Northern Lancaster County Groundwater Study Executive
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Northern Lancaster County Groundwater Study: A Resource Evaluation of the Manheim-Lititz and Ephrata Area Groundwater Basins Executive Summary September 2005 Achieving a balance among environmental, human, and J. Howe economic needs in the management of the basin’s This executive summary and the water resources is a critical full report (SRBC Publication #235) mission of the Susquehanna River Basin Commission are available on the web site at (Commission), as described www.srbc.net/waterbudgetstudy.htm in the 1971 Susquehanna and by CD-Rom. For copies of the River Basin Compact. The Commission carries out its CD-Rom: e-mail at [email protected] water resource management or call (717) 238-0423, ext. 302. responsibilities in a number John Hauenstein, SRBC Engineering Technician, of ways through its regulatory checking the well at a farmhouse in Elizabeth Township. Report Authors program, public education Robert E. Edwards, P.G. and information, and resource evaluation. The Commission, in partnership Special Projects Manager In areas of intense water resource with the Lancaster County utilization, the Commission may Conservation District, performed a Robert D. Pody, P.G. conduct special studies, water budget groundwater resources evaluation Hydrologist analyses, and identify critical aquifer of a carbonate valley located in recharge areas (CARAs). northern Lancaster County, Pennsylvania. The project was funded by the Historic changes in land use have What is groundwater? Pennsylvania Department of Environmental led to increased impervious areas, increased Groundwater is any water beneath the Protection (PADEP) through its Growing stormwater runoff, and reduced earth’s surface that supplies wells and Greener Grant Program. The study area infiltration. Impervious cover was 9 percent springs, and replenishes streamflow. For includes an isolated carbonate aquifer of of the 70-square-mile study area. This the purposes of this study, groundwater is 50 square miles and a surrounding siliciclastic potentially reduces average annual the water that has reached the water contributing area of 20 square miles. Parts recharge by 1,575 million gallons in the table and the saturated zone, where all of 13 municipalities, including the Boroughs study area. When one considers the of Manheim, Lititz, Akron, Ephrata, and carbonate areas of the Manheim-Lititz interconnected voids in unconsolidated Denver, are located in the study area. and Ephrata area groundwater basins, (loose) sediments, and fractures and Groundwater is the primary source of 12.6 percent and 8 percent of these openings between layers in consolidated water for municipal, domestic, industrial, areas are impervious, respectively. (hard) rock are filled. and agricultural uses. As groundwater The focus of the study is a valley withdrawals increase to meet growing approximately 50 square miles in area, Where does the water demands, stakeholders need information underlain by a highly productive found in aquifers come from? on the location and quantity of water carbonate aquifer, and herein informally Water in aquifers primarily comes resources available, and how to best termed the “carbonate valley.” The from precipitation — mostly rain. develop, conserve, and protect them. carbonate valley is surrounded almost Replenishment or “recharge” occurs on entirely by hills underlain by aquifers most of the land surface, wherever water J. Howe of much lower permeability. The can soak into the ground. Exceptions carbonate valley includes parts of include areas covered by impermeable the Chiques Creek, Cocalico Creek, materials like rooftops and paved areas, and Lititz Run watersheds. Streams and areas where groundwater is upwelling, generally flow from north to south across such as most perennial stream valleys. the study area, with the exception of Precipitation landing on the ground the largest stream, Cocalico Creek, surface must be absorbed by the soil in which flows from northeast to southwest. Hammer Creek The study area includes parts of order to become recharge. If the soil is Removal of groundwater resources 8 townships and 5 boroughs, and had a frozen or precipitation is delivered at a faster than the sustainable rate could lead population of approximately 61,000 in rate that exceeds the ability of the soil to to a growing water deficit, the gradual the year 2000. Water supply needs are absorb it, then some of the precipitation is failure of water supplies, diminishing met almost entirely by groundwater. “rejected” and becomes surface runoff to stream and spring flows, and degraded The valley was once largely agricultural, streams and wetlands. Surface runoff moves aquatic and riparian habitat. but is rapidly changing to a mosaic of downslope and becomes channelized flow. Project participants involved the urban, suburban, and agricultural areas. Some of the precipitation absorbed by local public during the course of the The population in the carbonate valley the ground is taken up by plant roots and study through a Water Budget Advisory is rapidly growing, as is the need for transpired; the remaining water filters Committee (WBAC) and educational water. However, the amount of water downward through the pores and fractures in workshops. Important resource areas are available is limited. Most of the ground- the soil in the unsaturated zone. Eventually, identified, and management recommen- water is derived from the carbonate this water reaches the water table, the dations for these areas are provided in this aquifer that underlies the valley. boundary below which all of the spaces Executive Summary and the full report. The presence of sinkholes, abundant and cracks in the soil or rock are filled with The study area has experienced closed depressions, large springs, and water. Water that filters through the ground rapid growth. From 1990 to 2000, lack of streams in many areas suggests several municipalities in the study area that dissolution of the carbonate to the water table recharges the aquifer. exceeded Lancaster County’s growth rate bedrock, a condition known as karst, Some water becomes “stranded” in of 11.3 percent. Warwick Township, has substantially enhanced the ability depressions or as drops on leaf (and other) located in the Manheim-Lititz groundwater of the aquifer to store and transmit surfaces. Most of this water evaporates and basin, experienced the highest growth rate water. Karst aquifers are known for is returned to the atmosphere. The water of 33.2 percent. Anticipated growth and their abundant water resources and returned to the atmosphere by plants development in the study area are expected extremely high well yields, as well as (transpiration) or by evaporation is grouped to result in increased water demand. their hard water, enigmatic flow patterns, under the single term evapotranspiration. Population projections from 2000 through sinkholes, and high susceptibility 2025 represent a 26 percent increase. to contamination. 2 FINDINGS From June 2003 to June 2005, the Annual Recharge in Million Gallons for the Study Area and Groundwater Basins Commission evaluated the groundwater 1-in-2 1-in-10 1-in-25 Area (sqmi) resources to address water quantity issues in a 70-square-mile area underlying Manheim-Lititz 5,822 3,531 2,449 21.8 parts of Chiques Creek, Cocalico Ephrata Area 11,676 7,077 4,917 48.4 Creek, and Lititz Run watersheds. Study Area 17,498 10,608 7,366 70.2 Normal annual precipitation was 43.5 inches, of which 14.4 inches was 25-year recurrence intervals, was based wastewater immediately upgradient or estimated to be groundwater recharge. on previous regional studies that employed adjacent to the impacted stream reach Two groundwater basins were extensive base flow separations, water table would largely mitigate this impact. delineated based on water table mapping, mapping, and groundwater modeling. Groundwater withdrawals in the and two sets of water level measurements The annual recharge of the Manheim- Ephrata area groundwater basin have were made during this study. Lititz groundwater basin, for the 2-, 10-, not exceeded 10 percent of the lowest The Manheim-Lititz groundwater and 25-year recurrence intervals, was flow for 7 consecutive days in 10 years basin is 21.8 square miles and contains estimated to be 5,822 million gallons, (Q7-10) for Cocalico Creek as it leaves the upper Lititz Run watershed and 3,531 million gallons, and 2,449 million the carbonate valley. However, most of part of Chiques Creek watershed. The gallons, respectively. The annual recharge the existing groundwater withdrawals groundwater basin is in the area of the Ephrata area groundwater are located in the southern half of the westward from Manheim to within a basin, for the 2-, 10-, and 25-year basin, and are compensated for by few thousand feet of the Cocalico Creek recurrence intervals, was estimated to be the discharge from the Ephrata area water gap, and includes parts of 11,676 million gallons, 7,077 million gallons, wastewater treatment plant. However, Rapho, Penn, Warwick, and Elizabeth and 4,917 million gallons, respectively. future withdrawals could trigger the Townships, and the Boroughs of The Commission uses the 1-in-10- passby requirement in one of the Manheim and Lititz. Groundwater year recharge as the sustainable limit subbasins. This can be avoided by level measurements taken during the of groundwater development. This limit locating wells in downstream areas study indicate a water table that gradually attempts to balance the amount of where the Q7-10 flow is higher. declines from 400 to 340 feet in elevation. groundwater available for development, Streamflows in the study area will be below 20 percent of their average “The Commission uses the 1-in-10-year daily flow approximately 30 days per year. Groundwater withdrawals in recharge as the sustainable limit of the Manheim-Lititz groundwater basin have exceeded the Q7-10 for the surface groundwater development.” water flow (combined flow from Chiques Creek and Lititz Run) as it East of the Manheim-Lititz ground- instream flow needs, and required leaves the carbonate valley.