Baja California was the only state in Mexico where beaches tested at levels considered unsafe for swimming during the March 2026 sampling period, according to federal data from COFEPRIS, Mexico’s health and consumer protection agency. The contamination, driven by fecal bacteria in the Tijuana-to-Rosarito coastal corridor, puts a practical question in front of every beachgoer from Playas de Tijuana to Popotla: is the water safe today?
The answer depends on which beach you pick, when it last rained, and how recently anyone actually tested. That gap between what people assume and what the data shows is the real story here.
Decades of Wastewater Failures Feed the Tijuana River Outfall
The contamination is not new. Tijuana’s wastewater system has struggled for decades to keep pace with the city’s growth. CESPT, Tijuana’s municipal water and sewer utility, operates aging collection infrastructure across a metro area that has grown from roughly 750,000 residents in 1990 to over 2 million today. Broken sewer lines, illegal connections, and insufficient pumping capacity mean raw or undertreated sewage regularly enters the Tijuana River channel and its tributaries.
When it rains, the problem intensifies. Stormwater washes trash, sediment, and sewage into the river, which flows west toward the ocean. The mouth of the Tijuana River sits just south of the U.S. border at Imperial Beach, California. Contaminated flows reach both sides of the coastline. On the U.S. side, Imperial Beach has posted more than 1,000 closure days since 2020 due to sewage contamination from the Tijuana River, according to San Diego County environmental health records.
South of the border, the same contaminated plume affects Playas de Tijuana, the northernmost beach neighborhood in the corridor. But conditions shift significantly as you move south. San Antonio del Mar sits about five kilometers south of the river mouth and has its own runoff channels. Baja Malibú and Playa Blanca, farther along the coast toward Rosarito, face contamination from localized drainage outfalls rather than the river. Rosarito proper has multiple beach access points, and water quality varies block by block depending on proximity to storm drains and the local arroyo system.
South of Rosarito, beaches near Popotla and Puerto Nuevo generally test cleaner because they sit farther from the major discharge points. But “generally” is not “always.” A single heavy rain event can change conditions within hours.
COFEPRIS Tests Seasonally, Not Daily
The March 2026 COFEPRIS data, published in a state-by-state PDF on the agency’s federal website, measured enterococcus bacteria levels at designated monitoring points along Baja California’s coast. Enterococcus is an indicator of fecal contamination and a standard metric used by health authorities worldwide. Beaches that exceed 200 colony-forming units per 100 milliliters are considered unsafe for recreational contact.
The problem is timing. COFEPRIS, which operates under Mexico’s federal health ministry, publishes beach water quality reports around major vacation periods: Semana Santa, summer, and winter holidays. The agency does not maintain a daily or even weekly monitoring dashboard. So the March data reflects a snapshot, not a live feed.
Local groups have tried to fill the gap. Proyecto Fronterizo de Educación Ambiental, also known as Tijuana Waterkeeper, conducts weekly sampling at multiple points along Playas de Tijuana. The group posts results on its social media channels and website, often within days of collection. Their data has consistently shown elevated bacteria counts near the river mouth and near storm drain outfalls, with cleaner readings at points farther south.
On the U.S. side, San Diego County’s Beach and Bay Water Quality program posts daily advisories at sdbeachinfo.com. The site covers beaches from Oceanside to the border, including Imperial Beach and Border Field State Park. While it does not cover Mexican beaches, the readings at Imperial Beach and Tijuana Slough offer a useful proxy for conditions just south of the border.
Practical Steps for Swimmers from Playas to Popotla
There is no single website that provides real-time Baja beach water quality data. So swimmers need to layer several sources before heading out.
First, check the most recent COFEPRIS report, available at gob.mx under the agency’s beach monitoring section. The March 2026 PDF is the latest as of this writing. Second, look for Tijuana Waterkeeper’s weekly sampling updates on social media. Third, check sdbeachinfo.com for the Imperial Beach and Tijuana Slough readings as a directional indicator for northern Playas de Tijuana.
Beyond data sources, basic precautions apply. Do not swim for at least 72 hours after any rainfall. Avoid water near visible storm drains, pipes, or arroyo outlets. Stay out if you see discolored water, foam, or smell sewage. Children, surfers who spend extended time in the water, older adults, and anyone with open wounds or compromised immune systems face higher risk of gastrointestinal illness, skin infections, and ear or eye infections from contaminated seawater.
Beaches south of Rosarito, including stretches near La Misión and the Ensenada coast, have historically tested cleaner. But summer brings Baja’s brief rainy season, and tropical storm remnants can push contaminated runoff into areas that are normally safe. Hurricane season runs from June through November.
COFEPRIS is expected to publish its next round of beach water quality data ahead of the summer vacation period in July. Swimmers planning beach days along the Tijuana-to-Rosarito corridor should check all available sources before getting in the water. The COFEPRIS March 2026 Baja California beach report is available as a PDF at gob.mx.