Geographic Information System Program
Tuolumne County has had a Geographic Information System (GIS) program for over 20 years and provides GIS services to a variety of functions within Tuolumne County government as well as the public.

Originally designed as a tool for use in planning, the GIS program is now in use by Public Works, the Assessor's Office, and the Elections Office. A particularly significant user of GIS data is the Sheriff's Department, which employs data maintained by GIS for dispatch, investigations, and search and rescue. In addition, hundreds of companies, organizations, and individuals outside of the government download and use Tuolumne County data routinely at no cost.

Data Sets
The two primary data sets maintained by Tuolumne County are the cadastral parcel layer and the road centerline files. Attributes for parcels include zoning, and related layers include the general plan land use designations, supervisor districts, school districts, voting precincts, and other special districts such as fire prevention, water, and other utilities. The road files include official road names and address ranges and are used by the Transportation and Engineering divisions.

Online GIS Maps and Tools
We have two types of GIS map viewers available to the Public:

Flex Viewers:

    (A map viewer built with Flex technology uses an Adobe Flash Player which can be freely loaded on your computer that uses Microsoft operating system.  You can download it here: Adobe Flash Player.  The Flex application allows us to make more layers and tools available, with better customization than the old JavaScript viewers.  However, Flash Player cannot be loaded on most Apple products that use a form of the iOS operating system.  So, we still offer the JavaScript viewers, and are researching other apps that may work better on iPhones, iPads and similar devices and will release them once we have been successful.)

•  A new Flex viewer for General Plan and Zoning  is now available.  Layers include General Plan Land Use Designation, zoning as an attribute to the parcels, and Supervisor District boundaries.
• Supervisors Map Viewer has layers such as Supervisor District boundaries, Voting Precinct boundaries, parcel information such as zoning, General Plan Designations.
• Building Viewer has information needed for designers when preparing new building plans, such as Snowload values, elevation, Climate zone, and parcel zoning districts.
• Proposed General Plan Update has layer representing the parcels that are involved in the County project to change the Land Use Designations for approximately 4,000 parcels in the County.  Users can see where the parcels are located and what is being proposed to change.

JavaScript Viewers
   

• JavaScript Viewers work better on mobile devices such as iPads and iPhones that cannot use an Adobe-based Flexviewer, so we have one that enables the user to look up similar information such as zoning and General Plan Land Use Designations for properties: Zoning and General Plan.

File Access
The most requested GIS files the County maintains are available for download by users who have GIS software that would allow them to load and view those files.  Users are asked to read a disclaimer statement and provide some basic information via the File Access Request Form. Upon completion of that process, users will be notified of the path to the GIS file list page where they can download zipped folders containing shapefiles.  Once you have that path address, you can keep that as a favorite on your browser and return there regularly.  We hope to update the shapefile packages of the regularly maintained files (roads, parcels, General Plan) frequently, the others as needed.