Baja California’s state government declared the last uncemented stretch of Tijuana’s Arroyo Alamar a conservation area on June 5, placing 41.67 hectares of riparian habitat under legal protection after more than 15 years of civic organizing. The decree, published in the state’s official gazette, bans illegal dumping, unauthorized wastewater discharge, land clearing, and incompatible construction across a three-kilometer corridor in eastern Tijuana. But the Arroyo Alamar conservation fight is far from over: tons of waste still choke the creek bed, and no management plan exists yet.
A Cross-Border Creek That Lost 7.5 Kilometers to Concrete
Arroyo Alamar begins in the United States as Cottonwood Creek, rising in the eastern hills of San Diego County. It flows south through the municipality of Tecate, crosses into Tijuana, and eventually joins the Río Tijuana before the combined waterway re-enters the U.S. at the Tijuana River Estuary. Of the creek’s 10.5 urban kilometers inside Tijuana, 7.5 were encased in concrete between 2011 and 2012 under then-Governor José Guadalupe Osuna Millán of the PAN party.
Environmental groups filed a legal injunction (amparo) that year to halt the channelization. They lost the case, but authorities had failed to meet requirements for rescuing and relocating wildlife. That procedural gap forced work to stop, leaving the final three kilometers intact. Those three kilometers became the focus of a sustained campaign to find an alternative to concrete.
The formal push dates back even further. In 1998, Tijuana’s municipal planning institute, now known as Implan (Instituto Metropolitano de Planeación), proposed an ecohydrological project to preserve the creek’s natural features. That proposal stalled, but it created a technical baseline that activists would later use.
In 2016, the Colectivo Chilpancingo Pro-Justicia Ambiental (now Colectivo Salud y Justicia Ambiental AC) joined forces with the Coalición de Salud Ambiental and other groups on the Mesa Técnica del Arroyo Alamar to begin the formal technical study required for a conservation declaration. Six years passed before Tijuana’s city council instructed Implan, in October 2022, to draft the decree and open it to public consultation.
19.29 Hectares of Core Habitat Host 23 Bird Species
The protected polygon spans the Otay Centenario and La Presa delegations in eastern Tijuana. It is divided into three zones: a core conservation area, a conditional-use zone, and a restoration zone. The core area covers 19.29 hectares, about 46% of the total, and holds the highest ecological value.
Researchers have documented 23 bird species in the corridor. One of them, the elegant tern (Sterna elegans), is classified under special federal protection by Mexico’s NOM-059-SEMARNAT-2010 standard. Other species recorded include the great horned owl, Cooper’s hawk, great blue heron, barn owl, and northern mockingbird. The creek functions as a rest stop along migratory flyways linking habitats on both sides of the border.
The vegetation is equally significant. Native tree species such as western sycamore (Platanus racemosa), Fremont cottonwood (Populus fremontii), and willows (Salix spp.) form a living gene bank. According to the decree, these genetic strains no longer exist elsewhere in Tijuana. They could serve as source material for reforesting riparian corridors across the region. One plant species, Ambrosia monogyra, holds a 2B conservation ranking from the California Native Plant Society, meaning it is rare and threatened in California as well.
The creek also sits atop an active aquifer recharge zone. In a city that relies heavily on water piped from the Colorado River via CESPT (Tijuana’s municipal water utility), local groundwater recharge carries practical weight.
Illegal Dumping and Wastewater Persist Despite New Legal Framework
The Alamar Sustentable coalition, which grew out of the conservation campaign, welcomed the decree but cautioned against celebration. “The Alamar keeps accumulating trash, rubble, and illegal discharges, and that does not change overnight,” the group wrote in a public statement. “What does change today is that it creates the legal and institutional framework to make rehabilitation possible, for the environmental health of Tijuana.”
Community cleanups held in April and October 2022 removed more than 11 metric tons of solid waste from the creek bed. Volunteers also documented domestic and construction-site wastewater flowing untreated into the channel. Security concerns in the area complicated cleanup efforts.
The decree is legally binding on public agencies, private entities, and social organizations. All investments and actions within the polygon must now align with the conservation objectives. Prohibited activities include dumping any category of solid waste, discharging wastewater without authorization and compliance with federal standard NOM-001-SEMARNAT-2021, and clearing vegetation without technical justification and permits.
Still, enforcement will test the decree’s real strength. CONAGUA, Mexico’s national water commission, has held custody of the land since signing an agreement with the state government in 2014. Coordination between municipal, state, and federal agencies will be required to patrol and rehabilitate the site. Budget allocations for that work have not been announced.
The state must now draft a formal management program (Programa de Manejo) for the conservation area. No timeline for that document has been published. Until it is complete, day-to-day enforcement rules remain general rather than site-specific. The decree was first approved by Tijuana’s city council in February before receiving state-level publication on June 5, as reported by La Jornada Baja California.