From Source Water to Drinking Water Workshop Summary (2004) / Chapter Skim
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Pages 61-92
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From page 61... ...
. The scientific basis of and policy choices involved in regulating drinking water quality in the United States have changed as our experience has increased and as the SDWA has changed.
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From page 62... ...
Since enactment of the SDWA in 1974, great progress has been made in drinking water quality and regulation in the United States. It seems now that only the most difficult issues remain -- protecting sensitive populations, achieving sustainable water systems, providing affordable drinking water for small systems, avoiding riskrisk trade-offs, and controlling emerging waterborne pathogens, to name a few.
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From page 63... ...
For example, many compounds are present at such low concentrations that detection via standard methods is difficult. Furthermore, specific analytical techniques for the tens of thousands of chemical contaminants found in drinking water simply do not exist.
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From page 64... ...
Background The 1996 amendments to the Safe Drinking Water Act require, for the first time, that each state prepare a source water assessment for all PWS. Previously, federal regulations focused on sampling and enforcement, with emphasis on the quality of delivered water.
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From page 65... ...
Surface water supplies also are susceptible to contamination from point sources, which may include permitted discharges, as well as accidental spills or other introduction of contaminants. The development of a scientifically defensible methodology for assessing the susceptibility of Texas PWS to contamination, based on the most accurate, readily available hydrologic, hydrogeologic, point source, nonpoint source, and other natural resource and environmental data, will better enable the TCEQ SWAP staff to do the following:
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From page 66... ...
surface water assessments. The groundwater and surface water assessment areas are further defined as sets of components, where each component deals with a specific problem domain of the SWSA.
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From page 67... ...
user interface software for display of GIS coverage, database query, hard-copy output, or report generation; (4) spatial analysis software for delineation of contributing areas, and calculation or determination of weighted variables, characteristics, and threshold values; (5)
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From page 68... ...
These 29 aquifers have been subdivided and assigned some 450 aquifer codes, each having its own geologic, hydrologic, and water quality characteristics. These aquifer codes have been developed for several uses, including regulation of public drinking water; however, the 29 major and minor aquifers do not provide sufficient detail for the purposes of SWAP.
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From page 69... ...
contributing area for wells or springs in unknown aquifers. Nonpoint source component This component will involve a statewide investigation to develop statistical relations between known occurrences of nonpoint source contaminants in groundwater and the natural and anthropogenic factors or activities (referred to as environmental variables)
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From page 70... ...
and have characteristics representative of a range of environmental variables that may influence source water susceptibility. Samples are collected using specialized, low-level detection sampling procedures developed by the USGS and analyzed for selected soluble pesticides, volatile organic compounds (VOCs)
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From page 71... ...
Using spatial analysis techniques, water quality sampling sites will be identified within a 1-mile search radius around each PWS well and spring. If contaminants are detected within this area, the PWS would be assessed as being susceptible to either anthropogenic or naturally occurring contamination.
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From page 72... ...
The output of software using the decision matrix developed for this component will be a determination of whether the contaminant in question would be attenuated before affecting the PWS. Susceptibility summary determination component This component will determine the cumulative susceptibility of the PWS to each listed contaminant or contaminant group, as contributed by point and nonpoint sources.
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From page 73... ...
Land-use types within the contributing watershed must be determined to assess their potential nonpoint source effect on the water supply. Characteristics such as rainfall, runoff, and reservoir storage must be obtained for the contributing watershed to assess the intrinsic susceptibility of each surface water supply.
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From page 74... ...
Contributing watershed delineations are required for about 500 surface water supply intakes of which about 176 are unique (multiple intakes in various reservoirs)
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From page 75... ...
High sizeslope ratios indicate longer time of travel and thus less susceptibility; low ratios indicate shorter time of travel and thus increased susceptibility. Nonpoint source component This component will involve a statewide investigation to develop statistical relations between known occurrences of nonpoint source contaminants in surface water and natural and anthropogenic factors or activities (environmental variables)
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From page 76... ...
Although point source discharges may be included in the environmental setting variables used statistically, the existing water quality data sets may not adequately represent low-flow conditions when point sources have their greatest influence on the water quality of the receiving water body. Therefore, theoretical concentrations of point sourceassociated contaminants at low-streamflow and low-flow reservoir storage conditions will be calculated on the basis of permitted releases of contaminants from point source discharges in the contributing watershed of the surface water intake or supply reservoir.
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From page 77... ...
. Area-of-primary-influence component The proximity of a surface water intake to a point source discharge, potentially adverse land-use, major transportation corridor, or pipeline can result in the source water being susceptible to contamination.
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From page 78... ...
The watershed is rich in water resources and serves as home to about 1.5 million people. While its core mission is flood protection, MCD has integrated program efforts that include groundwater and source water protection, surface water quantity and quality monitoring, and the enhancement of river corridors within the watershed.
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From page 79... ...
As Dayton and its water needs grew, so did potential threats to the safety of the drinking water supply. In the 1980s, citizens' concerns for the safety of drinking water prompted the city to initiate a community-based effort to provide for the long-term safety of Dayton's source water.
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From page 80... ...
Environmental Protection Agency Inventory of Water Quality (USEPA, 2000) , nonpoint source pollution from agricultural lands is among the leading sources of impairment of our nation's waterways.
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From page 81... ...
In addition to the commonly cited contaminants in agricultural settings, pathogens and pharmaceuticals have emerged in recent years as potential water quality concerns. Pathogens may enter drinking water supplies from agricultural feedlots and fields fertilized with animal manure where conservation management either is not practiced or is not practiced adequately.
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From page 82... ...
Conservation technical assistance programs are the primary tools used by NRCS to improve water quality in agricultural settings. NRCS field personnel, in cooperation with other public and private technical service providers, supply technical assistance directly to farmers and ranchers to help them meet their goals for natural resource stewardship.
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From page 83... ...
The North Fork of the Potomac was plagued by elevated levels of fecal coliform bacteria, due primarily to polluted runoff from intensive animal agricultural operations along the waterway. As a result of the implementation of numerous BMPs funded under several federal and state water quality programs, the water quality of the North Fork of the South Branch of the Potomac River has improved to such an extent that the stream no longer exceeds criteria for the listing of impaired or polluted water bodies in West Virginia (Federal Clean Water Act, Section 303(d)
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From page 84... ...
The enhanced federal partnership between USDA and EPA in recent years has led to more effective interactions on significant water quality activities. Collaboration on the Concentrated Animal Feeding Operation Rule, the Chesapeake Bay and Mississippi River basin nutrient over enrichment challenges, and source water protection activities provide an impetus for additional successes in the future.
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From page 85... ...
This contribution is natural, and while it can be modified by human activities, it occurs with or without human intervention. Anthropogenic inputs of nitrogen and phosphorus to surface and groundwaters may be far greater in magnitude than natural inputs; the most significant anthropogenic sources are wastewater treatment plants, urban runoff, agricultural activity, and fossil fuel burning.
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From page 86... ...
Since 1978 a cooperative national monitoring effort has tracked the status and changes in wet deposition in the United States. The National Atmospheric Deposition Program (NADP)
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From page 87... ...
. Characteristics of wet deposition that must be considered in trend analysis include the influence of seasonality on data variability, typically nonnormal data distribution, missing data resulting from data screening steps, and considerable variation in the apparent form of trends exhibited at NADP sites (step-function, linear, or nonlinear)
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From page 88... ...
Sites with increasing trends in nitrate were predominantly located in the Western and Southeastern United States, while sites with declining trends were located mostly in the Northeast. The median trend of all 149 sites examined was less than +3.0 percent over the 17year period.
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From page 89... ...
While the Clean Water Act (CWA) has focused on protection of recreational waters, the Safe Drinking Water Act has focused on drinking water.
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From page 90... ...
with public health goals but has focused on treatment technology and has little authority for implementing watershed protection approaches except in a few cases. The complementary nature of the two laws is obvious, particularly for freshwater systems; however, changes that focus on pathogen targets in sources would have to be made.
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From page 91... ...
. The harmonization of a risk assessment framework to serve the goals of both the Clean Water Act and the Safe Drinking Water Act will ensure that efforts in the future to protect waterways from pathogens will be synergistic.
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From page 92... ...
92 FROM SOURCE WATER TO DRINKING WATER litical and economic aspects associated with rapidly changing population dynamics, political alliances, and economic power. If we are to solve the water problems remaining, new approaches, solutions, and ways of thinking must be applied.
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