SANTA CRUZ -- The Santa Cruz County Board of Supervisors will consider Tuesday weighing in on proposed state regulation of hydraulic fracturing, the controversial oil and gas production technique known as fracking.

In a report to the board, staff says county rules also could be strengthened if fracking proposals appeared likely here.

However, the report indicates staff found in a preliminary analysis that the county possesses some regulatory authority over fracking in its grading, hazardous materials, runoff and pollution control, zoning and water well ordinances.

The issue of fracking gained prominence last summer when a seismic study was conducted around Aromas in San Benito County. Such studies are used for oil exploration, and Aromas sits at the edge of the Monterey Shale Formation, a region that stretches from Santa Clara to Ventura counties and is estimated by federal energy officials to hold two-thirds of the nation's shale oil reserves.

No proposals have surfaced to drill for oil in the area, however.

But in San Benito County, where oil production is already occurring, mostly in its rural southeast, leaders are considering new rules for fracking.

Santa Cruz County staff says the potential for oil or gas production in this county is unclear. There has been "no viable extraction of oil" in the county in the last half century, the report notes.

The state also is developing rules, and a resolution to be considered by supervisors calls for full disclosure of chemicals used in the process, assessment of environmental impact and seismic risk, groundwater testing and public notification.