Water Testing with the San Dieguito River Park


One of the great things about our Water Quality Monitoring Program is that we have an opportunity to help other groups investigate their efforts at improving water quality.

Our newest partner organization, San Dieguito River Park, recently restored the tidal wetland area of the San Dieguito lagoon. In order to minimize the impacts of urban runoff on the lagoon, they built a series of four treatment ponds to capture the stormwater runoff from the surrounding residential area. These wetland ponds will hopefully be able to filter out pollutants from the runoff water before it dumps into the fragile lagoon.

In December, we tested the water coming in and going out of the wetland, and the results were very interesting. These three graphs show a sampling of the data collected. It looks like the treatment ponds successfully filtered out the Nitrogen-based nutrients (Ammonia and Nitrate) and increased the level of Dissolved Oxygen. In marine ecosystems, nitrogen is often the limiting nutrient. When you increase the levels of nitrogen, algae and phytoplankton have a chance to grow like crazy, a process known as eutrophication. These algae blooms tend to block available light to the plants we want to be growing in the estuary. Also, when they die and start to decompose, significant amounts of dissolved oxygen gets used up, further stressing out the coastal organisms.




Keep in mind that this data represents one sample at each location for one day, so it’s not very representative yet of the full potential of these treatment ponds. I am excited to see the results over the coming years as the treatment wetland area matures.

Read more about the San Dieguito River Park. They have a ton of volunteer opportunities that you can check out. If you want the opportunity to get out and take samples for the water monitoring project get in touch with our volunteer coordinator. And as always, you can check out the water monitoring data on our watershed wiki.