will occupy a large portion of the watershed. A low-density residential subdivision is located on the western edge of the basin and a small area of agriculture occupies the southern edge. The National Wetlands Inventory maps indicate the presence of small areas of emergent marsh and forested and shrub swamp adjacent to the streams in this basin. Based on these maps, wetlands constitute less than 5% of the total watershed area.
WATER QUALITY AND USES
Surface Water
No long term water quality data were available to allow a direct comparison
to water quality criteria. Grab samples were taken at three stations (Table 2).
Water quality was generally good at all stations. Nitrates were highest at
Station 1UCC probably due to a limited amount of agriculture in the upper part
of the basin. The instantaneous nature of grab samples precludes comparison to
applicable water quality criteria. The indigenous aquatic community is a better
indicator of long term conditions and is used as a measure of both water quality
and ecological significance.
There are no permitted surface water withdrawals or NPDES discharges in the candidate watershed.
Aquatic Biota
The total habitat score for aquatic biota at Station 3UCC was in the
Suboptimal range (Table 3). Instream habitat has been degraded by erosion and
the riparian zone has been impacted by the construction of the golf course.
Benthic macroinvertebrate samples were collected at Station 3UCC during the
April 1999 survey. The results of these sampling efforts are presented in Table
4. Benthic macroinvertebrates were collected using sampling techniques adapted
from the EPA Rapid Bioassessment Protocols. Taxonomic diversity was reasonably
good but the number of intolerant taxa is indicative of the negative effects of
human activity.
A total of 6 fish species were collected at Station 3UCC (Table 5). The fish community is a mixture of both warm water and cold water species. American eel, a migratory fish species, was also present. Communications from the Pennsylvania Fish and Boat Commission (PFBC) confirm that eels are present throughout the entire basin of Chester Creek. Streams within the candidate basin support all designated uses.
NATIONAL, STATE, REGIONAL, OR LOCAL SIGNIFICANCE
There are no known portions of the Unnamed Tributary Chester Creek basin that exhibit the characteristics of outstanding national, state, regional, or local resource waters under the Department's regulatory criteria.
ECOLOGICAL OR RECREATIONAL SIGNIFICANCE
Selected benthic macroinvertebrate community metrics were compared to a reference station with a comparable drainage area (Table 7). Birch Run (01563), a tributary to French Creek (see Table 1), was used as the reference stream. This stream is currently designated EV in Chapter 93 and has a drainage area of 6.5 square miles. Both candidate and reference basins are located in the Piedmont Uplands (64c) subecoregion. All sampling was conducted on the same day to minimize the effects of seasonal variation. This comparison was done using the following metrics which were selected as being indicative of community health: taxa richness; modified EPT index (total number of intolerant Ephemeroptera, Plecoptera, and Trichoptera taxa); modified Hilsenhoff Biotic Index; percent dominant taxon; and percent modified mayflies.
Based on these five metrics, Station 3UCC had a biological condition score that was 60% of the reference station. The candidate basin does not meet the 83% comparison standard required for redesignation to High Quality (HQ).
PUBLIC RESPONSE AND PARTICIPATION SUMMARY
The Department provided public notice of this redesignation evaluation and requested any technical data from the general public through publication in the Pennsylvania Bulletin on December 25, 1999 (29 Pa.B 6524). A similar notice was also published in the Daily Local News, West Chester on December 27, 1999. In addition, Thornbury Township was notified of the evaluation in a letter dated December 23, 1999. The Delaware County Planning Department was also notified at the same time. No data on water chemistry, instream habitat, or the aquatic community were received in response to these notices.
The Department sent copies of this draft report along with a cover letter dated May 17, 2001 requesting comments within a 30-day period, to Frank Akutowicz, the Delaware County Planning Department, and Thornbury Township. No comments were received in response to this request.
RECOMMENDATION
Based on applicable regulatory criteria the Department recommends that the Unnamed Tributary Chester Creek basin (00595) retain the current Trout Stocking (TSF) use designation with the addition of Migratory Fishes (MF) based on the presence of American eel. This recommendation affects approximately 2.5 stream miles. This designation provides less protection than the EV designation requested by the petitioner. The Department also recommends adding MF to the entire Chester Creek basin.
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