The city of Imperial Beach has experienced closure to its beaches for many years now due to sewage contaminated water. But in 2020 it was closed for almost half the year because of a broken water pump in the Tijuana River. This trend has continued into 2021. Closures happen when the E.coli levels in the water are dangerous to humans. This has been the main concern of community members for years because it puts a stop to swimming and surfing.
But there is another problem with the pervasive damage the sewage creates in the ecosystem. We know that wastewater leaves behind nutrients such as carbon, nitrogen, and phosphate. This nutrient pollution can create harmful algal blooms and lead to the deoxygenation of water. These effects are already being seen in most of the ocean due to ocean warming, upwelling, and other localized pollutions. This can drastically change the important ocean and estuary ecosystems in ways that we aren’t even sure of yet.
Imperial Beach is connected to three important ecosystems, the bay, the estuary, and the beach. This nutrient pollution is entering and possibly damaging all three. It is hurting the wildlife and changing the ecosystem. My science proposal looks to answer the question, are these nutrients present in the water beyond when the water is harmful to humans? If it is, this research could be used to persuade boards like the International Boundary and Water Commission to put more urgency on helping the city.
What I plan to do is measure nitrogen levels at different distances from the source and from different times from beach closures. These numbers will help see how long the nutrient pollution remains prevalent after contamination and how far its affects reach. From this, a model can be created to predict the long-term effects of the pollution. The model can also be applied to a proposed fixed sewage system to find the best way to safely get rid of waste in the ocean.
Even if all of this is accomplished, only the issue of localized pollution is solved. The ocean is continuing to get warmer. A recent study at UCLA has shown that even the sewage that we believe to be dumped at a safe distance brings nutrient pollution to the shore due to upwelling. This is just one step to hopefully slowing ecosystem changes in the ocean and curving the effects of global warming.