Its estuaries and moss-covered islands sweep the horizon, across a landscape barely touched by civilization. Hundreds of tiny passerine birds whiz by in a shape-shifting black cloud often centimeters above the water.

Visiting the nature reserve is akin to walking through a prehistoric museum frozen in time.

Yet a mile down the southernmost trail into the marshes stands an oil well. And another lies just behind it, both surrounded by barbed wire fences.

To transform more than 1,300 acres into a dedicated nature reserve was an expensive venture. The final cost per acre is staggering. But the dozens of photographers, joggers, birdwatchers, and hikers that visit the reserve each day believe it is worth it.

Development began in 1997, when the California State Lands Commission purchased 880 acres from Signal Landmark, a property development company, for more than $26 million. It cost another $120 million to secure construction contracts for development, to buy out 64 oil wells on site and abandon them, and to pay off the nine other public agencies involved in the sale. Compared to the original cost projections of $80 million in 2000, the project grew both more expensive and time consuming investment than planned.

Between the land purchase in 1997 and the completion of restoration projects in 2006, each acre on average cost $167,000 to maintain.

Only 118 acres of the entire reserve are above water; there are five miles of public walking trails throughout. The rest remains covered by fluctuating tidal waters, which provide a stable home for many threatened and endangered fauna.

These include the California least tern, a federally endangered breed of small bird that nests in the bays of the Pacific Ocean -- at least ten-percent of the world’s least tern population resides in the sensitive ecosystems of Bolsa Chica.

Displays in the Bolsa Chica Conservancy’s educational center, at the westernmost boundary of the reserve, point out that the wetlands are vital to the survival of many other species of bird, fish, and flora -- and that the ecosystem pays for itself.

“It protects against flooding and storm surges by acting like a sponge,” reads a display that stands next to a line of small terrariums, some filled with live black widow spiders and alligator lizards collected from nearby marshes.

The land soaks up water dropped during storms and prevents it from reaching populated areas, and the sign at the Interpretive Center reads that this form of “natural flood control saves millions across the country.” Across the country, “the water purifying mechanism of wetland areas saves billions and fisheries depend on them to keep a billion-dollar industry running smoothly,” it reads.

Shirley Roth, a volunteer hostess with the Bolsa Chica Conservancy, has been with the non-profit organization for six years. She stands once a week in the exhibit room of the Interpretive Center, dedicated to local wildlife and marine research. Roth is also eager to tell others about the land’s rich history.

“When you think of it here in this metropolitan area, it’s like a hidden secret,” said Roth. “People in the 1970s said they didn’t want this to become another developed area. And we’ve proved it could happen.”

In 1890, a local gun club established the first settlement on the wetlands. Known for its unrivaled bird populations, greater than anywhere else in southern California, Bolsa Chica was a prime location for duck hunting. The duck-hunt was transformed into valuable territory when oil prospectors struck oil in 1922. More than 400 oil wells sat atop the wetlands by the 1950s; oil drilling continues here today.

As evidenced suddenly at the end of the southern walking trail stand two oil wells, rocker arms swaying back and forth. They stick out in the scenery like remnants of a compromise reached in haste -- the compromise between the oil companies that once controlled the wetlands and the State Lands Commission.

Signal Landmark acquired more than 2,000 acres of the wetlands in the late-1960s, planning to erect a housing development with 4,884 units, according to the California Public Utilities Commission. When Signal announced it was setting aside 300 acres as part of an ecological reserve for the public, it was not enough for some local members of the League of Women Voters. They were the first to object to the development and in 1976, eventually formed the Amigos de Bolsa Chica.

Stopping Signal’s advance on the area was the first priority for the Amigos. Preserving the natural habitat for the species that depend on Bolsa Chica’s ecosystems for survival was their second goal, and the Amigos succeeded at both.

After three years of bargaining with politicians and protesting at town hall meetings, the voters-turned-conservationists convinced the state to write a blank check for the restoration of the wetlands. The influx of water from the Pacific Ocean was dammed from reaching the wetlands under the gun club’s ownership in 1890, but the tides flow freely again into Bolsa Chica’s estuaries because of the Amigos’ persistence.

On the first and third Saturdays of each month, dozens of volunteers suit up for a messy morning. Donning rubber boots, gloves, and by the 11 a.m. a thick layer of mud, they tidy up the five miles of walking trails throughout the nature park. It is hard work to maintain the paths around the estuaries, with an all-volunteer staff, where the constant ebb and flow of the tide wears at the edges of the landscapes designed for public access.

Each passing season brings new species to the Bolsa Chica Ecological Reserve. Every day of the week, photographers, bird watchers, and students cross the footbridge at the head of Bolsa Chica’s southernmost trail to experience nature in the midst of the coastline city.

Each half-hour, between the majestic flights of the once-endangered brown pelicans and the occasional vulture, large white featherless birds roar overhead, carrying their passengers to the Long Beach Airport. The constant hum of the Pacific Coast Highway seems distant, but it lies just a few hundred yards away from the walking trail.

Reach contributor Christopher Foy here.