LITTLE CONESTOGA CREEK WATERSHED ASSESSMENT, LANCASTER, PA.

Bowers, Fallon, and Hawes, figure 3 Longitudinal profile for the east branch of Bachman Run is closer to the expected exponential curve.

FACULTY STUDENTS Andy deWet, Franklin & Marshall College Garrett Bayrd, Whitman College Jeff Marshall, Franklin & Marshall College Abby Bowers, The College of Wooster Dorothy Merritts, Franklin & Marshall College Kyle Cavanaugh Trinity Univesrity Steve Weaver, Colorado College Aaron Davis, Colorado College Jesse Yoburn, TA, Franklin & Marshall College Jennifer Fallon, Washington and Lee Univbersity Nancy Harris, Carleton College Ashley Hawes, Smith College James Orsher, Amherst College Lauren Manion, Frankln & Marshall College Jaime Tomlinson , Frankln & Marshall College LITTLE CONESTOGA CREEK WATERSHED ASSESSMENT, LANCASTER, PA.

ANDREW P. DE WET, Franklin & Marshall College JEFF MARSHALL, Franklin & Marshall College DOROTHY MERRITTS, Franklin & Marshall College STEVE WEAVER, Colorado College

Title: (lcwmapf.eps) INTRODUCTION Creator: Adobe Illustrator(R) 8.0 Preview: This EPS picture was not saved with a preview River systems have been dramatically impacted (TIFF or PICT) included in it Comment: This EPS picture will print to a postscript printer by dams, reservoirs, channelization and land-use but not to other types of printers changes. Impacts include loss of water quality and biodiversity and changes in the functional characteristics of streams (Petts & Calow, 1996). At the same time there are increasing demands being placed on river systems. Over the last few decades numerous attempts have been made to restore damaged stream ecosystems. Given the complexity of river systems there is an increasing efforts to apply scientific principles to the development of environmentally sensitive approaches for managing rivers. In numerous individuals and organizations, including the state government, have recognized the urgency of the situation and are encouraging restoration efforts through legislative initiatives and funding opportunities. Most streams in Lancaster County, southeastern Pennsylvania, have been heavily impacted by human activities. Land-use change has dramatically accelerated over the last few Figure 1. The Little Conestoga Creek Watershed in decades and concern over stream health has Lancaster County, PA including project locations (1 = resulted in numerous stream restoration projects. Bachman Run, 2 = Swarr Run, 3 = Long’s Park Creek). Local watershed groups have been formed and stream restoration projects are being initiated or Unfortunately many of these initiatives are proposed in numerous locations in the county. occurring without significant scientific input. There is a need to provide this information to these efforts in order to maximize the potential groups including trout fishermen, conservation for success. organizations and local governments. At least 6 BACKGROUND stream restoration projects have been completed or are in progress in the County. Prior to 1700, the area of Lancaster County was inhabited by Native Americans, particularly the The Little Conestoga Creek Susquehannock group (Kent, 1984; Wallace, 1989). In the early 1700's the area was settled The Little Conestoga Creek is one of the main and rapidly cleared by Europeans. Lancaster tributaries of the Conestoga Creek and is located County was founded in 1729 and Lancaster City completely within Lancaster County (Figure 1). 2 in 1730. By 1999 the County's population was The watershed covers an area of 65.6 mi and is 460,000 (US Census Bureau, 2000). Since the 68% agricultural, 22% urban and 10% forested 1950's the population has increased by between (Loper & Davis, 1998). Much of the watershed 9 and 15% per decade and it is projected that is within the Urban Growth Boundary of around 110,000 people will be added to the Lancaster City and is undergoing rapid change county population over the next 20 years. from agriculture to suburban and urban land use. Lancaster County also ranks as one of the most About 90% of the watershed is underlain by agriculturally productive areas in the US. It fractured carbonate bedrock particularly of the supports large Amish and Mennonite Conestoga Formation. The thick residual soils communities and is a top tourist destination in produced from the carbonate produce rich Pennsylvania. agricultural topsoil and as a result agriculture is still the leading land-use in most of the sub- The steady increase in population has resulted in basins of the watershed. However, at least one gradual conversion of woodlands to fertile sub-basin is 82% urban. agricultural land and increasingly the conversion of agricultural land to urban and Stream water in the basin is used for irrigation, suburban development. Between 1970 and livestock, and commercial operations but is not 1990 the proportion of county land defined as used for public supply. Residents in the basin urban more than doubled, from 44 square miles obtain their water from municipal water systems to 105 square miles, out of a total of 946 square (83%) which obtain their water from the miles (Lancaster County Water Resources Task and the , or Force, 1996). At present, only about 11% of a from private wells. Discharges into the basin once fully forested county consists of woodland. include industries with National Pollution Most of these wooded areas occur as narrow Discharge Elimination System (NPDES) strips along the Conestoga and Susquehanna permits, storm-water, and sewage treatment rivers where the banks are steep and unsuitable plants (Loper & Davis, 1998). for farming, as small woodlots, or on elevated Nutrient levels in the basin are high with the ridges beyond the border of Lancaster City. lower part of the West Branch of the Little The Conestoga Creek, the main drainage in Conestoga frequently having nitrate Lancaster County, flows into the Susquehanna concentrations above 10mg/L. As expected River and then into the . Most nutrients are highest in sub-basins with the of the rivers in the county are highly impacted highest agricultural land use. Urban/suburban by agricultural and urban land use. For development produces other impacts such as example, the Conestoga Creek has the highest increased sediment loads and bioassessment nutrient yields entering the Susquehanna River studies have shown that almost the whole (Ott et al., 1991). Concern about local and watershed is impaired (Loper & Davis, 1998). regional environmental issues has led to a Recently a grassroots watershed alliance has dramatic rise in interest in stream restoration in been formed for the Little Conestoga Creek the county. Interest has come from numerous (The Little Conestoga Watershed Alliance - LCWA). Several stream restoration projects is bank erosion, channel incision, and channel have been proposed but little is known about widening. Many landowners are responding where the main problems exist in the watershed. with hard engineering ‘solutions’. To some extent projects are determined by opportunity - developers that are prepared to Project 2: Swarr Run modify plans to accommodate environmental Students: Garrett Bayrd, Aaron Davis, and friendly stream development or land owners Nancy Harris. prepared to allow a stream restoration project on their land. However, there is a need to study the This sub-basin includes agricultural land-use as dynamics of the stream system in order to well as suburban developments. Many of the understand how the system is responding to the suburban areas were developed before the changes that are occurring in the watershed. implementation of storm water management regulations in Pennsylvania. The resulting dramatic increase in discharge, combined with a reduced sediment load, has resulted in channel incision. Where bedrock, or armored channel beds occur, lateral erosion and channel widening is evident. Straightening of many of the stream channels during the 1940’s and 1950’s has exacerbated the problems by increasing the stream gradients. Uncontrolled access to the streams by livestock has resulted in wide, shallow channels in many areas.

Project 3: Long’s Park Creek Figure 2. The Little Conestoga Watershed Assessment Students: Kyle Cavanaugh, Lauren Manion, participants on a field trip to the Chesapeake Bay. James Orsher, and Jaime Tomlinson. PROJECTS From the beginning it became clear that we The urban development in this small sub-basin could not study the whole watershed in detail. distinguishes it from the other tributaries of the We decided to divide into 3 groups and each LCW. The channel is highly modified by group would study a sub-basin of the LCW that channelization, hard engineering of the banks, represented a different land-use history. and floodplain destruction. The nutrient and sediment content of the creek is generally lower Project 1: Bachman Run that the other tributaries of the LCW, while the Students: Ashley Hawes, Jennifer Fallon, and metal content of the sediment is much higher. Abby Bowers. CONCLUSIONS This sub-basin is experiencing rapid sub- During this study it became abundantly clear urbanization. Conversion of agricultural lands that streams are complex systems. Streams, to suburban developments and improved erosion particularly in areas undergoing rapid land-use controls during construction appear to be changes, are often out of equilibrium. In the reducing the sediment flow into this stream. LCW, deforestation since the 1700’s probably Reduced sediment loads and increased resulted in a dramatic increase in the sediment discharge is resulting in the remobilization of flux to the floodplain system. Improvements in the floodplain and channel sediments. The result agricultural practices and sub-urbanization have reduced this sediment influx, while rapid run-off has increased. Floodplain and channel sediments are now being remobilized. Locally this results in complex, and frequently unwelcome changes in the channel morphology. Perhaps more importantly increased sediment in the streams is negatively impacting ecosystems downstream such as the Chesapeake Bay. ACKNOWLEDGEMENTS We thank the KECK Geology Consortium and NSF for supporting this project. Jesse Yoburn helped with logistics and technical problems and was funded through the Franklin & Marshall College Hackman fellowship program. Janie Wissing helped in countless ways. REFERENCES CITED Kent, B. C., 1984, Susquehanna’s Indians. Anthropological Series n.6, The Pennsylvania Historical and Museum Commission, Harrisburg, PA, 438 p. Lancaster County Water Resources Task Force, 1996, Lancaster County Water Resources Plan: Water Supply Plan and Wellhead Protection Program. Lancaster County Planning Commission, Lancaster, PA. 245p. Loper, Connie A. and Davis, Ryan C., 1998, A Snapshot Evaluation of Stream Environmental Quality in the Little Conestoga Creek Basin, Lancaster County, Pa. USGS Water Resources Investigations Report 98-4173. Ott, Arthur N., 1991, Nutrient Loading Status of the Conestoga River Basin - 1985-1989, Susquehanna River Basin Commission, Publication No. 133, 14p. Petts, Geoffrey and Calow, Peter (Editors), 1997, River Restoration. Blackwell Science, 231p.

Wallace, P. A.W., 1989, Indians in Pennsylvania. Anthropological Series n.5, The Pennsylvania Historical and Museum Commission, Harrisburg, PA, 200 pp. A GEOMORPHIC INTERPERATION OF THE SWARR RUN WATERSHED OF LANCASTER COUNTY, PENNSYLVANIA

GARRETT B. BAYRD Department of Geology, Whitman College Sponsor: Pat Spencer, Whitman College

AARON G. DAVIS Department of Geology, Colorado College Sponsor: Christine Siddoway, Colorado College

NANCY J. HARRIS Department of Geology, Carleton College Sponsor: Mary Savina, Carleton College

the Swarr Run along the Mann farm to see how the presence of cows can affect the INTRODUCTION channel's geomorphology. This area is also The Little Conestoga Waters drains directly interesting because the channel was into the Conestoga River which, in turn, drains straightened between 1947 and 1958 in order into the Susquehanna River, the largest to create more usable farmland(Carlson, tributary of the Chesapeake Bay. This 2001). Our final study location is immediately watershed is of particular concern because upstream in the Snavely Farm, which recent studies have shown that increased historically has had similar land use to the amounts of sediment in the Chesapeake Bay Mann Farm but stopped allowing cows in the tributaries result in lower light levels in the river fifteen years ago. In each location we shallow and sensitive Chesapeake Bay. This observed differences in channel stems from areas such as the Little Conestoga, geomorphology which reflects differences in where current land practices encourage land use, local geology, and temporal change erosion through impervious land cover, poor in the river to maintain a state of equilibrium. livestock management, and the deterioration and confinement of riparian zones. In our Swarr Run Watershed watershed we looked at three different 2 locations in order to examine how the river's Swarr Run has a drainage area of 7.2 mi physical parameters change in areas of which represents a significant portion of the different land use. We examined a small Little Conestoga watershed. (Lopar, Davis, tributary of Swarr Run called Miller's Run 1998) Historically, agriculture has been the which is representative of the upper reaches of primary land use and 68% of the land the watershed. Miller's Run gives us a picture continues to be used by agriculture. Many of how suburban sprawl can affect river farms continue to use poor livestock and geomorphology. We also studied a stretch of farming practices such as allowing cows to graze freely in the stream channel, clearing of grain size distribution for each sample using a riparian vegetation, and straitening channels to series of sieves in a Rototap for fourteen maximize useable farmland. Within the last minutes. This gives us clues to establishing twenty years urban sprawl from the city of how the sediment record preserves major Lancaster has prompted significant regional land use changes. When analyzing development in the Swarr Run watershed. Miller’s run we used a hand level and hipchain Currently, 19% of the land is characterized as to create fairly accurate longitudinal profile urbanized. This development increases for an 800m stretch of the run. We were able impervious cover that tends to make streams to use this method because the elevation prone to flash floods. Development adjacent changes in Miller’s Run are far greater than in to the stream tends to confine and straighten the Snavely and Mann Farms. We then fit this the channel through the use of riprap. Also, data into the context of the entire Miller’s Run many homeowners mow riparian vegetation longitudinal profile based on TOPO map. that is important for maintaining stable banks. Presently, only 12% of the watershed remain RESULTS AND DISCUSSION forested resulting in a huge change in run-off Our data suggests there is a significant from precolonial pristine conditions. As a difference in channel morphology between the result, the natural equilibrium the streams Snavely and Mann Farms. The Snavely established is no longer balanced with this section of Swarr Run exhibits a more natural land use changes. stream pattern while the Mann Farm stretch shows a significant need for future stream restoration. The Snavely stretch shows a METHODS much tighter meandering pool riffle pattern as Our work revolved around gathering data that opposed to longer and deeper pools in the accurately reflects the channel morphology of Mann property with a lower sinuosity. (See our specific site locations. For both the figures 1 and 2) The channel shape also Snavely and Mann Farm locations we used the changes from a confined "V" shape with a total station to establish the water level width, very well defined thalweg in the Snavely Farm depth, and elevation. The Total Station was to a broad "U" shape with a less defined necessary because a considerable degree of thalweg in the Mann Farm. (See figure 3) accuracy was needed to establish the subtle Further comparison shows that the average elevation changes over a long distance. A stream width is nearly twice as wide in the considerably more concentrated number of Mann Farm as well as being deeper, which data points were taken in the Snavely stretch further suggests abnormally large pools of Swarr Run because the stream was much more complicated. Generally, we tried to Mann and Snavely Cross Sections establish a set of data points at the beginning 20 0 -20 -40 -60 -80 -100 -120 -140 and end of each riffle and in the middle of -5 most pools. In order to place this highly accurate, dense data in a larger context we -15 constructed a stream profile for the entire -25 length of Swarr Run using Pennsylvania State Altitude

TOPO maps with five foot intervals. In -35 addition to the total station, we constructed 18 cross sections over the Snavely and Mann -45 Farms using a mounted level to determine -55 elevation and a tape measure to establish Dist From Flood Plain distance. These cross sections give us a Fig 1. Cross sections of the Mann and Snavely Farms, representation how the channel shape varies in showing the change from v-shaped profiles to less the two farms. Finally, we analyzed soil healthy, u-shaped profiles. samples from cut banks and a core sample we creating slow moving water. Slowing water obtained using a vibracore. We analyzed the down over large pools is problematic to water Longitudinal Profile of Swarr Run Longitudinal Profile of Snavely Farm

12 329.5 329 10 328.5

8 328 Thalweg 327.5 Water elevation 6 Water Level 327 Thaweg elevation Elevation 4 326.5

2 326 325.5 0 325 0 1000 2000 3000 -2 0 200 400 600 Distance (ft) Distance Downstream

Fig 2. Longitudinal profile of the larger area, Fig. 3. Longitudinal profile of Snavely farm, showing including that of the Snavely farm. the more healthy, tighter pool-riffle system. quality because it reduces the dissolved outcropping marks the hinge point of this oxygen. Also, the large width of pools transition. We observed extensive, extreme increases water temperature, particularly in cutbanks upstream of the bedrock were the this location because there are virtually no stream incised into the ancient alluvial fan. trees for shade. Finally, these large pools The ideal alluvial fan plane is represented as force the stream to deposit much of its the line on the figure four. (Knighton, 98) suspended and bed load creating the mucky Below the outcrop we observed aggregating silty bottom we observed. These conditions piles of gravel. This is consistent with do not promote a natural diverse stream increased discharge in the stream caused by ecosystem and suggest that the Mann Farm greater impervious cover after development. stretch of Swarr Run be not in a natural state (Trimble, 1997) The stream appears to be of equilibrium. We believe that the presence more sinuous in historical aerial photography, of cows in the stream is the primary cause of implying development resulted in this change in channel morphology. Cows straightening that could also be a major factor exert a tremendous amount of pressure and in the degradation. The upper stream appears cause considerable bank erosion that tends to to be reestablishing meanders to further reduce widen the channel. (Trimble, 1993) Also, its slope because it is easier to cut away the cows destroy riparian vegetation that is softer side banks than continue to incise the important for bank stabilization. This further illustrates the importance of simple livestock management practices such as fencing off cows from the stream. Over a period of 15 years the Snavely Farm stretch of Swarr Run Degradation Aggradation Idealalluvialfan appears to have recovered significantly from longitudinalProfile the presence of cows. However, there is a significant drop in channel slope from the Snavely Farm to the Mann Farm that could cause some of the observed difference. More work needs to be done to understand the cause and effect of this change in slope. MILLERS RUN Fig 4. Longitudinal Profile of Millers Run, Showing Miller’s run is an excellent example of a small the Areas of agradation and degration. tributary that has been thrown out of equilibrium by excessive development. Our longitudinal data suggests upper reaches of the stream are degrading, while lower sections are gravel bed. aggrading. (See figure 4) A bedrock REFERENCES Trimble, S., 1993, Erosion effects of cattle on streambanks in Tennessee, U.S.A.. Earth surface processes and landforms, vol. 19, 451-464 (1994) Trimble, S., 1997, Contribution of stream channel erosion to sediment yield from an urbanizing watershed, Science vol. 278, 1442-1444 Knighton, David,1998, Fluvial forms and processes: a new perspective, Oxford university press Inc, New York, 242-322 Carlson, Erin, 2001, Comprehensive stream assessment in the Little Conestoga Creek Watershed, Franklin and Marshall College Lancaster County GIS Department, 2001 Loper, C.A. and Davis, R.C., 1998: A snapshot evaluation of stream environmental quality in the Little Conestoga Creek Basin, Lancaster County, P,A, U.S. Geological Survey, Water Resources Investigations Report. 98-4173: September, 1998.

GEOMORPHIC ASSESSMENT OF BACHMAN RUN WITHIN THE LITTLE CONESTOGA CREEK WATERSHED

ABBY L. BOWERS Department of Geology, The College of Wooster Greg Wiles, The College of Wooster

JENNIFER FALLON Department of Geology, Washington and Lee University Sponsor: Elizabeth Knapp, Washington and Lee University

ASHLEY G. HAWES Department of Geology, Smith College Sponsor: Robert Newton, Smith College

INTRODUCTION the stream, but urbanization greatly reduces these capabilities. A recent study by the U. S. Geological Survey(USGS) found that the Conestoga One of the impacts urbanization has had on River and its tributary subbasins contribute the the watershed is the increase in the amount of highest nutrient yields to the Susquehanna impervious surfaces in the form of city streets, River (Loper and Davis, 1998). As the largest buildings, parking lots, and even residential river emptying into the Chesapeake Bay, the lawns, which inhibit rainwater infiltration. Susquehanna is the focal point of restoration Rather than soaking in, the water pours off efforts to improve the Chesapeake’s water streets, carrying pollutants picked up along the quality. Recent point source pollution way and running into drainage pipes that often regulations by the EPA are effectively empty directly into a stream or river. Thus, controlling the amount of industrial waste that impervious surfaces not only contribute to enters the Bay, but the water quality of the higher levels of contaminants, but they also Chesapeake Bay Watershed remains poor. are responsible for flash flood behavior and Although the next step in the process of increased erosion (Simon and Downs, 1994). restoring the Chesapeake Bay must be to Increased erosion is often a sign of an unstable improve the water quality of its tributaries, stream, which develops when the scouring many of the streams and rivers that empty into process to degradation or when sediment the Bay, such as the Conestoga River, do not deposition leads to aggradation. Degradation have significant point source pollution. These results from a fall in base level, a decrease in tributaries pick up contaminants as they flow sediment supply, or an increase in discharge. through agricultural areas and receive runoff Aggradation occurs with a rise in base level, from city streets and highly fertilized an increase in sediment supply, or a decrease backyards. Ordinarily, streams and rivers in discharge (Knighton, 1998). To remain in have mechanisms that help them reduce the its natural stable state, a stream needs to carry amount of runoff and contaminants that enter a consistent sediment load to prevent aggradation and degradation. A stream may

remain in equilibrium, even as it laterally migrates, as long as the stream’s bankfull width and width/depth ratio remain constant (Rosgen, 1996). Stable streams are desirable because they exhibit low erosion rates and less flashy flood behavior. Bachman Run, a small subbasin of the Little Conestoga Creek Watershed, is experiencing rapid development that is affecting the stability of the stream and both Figure 1 The sinuosity and low width-depth ratio of the erosion and more frequent flash floods have west branch contrast with the straightened and more been observed (Figures 1 and 2). shallow channels of the east branch and main trunk. PROJECT AREA the west and east branches were created by The headwaters of Bachman Run are located digitizing information from Lancaster County in the northeast corner of the Little Conestoga Geographic Information System (GIS) Creek Watershed in Manheim and Warwick database (2001) and ArcView GIS. A detailed townships. The stream’s two branches drain longitudinal profile showing thalweg depth, an area of 9.9 km2 with an average discharge water level, channel bank, and flood plain of 0.15 m3/sec. The area land use is primarily locations was created by using a total station agricultural, but farmland is being converted (TS). The depth to bedrock was found by to residential areas. A recent survey by the driving a six-foot rod into the stream USGS using 1994 Landsat data, found the bottom sediments at the thalwag depth, and land use of Bachman Run Watershed to be measuring the depth relative to the channel 10% urban, 85% agricultural, and 4% forest bottom and the water level. The location of land (Loper and Davis, 1998). the points where the bedrock was measured was established with Global Positioning System (GPS). This data was then added to The underlying geology of the watershed the data collected with the total station to includes the Cocalico Shale, Eplar Limestone create a longitudinal profile that included and Dolomite, Stonehenge Limestone, Buffalo bedrock depth. Aerial photographs from 1947 Springs Dolomite, Zooks Corner Dolomite, to 1988 and color infrared photographs from and Ledger Dolomite. The stream channel 2000 were studied to compare the consists of cut banks, point bars, mid-channel morphologic changes of the stream that bars, and gravel bars. The streambed is also accompanied the land use transition from characterized by multiple outcrops of bedrock entirely agricultural to significantly urbanized. and has been altered by human additions of RESULTS AND DISCUSSION dams and bridges. The channel banks and flood plains include sandy/silty loam deposits, Cross-sectional data from several reaches and the meanders range from gentle to tortuous and irregular. The confluence occurs in a recently developed neighborhood, providing an easily accessible study site to observe the morphological changes a stream undergoes in response to development.

METHODS

Cross-sections of various stream reaches were Figure 2 Longitudinal profile for the West Branch obtained using an automatic level. Bachman Run deviates from an expected Longitudinal profiles of the confluence area of exponential curve.

along Bachman Run show that channels in the 3). However, the GIS profiles approximate an west branch have a lower width/depth ratio exponential curve, characteristic of a profile of than those located in either the east branch or a stream in its natural state. The closer the the main trunk (Figure 1). Streams with low curve is to exponential, the closer that stream width/depth ratios generally tend to be less is to its stable state. impacted and more sinuous. In addition to the While constructing the cross sections, bedrock lower width-to depth ratio, the west branch also had more meanders than the east branch or the main trunk, resulting in higher sinuosity values. When sinuosity was calculated using valley lengths and thalweg lengths measured in ArcView from the Lancaster County GIS database, the values for the west branch ranged from 1.18 at the headwaters to1.03 in the mid-valley to 1.29 at the confluence. The east branch sinuosity values ranged from 1.0 to 1.18 and the value for the main trunk was 1.05. Figure 4 Longitudinal profile of the West Branch of In the short duration of the project, active Bachman erosion was observed. Many residents owning out Rucnr opscrea tofed Bfroufmf aTloota Sl Sprtaitngsion dDatola. omite were property along the banks of Bachman Run observed in west branch of the stream. Core mow their lawns to the edge of the stream, a samples taken downstream of the confluence practice that destabilizes the banks and limits revealed bedrock of the same formation buried the infiltration capacity for rainwater. Banks half a meter below the channel bed. This data where riparian vegetation is allowed to combined with a longitudinal profile allowed remain tend to be more stable and resist us to compare the bedrock depth along the erosion. A small rainfall event resulted in length of the stream, indicating the presence of multiple slumps in which portions of a Colonial deforestation sediment wedge that residents’ lawns fell into the stream. Large is slowly being transported downstream scale bank erosion and meander migration was (Figure 4). observed from comparing old aerial photos and 35 mm snapshots taken by residents. CONCLUSIONS As erosion allows for sediment transport, it is With increasing population pressures, expected that the longitudinal profiles will suburban sprawl will continue as more land is converted from farms to housing developments. The amount of impervious surface in Bachman Run watershed will parallel the increase in development, resulting in larger volumes of runoff entering the stream. An increase in discharge causes several changes in stream dynamics that can already be observed in Bachman Run. One of these is flashier flood behavior due to the Figure 3 Longitudinal profile for the east branch of Bachman Run is closer to the expected exponential lower rainwater infiltration rates. Flash floods curve. not only pose a problem for the residents who must deal with the high waters but also reveal a sediment wedge advancing through contribute large-scale erosion events. the watershed. Longitudinal profiles generated from the Lancaster GIS database did Another change resulting from an increase in not provide enough detail to ascertain whether discharge is channel incision; incision is an or not the wedge was present (Figures 2 and indicator of a stream’s instability, and a stream will continue to incise until it reaches a new

state of equilibrium. Bachman Run is degrading, and is not in equilibrium. The depth to which the stream may incise is limited by the presence of bedrock near the surface. Once the post-Colonial sediment wedge overlying the bedrock is removed, the stream will most likely erode its banks and widen its channel. Although some bank erosion has already occurred, it will become much more severe once the bedrock base level is reached. Bachman Run appears to be one of the least impacted streams in the Little Conestoga Creek Watershed, but the increase in development could easily change this. Any changes in the morphology and carrying capacity of Bachman Run directly impact the Little Conestoga Creek, Conestoga River, and the Chesapeake Bay. Thus, measures that can be implemented now in order to prevent further impact to Bachman Run should be considered so that this watershed does not become a future restoration project or contribute to the water quality problems plaguing the Chesapeake Bay. REFERENCES CITED Knighton, D, 1998, Fluvial forms andprocesses: a new perspective. OxfordUniversity Press Inc., New York, NY, USA. Lancaster County GIS Department, 2001. Loper, C. A. and Davis, R. C., 1998: A snapshot evaluation of stream environmental quality in the Little Conestoga Creek Basin, Lancaster County, PA. U. S. Geological Survey, Water Resources Investigations Report, 98-4173: September, 1998. Rosgen, D., 1996, Applied river morphology. Wildland hydrology, Pagosa Springs, CO, USA. Simon, A. and Downs, P. W., 1995: An interdisciplinary approach to evaluation of potential instability in alluvial channels. Geomorphology 12, 215-232.

LAND USE ASSESSMENT OF LONG’S PARK CREEK WATERSHED

KYLE CAVANAUGH Geosciences Dept., Trinity University Sponsor: Diane Smith, Trinity University

LAUREN MANION Dept. of Geosciences, Franklin & Marshall College Sponsor: Andy de Wet, F&M College

JAMES ORSHER Geology Dept., Amherst College Sponsor: Jack Cheney, Amherst College

JAIME TOMLINSON Geosciences Dept., Franklin & Marshall College Sponsor: Dorothy Merritts, F&M College

INTRODUCTION varied setting, the creek exemplifies many of the issues of Lancaster County streams. Each The Little Conestoga Creek Watershed, of these land types affects the health of the covering 65.5 mi2 in the south central stream differently. The urban development Pennsylvania county of Lancaster is a key part along LPC distinguishes it from other of the drainage basin of the Conestoga River. tributaries of the Little Conestoga Creek, This watershed lies in the Susquehanna River which flow mainly through suburban Watershed, which is the largest tributary of the developments and agricultural lands. Changes Chesapeake Bay. This estuary is the largest in in land use in LPC Watershed are reflected in the United States and has been plagued with both the stream channel geometry and the environmental problems for decades. Since chemistry of the water and sediment. Through the 1980s many restoration efforts have been a study of these aspects one can gain a better made to reduce some of the effects of understanding of the condition of this stream pollution in the Chesapeake Bay Watershed. and the possibility for restoring equilibrium. In order for large-scale restoration projects to be successful, efforts must begin at headwater sites such as the Little Conestoga Creek and METHODS its tributaries. Field Work Long's Park Creek (LPC) is one of the Nineteen sites along LPC were chosen to tributaries that is a possible candidate for a 2 survey in order to provide examples of both small-scale restoration project. This 2.05 mi impacted and more natural reaches of the watershed contains highly impacted urban stream and thereby determine the affects of areas, a stretch of woodlands, a number of urbanization on channel morphology. At each highways and a small farm. Because of this site, the cross-section was performed using an automatic level and a stadia rod. A separate All geochemical and nutrient data for LPC can group of sites was chosen as water and be found on Table 1 and their corresponding sediment testing locations, again for their locations are in Figure 1. On 6/19/01 nitrate representation of differing levels of levels varied from 5.0 mg/L to 9.2 mg/L. On development. On site, the water was tested for 7/3/01 levels ranged from 1.9 mg/L to 6.2 temperature, dissolved oxygen, pH, and total mg/L. Additional sites tested on 7/3 were also dissolved solids, and in the lab, the water relatively low. Phosphate levels on 6/19 samples were tested for nitrate and phosphate averaged 0.34 mg/L; on 7/3 they averaged levels. A sediment sample was collected at the 0.27 mg/L. The average of the additional sites same locations to determine heavy metal was 0.26 mg/L. concentrations. In order to provide a background with which LPC data could be compared, sixteen USGS sites were also sampled (Lopar and Davis, 1998). Lab Work All the water samples were tested for both nitrate and phosphate levels using a Spectronic 20D spectrometer. The sediment samples were tested for concentrations of , Fig. 2 Sample sites along Long’s Park Creek , , , and iron in an Plotting amounts of cadmium, zinc, and lead Inductively Coupled Plasma Atomic in stream sediment samples collected on Emissions Spectrometer (ICP-AES). The 7/3/01 against a ratio with respect to a mean samples were put through EPA acid digestion value of metal concentration found in process 3050 and then run through the ICP- uncontaminated soils (data from Bowen, AES. All of the sampled sites were entered 1979), the trends of metals throughout the into an ArcView GIS Database, along with the watershed can be seen. Cadmium location of all out fall pipes along LPC. concentrations stay relatively constant Building cover for 1947, 1971, and 2000 was throughout the watershed except for sites 18 calculated on the database by digitizing and 23. Lead and zinc, however, show a buildings from aerial photographs for those distinct change upstream of site 10, where years. concentrations surpass the mean. Also there is a distinct drop below the mean, for lead, RESULTS upstream of site 22. The zinc concentration drops below the mean upstream of site 23. The physical characteristics of LPC proved to be highly variable. Three cross-sections were Re-sampling of multiple sites on different chosen to represent the characteristics of dates revealed consistently proportional differing land-uses. Cross-section “A” was relations in concentration of metals at each taken in a wooded area near the confluence of site. When overlapping sites were compared LPC and the Little Conestoga Creek, and for two different dates (6/27/01 and 7/3/01), cross-section “G” was taken approximately 15 trend lines for cadmium, zinc and lead all had meters upstream. Both show a healthy a slope of 1±0.2. This shows that the data riparian zone and a well-developed floodplain. remained relatively consistent between the two “A” is a good example of a more natural sample dates. stream. “G” is located just downstream of an artificially straightened stretch of the stream, DISCUSSION which was altered to protect a sewage line The shape of Cross-section “Q” is most likely from erosion. Upstream of cross-section “G”, caused by developing the land along the where cross-section “Q” was taken, stream banks, straightening the stream, and development is more prevalent. “Q” has a reinforcing it with riprap to protect the characteristic V shape. Tabel 1. Water sampling results for Long’s Park Creek sites on 6/19 and 7/3*

Site TºC TºC pH pH TDS TDS DO DO Nit Nit Phos Phos 6/19 7/3 6/19 7/3 6/19 7/3 6/19 7/3 6/19 7/3 6/19 7/3 1 21.3 19 7.8 8 380 244 6.50 9.28 8.5 5.7 0.45 0.17 2 21.6 19 7.6 8.1 369 334 7.74 8.75 9.2 6.2 0.35 0.26 3 21.0 18 7.7 8.3 395 390 7.41 9.51 5.4 2.4 0.57 0.12 4 21.3 19 7.7 8.4 393 392 7.43 9.39 5.0 2.9 0.11 0.04 5 16.1 16 6.7 7.2 461 453 NT 5.95 5.9 3.2 0.44 0.16 6 NT 20 NT 8.4 NT 395 NT 9.02 NT 2.5 NT 0.05 7 19.5 18 7.5 8.2 417 415 6.44 8.52 6.8 3.1 0.13 0.15 8 NT 20 NT 8 NT 422 NT 7.71 NT 3.3 NT 0.29 9 NT 20 NT 8 NT 424 NT 7.8 NT 3.4 NT 0.24 10 NT 19 NT 7.9 NT 391 NT 8.75 NT 2.9 NT 0.2 11 NT 20 NT 8 NT 389 NT 11.1 NT 3.5 NT 0.22 12 NT 18 NT 8.1 NT 426 NT 8.58 NT 3.2 NT 0.08 13 NT 18 NT 7.9 NT 428 NT 9.1 NT 3.1 NT 0.25 14 17.5 18 7.6 8 426 430 7.33 9.12 5.5 3.3 0.33 0.21 15 NT 17 NT 8.1 NT 426 NT 8.62 NT 2.9 NT 0.13 16 NT 16 NT 8.1 NT 427 NT 9.08 NT 3.3 NT 0.18 22 NT 21 NT 7.6 NT 419 NT 5.86 NT 2.6 NT 0.27 24 NT 29 NT 7.9 NT 356 NT 8.98 NT 1.9 NT 0.61 25 NT 28 NT 7.7 NT 362 NT 15 NT 1.9 NT 0.7 26 23.1 24 7.1 8 385 385 5.46 9.41 5.3 1.7 0.37 0.01 27 25.8 27 8.3 9.2 294 300 10.22 14.6 8.1 1.9 0.33 0.78 28 NT 26 NT 9.1 NT 286 NT 13.5 NT 1.9 NT 0.66

*(TDS-Total Dissolved Solids (ppm), DO- Dissolved Oxygen (mg/L), Nit-Nitrates (mg/L), Phos-Phosphates (mg/L), NT-Not Tested surrounding areas from erosion. These actions Table 1 shows both nitrate and phosphate data increase runoff and therefore discharge, for the 22 samples collected from LPC and the increasing sediment load, which leads to 16 USGS sites that were re-sampled. LPC incising and steepening of banks. Cross- nutrient levels were lower than the USGS sites sections “G” and “A” are located in a less because the land use anthropogenically impacted area. These cross around LPC is primarily commercial. Over sections exhibit a more natural shape. Cross- 80% of the land in the Little Conestoga Creek section “G” shows a traditional meander Basin is used for agriculture, and most of the profile, with the deposition bank on the left USGS sites are located on streams that flow and the cut-bank on the right. Cross-section through farmland. As suspected, the runoff “A” shows a traditional pool profile. The from fertilized fields is a major contributor of dramatic difference between the channel nutrients. geomorphology of the urban area and that of When compared to sediment samples from the the forested area is an example of how land USGS sites, the LPC is elevated in zinc, use practices have affected the physical cadmium, and lead (Fig. 2). Between sites 10 properties of the stream. and 11 there is a dam on the LPC. Upstream When viewed against the backdrop of the rest of this dam, concentrations of lead and zinc of the Little Conestoga Creek Watershed, the are higher than the rest of the stream. The nitrate and phosphate levels of LPC are lower dam may be acting as a trap for sediment than average. All of the nutrient laden with heavy metals, keeping them in the concentrations fall below the safe limit of 10 upper reaches of the stream. The upper sites, mg/L of nitrates for drinking water 24 and 25, lie in the Dillerville swamp, which (Commonwealth of Pennsylvania, 1994). is upstream of major industries. Site 26 is CONCLUSIONS This study has attempted to indicate some the effects of urbanization on a stream. LPC is a unique section of the Little Conestoga Watershed and while development clearly has had many negative effects, the stream does have some positive characteristics as well. Negative aspects include radically altered physical characteristics such as the artificially steepened and straightened stream channel, and lack of a natural flood plain. All of these problems contribute to frequent flash floods and overall degradation. Positive characteristics include the lack of farmland, which has resulted in lower nutrient pollution, and a fairly healthy riparian zone in some stretches that helps reduce erosion and keeps temperatures lower. The high metal concentrations are also a cause Fig. 2. Levels of Zn, Pb, and Cd in LPC sediments of concern. The concentrations of zinc and are much higher than those found in USGS sites. lead are up to ten times the uncontaminated Long's Park Pond and is therefore not subject mean (Bowen, 1979) and cadmium to industry. concentrations exceed one hundred times the uncontaminated mean (Bowen, 1979) in some The most probable sources for zinc and lead areas. If the dam between sites 10 and 11 are industries in the northern area of the city of were removed, large amounts of suspended Lancaster. In this area there are companies sediment would increase metal concentrations with a history of metal pollution (EPA Toxic downstream. Organisms lower on the food Release Inventory, 2001), including the metal chain, such as bottom feeders, could take processing plant, Alcoa, a Superfund site. greater concentrations of heavy metals into Additionally, the watershed is underlain by the their tissues. In turn, higher organisms that eat Ledger Formation, a limestone-dolomite unit the lower organisms would accumulate even that contains some layers of zinc ore higher concentrations of these toxic metals in (Freedman, 1972). Runoff from road surfaces the process of biomagnification. (motor oil, tire tracks, gasoline) or fly ash (Page et al., 1979) from smokestacks could Due to the time constraints of the project, the also be sources of metal pollution. number of sampling locations had to be limited. For better results, many more Cadmium levels are relatively consistent sediment and water samples would have to be throughout the Little Conestoga Creek taken in a more systematic way and averaged watershed, with the exception of the two LPC together. Rather than collecting the sediment sites, which are high due most likely to point from the same part of the stream channel each source pollution. Still the Little Conestoga time, the samples were selected on the basis of Watershed concentrations are very high where the finest grains could be gathered. In (between 4 and 22 times the mean value of the future, the tests should be conducted uncontaminated soils (data from Bowen, several times throughout the year in order to 1979)). The consistency of cadmium levels rule out seasonal variations. Finally, a more in suggests a background source for the metal, depth look at the sediments trapped behind the perhaps in the bedrock or from long term dam in LPC could possibly provide a record of discharge of fly ash. Further research is industrialization through metal concentration. required to determine the exact source. REFERENCES CITED Bowen, H.J.M. (1979). "Environmental Chemistry of the Elements". Academic Press, London and New York. Commonwealth of Pennsylvania. (1994) Pennsylvania Code, Title 25, Environmental Resources, Department of Environmental Resources, Chapter 93, Water Quality Standards, Paragraph 93.7, Section C. EPA Toxic Release Inventory: http://www.epa.gov/enviro/html/toxic_rele ases.html Freedman, Jacob (1972) "Geochemical Prospecting for Zinc, Lead, , and Silver, Lancaster Valley, Southeastern Pennsylvania". Geological Survey Bulletin 1314-C. United States Government Printing Office, Washington D.C. Lancaster County GIS Information Database Lopar, Connie A. and Davis, Ryan C. (1998) A Snapshot Evaluation of Stream Environmental Quality in the Little Conestoga Creek Basin, Lancaster County, Pennsylvania. In "Water-Resources Investigations Report 98-4173". US Department of the Interior. ACKNOWLEDGEMENTS We would like to thank our Keck Sponsors and Advisors, the Keck Consortium, F&M College and the department of Geosciences, our fellow project colleagues, Jesse Yoburn, and Janie Wissing for their invaluable help and guidance.