Water Resources Challenges in Adams County, Pennsylvania

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1 Water Resources Challenges in Adams County, Pennsylvania Water Availability in the Upper Monocacy River Basin (Marsh, Rock, Alloway, and Toms Creeks) May 13, 2010 Cherie Schultz, Ph.D. Interstate Commission on the Potomac River Basin

2 How much water is there? How much risk can you tolerate? What level of adverse impacts are acceptable to you?

3 Water Resources in Fractured Bedrock Geology Groundwater and surface water are a shared resource Availability of water is highly variable Annual variability Seasonal variability Water planning requires Integrated analyses Risk based approach

tributaries: Marsh Creek Rock Creek Alloway Creek

4 THE MONOCACY RIVER BASIN Marsh Cr Toms Cr Rock Cr Alloway Cr Pennsylvania Maryland Main Pennsylvania tributaries: Marsh Creek Rock Creek Alloway Creek Toms Creek Monocacy River USGS stream gage at Bridgeport, MD

Bonneauville Joy Littlestown Germany Largest municipalities: Gettysburg,

5 THE MONOCACY RIVER BASIN Franklin HamiltonbanHighland Fairfield Carroll Valley Gettysburg Freedom Butler Cumberland Straban Mt Pleasant Mt Bonneauville Joy Littlestown Germany Largest municipalities: Gettysburg, PA Frederick, MD Liberty Emmitsburg Thurmont Walkersville Taneytown Frederick

Groundwater & Surface Water Are a Shared Resource Recharge within a watershed is shared: available for well withdrawals & discharge to streams Small size of

6 Groundwater & Surface Water Are a Shared Resource Recharge within a watershed is shared: available for well withdrawals & discharge to streams Small size of Adams Co headwater watersheds provides limited area for recharge Figure from USGS, Groundwater Atlas of the United States, at pubs.usgs.gov/ha/ha730/ch_g/g-text8.html

summer/early fall Well levels also respond rapidly to weather

7 Highly Variable Hydrology 2002 minimum of 0.17 mgd on August 19th Lowest stream flows tend to occur in late summer/early fall Well levels also respond rapidly to weather conditions Estimates of annual recharge may not capture risk of summertime shortages

8 ICPRB Water Availability Studies Annual recharge estimates for the Monocacy River basin, for 4 types of geology Seasonal water availability estimates in 4 watersheds of the Monocacy basin Ground water/stream flow model of upper Monocacy basin, estimating of impact of ground water withdrawals on stream flow

Annual Recharge Estimates Based on 4 geologic classes Mesozoic lowlands primarily shales, sandstones, diabase Blueridge crystalline rock Piedmont crystalline rock Piedmont carbonate rock Data from 34

9 Annual Recharge Estimates Based on 4 geologic classes Mesozoic lowlands primarily shales, sandstones, diabase Blueridge crystalline rock Piedmont crystalline rock Piedmont carbonate rock Data from 34 stream gages Used estimates of average annual recharge Statistical analyses to relate annual recharge to geology See Annual and Seasonal Water Budgets for the Monocacy/Catoctin Drainage Area, ICPRB, 2004

10 Annual Recharge Estimates Annual recharge - gallons per day per acre (gpd/acre) Recurrence Interval 2-year 10-year 20-year BR ML PCA PCR Legend Hydrogeomorphic Regions (CBP) Blue Ridge (BR) Mesozoic Lowland (ML) Piedmont Carbonate (PCA) Piedmont Crystalline (PCR)

11 Seasonal Water Availability Estimates For 4 watersheds Study period: Analyses based on: Mean seasonal baseflow Rates of streamflow recession (rate of decrease in dry weather) Results include time series of seasonal estimates for: Base flow (BF) Storm flow (SF) Evapotranspiration (ET) Net recharge (R) Storage (S) (above zero flow level) Legend HGMRs BR ML PCA PCR Study wtersheds

12 Seasonal Water Availability Estimates Annual water budget Based on estimates of annual recharge Assumes no annual change in storage Seasonal water budget Based on estimates of recharge and recession Estimates seasonal changes in storage Annual Recharge (gpd/acre) Seasonal Summer recharge + summer storage (gpd/acre) Station 1 in 20 year Median 1 in 10-year 1 in 20 year Catoctin Creek ( ) Upper Monocacy ( ) Big Pipe Creek ( ) Bennett Creek ( )

13 Upper Monocacy Basin Ground Water/Stream Flow Model Objective: investigate impact of ground water withdrawals on summertime stream flow Study period: 1960 to 2002 Funding: National Fish and Wildlife Foundation/ICPRB Toms Cr Middle Cr Marsh Cr Fairfield Carroll Valley Emittsburg Gettysburg Rock Cr Bonneauville Alloway Cr Piney Cr Littlestown Legend Taneytown County boundaries Upper Monocacy Basin Main streams Miles

14 Available Stream Flow Data Daily flow data: Monocacy R at Bridgeport, MD Piney Cr near Taneytown, MD Toms Cr at Emittsburg, MD Six flow measurements made for project on Marsh Cr & Rock Cr (USGS) Legend Toms Cr Middle Cr $ Marsh Cr Upper Monocacy Basin Rock Cr $ $ !.!. Alloway Cr Piney Cr Main streams $1 USGS stream gaging stations Miles!. Project flow measurments (USGS)

15 Available Well Data Data at 361 wells in 43 year study period 59% of wells had only 1 measurement 92% of wells had 3 or less measurements Legend Upper Monocacy Basin Main streams Available well data Miles

16 Model Grid 500 m x 500 m horizontal grid cells 10 layers each 10 m 271 stream miles

17 Classification of Summertime Conditions Condition Summertimes Mean summertime baseflow at (cfs) Dry 1962, 1963, 1964, 1965, 1986, 1988, 1991, 1997, 2001, to 6.6 Average-dry 1961, 1966, 1974, 1977, 1980, 1983, 1998, 1999 Average 1968, 1969, 1971, 1976, 1981, 1982, 1985, 1987 Average-wet 1960, 1967, 1973, 1978, 1990, 1992, 1993, 1994 Wet 1970, 1972, 1975, 1979, 1984, 1989, 1995, 1996, to to to to 92.8 data for calibration

18 Classification of Summertime Conditions Condition Summertimes Mean summertime baseflow at (cfs) Dry 1962, 1963, 1964, 1965, 1986, 1988, 1991, 1997, 2001, 2002 Average-dry 1961, 1966, 1974, 1977, 1980, 1983, 1998, to to 9.7 data for verification verification Average 1968, 1969, 1971, 1976, 1981, 1982, 1985, 1987 Average-wet 1960, 1967, 1973, 1978, 1990, 1992, 1993, 1994 Wet 1970, 1972, 1975, 1979, 1984, 1989, 1995, 1996, to to to 92.8 verification verification

Predictions of Dry & Losing Stream Reaches 60% 50% 40% 30% 20% 10% 0% 0 10 20 30 Simulated flow at 01639000, mgd % Dry

19 Predictions of Dry & Losing Stream Reaches 60% 50% 40% 30% 20% 10% 0% Simulated flow at , mgd % Dry stream miles % Dry or losing stream miles (Simulation of study scenario MGD increase in ground water withdrawals)

20 Summary Topography and geology create challenges for water resource planning in Adams County Care must be taken to preserve one of the county s important natural amenities its streams An integrated and risk based planning approach can take into account competing needs and benefits

21 References & Contact Information Annual and Seasonal Water Budgets for the Monocacy/Catoctin Drainage Area, Cherie Schultz, Deborah Tipton, James Palmer, ICPRB Publication No: ICPRB-04-04, available online at Seasonal Steady-State Ground Water/Stream Flow Model of the Upper Monocacy River Basin, Cherie Schultz and James Palmer, ICPRB Publication No.: ICPRB 08-04, available online at Cherie Schultz

GeoServices, Ltd. Environmental & Hydrogeologic Services

GeoServices, Ltd. Environmental & Hydrogeologic Services TABLE OF CONTENTS 1.0 INTRODUCTION AND PURPOSE... 1 2.0 BACKGROUND INFORMATION... 2 3.0 DESCRIPTION OF WATERSHED... 3 3.1 Relationship Between Recharge and Geologic Setting... 3 4.0 APPLICATION OF USGS