US-Mexico immigration: Even oceans have borders

The US government is erecting a fence in the ocean to divide California from Tijuana, Mexico. Immigration and environmental activists say it is a costly, dangerous endeavour that will do little to keep out unauthorised migrants.

On a sunny strip of beach south of San Diego, California, the US government is literally battling the tide of illegal immigration.

Border authorities are building a fence extending 300ft (91m) into the surf, in an effort to prevent would-be migrants from walking over the frontier from Mexico's Tijuana Beach to Imperial Beach, California, during low tide.

The US government's latest King Canute-like effort will make an existing fence longer, higher, tougher to scale and, officials say, more resilient to the tide.

'Operational need'

Border officials note that during November officers caught several undocumented migrants swimming in the Pacific Ocean or landing ashore in small fishing boats.

Years of tides, wind and corrosive salt spray have taken their toll

"There is a clear operational need for this development," says Michael Hance, field operation supervisor with the border patrol in the San Diego sector.

"The southern side of the border is densely populated and in the past many people found an easy way into the US through these beaches. We need physical infrastructure as well as border agents in the area."

But critics say the $4.3m (£2.79m) extension is unnecessary, noting that heavy surveillance near San Diego has driven most of the migrant flow eastward into the Arizona desert. And environmental activists fear the heavy metal barrier sunk into the ocean will harm marine life.

Meeting place

That physical infrastructure has interrupted the sandy landscape of the Tijuana and San Diego beaches since the early 1990s, when the first fence was built to run 22km inland from the Pacific shore.

On the beach, the fence is made of iron bars sunk into the sand, and further inland, the bars are replaced by graffiti-marred corrugated iron sheets, bent and torn by the marine wind.

The sections extending into the surf remain under construction, and today a visitor sees a pier constructed to allow heavy kit to pound support piles into the sand.

On the southern side of the wall, the Playa de Tijuana teems on weekends with families from the poor neighbourhoods along the border.

The beach is also a meeting place for friends and loved ones on either side of the border. Here, people chat and hug through the fence.

Loved ones separated by the border sometimes meet at the fence to share a moment together

The latest $4.3m renovation, just under way, will extend the fence further into the ocean and increase its height to about 18ft (5.4m) from about 13ft, allowing it to protrude above the surface no matter the tide.

The steel poles holding up the wall will be treated with an anti-corrosion coating. The poles will also be given a slick coating to make them harder to climb.

The wall is scheduled to be completed in March and is expected to last 30 years.

'Symbolic move'

For all the expense and effort the government is throwing into fencing off the ocean, statistics show arrests in the area are already at an all-time low.

Before the new work, low tide exposed a stretch of passable ground. Here, the wall is shown in 2001

Border patrol agents detained 68,000 undocumented immigrants in 2010 in the San Diego sector, down from 630,000 in 1986, according to Customs and Border Protection (CBP) agency statistics.

Local immigration activists put the decline down to a steady increase in manned patrols and surveillance over the last six years.

"We don't understand why they are spending so much money here: it is just a symbolic move to say that they are actually doing something to prevent undocumented immigration," says Pedro Rios of the San Diego Immigrant Rights Consortium.

"The new surf fence is being built in what is probably the area where the rate of border crossings has gone down most dramatically."

Wildlife affected

Furthermore, environmental organisations say the metal barrier in the water is an invasion of the ocean that will most certainly take its toll on the local fauna.

"The wall could block the circulation of species, especially surface marine species," says Matt Clark, spokesman for Defenders of Wildlife.

US engineers built a pier to facilitate the fence's construction

Dan Millis, borderlands team coordinator at the Sierra Club, says sections of the wall erected in the Arizona desert have had "a major effect on the migration patterns of desert species".

Architect Teddy Cruz of the University of California at San Diego predicts the fence will increase sedimentation and flooding in the Tijuana estuary.

"There are natural canyons in the region that cross the border without following political conventions," Mr Cruz says. "The effect will be worse for those that live in settlements on the Mexican side of the border, the waste from these settlements flows towards the estuary blocking water circulation."

The Border Patrol argues the surf fence's environmental impact will be minimal.

"Our experts have done environmental assessments and they did not find any evidence that the habitat will be damaged," says Mr Hance.

"We do what we have to do. And this project, both in terms of design and investment, is appropriate for the safety requirements in the San Diego area."