Utilizing GIS Technology to Identify Potential Sites for the Oregon Correctional Facility Expansion Program

ABSTRACT: In November 1994, voters in Oregon passed two measures that resulted in the need to build a number of new correctional facilities. The Oregon Department of Corrections (ODOC) was tasked by the legislature to support the newly created Oregon Prison Siting Authority in developing and presenting a list of suitable site locations for review. GIS was identified as a potential source of valuable analysis capability in the siting process. Working together, ODOC and the State Service Center for GIS (SSCGIS) developed a list of siting criteria and identified preliminary GIS analysis needs for the siting process. The SSCGIS then proceeded to provide GIS analysis and output production services, (using ArcInfo and ArcView 3.0), that helped ODOC identify suitable locations for siting new correctional facilities and present the findings to the Governor and the people of Oregon. This paper describes the coordination, data, analysis and output product requirements involved in providing GIS analysis capabilities to the correctional facility siting process.


In response to increasing crime rates and a perceived decrease in the level of safety in their communities, voters in Oregon passed two measures in 1994 that required mandatory sentencing guidelines and an increase in available prison space. The state determined that as a result of the passage of these two measures, approximately 10,000 new prisoners would be added to the already crowded Oregon prison system over the next decade. To absorb the inflow of new prisoners, it was determined that, in addition to expanding the size of some existing facilities, seven new minimum and medium security correctional institutions would need to be constructed by the year 2005. This recommendation was forwarded to the Governor who, with legislative approval, then tasked ODOC with identifying seven sites within the state that would be suitable for the construction of these new facilities.

ODOC and the Siting Authority were given one year to complete the site selection process and present a list of suitable locations for review. The first priority was to identify the siting criteria that would be used in the initial phase of analysis. Once the process of identifying the basic criteria was complete, ODOC needed a way to identify those areas in the state that met these identified siting criteria. At this point, SSCGIS was contacted and asked to help identify the feasibility of performing GIS analysis to support the prison siting team. SSCGIS ran a search through Esri to determine if GIS had been used in other states during prison site selection efforts. The search came of negative. Through discussions with ODOC, SSCGIS determined that the majority of identified siting criteria contained a geographic component and could be effectively analyzed using a GIS. SSCGIS proceeded to perform essential GIS support services through the duration of the siting process and provide ODOC with information and output products that were instrumental in developing the final list of suitable sites.

The Site Selection Process - Initial Screening

Using the initial siting criteria identified by ODOC, the SSCGIS developed a GIS screening process that incorporated a wide variety of geographically linked features to identify general areas in the state that would be potentially suitable for a new correctional facility. Because of difficulty obtaining some necessary datasets within the necessary timeframes, the number of criteria for the initial screening was reduced to include ten key criteria (Table 1). In order for specific areas to be considered for more intensive, site-specific analysis, they needed to meet all identified criteria.

Table 1 - Initial Screening Criteria Identified by ODOC and the Siting Authority

Data Development

As mentioned above, the first step in the project was identifying the availability and quality of all necessary data. Much of the data was available in the existing SSCGIS database. These layers included: Hospital and communtiy college locations (Oregon GNIS), generalized zoning of Oregon, and Federal ownership. We also obtained a Halocene (active) earthquake coverage from USGS in Denver. We developed a slope coverage from an available Digital Elevation Model (DEM) using the ArcInfo Grid module. To identify areas within 30 miles of 30,000+ people, SSCGIS took ArcInfo coverage containing 1990 Census block data and converted it into an Arc Lattice. A population value was calculated for each cell based on the associated Census block value/# of cells within each respective block. The lattice was then converted back into a polygon coverage using the derived values as the dissolve item.


The screening process was fairly simple. Each feature was buffered by the appropriate distance (if necessary) and then given a value describing whether or not the identified criteria were met. We then overlayed each of the individual data sets to create a coverage containing suitable and non-suitable areas for each criteria. We then reselected the data to determine those polygons that met all site selection criteria and added a value indicating this into the feature attribute table. The final site selection criteria was the determination of area. Polygons that met all identified criteria were dissolved. A reselect was then performed to determine those sites that were greater than 200 acres. This produced the final coverage used to display sites within the state that met all initial siting criteria.


A statewide map displaying the results of the screening analysis was then developed for use during initial planning meetings and for discussions with various counties (Figure 1). As certain areas were identified by ODOC as being most suitable for further analysis and review, smaller areas of the screening map were produced and taken to various counties for use in locating specific taxlots that would require more extensive review.

Figure 1: Results of Screening Process

Site Specific Analysis

Using the map developed during the screening process, ODOC was able to narrow the area in which it would conduct a more intensive search for specific sites. Through a rigorous research and review process involving numerous meetings with various local governments, ODOC identified a list of approximately 25 sites that appeared to meet the initial requirement and that would need additional research. The SSCGIS was then asked to provide site specific GIS analysis and output products for each of these sites through the remainder of the initial site selection process. Once again, ODOC identified certain features that would preclude development of a correctional facility. Additional criteria included: Outside FEMA flood zones, outsite identified wetlands, and outside lands zoned "Exclusive Farm Use" Each potential site was mapped and analyzed with respect to these and other features (Figure 2). This process resulted in the further screening of the remaining suitable areas.

At this point in the process, specific sites were identified as meeting preliminary siting requirements and public meetings were scheduled.

Once all analysis was complete, the Siting Authority presented to the Governor, a list of 7 sites that were found to be suitable for siting new correctional facilities. From this list, four sites were accepted and three sites were returned for further analysis. In addition, a number of newly nominated sites were added to the list of sites needing further study.

Figure 2: Example of Site Specific Map Product

Ongoing Functions

SSCGIS continues to provide GIS analysis and report/map development functions to ODOC in support of this on-going effort. ODOC is now in the final stages of reviewing and selecting the last three sites that will be presented to the Governor by the Siting Authority. Due to the controversy surrounding some of the potential sites, several proposed bills related to prison siting are currently being reviewed by legislative committees. SSCGIS is supplying ODOC with detailed maps and additional analysis to assist in the formulation of a response on the effects the proposed legislation. In some cases, proposed legislation would, if implemented, effectively remove the vast majority of formerly suitable sites from consideration. The SSCGIS is producing maps that show the legislature the true impact of any proposed legislation.

What We Learned

The correctional facility site selection process is a complex, controversial, and ever-changing operation. One of the key requirements for successful implementation of GIS analysis and support during the process is identifying a person within the siting agency that understands the benefits of GIS and is committed to using GIS as a tool for analysis. Another requirement is the ability to allocate resources and work quickly to produce accurate analysis results and output products. Many of the analysis and output product requests made by ODOC were driven by the need to respond to a rising controversy or to defend a decision before a legislative subcommittee or at a public meeting. Finally, this process requires the ability to be flexible and to produce defensible products in the face of ever-changing priorities, mandates and requests. Since the entire site selection process is extremely controversial and open to public review, GIS services over the course of the project often take unexpected twists on their way to completion. Being prepared to deal with any potential change or last-minute request is essential.


Using GIS technology, SSCGIS was able to provide information that enabled ODOC and the Siting Authority to make informed decisions about the ability of various locations to meet identified siting criteria. GIS provided accurate, objective, and documentable analysis during an often times contentious debate over where to site future correctional facilities. GIS also provided the foundation for developing a wide variety of map products used in the many public, legislative and planning meetings required during this process. The details of this paper are specific to the correctional facility site selection process in Oregon but are likely to have many similarities to other correctional facility siting programs. The process may proceed differently depending on the state involved, but we believe that GIS technology can and will play a valuable role in providing the essential analysis required for the successful completion of future correctional facility site selection efforts.


The authors would like to acknowledge the efforts and input of the following people:

ZaDean Auyer - ODOC's site selection lead. It was ZaDean's initial vision and ongoing efforts that made the incorporation of GIS in the siting process a reality. She also provided valuable background information about the site selection process.

Steven Barnett - SSCGIS GIS Analyst. Steve completed most of the GIS analysis and map production for this project and provided input for this paper.

Mark W. Kinslow

Theresa J. Valentine

Oregon State Service Center for GIS

Department of Administrative Services

155 Cottage St. N.E.

Salem, OR 97310

Telephone: (503)373-7461

Email: Mark.W.Kinslow@state.or.us