Saltwater or seawater intrusion?

Saltwater or Seawater intrusion?

A sidebar to “A water war in Salinas,” published by The (Salinas) Californian, Feb. 8, 2003.

While the fact of saltwater contaminating freshwater supplies near the coast has been accepted since the 1940s, a new controversy over what’s causing that contamination has recently bubbled to the surface.

For half a century, the saltwater intrusion spoiling the water beneath Castroville has been blamed on the creeping advance of the ocean underground. Conventional wisdom has long held that people, mostly farmers pumping fresh water out of the ground for their crops, have upset the balance of underground water.

Because nature hates a vacuum and water seeks the lowest ground, the prevailing theory has been that the salty water from the ocean is moving inland to take the place of the fresh water that is pumped up wells.

Representatives of the Monterey County Water Resources Agency, whose project will be up for election in January, even insisted in a recent interview on calling the process “seawater intrusion,” just to make clear the cause of the problem.

But a leading hydrologist says the sea is getting a bum rap. Dr. Robert Curry, who directs the Watershed Institute at nearby CSU Monterey Bay, said the saltwater killing crops around Castroville is not coming from the ocean, but from geologically older, deeper pockets of water that are leaking into the more shallow ones the valley taps for its fresh water.

Curry said most scientists are acknowledging the impact of what he called “leaky aquifers,” underground reserves of groundwater that aren’t as isolated and separate as once thought. “When you pump on one, it sucks up water from the others.”

The region’s water policies are based on a “very simplistic geological model that’s completely wrong,” Curry said. “It doesn’t fit the reality of what’s out there.”

Salinas’ water resources planner, Leo Havener, Jr., said the clay layers beneath the city are broken. Havener said that means the water agency ought to plan for the likelihood that the increasingly salty water 180 feet deep could spill into the 400-foot aquifer below the city, spoiling the region’s two main sources of underground freshwater.

But Bob Meyer, the water agency’s chief of operations and maintenance, said “99 percent” of the region’s problems with saltwater come from the coast. The contamination coming from the “leaky aquifers” Curry described is “minimal,” Meyer said.

“You’re not going to contaminate the whole world with oil from a slow leak in your (car’s) engine,” he said.

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