Eleven storm drains empty into Colorado Lagoon in Long Beach, and its only outlet to the sea -- a 900-foot underground culvert -- is choked with mussels, clams, sand and barnacles.

So it’s no surprise that one of Southern California’s only lagoons -- shallow saltwater bodies sheltered from the ocean -- is among the dirtiest around. Last year, Colorado Lagoon was ranked as the state’s fourth most-polluted beach in Heal the Bay’s “Beach Bummers” list.

FOR THE RECORD:

Lagoon restoration: A story in Monday’s Section A about the restoration of Colorado Lagoon in Long Beach misidentified the State Water Resources Control Board as the State Resources Control Board. —



Yet the Y-shaped basin is one of the most popular swimming spots in the city, packed with sunbathers and swimmers on hot summer afternoons.

Conservationists have been working for more than a decade to restore the 18-acre lagoon, often removing as much as 100 pounds of trash at weekly cleanups.

But only now are their aspirations starting to take shape in a big way.

On March 1, the city will begin the first phase of a $15-million restoration project that will catch trash before it reaches the lagoon, remove contaminated sediment and revegetate its banks, and it could soon carve out an open channel to the sea to restore cleansing tidal flows.

“Everyone that lives around here knows the lagoon is in really bad shape, and a lot of people have written it off and said it’s too dirty to fix,” said Dave Pirazzi, president of the nonprofit community group Friends of Colorado Lagoon. “We’re trying to turn that around.”

Once part of the Los Cerritos Wetlands, Colorado Lagoon was dredged in the 1920s along with other low-lying tidelands in Alamitos Bay for recreational rowing. Divers leaped from a three-story floating platform to compete in trials for the 1932 Olympic Games in Los Angeles

But over the decades, the ecological health of the lagoon has deteriorated.

Today, the lagoon’s water has elevated bacterial levels, and its sediment is contaminated with lead and other metals. Mercury, DDT and other toxins have infested the fish and mussels that call it home.

In 2002, the state designated the lagoon an “impaired water body” as trash, debris and sediment from a vast watershed continued to drain into the lagoon, the area’s low-point. The beach on the lagoon’s southern edge is often closed because of sewage spills, most recently on Jan. 12, when 876 gallons of waste from a clogged sewer made its way into the lagoon.

Long Beach public health officials, who take weekly water samples at the lagoon to monitor bacteria levels, say the measurements only intermittently spike to unsafe levels. But there is no doubt that urban runoff and inadequate circulation have fouled the water.

“People love the Colorado Lagoon; it’s something that’s near and dear to the hearts of a lot of people that live there and have swam there,” said Nelson Kerr, manager of the city’s bureau of environmental health. “So we’re looking with a lot of anticipation at this project. It’s very promising.”

The project is being paid for with federal stimulus funds doled out by the State Resources Control Board. The Port of Long Beach also advanced $1.3 million toward the restoration and paid for environmental and engineering studies.

If the entire restoration is completed, the port stands to receive credits from state regulators that could offset future expansion.

Some other improvements could help speed along the lagoon’s recovery.

The city is building a new drain on nearby Termino Avenue, designed to route some runoff to the ocean instead of depositing it directly in the lagoon. And three of the lagoon’s other storm drains will be diverted to surrounding sewers.

The restoration project is kindling hopes that cleaner times will come to this urban sanctuary, ringed by houses and apartments and used by wildlife, swimmers and model boat enthusiasts.

“The lagoon is kind of an underdog wetland,” said Eric Zahn, restoration director for Friends of Colorado Lagoon. “But what I’ve learned is that it’s a rare place. Where else can you swim with a great blue heron?”

tony.barboza@latimes.com