Multi-Year Study Finds Trouble at Malibu Creek
Quantifiable data is a necessary first step in establishing a baseline for future improvement in any undertaking. But when it came to the health of watersheds, there wasn't much of that available until the 1990s, when the environmental non-profit Heal the Bay and their team of more than 500 volunteers began to gather high quality data that would shed light on how exactly humans are affecting their surroundings.
The team focused their efforts on the Malibu Creek watershed, the second largest watershed draining to Santa Monica Bay. Despite its size, over 75 percent of the 110-square mile watershed is still undeveloped. Within the watershed, pristine habitats, urbanized areas, and everything in between could be found. It was an ideal real-world laboratory.
Heal the Bay has now published a comprehensive report detailing findings culled from 12 years of data gathered by their Stream Team volunteers.
"It's an unprecedented look at the health of the Malibu Creek watershed," says Mark Gold, former Heal the Bay president and current associate director at the UCLA Institute of the Environment and Sustainability.
In addition to monthly water sampling and an annual biological sampling, volunteers and staff walked and mapped over 70 miles of stream in the watershed between 2000 and 2004 to identify major impairments.
Representing more than 40,000 hours of work in the Creek, the report finds that even though the watershed is largely open space it still hasn't escaped the effects of environmental degradation.
A much lower amount of impervious cover (such as roads, parking lots or buildings) than previously thought is enough to affect water quality, ecology, and habitat. "At 3.5 percent impervious cover, you start seeing impacts. At 6.5 percent, there's evidence of severe impacts," says Gold.
The report also finds that 31 percent of all streambanks were either concretized or had hard materials on their banks; 61 percent of that was already degraded. Though these were probably originally installed to protect private property from erosion or allow for access, these "solutions" actually sped up water flow and increased erosion.
"Water doesn't slow down for us," says Shelley Luce, executive director of the Santa Monica Bay Restoration Commission, who received her doctorate working with the Stream Team program. "It slows down when it meanders or when it encounters plants."
Instead of channelizing these streams, Luce recommends using natural vegetation. "We should put in something that will only get stronger over time. If [plants] gets pulled out in a storm, it can even fix itself," she says.
Heal the Bay espouses that local governments introduce policy that requires developments to be at least 100 feet from the outer edge of riparian habitat. It also wants to see more low-impact developments go up, which would capture and re-use all urban runoff.
The non-profit supports the removal of Rindge Dam, a 102-foot high, 140-foot wide obsolete concrete barrier that sits by a busy two-lane cliffside road on the way to Pepperdine University. At present, about 800,000 cubic yards of sediment has collected behind it. If boulders and cobbles could make its way through to the ocean, they would form surfbreaks and reefs on which kelp could grow.
This man-made barrier also blocks the path of southern steelhead trout that want to swim upstream to lay its eggs and go back down to the ocean, according to Luce.
The volunteers have found invasive species in the watershed, including crayfish and New Zealand mudsnails. These small snails -- one-eights of an inch in length and reproduced asexually -- are particularly hardy, says Sarah Sikich, Coastal Resources Director at Heal the Bay. "[They] can survive passing through the gullet of a steelhead trout."
Their small size makes it easily transportable, even to unsuspecting Malibu Creek visitors. Sikich recommends putting your boots in a plastic bag and sticking them in the freezer overnight, just to make sure you don't accidentally introduce it to yet another environment.
Despite showing signs of wear, the watershed isn't a lost cause. It also doesn't mean the non-profit is looking to halt developments within the watershed. Heal the Bay's report provides a good place to start a concerted effort to improve the Malibu ecosystem and monitor its progress. Sikich adds, "it's not a no-development stance; it's more how can we take better care of our watershed."
Heal the Bay and SMBRC will host a public presentation and discussion on its findings March 19, 6:30 p.m. to 8:30 p.m. at the Diamond X Ranch on Mulholland Highway at Wickland Road in Calabasas.
Read the full report here.
