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Gis and outreach programs -Reply



Rick Cobb (217 - 785-4787) of our Bureau of Water's Groundwater
Section offers the following responses to your questions:

"1.  Yes, the Illinois EPA's Groundwater Section uses GIS (ARC/INFO) and
ArcView) to display, and map modeled community water supply recharge
areas (Visual MODFLOW) in relation to inventoried existing potential
sources of groundwater contamination, land use zoning, geologic
susceptibility.  In addition, we relate this information to GIS date available
from the Illinois Department of Natural Resources (IDNR) and the USGS.
We have done a detailed field inventory, and file search for potential
sources of groundwater contamination for each community water supply,
and have coded the data into a relational database management system
(FoxPro).  The well locations and potential source scanned/and rectified
(e.g., rectified to the digital line graph roads [DLG]) into GIS.  Thus,
for the
groundwater systems, we have not needed any commercial data bases
to represent potential sources since we have the site specific data.

We have also used ARC/INFO and ArcView GIS to assess delineated
watersheds for community water supplies using surface water.  We
started doing this assessment on 40/114 surface water supplies with
pesticide drinking water standard violations.  In addition, we have done a
GIS analyses of the 7 supplies with nitrate drinking water standards
violations.  GIS has been used, for the above, to look at :  NPDES
discharges (classified by excess pollutant loads) (IEPA data);TRI
discharges (IEPA data) to POTWs and receiving streams; groundwater
susceptibility to pesticide and nitrate leaching potential maps (IDNR data);
digital elevation models or surface topography (USGS); Envirofacts Data
(e.g., RCRIS, CERCLA, PCS, AIRS [USEPA]), and 28 meter resolution land
cover data (IDNR).  Additionally, we have assessed the surface water
intakes on the large rivers (e.g., Mississippi, Illinois etc.,) by
progressively
looking at the information described above using a segmented watershed
approach, upstream from the intakes.

2.  We have done some preliminary evaluation of commercial data base
information on Illinois LUST locations, and using the DUN & BRADSTREET
data.  We are also trying to obtain USDA selected farm count data all ZIP
codes with five or more farms.  Data items include total number of farms;
farms by size; operator characteristics; cropland harvested, land use
characteristics; value of agricultural products sold; inventory and sale of
livestock and poultry items; and major crops harvested.  We will be using
this data with other information to estimate potential for crypto sporidia
impacts.

3.  We have not necessarily used a lot of commercial data bases, but the
tools that we have used to generate maps for local stakeholders have
been used very successfully to generate "awareness" of where locals
drinking water is coming from and what its vulnerability is to
contamination.  it is because of this general awareness that we have had
success with implementation of local source water protection programs. 
pollution prevention is an integral part of our strategy for managing
existing, and new potential sources of contamination.  (Reference Cobb,
R.P., A. Wehrmann, and R. C. Berg. 1995. "Guidance Document for
Conducting Groundwater Protection Needs Assessments, Illinois EPA
report).

In terms of experience with data bases that have not worked.  We were
doing a project with the Waste Management Research Center (Illinois
Non-Regulatory Assistance Provider), and they were using the Dun &
Bradstreet data base to potentially target businesses that have Class 5
injection wells.  The information was very inaccurate."

I hope the above is helpful.  If you need clarification or have additional GIS
questions, feel free to call Rick Cobb.