Once the wellhead protection area has been delineated, potential threats to the public water supply need to be identified within that area. The identification and inventory of all sources of contamination is an integral part of every wellhead protection program. One such source that has the potential to reach the well and contaminate the water supply would be a chemical release.
It is important to become familiar with the State's approach to contaminant source identification as outlined in its Wellhead Protection Program. Some State agencies will have requirements for how public water supplies should conduct a source inventory or how to map the sources of contamination. Other State agencies have opted to conduct the source identification themselves for all the public water supply wells in the State.
It is likely that records of potential sources of contamination already exist and it is a good idea to gather as much existing information as possible in order to avoid unnecessary duplication of work.
There are a number of resources
available to assist in gathering existing information.
First, regulatory and other governmental agencies at the
Federal, State, and local level maintain records for
activities and facilities that may release contaminants,
such as permits issued, records of zoning, or property
transfers.
In addition, existing information can be obtained through
literature and historical records searches. Existing
information can provide a useful picture of past land
uses and potential sources of contamination that have
since been abandoned but could still be causing a threat
to the water supply.
Since records may not exist for all potential sources of
contamination, an effective way to collect additional
information and identify potential sources of
contamination is to conduct a search or survey. The
search needs to focus on past as well as present
activities. The types of surveys can range from simple
mail and phone surveys to detailed field studies.
Surveys can be conducted by either paid staff or
trained volunteers. Some communities have found that the
survey does not have to be an expensive effort. Local
volunteers, once trained, have proven very effective in
identifying potential sources of contamination.
Once data gathering and surveying is complete, the
location of the potential contaminant sources and
boundaries of the wellhead protection area can be placed
on a map. Mapping this information not only can help
organize the information, but can provide a visual
perspective of the location of threats relative to the
water supply. The map can be valuable as a public
education tool as well as being useful for potential
contaminant source management, contingency plan
development, and new well siting.
View the "List of Common
Sources of Groundwater Contamination"
View the "Common
Activities Related to Groundwater Contamination"
Continue to 4-Manage the Wellhead Protection Area