Indiana Epidemiology Newsletter
R. J. Beck
Water and Vector Control Specialist
Tippecanoe County Health Department
In recent years, many of Indiana’s local health departments (LHD) have incorporated GIS into their existing public health programs. What once was marked on a paperboard map with pushpins has been replaced with detailed information stored in databases, mapping software, and aerial photographs. For those of you who may not be familiar with GIS or GPS units, they are simply defined as:
GIS - Geographic Information System - a collection of computer hardware, software, and geographic data used to store, view, manage, and analyze all forms of geographic information, especially maps.
GPS - Global Positioning System - a system of satellites, computers, and receivers able to determine the latitude and longitude of a receiver on earth by calculating the time difference for signals from different satellites to reach the receiver.
Mapping techniques, variations in GPS receivers, and software can be tailored to fit the individual needs of any program. LHDs in rural areas may not have an immediate need for a GIS program, while larger, more urban LHDs may have several advanced mapping units and staff specifically responsible for a GIS program. The program being developed in Tippecanoe County lies somewhat in the middle of these two extremes. While we have the luxury of GIS staff at the county level for assistance, Health Department personnel have developed a GIS program to fit our specific needs. The following is an overview of how the Tippecanoe County Health Department (TCHD) saw a need and implemented GIS to enhance our existing environmental programs.
In 2003, Tippecanoe County and the City of Lafayette launched a GIS Web site which included parcel information and many useful layers such as floodplain boundaries, soil descriptions, topography, and catch basins, to name a few. Although no TCHD staff had any prior training or experience with GIS, they quickly gained hands-on experience from accessing the Tippecanoe County Web site and using the layers and tools available. Staff within the TCHD environmental division realized an immediate use for mapping of on-site sewage systems, mosquito surveillance, and water sampling locations. Fortunately, we had a wealth of knowledge within the information technology department at the county level and very helpful GIS personnel to assist when necessary. After several brainstorming and tutorial sessions, we were on our way!
In 2004, the Indiana State Department of Health (ISDH) received grant dollars from the Centers for Disease Control and Prevention (CDC) to purchase GPS handheld units (Garmin Etrex Legend, valued at $170 apiece) for each county in Indiana that requested a unit. We quickly jumped at the opportunity to incorporate a field unit to complement the existing mapping capabilities from the county Web site. The Garmin Etrex Legend is a “basic” handheld unit capable of multiple data sets and vague mapping. Although there are more advanced mapping and surveying units capable of managing datasets and detailed mapping, the Garmin Etrex Legend fit the scope of our program.
During 2004, TCHD environmental staff began using the handheld units for marking locations in the field during routine inspections. Although the units seemed intimidating and clumsy at first, staff quickly became familiar with the setup and features available. One important feature that any handheld unit should have when marking a location is Wide Area Augmentation System (WAAS). WAAS allows the user to have a much more precisely marked location, which, in turn, will help to retrieve the location in the future.
Interest began to grow within the department pertaining to GIS, its uses, and benefits. Two additional Garmin Etrex Legend units were purchased for staff and interns to use when conducting field work. What started with single handheld units marking septic systems quickly grew into a large database and mapping program for all permitted residential sewage systems, all mosquito-related activities, and surface and groundwater monitoring locations.
Handheld units are used to mark and locate septic tanks, distribution boxes, and perimeter drain outlets. Each year, saved locations can easily be downloaded to a personal computer and incorporated to the county GIS Web site with detailed information available to staff and the public. Features available on the county GIS Web site allow staff to view layers such as soil characteristics, topography, and floodplain information when planning and determining feasibility for on-site sewage systems. Mapping techniques have also been used with great success in local watershed management plans. Areas of a watershed with dwellings that have no records of sewage systems were highlighted and targeted to educate those individuals about the importance of proper sewage disposal.
The two environmental programs significantly enhanced by GIS are the mosquito and water sampling programs. With very limited staff and resources, GIS has helped us to identify and target areas known to have mosquito-breeding problems. By using floodplain data and tracking precipitation amounts, maps can be generated that direct staff in response to various rainfall amounts to particular areas that hold water following rain events. In addition, adult mosquito trapping locations and locations of dead birds provide evidence of West Nile virus activity that can be mapped to identify clusters of elevated virus activity. This aids in the effort to warn the public of the potential for human infection and the need for personal protection strategies.
During 2005, handheld units were used during a county-wide groundwater sampling program. Well locations were mapped along with results from the nitrate tests being conducted. By overlaying soil maps along with testing location and results, clusters of elevated nitrate levels were obviously recognized in areas of sandy-based soil coupled with shallow well depths. Although soils information is not described in the illustration, a trend of elevated samples can be followed along the stem of the Wabash River where there are primarily sandy-based soils.
Each recreational season, public access sites along local waterways are tested for bacteria levels. Should any location exceed bathing beach standards, signs are posted to warn patrons of elevated levels of bacteria. Beginning in 2007, the public can access the county GIS Web site to learn testing dates and test results on an interactive map as illustrated below.
Interest within the TCHD continues to grow and new uses for GIS will soon become commonplace not only in the environmental division but also in the foods and swimming pool inspection programs. Soon, staff members from both programs hope to have inspection reports available on the county GIS Web site along with a link to the Visitors Bureau to aid patrons in making informed decisions and to facilitate establishment owners striving for excellence.
Establishing a GIS program, or simply becoming familiar with GPS units and mapping software, can be a daunting and intimidating task. There certainly will be obstacles with cost, technology, or personnel, but the development and enhancement to public health programs far outweigh the initial hurdles. Not all GIS programs require elaborate software or units. For example, the TCHD began with a single donated handheld unit, helpful information technology staff, and a willingness to be open to change and possibility. Recent budgets for the environmental division have been a meager $2,500 for supplies, which translates into utilizing available resources on the Web and within the county. If you are interested but do not know where to begin, contact ISDH representatives who can provide information on several counties in Indiana that have established GIS programs and would be happy to assist in your efforts. Training opportunities and Internet Web sites offering free downloads of data and aerial photography include:
For more information on GIS technologies and services, contact Ed Lutz, ISDH GIS Program Supervisor, at 317.233.7695 or firstname.lastname@example.org.