April 23, 2018

Topanga Beach Water Quality Update


What microbes can tell us about water quality


Topanga Beach Water Quality Update

Topanga Mountain School students Girnar Joshi, James Werbve, John Kahle, Mandy Deitelbaum, Akasha Ross and friends prepare their bacterial cultures with UCLA student mentor Joshua Kameel-Ishmael.

Since fall 2012, a team of dedicated scientists from the Jay Lab at UCLA and the RCDSMM Topanga Creek Stream Team has been waking up really early and hiking into Topanga Lagoon and Creek before the sun rises to collect water samples. The goal is to figure out what is causing high bacterial levels at Topanga Beach. Preliminary results are pretty interesting, and will be presented at a community meeting on Thursday, May 30 from 6:30 – 8pm at the Topanga Library.

Topanga Beach has been on the Heal the Bay list of “Beach Bummers” for several years, with water quality grades that exceed the Fecal Indicator Bacteria (FIB) standards regularly.

With funding provided by Los Angeles County Supervisor Zev Yaroslavsky, District 3, and augmented by funding from the California State Water Resources Control Board (Clean Beach Initiative, Source Identification Protocol Project), researchers have been testing samples from possible contributing sources and applying state-of-the-art molecular testing to identify if the bacterial sources are human, dog, gull or something else. The sampling strategy is designed not only to identify the source of the problem, but to clarify what contribution, if any, is coming from Topanga Creek.

The team from Dr. Jenny Jay’s lab is using both the traditional culture-based analysis called IDEXX to count the number of total coliform (TC), Escherichia coli (EC) and enterococcus (ENT), which is consistent with the methodology used by the City of Los Angeles and required by the Regional Water Quality Control Board. While useful in providing a snapshot of overall bacterial levels, they do not specifically tell us from what animal the bacteria originates. Using molecular markers, the Jay lab has been able to determine that the lagoon waters appear to be the most significant contributor of FIB to the beach, and while human markers have been detected, the high levels of gull and dog markers indicate that they are also important contributors to the high bacterial levels.

Investigating further, samples have been collected upcoast from the lagoon, just west of the metal groin at the west end of Topanga Beach, as well as from several locations moving upstream in the lagoon and creek. Samples from the lifeguard septic system have also been tested. The patterns are a bit baffling. It makes sense that the levels are low in the creek, increase in the lagoon, and then get diluted in the surf, but we did not anticipate finding high levels upcoast.

The mystery continues, but to help us learn more, we enlisted the aid of fifth graders from Topanga Elementary and sixth to eighth graders from the Topanga Mountain School. Working with UCLA undergraduate student mentors taking a service learning class with Dr. Jay, the Topanga students are conducting microbe safaris to learn more about bacterial sources. Students collected samples on petri dishes at school and prepared IDEXX samples of sand and water during a field trip to Topanga Beach.

“I was so excited that our students could be a part of this project,” Nicole Sheard, principal at Topanga Elementary added. “Not only did I think they would really enjoy it, but I loved the idea of them learning about something so meaningful and close to home. It is my hope that they can take the information and knowledge they gained to help educate others about the steps they can take to improve the water at our beloved Topanga Beach and beyond.” The students will be getting their results back soon and working with their UCLA mentors to present posters of their research both at UCLA and at the community meeting on May 30.

But the study is not just limited to bacteria…Topanga Creek is unique. It is the only creek in the Santa Monica Mountains that still retains much of its ecological function and biodiversity, while supporting more than 10,000 humans. We have all three native fish species and many of the native insects that they rely upon for food. While the students were at the beach, they had a chance to work with the RCDSMM biologists to try and identify the bugs found in the creek, test salinity and pH, and also seine for fish in the lagoon. Tying together how the bacteria and water quality factors influence the diversity and health of macro-invertebrate and fish communities is another facet of the study. The student results will be added to the observations collected by the Topanga Creek Stream Team as they re-visit study sites throughout the creek.

Since 2000, the Topanga Creek Stream Team has monitored the same 500- meter reaches of creek near the Backbone Trail in Old Topanga Canyon, along the main stem of the creek from Greenleaf Road to Highvale Road, and at two locations within lower Topanga State Park. Each spring, we count every frog, tadpole, dragonfly nymph, newt, egg masses, fish, snakes, and whatever else we can find in the creek. This year, we are also collecting samples of diatoms and algae. Pulling together 13 years of data on these indicators of creek health will give depth to our understanding of the overall ecology of the creek.

We know that there are problem “hot spots” with poor water quality in the upper watershed, where graywater and septics that are not properly functioning can cause problems, dog and horse manure gets deposited in the creek, and homeless folks who use the creek rather than a restroom. The pattern of high levels of bacteria in town, which naturally gets cleansed as it moves downstream through lower Topanga State Park appears to be holding, but we still are not sure how much we can continue to input into the system before it stops working.

Which brings us back to the mystery of what is causing the bacterial problems at Topanga Beach. As part of this study, Richard Sherman of Topanga Underground is working with State Parks to test the septic systems at the Feed Bin, Reel Inn, the ranger residence at Topanga Ranch Motel, the Rosenthal Winery, Wylie’s and Cholada’s. The goal is to determine if any of these systems are contributing to the problem. BioSolutions has been maintaining the state-of-the-art septic system that serves the lifeguard station on Topanga Beach, and samples from there do not appear to be contributing bacteria. To learn more about the details, enjoy discussing the problem and results identified by the students, and learn about what steps you can take to help improve water quality at Topanga Beach, please join us at the library on Thursday, 30 May.