Review of May 1988 Water Resources Study March 26, 2009
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Carroll County, Maryland Water & Wastewater Options & Strategies for WRE Review of May 1988 Water Resources Study March 26, 2009 This memorandum has been prepared based on Malcolm Pirnie’s review of R.E. Wright Associates’ May 1988 Carroll County Water Resources Study. Our principal focus has been to identify limitations and changes to the original findings based on current regulations and more recent data or efforts undertaken by the County. Our comments are organized according to the chapter format used in the 1988 study. Chapter 1 - Preface Source water assessment and protection (including wellhead protection) should be added to the basic purpose and objectives because these are now considered an essential part of water supply management, and Carroll County has existing efforts in this regard. Although this report predates the 2000 Chesapeake Bay Agreement, Chapter 15 does emphasize the importance of pursuing water quality protection programs. In addition, Carroll County published a Water Resource Management Manual in May 2004 that describes the County’s delineation of management areas and identifies measures to protect drinking water supplies from both existing and future ground and surface water degradation sources. Introductory sections to this report, or future documents such as the WRE, also provide an opportunity to emphasize the importance of improved local water resource policy to support population and economic growth in a sustainable manner, rather than encouraging well and septic-based sprawl. Authors should be familiar with the Final Report of the “Advisory Committee on the Management and Protection of the State’s Water Resources”, which is available on the Maryland Department of the Environment (MDE) web site. This report makes a number of important conclusions and recommendations for statewide water resources policy, including the recommendation for a greater emphasis on water and sewer planning at the local level. Chapter 2 - Groundwater Quality of Carroll County Updated Drinking Water Quality Standards. The National Primary and Secondary Drinking Water Criteria presented in Tables 2-1 and 2-2 have been expanded to include a number of new constituents. A current listing of these criteria is available from the USEPA’s web site. Potential County Mapping Using Current GIS Tools. The summary of background water quality in Table 2-16 is only presented by aquifer type. For future studies beyond the current Water Resources Element (WRE) effort, it may also be useful for the County to develop this summary by land use category and designated growth area. It may be desirable for County planning staff to apply current GIS tools (unavailable at the time of the 1988 study) to provide a spatial depiction of groundwater quality as opposed to only tabular results. Spatial analysis would more clearly show where problem areas may exist or what trends exist. In addition, potential sources of surface contamination are also of importance for groundwater vulnerability evaluations. Therefore, it may be desirable for County planning staff to overlay zones of elevated groundwater concentrations with the County’s existing land use mapping information as well as locations 6531001 INDEPENDENT ENVIRONMENTAL ENGINEERS, SCIENTISTS AND CONSULTANTS Carroll County, MD - Water & Wastewater Options & Strategies for WRE Review of May 1988 Water Resources Study 2 March 26, 2009 of potential sources of surface impacts such as landfills, industrial or municipal facility discharges, golf courses, agricultural operations, road salt, impervious surfaces, etc. Recent Groundwater Quality Studies. There has been relevant groundwater research conducted since 1988 that sheds some additional light on groundwater quality within Carroll County. For example: Pesticides in Groundwater of Central and Western Maryland (USGS Fact Sheet 2008-3068): Selected pesticides and products of pesticide degradation are detectable in groundwater in many parts of central and western Maryland, although concentrations are generally less than 0.1 micrograms per liter. Groundwater samples collected from 1994 to 2003 from 72 wells in areas of Maryland underlain by consolidated carbonate, crystalline, or siliciclastic aquifers (areas north and west of the Fall Line) were analyzed for selected pesticides and products of pesticide degradation. For future studies beyond the current WRE effort, it may be useful for the County to access this USGS research to determine if and where in Carroll County pesticides were detected in groundwater samples. Chapter 3 - Study of Nitrate Concentration in Soil-Water and Groundwater Potential County Mapping Using Current GIS Tools. There is repeated mention made of locally- contaminated groundwater, but no mapping provided to show where these wells are located. For future studies beyond the current WRE effort, it may be desirable for County planning staff to apply current GIS tools to summarize where problems exist and what land use may be contributing to these problems. Recent Groundwater Quality Studies. Recent USGS research on vulnerability of groundwater to nitrate concentration sheds some additional light on groundwater quality within Carroll County. For example: Groundwater Vulnerability to Nitrate Contamination in the Mid-Atlantic Region (USGS Fact Sheet 2004- 3067): The USEPA Regional Vulnerability Assessment Program developed a set of statistical tools to support regional-scale, integrated ecological risk-assessment studies. One of these tools, developed by the USGS, is used with available water quality data obtained from USGS National Water Quality Assessment and other studies in association with land cover, geology, soils, and other geographic data to develop logistic-regression equations that predict the vulnerability of ground water to nitrate concentrations exceeding specified thresholds in the Mid-Atlantic Region. The regression models were developed and applied to produce spatial probability maps showing the likelihood of elevated concentrations of nitrate in the region. According to this mapping, areas of high probability exist within Carroll County. For future studies beyond the current WRE effort, this spatial output could be used by County staff to help identify areas in Carroll County that currently are at risk and to identify areas where groundwater is more likely to have been affected by human activities. County Requirements Adopted Since 1988 Study. Several remedial actions are identified such as education of persons associated with point source of nitrate-nitrogen within agricultural areas and repair or replacement of malfunctioning septic systems. Carroll County’s May 2004 Water Resource Management Manual provides information on various aspects of groundwater resource protection including the delineation of protection zones (e.g., wellhead and aquifer protections areas) and management standards and design criteria relating to land use activities and management areas. In April 2004, Carroll County adopted Ordinance No. 04-08 which created Chapter 218 Water Resource Management to the County Code. This chapter provides for the delineation of management areas, and 6531001 INDEPENDENT ENVIRONMENTAL ENGINEERS, SCIENTISTS AND CONSULTANTS Carroll County, MD - Water & Wastewater Options & Strategies for WRE Review of May 1988 Water Resources Study 3 March 26, 2009 the ability to perform a water resource impact review on all proposed development projects within the County. In addition, water resource protection easements are required adjacent to streams, wells, and well sites when land is developed. Also, adopted by resolution was the Water Resource Management Manual. Several municipalities including the towns of New Windsor, Manchester, Sykesville and Mount Airy have also adopted Chapter 218. These important measures to protect drinking water supplies from both existing and future degradation sources should be clearly identified in future County studies relating to groundwater quality. Health Department Nitrate Testing: The Carroll County Health Department is required to analyze groundwater nitrate concentrations in subdivision with four or more lots, if the average lot size is less than two acres. If results indicate that nitrate exceeds 10 mg/L, pre-treatment for nitrate is required on one or more lots. These data are likely to provide useful information for mapping nitrate concentrations in the County. Chapter 4 - Groundwater Resource Development in Carroll County According to Chapter 7 of the 1988 study, drought groundwater recharge available within the Planning Area was 12.9 mgd, and 14.6 mgd within 2,000 feet of the Planning Area. This range of groundwater recharge is somewhat lower than the projected Year 2020 total public water supply requirement of about 17 mgd, listed in Chapter 15 of the 1988 study. Groundwater water recharge estimates will be updated as part of the water balance task being performed to support the water resources element (WRE) of the County’s comprehensive plan. Impacts of Current State Groundwater Regulations on Potential Groundwater Withdrawals. The 1988 study was performed prior to the effective date (1989) of Maryland’s current water appropriation and use regulation (COMAR 26.17.06). Since that time, MDE’s policies and administrative approaches for permitting groundwater appropriations have evolved. MDE’s current permitting practices would reduce the amount of groundwater that could be appropriated by Carroll County, compared with groundwater availability stated in the 1988 study. Therefore, the