What is GIS, and why do we use it?

A Geographic Information System, or GIS, is a computer-based application that allows us to view, analyze, and manipulate spatial data.  More than just “map making,” GIS integrates geographic data with information about the geographic features.  Using the GIS program, not only can the location of something be shown on a map, but information about the features can also be seen and used for a variety of purposes.

The Delaware SWCD uses GIS for drainage projects and agricultural services, drainage maintenance, conservation education, and watershed planning.


GIS Data

The data used in our GIS applications comes from a variety of sources including the Delaware County Auditor, the Ohio Department of Administrative Services, the Ohio Department of Natural Resources, and “in-house” created data layers.


Delaware County Auditor

The Delaware County Auditor’s GIS office was established in 1994 and has been the recipient of numerous international, national, and local awards for its exemplary and innovative use of GIS technology in property taxation (as well as many other applications).  The Auditor’s GIS office is the source of the majority of spatial data specific to Delaware County including parcels, roads, municipal boundaries, township boundaries, flood plains, school district boundaries, census data, topography, and other information.  The Auditor’s GIS Office also provides digital orthophotography (an aerial photograph that has been geometrically corrected so that it can be used to measure true distances) for 1997, 2002, 2006, 2008, and 2010.  All of the Auditor’s GIS data can be viewed for free by accessing the Auditor’s Office GIS Website.


State of Ohio – Ohio Geographically Referenced Information Program (OGRIP)

OGRIP, part of the state’s Department of Administrative Services, Office of Information Technology office, is comprised primarily of volunteers from state agencies, local and regional governments, utilities, universities, private organizations, and other interested individuals.  The goals of OGRIP are to encourage the creation of digital geographic data, foster the ability to easily determine what geographic data exists, and foster the ability to easily access this data.  One of the major projects of OGRIP includes the publication of digital orthophotography for every county in the state.  Additionally, OGRIP published LIDAR images for almost every county.  LIDAR, a remote sensing technology, measures distance by using lasers.  It allows for the creation of a “photo” with surface elevations embedded within it.  We use these LIDAR images to analyze surface topography and map watercourses and drainage areas.  Other data available through OGRIP includes state and county boundaries, census data, statewide road information, municipal boundaries, major streams and rivers, and water well log locations.


State of Ohio – Department of Natural Resources

The Department of Natural Resources, maintains a vast amount of GIS data primarily focused in the environmental area.  This includes soils, land cover, watersheds, erosion potential, groundwater resources, land use/land cover, the Ohio Wetlands Inventory, and farmland information.


Delaware SWCD Data

    • Drainage Maintenance Data
      The Drainage Maintenance Guide program maintains drainage infrastructure in agricultural, suburban, and commercial areas.  Our Drainage Maintenance GIS data consists of project boundaries, agricultural tile, waterways, storm tile, storm tile features (such as catch basins, curb inlets, manholes, retention and detention basins, and flood routing).  These data layers are dynamic as new features are added due to new projects incorporated into the program.


    • Historic County Drainage
      The process that allows for landowners to petition the County Commissioners for drainage improvements (ORC 6131) has been codified since the late-1800s.  The Drainage Maintenance provision of this law (ORC 6137) was enacted in 1957 and requires all projects done under the petition process to be placed in the drainage maintenance program upon completion.  As such, many of the projects done under the petition process are not included in the maintenance program and thus, are not included in our drainage maintenance GIS data layers.  This data layer specifically contains the location of those projects including open ditches and subsurface drainage tile.  This data layer was not created by the SWCD; however, we currently maintain it.  In some instances, the data was created from historic hand-drawn records.  Because of this, the locations of some features are approximate.


    • Technical Assistance
      Beginning in 2004, the Delaware SWCD began tracking all technical assistance contacts based on parcel location.  This data layer allows us to track the type and location of assistance provided, as well as tie assistance notes to the parcel.  Using this system, our technicians can easily access information concerning previous contacts with a parcel (allowing the technicians to better assist landowners).


    • Historic Conservation Practices
      The creation of a digital inventory of all conservation practices designed by the Delaware SWCD originally began in the Upper Big Walnut Creek Watershed (as part of an on-going partnership with the USDA Agricultural Research Service (ARS) Soil Drainage Research Unit studying the effects of conservation practices on water quality improvement). Once the Upper Big Walnut Creek Watershed was completed, the project was expanded to the entire county.  Every conservation practices designed by the SWCD since its inception in 1944 has been scanned, and its location digitized based on photo and parcel data.  Using this layer, we can view the locations of practices, and access digital copies of engineering plans directly from the GIS program.


    • Historic Stream Names
      This project started as an effort to create a roster of historically accurate names for streams and channels in Delaware County.  Names were researched using a variety of sources. Current aerial orthophotography was used for spatial accuracy.  All known names have been recorded with preference given to the earliest known and/or most legally-binding name. Record sources used to create this layer include Historical Plat Records, USGS databases and topographic maps, 1866 Historical Township maps obtained from the Delaware County Historical Society, Delaware County Ditch Records, Delaware County Engineer’s Office Bridge Records, and USDA NRCS project watershed records.


  • Historic Aerial Photography
    In addition to the digital orthophotography available from the Delaware County Auditor, the SWCD possesses digitized and georeferenced historic aerial photographs.  Years available include 1939, 1951, 1957, 1964, 1971, 1980, and 1988 (color infrared).


For more information, contact:

Bret Bacon, Conservation Services Coordinator
(740) 368-1921



Delaware County Auditor’s GIS Office

Ohio Geographically Referenced Information Program (OGRIP)

OGRIP Statewide Imagery Downloads

Ohio Dept. of Natural Resources Geographic Information Management Systems Statewide Data

USDA NRCS Web Soil Survey


United States Geologic Survey Digital Map Products

USGS National Hydrography Dataset (NHD)