Products and Services:

• Identified and mapped the locations of 8,700 on-site sewage disposal systems in unincorporated areas of Santa Barbara County.
• Created 1:24,000 Digital Line Graphs of hydrographic features in urbanized areas.
• Completed a risk analysis of on-site sewage disposal system vis-à-vis surface water resources of the County.

Santa Barbara is one of numerous coastal communities in the United States with problems of ocean water contamination following periods of heavy rainfall. A significant effort has been undertaken by local government, environmental organizations and the business community to find solutions to bacterial contamination triggering beach closures.

In 1999, GDM applied its significant mapping capabilities to locate and map the numerous on-site disposal systems that may be contributing to high levels of contaminants in the near shore zone.

In a collaborative effort involving all segments of the community, a working group was formed to establish risk criteria and define areas within the County where on-site disposal systems might be problematic. Areas potentially at risk included:

• Parcels within 200 feet of the ocean or creek.
• Parcels within the 100-year flood plain or a designated wetland.
• Parcels within areas previously known to be problematic for on-site disposal system because of poor soils, small lot sizes, or a history of maintenance problems associated with such systems.

System Inventory: GDM worked closely with the 21 sanitary districts serving the County to identify the location of occupied properties not served by sewer systems. Each such property was identified on the Assessors Parcel Map.

Locating areas at risk: GDM produced new base maps for the County to locate the presence of surface water features subject to potential contamination. Many diverse data sources were integrated to form a complete picture of the County's suface water resources.

Performing the risk assessment: Using GIS tools, GDM examined the on-site septic system inventory with respect to surface water resources, based on rules established by the County's working group. GDM prepared a final report for presentation to the Board of Supervisors.

Using this analysis, the County is working with the State to replace on-site sewage disposal systems with sewer connections in areas that are at most risk.