We talk a lot about water quality here at Coastkeeper. We also talk a lot about water supply and conservation. Below, we’ll take a deep dive into just how those two topics are connected, and explore the science behind how wasting water leads to increased pollution in our communities.
Outdoor water use in San Diego’s urban and suburban communities has significant downstream effects in our watersheds. Receiving waters (the creeks, rivers, lagoons, bays, and ocean waters that are downstream of urban areas and receive water running off concretized streets and storm drains) are exposed to variety of stressors from untreated urban runoff. Often that runoff is created not by big winter storms, but by what officials call dry-weather flows, nuisance runoff, or my personal favorite – urban drool. This wasted water from over-watered lawns, leaky pipes, hosing down driveways, and so on, not only strains our water supply but creates a chronic means for pollution to reach our local waterways.
Excessive nutrients like nitrogen and phosphorus found in fertilizers and detergents are major contributors to a condition called eutrophication in urban receiving waters. Eutrophication occurs when naturally occurring algae are stimulated to bloom by excess nutrients in the water. Dense algal blooms reduce water clarity, limit light penetration, and choke narrow waterways. And when the algae eventually, microbes get to work decomposing the dead algae cells, creating bad odors and severely reducing dissolved oxygen levels. These conditions damage habitat quality for aquatic life and reduce aesthetic and recreational opportunities in local waterways.
The Monitoring Program
Volunteers with San Diego Coastkeeper’s water quality monitoring program have been measuring nutrient concentrations at fixed sites in local waterways since 2010. While many local streams see spikes in nutrient levels during the winter rainy season, several watersheds have sites that are chronically elevated throughout the year. Our volunteers frequently witness the signs of eutrophication when they’re out collecting samples, such as seeing the slimy green or brown sheen of dense algal growth in the water, smelling their noxious odors, and even occasionally encountering fish kills on stream banks (from rapidly depleted oxygen levels).
How You Can Make a Difference
Recent research published in the Proceedings of the National Academy of Sciences shows that residential sources dominate nutrient inputs in urban watersheds. In fact, the study found that nitrogen loading from household lawn fertilizer exceeded the combined inputs from golf courses, parks, schools, and other non-residential vegetated areas. Check it out here.
So, upstream solutions, or individual practices that stop or limit the problems of urban runoff in the first place, are key to managing urban eutrophication. You can limit the excess water and nutrients running off your property with a few simple steps:
- Choose landscapes that need little or no fertilizers and water to thrive. Many native, drought tolerant plants are already adapted to low nutrient soils and the dry southern California climate, and as a bonus, provide habitat for native wildlife like birds and butterflies.
- For plants that need a little extra water, try compost or mulch to help your soil store water and replenish nutrients more slowly than chemical fertilizers.
- Use properly installed drip- or other water-efficient irrigation systems and check them frequently for breaks or leaks.
- Sweep debris from decks or driveways, rather than using a hose.
- Wash vehicles at a professional car wash, which recycles water, instead of washing them in your driveway.
And there you have it. Simple choices that will save you money on your water bill, and end up protecting the waterways and wildlife downstream.