On Tuesday, the San Diego City Council will decide whether to join litigation over ongoing sewage pollution in the Tijuana River Valley. We would be honored to call the city of San Diego a partner in our effort to once-and-for-all solve what Mayor Kevin Faulconer recently and correctly called a “crisis.” 
Should it vote to sue, San Diego will face what is perhaps a more critical decision: whether its lawsuit targets all of the pollution sources in the valley, or merely a small subset.
Far and away, the major source of pollution in the Tijuana River is the federal government’s “flood control channel,” which was built by the U.S. International Boundary & Water Commission in the late 1970s and routes wastewater from Mexico into the Tijuana River Estuary. Since 2015, dozens of spills have dumped hundreds of millions of gallons of polluted wastewater through the IBWC’s channel and into the Pacific Ocean — including a spill of up to 256 million gallons in early 2017  that closed beaches, sent disgusting plumes of sewage into the ocean and sickened San Diegans.
Currently, about 50 million gallons a day of sewage-polluted water  is flowing through the Tijuana River and reaching the Pacific Ocean. It is the result of a sewage collector pipe in Tijuana that ruptured in early December that so far has not been repaired. Beaches in Coronado and Imperial Beach have been closed off and on ever since.
These spills are contaminated with toxic and hazardous wastes, including raw sewage and bacteria, heavy metals, pesticides and industrial waste that threaten public health and the environment. They impact all of us who use San Diego-area beaches.
The ongoing border pollution hurts local businesses and the economy because tourists are not interested in vacationing when the yellow beach closure signs are posted. The toxic Tijuana River waters also poses a serious health threat to the residents of San Ysidro and Imperial Beach who are exposed to sewage fumes. Surfers and beach-goers, city of San Diego and Imperial Beach Lifeguards, Navy SEALs who train nearby, and the Border Patrol agents who work in the areas most impacted by the muck.
The other major pollution source is the “canyon collectors” in the hills above the Tijuana, which have dumped about 12 million gallons of polluted wastewater  into the river since 2015.
That’s a substantial and dangerous amount of pollution, but it’s also a tiny fraction of the hundreds of millions of gallons that have spewed through the channel in the same time frame.
That is why Imperial Beach, along with Chula Vista and the Port of San Diego, filed suit last March to stop the pollution  from both the canyon collectors and the flood control channel. If we are going to fix this problem, we have to address all of the pollution sources, not just one of them.
San Diego-area communities deserve a revitalized Tijuana River Valley, healthy beaches, a vibrant economy and a clean bill of health. So while fixing the canyon collectors is an important piece of the puzzle, it will not stop the vast majority of the pollution and spills that primarily impact San Diegans.
We hope the San Diego City Council will do the right thing and approve a lawsuit that addresses pollution from the canyon collectors and the flood control channel. The Tijuana River is hemorrhaging pollution. For this crisis, a Band-Aid simply will not do.
Serge Dedina is the mayor of Imperial Beach. Mary Casillas Salas in the mayor of Chula Vista. Dan Malcolm is a Port of San Diego Commissioner representing Imperial Beach.