On a recent afternoon, Pebble Beach resident Diane Cassam stoops down near 17-Mile Drive to point out what appears to be a Styrofoam packing peanut in the dirt.

She’s been looking out for these white pellets along the pristine coastal area since she found them four years ago while practicing yoga on the nearby beach. Since then, she says, she’s spotted them in drainage ditches, roads and the bay near the elite Monterey Peninsula Country Club. The coast off Pebble Beach is a federally protected sanctuary, and Cassam worries the peanuts could harm its marine animals.

But their source eluded her. It didn’t make sense that Pebble Beach tourists or golfers would routinely litter packing peanuts. “What kept going through my mind was, ‘Where is this coming from?’” she says.

This summer, the mystery was solved. Cassam was walking by the MPCC Shore Course while a grounds crew repaired the underground drainage system near the 18th hole.

“We saw them filling that with the peanuts,” she says.

In 2002, the country club renovated its Shore Course (which is internationally known as a host of the AT&T Pebble Beach National Pro-Am tournament) and installed a drainage system called the EZflow French Drain.

While it is common to use a layer of gravel or pebbles around drainage pipes to filter out silt, the EZflow system uses “synthetic” pebbles – Cassam’s mystery peanuts – encased in plastic netting. The recycled polystyrene pellets are manufactured by Infiltrator Systems Inc.

About 3,000 yards of the EZflow material is buried under most of the 200-acre golf course, according to MPCC General Manager Michael Bowhay.

In response to Cassam’s concerns about the peanuts polluting the sanctuary, Bob Yerena, an enforcement officer with the National Oceanic and Atmospheric Administration, visited the golf course early this summer. Although Yerena saw some peanuts on the course, he declined to get involved: “We found no evidence that any of the Styrofoam peanuts had made it out to the sanctuary.”

Bowhay says the peanuts became a concern to the country club in August, when “quite a few” loose peanuts appeared on a patch of rough at the golf course’s perimeter. He believes gophers and voles burrowed underground and chewed holes in EZflow’s plastic netting. “It was obvious [the peanuts] were coming up through gopher holes,” he says.

MPCC has since instituted a vigorous campaign to contain the problem, Bowhay says. Country club grounds crews check the area several times a day for peanuts. They have installed screens in the drainage ditches to prevent the pellets from flowing into the acquifer or the ocean.

“To monitor this on an ongoing and forever basis is something we are committed to doing,” he says.

He even hired a wildlife ecologist to do a scientific survey of the entire golf course. But since gophers and voles only inhabit a tiny percentage of the area where the peanuts are buried, he says he doesn’t think the problem of escaping peanuts is widespread.

But Cassam says she’d like to see the polystyrene material banned from coastal land altogether. “The point,” she says, “is to take this out of the earth and not use it again.”