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Encinitas exploring irrigation ordinance

CHRISTINA S. JOHNSON
Staff Writer
ENCINITAS ---- To help prevent the kind of landslide that killed a Leucadia woman last month, the city is considering an ordinance that would limit irrigation on bluff-top properties.

Drier cliffs are stronger and lighter, and thus less prone to collapse than over-watered ones, a geologist and an engineer say. Solana Beach has an ordinance that limits watering on all bluff-top properties, precisely to increase public safety.

"We are not necessarily going to ask everyone to dig up their yards" and dismantle their irrigation systems, said Cathy Stone, a program manager for Encinitas.

She said the city is not exactly sure how to reduce the amount of water sprinkled, hosed and piped on bluff-top lawns without upsetting property owners.

That, she said, is the purpose of looking into an ordinance.

"We will be talking about a comprehensive bluff-erosion plan (this) week," she said.

Rebecca Kowalczyk, 30, was killed in a landslide Jan. 15 in Leucadia while sitting on the beach watching her husband surf. Her death prompted the City Council to ask city staff to investigate ways, such as limiting irrigation, to prevent similar tragedies.

Encinitas has a 6.1-mile-long coastline, and its most developed areas are on seemingly fragile sea cliffs. While it is impossible to halt erosion, keeping cliffs from becoming saturated with water is one way to slow the frequency of bluff collapse.

To this effort, the city also is trying to rebuild beaches with extra sand to help stabilize the cliffs behind them. It also is considering building an artificial offshore reef that would further protect the coast from ocean waves and help retain sand.

Reducing irrigation ---- and thus ground water ---- is not a new concept for staving off landslides and bluff collapses, said Pat Abbott, a professor of geology at San Diego State University. People have long suggested that homeowners in San Diego County landscape with drought-tolerant plants or switch to drip-watering systems.

"Water cuts the strength (of the bluff) in half, and it doubles its weight," said David Skelly, a coastal engineer in Encinitas.

While San Diego County gets about 10 inches of rain a year, sprinklers effectively drop 80 to 90 inches a year, he said.

"This means we are aging the land at an eightfold rate," Skelly said.

Still, rising sea levels are the No. 1 reason the coastline is eroding and why halting erosion is nearly impossible, scientists say.

In the past 18,000 years, the coastline has retreated about 1 1/2 miles, while sea level has risen some 400 feet. Recent studies have suggested the sea level could rise an additional 5 feet in the next century if the Earth keeps warming.

Not all bluffs in Encinitas are vulnerable to over-watering. The effects of irrigation vary with local geology.

The 200 block of Neptune Avenue, which is the first street back from the sea along Leucadia, is less prone to water damage than other areas because the cliffs there are largely made of porous sandstone, geologists say. The landslide that killed Kowalczyk occurred in that area.

Just four blocks away, the geology changes. By the 600 block of Neptune, Skelly said, "you are in an area that is very susceptible to collapse." The walkway down to Beacon's Beach is an old talus pile, debris from a landslide.

"The whole section of the coast is predisposed to sliding," he said.

Just one leaky toilet in the 600 block of Neptune, Skelly said, caused a failure of a retaining wall.

Farther up the coast, in the 800 block of Neptune, there are a number of homes that are literally hanging off the cliff's edges.

The Self-Realization Fellowship at Swami's in Encinitas is one more area that has had to finesse nature to survive. In the early '40s, the SRF building fell into the sea because ground water from surrounding areas had saturated the rugged cliffs. Today, its owners have wells that keep the water table down, Skelly said.

Water greases up everything, Abbott said. It makes a bluff both heavier and weaker. Water usually flows in fissures in the ground or along junctures of distinct rock layers. Too much water can destroy the bluff's structural integrity by washing the cliff out from beneath itself.

"The city should pass an ordinance prohibiting lawns and trees" that need watering, Abbott said.

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