County planners say a limestone quarry in the hills above Davenport, owned by Cemex, could be expanded with little risk to local water supplies.

In a recent review of Cemex’s long-proposed quarry expansion, the county concludes that precautions can be taken, like filtering the runoff from mines, to prevent contamination of an underground spring used by Santa Cruz for drinking water.

Cemex, which also runs the cement plant in Davenport, has sought for more than a decade to enlarge its 87-acre quarry - by 17 acres. But environmental concerns, namely the fate of the city’s Liddell Spring, have slowed that effort.

The environmental impact report released this summer downplays the possible threats.

"There are no significant unavoidable impacts," said county planner David Carlson in a presentation Tuesday before the Planning Commission.