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Malibu Creek Watershed
The Malibu Creek Watershed is one of the last spots that’s relatively undeveloped in the Los Angeles urban area. However, the area also offers up a clear picture of the harm humans are causing this fragile ecosystem — as well as ways to safeguard it from future degradation.
For 12 years, Heal the Bay’s Stream Team collected data to assess the health of this watershed, which is the second largest draining to the Santa Monica Bay in Malibu, where polluted water can harm humans and marine life. Now it’s time to share our first comprehensive assessment, detailed in our report: Malibu Creek Watershed: An Ecosystem on the Brink.
More than 75% of this area remains undeveloped and in a mostly natural state. We have an unprecedented opportunity to protect and improve the remaining natural resources for the benefit of countless marine, animal and plants, as well as for swimmers, surfers and hikers. The report was researched and written by numerous Heal the Bay staff members, some of whom currently work at the Santa Monica Bay Restoration Commission and UCLA Institute of the Environment. The researchers assessed the habitat, water quality, as well as the flora and fauna of the Malibu Creek Watershed. Despite minimal development in the watershed, we find evidence of degradation and make recommendations that will reverse this deterioration. We detail several trends in watershed health and recommendations for improvement throughout the report, three of which are hardened streambanks, polluted waterways, and invasive animals and plants.
What You Can Do
Channelized (i.e., straightened and widened) streams and armored banks, lined with concrete or riprap (rocks for stabilization). Surveying 68 miles, we found 21 miles of streambank that were modified or hardened.
The Effect: Streambanks are armored for stabilization but the effect typically causes further erosion downstream of the hardening. Erosion results in the loss of riparian habitat and an increase in fine sediments in the stream, negatively impacting in-stream habitat for aquatic life, such as the endangered southern steelhead trout.
The Solution: Adopt Stream Protection Ordinances in Los Angeles County and cities in the watershed that prohibit new streambank armoring. Encourage the Coastal Commission to adopt a policy prioritizing bioengineered solutions (i.e., vegetation) for streambank stabilization.
Use the Stream Team Data Portal to analyze water quality data from the Malibu Creek Watershed, collected by Heal the Bay’s Stream Team since 1998
Streams are polluted and don’t meet current water quality standards. In the Malibu Creek Watershed, 14 different streams, lakes, and beaches are listed as impaired for over 20 different pollutants under the Clean Water Act, such as nutrients, bacteria, trash, and invasive species. Local pollution sources include stormwater runoff, septic systems, wastewater discharge as well as runoff from vineyards and equestrian facilities. Levels of nutrients and bacteria frequently exceed water quality standards; at some sites, fecal indicator bacteria, E. coli and Enterococcus, are over the limit 100% of the time.
The Effect: An impaired waterbody can’t support beneficial uses, such as swimming, aquatic life habitat, and water supply. The health of a watershed affects the well-being of humans. Excess bacterial pollution can cause stomach flu and various infections not only in the watershed itself, but also downstream at public beaches. Poor water quality can also harm industries, such as tourism, which depend on clean beaches and clean water to attract visitors.
The Solution: Reduce nutrient and bacteria levels to background levels. In order to do this, we recommend several steps, such as to adopt and implement low impact development ordinances by municipalities in the watershed; and reducing sediment, nutrient, and bacteria runoff from agricultural use in the watershed. We also recommend increasing water storage at Tapia Water Reclamation Facility for more water reuse, and further study to identify and remediate discreet pollution sources. The regional Water Quality Control Board needs to implement and enforce Total Maximum Daily Loads (TMDLs) to regulate the amount of pollutants waterbodies can receive and still meet water quality standards set by the Clean Water Act. For example, if current TMDLs were being met, we wouldn’t have to worry about human health impacts of high bacteria counts in Malibu Creek rock pool, a popular swimming area.
Invasive aquatic animals and plants are widespread throughout the Malibu Creek Watershed. The Stream Team found that 26% of the 68 total stream miles mapped in the watershed are impacted by invasive vegetation, i.e. “weeds,” which strangle natural habitat. The five most common invasive plants species are periwinkle (Vinca), spurge, fennel, giant reed (Arundo donax), and eucalyptus trees.
Invasive aquatic animals, such as the New Zealand mudsnail, bullfrogs, red swamp crayfish, and mosquitofish are also found in many streams in the watershed.
The Effect: Invasive species have negative impacts on native species through competition, displacement, and predation. Amphibian populations in the Santa Monica Mountains are heavily impacted by predation (at the egg and larvae stages particularly) from non-native red swamp crayfish, bullfrogs, and non-native fish. Invasive species can also alter the natural ecosystem, changing the natural fire regime or availability of water. The giant reed grows along streams and spreads very easily, crowding out native species, offering little benefit as food or habitat, and is highly adapted to fires.
The Solution: Educate watershed visitors about how to minimize the spread of the invasive species. For example, cleaning your boots or freezing them overnight after visiting a stream. Encourage use of native plants when gardening and education about what to do with unwanted aquatic pets.
- Malibu Creek Watershed Report
- Appendix A: Impaired Waters in the Malibu Creek Watershed
- Appendix B: Impacts of Impervious Surfaces on Stream Health
- Appendix C: Percent Impervious Area Analysis Methods
- Appendix D: Index of Biotic Integrity (IBI)
- Appendix E: Rapid Bioassessment Physical Habitat Metrics
- Appendix F: Biotic and Physical/Habitat Condition of Selected Sites
Three hidden gems along Malibu Creek
Watch the amazing demolition of the Texas Crossing, a major fish migration barrier in Malibu Creek, over two months.
Heal the Bay’s Watershed Scientist reflects on presenting Malibu Creek Watershed data to the public