The Water Quality Monitoring Lab here at San Diego Coastkeeper is proud to announce our 2009-2010 Watershed report. It’s taken us a while, but we have crunched down the data that our volunteers and partners have collected. You can read the full report here.
Here are some highlights–
Coastkeeper data consistently points to ammonia, phosphorus and Enterococcus as the most widespread pollutants in San Diego County. Below I have attached a table (that is not in the watershed report) that shows percent of samples that exceed Basin Plan standards during the 2009-2010 period covered in the report. The color coding highlights the problem areas. As you can see, every watershed in San Diego struggled with ammonia, Enterococcus and phosphorus concentrations.
The very beginning of the watershed report highlights the impacts of urbanization and the water quality degradation due to watersheds becoming impervious. Every chapter in the report tells a similar story:
- Los Penasquitos: Rapid development since the 1970s has led to high levels of total dissolved solids and fecal indicator bacteria during both the wet and dry seasons. The fragile Los Penasquitos Lagoon is filling up with sediment transported by the flows that have increased over 200% in the past 30 years. A TMDL (Total Maximum Daily Load) has just been written to try to limit the amount of sediments flowing into the lagoon.
- Pueblo: “The dominance of hard surfaces drives many of the urban runoff problems in the creek, which in turn contributes to the degradation of water quality in San Diego Bay.” Nutrients, bacteria and trash are major problems in this watershed. These three constituents are very strongly correlated with development. This watershed is our most developed and is mixed residential, commercial and industrial development. Pretty much all of Chollas Creek is channelized or driven underground. The natural hydrology has been greatly disrupted. The water flows are quickly pushed into the creek and into the bay with almost no chance of remediation.
- San Luis Rey: Our least developed watershed, yet it still has problems. While half of the watershed is open space, agricultural (cattle grazing, nurseries, citrus and avocado groves) and residential each account for about 15 percent of the watershed. This high amount of agriculture is probably responsible for the high nutrient concentrations we see. This river is home to historic steelhead trout runs, but habitat degradation threatens the dwindling number of these salmonids.
- Tijuana: Not surprisingly the worst watershed in the county, in terms of water quality. Poor infrastructure across the border accounts for the vast majority of water quality problems in this watershed.
Other reports have established a strong relationship between percent developed and stream health.
We encourage the municipalities in San Diego to work closer with Coastkeeper, our members and our volunteers to continue to identify priority pollutants. Our input is a valuable component to protecting and restoring clean water in San Diego County.
These priority pollutants can be tied to development of the watershed and traditional storm water practices. Old school stormwater management was more concerned with flood control than water quality. The goal was to move stormwater away as quickly as possible. This is why you see many channelized rivers in San Diego. These allow us to push water quickly to the ocean. Unfortunately, this also limits the landscapes ability to rid itself of pollutants. Nutrients are not able to be taken up by plants as sediments with pollutants bound to them are not able to settle out.
Research shows that LID (low impact development) can remediate many of the problems that development has introduced. See “Widespread application of LID across basins will result in much needed pollutant concentrations.” LID irestores natural hydrologic processes to our disrupted system. LID works, and it looks nice also. Not only would it help with our water quality problems, we would reconnect our neighborhoods with their waters.
Collecting all this data is not easy, and our volunteers and groups like Surfrider San Diego and Golden State Flycasters have dedicated many many hours to it. We would like to thank the dedication and the tireless work our volunteers and project partners have put in over the years.