| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Habitats
The Tijuana Estuary is a habitat under siege. It is hemmed in by a periodically polluted portion of the Pacific Ocean to the west and a rising sea of four million-plus people to the north and south. It is bisected by the Tijuana River, the main artery of its vascular system, but also the source of toxins, sewage, silt, tires, mattresses, and tons of other unwanted junk. Its southern boundary is the United States-Mexico border, marked by a brown metal fence that rides up and down the steep terrain like an aging Christo sculpture. The southern portion of the estuary is scarred by a crazy quilt of dirt roads used by the U.S. Immigration and Naturalization Service Border Patrol to chase down undocumented migrants. And from above comes the relentless whump-whump-whump of Navy supply helicopters from the Imperial Beach Naval Air Station next door. Despite the onslaught, this ecosystem constitutes some of the highest-quality remaining salt marsh in southern California and is the first leg in a continuous succession of rare habitats running 14 miles from the beach east to Otay Mountain. One can walk from the dunes, which contain colonies of endangered least terns and snowy plovers, through salt marsh hosting breeding populations of endangered light-footed clapper rails, along forested riparian habitat where endangered least Bells vireos nest, up into the maritime scrub that's home to the endangered California gnatcatcher, and on into the upland coastal sage scrub highland habitat where the state-listed savanna sparrow nests at Otay Mountain. Over all of it flies one of the most diverse arrays of raptors and other birds found anywhere in the United States. And unlike almost any other west-to-east running wetland-to-scrub corridor in southern California, the five miles of the Tijuana River Valley north of Mexico are not crossed by any major highways or train tracks. It is also a fascinating and beautiful retreat for human visitors seeking refuge from the hardships of the San Diego-Tijuana urban environment. "Even when you fly over Los Angeles at night, there are still fingers of darkness below you that represent undeveloped land," says Brian Collins, a U. S. Fish and Wildlife Service biologist here. "Down here in San Diego there are almost none. We need to be very protective of what's left." As southern California wetlands were shaved away by development over past decades, the patches that remained became islands of concentrated endangerment. In this tiny, 2,500-acre coastal preserve alone there are six federally listed threatened or endangered species. And despite the pressures from every direction, Collins and others are determined to defend what remains of this place, and even to restore some of its ecological integrity. Officially known as the Tijuana River National Estuarine Research Reserve (TRNERR), it is composed of land cooperatively managed by state and federal agencies. In April, Border Field State Park, in a program coordinated by the California State Coastal Conservancy, christened a new, experimental wetland restoration project known as the Model Marsh. Most of this area, once part of the vast stretch of salt marsh running along San Diego Bay, was filled for farming and military use. Erosion deposited by the Tijuana River further buried the former marsh, which has long been cut off from the tidal incursions and flushings that should vitalize it. By excavating a mudflat down to historic levels and connecting it with inlets to the tidal flows of the Pacific, environmental engineers have created a 20-acre living lab where they can study and encourage recolonization by marsh creatures and plants. The fruits of this research will be applied to a 500-acre restoration project known as Friendship Marsh, which estuary managers hope will become a major stopover point for waterfowl and other (non-human) migrants in decades to come. Meanwhile, less than a mile south of the $3.1 million Model Marsh, the U.S. Border Patrol is considering filling in and paving over about ten acres of the remaining intact salt marsh. In the 1980s and early 1990s, Mexicos depressed economy caused a mad rush of undocumented Mexicans crossing through the park. All that activity had ecological effects, but also social and political ones. Residents of Imperial Beach said that refugees were running through their backyards, hiding out in their garages and under their cars. In 1996, during the wave of anti-immigration sentiment that gripped border communities throughout the Southwest, Congress passed, and President Clinton signed, the Illegal Immigration Reform and Immigrant Responsibility Act. It was authored by San Diego Representative Duncan Hunter and mandates: "The U.S. Attorney General shall provide for the construction along the 14 miles of the international land border of the United States, starting at the Pacific Ocean and extending eastward, of second and third fences, in addition to the existing reinforced fence, and for roads between the fences." The existing fence here in the Tijuana Basin is made out of metal sections of Army surplus portable landing strip recycled from the Vietnam War. It is only about eight feet high and is relatively easy to get over. The dense riparian habitat and scrub on the north side of the fence are easy to hide in. Catching illegal migrants here is as dangerous as it is difficult for Border Patrol officers. The proposed impediment two parallel, 15-foot-high fences with an 80-foot road running between them should simplify the job. Border Patrol officers will drive back and forth along the road, which will be as straight and level as possible in this steep terrain, and will apprehend anyone with the audacity to enter it. The US Army Corps of Engineers has already completed work on about five miles of the inland portion of the road near Otay Mountain. Congressional mandate or not, its hard to build a major road through such critical habitat without at least a nominal salute to the Endangered Species Act. The Border Patrol tried to proceed without so much as a tip of their hat about two years ago, when they released a preliminary proposal for the road. It cut through the marsh, as pretty much everyone knows a new road might have to, but environmentalists and land managers with stakes in the conservation of the estuary complex hit the roof. The Border Patrol retreated and agreed to do an environmental review of the westernmost portion of the project. That review is expected sometime in 2001, but for the moment, Border Patrol officials, and the Corps, which is designing and will build the road, are holding their cards very close to their chests. "It would be premature to go into that at this time," says Loui Cross, Assistant Chief Patrol Agent at the Border Patrol, when pressed for details about likely scenarios. "We went off a little fast in the beginning. I don't want to do that again." One thing seems clear though. whatever the final road design, it will either cut through the marsh or coastal scrub habitat and will likely require filling in Smuggler's Gulch, the deep valley where a tributary of the Tijuana River crosses the border into the preserve. In addition to the acres of marsh lost to the road outright, and the inevitable alteration of the area's hydrology, the new border fences will also create an even more formidable north-south barrier to crossings by wild animals, who do not recognize either nation's flag. Ironically, while the Border Patrol prepares to build this expensive new fence, illegal crossings at the estuary are at their lowest in years. In the early '90s, congressionally funded Operation Gatekeeper added a "massive amount of manpower" to these coastal areas, according to Cross, forcing most border crossers into the dangerous desert and mountain areas further inland, where many die of exposure each year. Last year, there were only 15,974 apprehensions in the westernmost, Imperial Beach portion of the border. That's down from 202,173 apprehensions in 1992. Perhaps now that the amount of illegal action-and the risk to Border Patrol agents-in the estuary area has been reduced, the government's plan could be modified a little to make it less damaging to the preserve. Tessa Roper, assistant reserve manager at trnerr, suggests stopping the new double fence at the refuge's eastern bound-ary, and converting it from there into a single, high, and reinforced fence running the final mile to the Pacific. Such a system would have a far gentler effect on the refuge's ecological systems. So far, the Immigration and Naturalization Service has shown no sign that it would favor such an alternative, but they don't dismiss it completely. When asked if the plan could be modified even though the law called for two fences and a road, Alain Bernier, the project manager for the coe's border-bolstering effort, said: "I won't say yes, and I won't say no." Whatever happens with the new border road, the Tijuana watershed will remain a crucible of hope and anguish in the coming decades. In that respect, it is an apt metaphor for so much of California's wildlands. It is diverse, beautiful, and unique. And it is straining to the breaking point under the combined weight of too many poor people seeking a promised land and too many rich ones over-exploiting the promised land they already have. Gordy Slack is Senior Editor of California Wild. |
Fall 2000
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