SWAP Vulnerability Assessments

Arkansas Department of Health
Center for Local Public Health - Environmental Health Branch - Engineering Section

Drinking Water Information for Arkansans

SOURCE WATER PROTECTION PROGRAM

II. Vulnerability Assessments

It is our intent to implement the assessment process with a phased approach. The initial phase or Phase I Assessments will be done in full accordance with EPA guidance and will be completed by the statutory deadline. Phase I Assessments will provide completed assessments that will allow the initiation of local source water protection plans and provide a priority system for the refinement of the assessments on a continuing basis.

Within a delineated assessment area, each Potential Source of Contamination (PSOC) will be identified, mapped, categorized according to its relative public health significance and proximity to the drinking water source intake.

We have entered into an agreement with the United States Geological Survey (USGS) to perform database and Geographical Information System (GIS) development. Each water source will have an assessment area delineated and the PSOCs in that area located and mapped. Each water source will then be assessed to determine its susceptibility to contamination. The USGS will provide the results of the susceptibility analysis and other data to the Arkansas Department of Health. The Arkansas Department of Health will compile and summarize all data, maps, and the susceptibility analysis in a report that will be sent to the appropriate public water system for dissemination to its customers.

PHASE I ASSESSMENTS

The vulnerability assessment is a multi-step process consisting of source location, delineation of source water assessment areas, identification of potential sources of contamination, and a susceptibility analysis. The culmination of the Vulnerability Assessment will result in a designation of low, medium, or high source susceptibility. Within a delineated assessment area, each Potential Source of Contamination (PSOC) will be identified, categorized according to its relative public health significance and proximity to the drinking water source intake, and mapped on a GIS database.

A source water susceptibility analysis will be performed for each public water supply. The intrinsic characteristics of each source will be evaluated to determine the sensitivity of the source to possible contamination. PSOC�s within the assessment area will be incorporated into the overall analysis. Their location with respect to the source, and the hazard they present, will be considered to determine if the source is susceptible to contamination at a level that may be of public health significance. Potential sources of contamination that are outside the delineated assessment area may be incorporated into the susceptibility analysis and/or vulnerability assessment at the discretion of the State dependant upon the prevalent topographical and hydrogeologic characteristics of the area.

All the data, maps, and the susceptibility analysis will be compiled and summarized. A report on each drinking water source will be generated and sent to the public water system for dissemination to its customers. Copies of each summary report will also be placed on the Internet.

Phase I will provide completed assessments that will allow the initiation of local source water protection plans. After completion of all Phase I Assessments the Arkansas Department of Health (ADH) will provide technical assistance to the public water systems in developing their local source protection program. This assistance will be rendered upon request and / or using the priority system established in Phase I. ADH assistance will include (but not be limited to) implementation of guidance, updating Phase I assessments and / or conducting a more detailed Phase II Assessment.

PHASE II ASSESSMENTS

Phase II Assessments will utilize the priority system developed by Phase 1. These assessments may include any or all of the following:

Assessment of the entire watershed within the State boundary for rivers and impoundments and recharge basins for springs

Expand and / or refine the assessment area utilizing more detailed site specific data

On-site inspections of PSOCs to more accurately evaluate site conditions and locations. Such on-site inventories will include accurate siting of significant PSOCs with GPS.

Evaluation of individual PSOCs to determine the likelihood of contaminant release and its actual public health significance

Incorporation of any other new information obtained

Re-evaluation and updating of the data used to determine the degree of source susceptibility

(The reader should note that this will be an evolving program. Delineation methodology and other program components will continue to be refined as staff gain training and experience in administering the program.)

For information on the national level, try EPA's Source Water Protection site

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