Eighty percent of the pollution in the marine environment comes from land. Not just the large municipal and industrial sources that we’d hope are treated sufficiently before discharge. One of the largest sources is called “nonpoint source pollution” from urban runoff.
One of the outcomes of our desire to live near the beach is the dense development with great expanses of paved impervious surfaces. These lead to runoff taking a load of toxic substances into the ocean. When it rains after months without rain there is a flood, but errant watering, leakage, on street car washing, lead to a steady stream of toxins to the ocean on these impervious surfaces
When natural vegetated soil dominated, the filtering action of the soil would cleanse the water percolating down into the water table. Now the toxic mix of motor oil, brake lining residues, animal feces, heavy metals, pesticides, herbicides and others require our attention. Use as little water as possible, this addresses another problem in Southern California, water shortage. Adjust sprinklers, fix fluid leaks from your car, pick up pet feces, avoid chemical insecticides and weed killers, plant native-drought tolerant flora, be aware of where your waste.