Border Fence to Carve up Nature Reserve

Another chapter in U.S.-Mexico border relations is about to close. In the waning days of the George W. Bush administration, the U.S. Department of Homeland Security is completing construction of a 22-kilometre triple fence along the San Diego-Tijuana border.

It is being done over the objections of environmental activists living near the border, who are worried both about the toll on wildlife and those seeking entry into the United States. A patch of green encircled by two cities, the Tijuana estuary lacks the grandeur of a mountain range but to biologists and conservationists it's an invaluable piece of real estate.

Created in 1981, the Tijuana River Research Reserve is an island of relative calm at the centre of a political maelstrom that pits conservations against advocates that promote tighter border controls.

Nesting amid coastal sage and tall grass, 400 species of birds inhabit the wetlands. Thousands more birds return each year to one of the last vestiges of salt marsh existing in Southern California, where 90 percent have been lost to development.

"The estuary is one of the few remaining in Southern California without heavy human intrusion," said Mike McCoy, president of the South West Wetlands Interpretive Association.

However, the estuary has been part of contested territory for generations. The land was granted to the United States after the Treaty of Hidalgo in 1848, which ceded much of what is now southwest Arizona, Texas, New Mexico and California to the United States in the aftermath of the U.S-Mexican War.

The estuary has also been labeled a haven for drug-running and illegal border crossings, according to border officials, making it a flash point for U.S. immigration policy and government agencies entrusted with protecting rare and endangered species living in the estuary.

The nearby Otay Mesa border crossing is the most active border crossing in the world. On average, more than 31 billion dollars worth of products cross through the checkpoint each day, nearly all of it related to the regional maquiladora/manufacturing and agricultural industries. Others seek entry through different methods.

"The immigration problem is overblown," remarked a docent on a recent trip to the Tijuana River Research Reserve. The border, however, does have a dark side.

According to U.S. border officials, the region is a magnet for illegal activity -- 162,000 arrests have been made, and 49,000 pounds of marijuana and 699 pounds of cocaine intercepted since November 2007. Drug cartels waging war on the streets of Tijuana also add an element of fear and apprehension.

Here the border is tangible. After 3,200 kilometres, the line tumbles into the Pacific Ocean, and a steel fence divides the United States from Mexico.

During the 1980s, the estuary was in danger of being overrun. Social trails scarred the land. Migrants seeking entry into the United States used the estuary as a crossing point, prompting local politicos to take action.

Also known as Operation Gatekeeper, the 60-million-dollar construction project comprises the western portion of the San Diego Border Infrastructure System. A federally funded programme put in place by Rep. Duncan Hunter of California, it dates back to 1996.

In the coming weeks, two fences will flank the existing one, leaving a gap wide enough to provide access to patrol vehicles, along the westernmost 5.6 kilometres of the U.S.-Mexico border. It will enable agents to monitor a border that marches across the edge of Tijuana's city limits, stretching into the arroyos and mesas beyond.

The plan calls for infilling Smugglers Gulch, a steep canyon through which contraband and people pass. It requires the movement of 2 million cubic yards of earth and calls for building a culvert to divert rainfall that flows down denuded hillsides during storms.