Removal May Be Key to Steelhead Trout Survival

In the 10,000-year history of the southern steelhead trout, Aug. 11, 1997, was particularly noteworthy. On this day, the fish was listed as an endangered species by the National Marine Fisheries Service (NMFS).

The steelhead is closely related to the Pacific salmon; like the salmon, the steelhead is anadromous--meaning it migrates to sea and then returns to its native coastal streams and rivers to spawn. According to the NMFS, 23 species of steelhead have become extinct this century and another 43 are in dire straits.

Dwindling populations of southern steelhead are found in the Ventura and Santa Clara river systems. The NMFS believes that their southernmost habitat is Malibu Creek, which drains a 105-mile watershed including parts of Calabasas, Agoura Hills and Thousand Oaks before plunging through a steep canyon to the sea. In the creek, two miles upstream from the ocean, is 100-foot-tall Rindge Dam.

The dam was built in 1924 to impound water and provide flood control. By the 1960s, it had filled with silt. The state decertified the dam in 1967, and in 1994 the U.S. Bureau of Reclamation estimated it was holding back 800,000 to 1.6 million cubic yards of sediment.

In the last decade, a growing number of government agencies and environmental organizations have become concerned that Rindge Dam is blocking critical upstream habitat needed by the southern steelhead. The NMFS, the California Department of Parks and Recreation, the California Department of Fish and Game have gone on record calling for the dam to be removed.

The Army Corps of Engineers will study the Malibu Creek watershed to determine if the creek is worthy of a civil works project. The corps sponsored a public workshop recently to get input about the watershed, but the subject people kept returning to was the southern steelhead and Rindge Dam.

Jim Edmondson is the executive director of California Trout, a statewide organization dedicated to protecting and restoring trout habitat. He recently talked about the Rindge Dam controversy:

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Question: What reasons would you give the average citizen to spend tax money on tearing down the dam?

Answer: The dam is a public nuisance. It’s no longer a reservoir and it no longer provides any flood control. It’s retaining sand that could nourish our eroding beaches. It’s a barrier to hiking. And it has some rather profound implications on a salmon-like fish that lives next door to 10 million people.

We don’t know how to engineer, manufacture or recreate these fish. How much is the Mona Lisa worth? I don’t know. So I tell the average person on the street that we have a run of salmon-like fish next door to Los Angeles, which is part of our heritage. And that dam blocks those fish from going home to reproduce.

Q: How many steelhead currently reside in Malibu Creek?

A: Nobody really knows. Experts have a range of estimates--and they are all very low, from 20 to 60. Adults are very difficult to see because they are in the creek during high-water conditions. For safety purposes, no one wants to get into Malibu Creek when it’s gushing. However, every time scientists have gone into the creek to do swim surveys, they have found steelhead.

Q: How much additional habitat would be provided for the steelhead if the dam were removed?

A: Studies indicate that the trout would have access to 4.8 miles of additional habitat from Rindge Dam upstream to the next dam, Century Dam. The trout would also have access to tributaries like Cold Creek and Las Virgenes Creek. Spawning could increase by as much as 580% and rearing would increase by 180%. There would be, at the least, a threefold increase in population.

Q: There’s a 10-foot-tall waterfall just upstream from Rindge Dam. Could the fish get past that?

A: The Department of Fish and Game addressed that in 1995. In their opinion, a 10-foot-tall waterfall was not necessarily a barrier to steelhead--which have been known to pass over such barriers under certain high-flow water conditions.

How? In a high flow, the 10-foot waterfall might be reduced to something like seven feet. Below the waterfall is a five-foot deep pool of water. The fish swim around the bottom of that pool, gathering speed. And then they take off.

Remember this--because of the dynamic nature of Malibu Creek, and the erosion that occurs during high flows, the reservoir behind Rindge Dam filled up with sediment in 25 years. So what might be a waterfall today could be a riffle tomorrow.

Q: Given the development in the watershed, is the water quality good enough to support steelhead?

A: Most of the development since the 1950s has primarily occurred in the headwaters of Malibu Creek, unlike the traditional development that starts at the ocean and moves upstream. In the case of Malibu Creek, the middle stretches are in relatively healthy and stable condition. That is a relative statement--and it does not answer your question. The water-quality issue isn’t as much a quality issue as a quantity issue.

Q: There is more water than ever in the creek.

A: The data says there was an increase in the summer flow regime that occurred in 1966. Why? With development in the watershed came imported water. The majority of that water is used outside the home for irrigation. That water eventually finds its way back into the creek.

The problem is that Malibu Lagoon has shrunk because of development, and the lagoon is now being overwhelmed with excess water from Malibu Creek. But the lagoon is the transitional zone, where the steelhead prepares to go from the freshwater environment to the sea. This is supposed to happen in the winter, when the lagoon is breached by high-energy storms. But when the lagoon is breached during the summer and the saltwater comes into the lagoon, the fish aren’t ready. They go into toxic shock and die. That’s your water-quality problem.

Q: A significant number of nonnative fish, like crayfish and largemouth bass, have been tossed into the creek over the years. Can steelhead fight off these predators?

A: One, you are not going to get rid of these unwanted guests. Two, the Malibu Creek habitat favors the native species, so if we provide them the opportunity to spread out--rather than imprison them in a small section of the creek below the dam--then you minimize the predation by things like bass. The nonnative fish are a problem but they are more like a mosquito bite than a cancer.

Q: Steelhead are often referred to as an important ‘indicator’ species. Could you explain that?

A: Steelhead are among the most cost-beneficial and biologically important indicator species of the health of that watershed. They are the canary in the coal mine. Anything that happens in that watershed ultimately gets in the creek. The steelhead needs to live in the creek, the lagoon and the ocean to fulfill its life cycle. It’s hard to imagine another species that provides that kind of barometer.

Q: Why is Cal Trout involved? There is no one who believes that steelhead in Malibu Creek will recover in sufficient numbers to support sports fishing, at least not in our lifetime.

A: This has nothing to do with fishing. It would be a crime to fish for steelhead in Malibu Creek. It would also be an equal crime, maybe greater, if these fish go extinct. This is about, as Aldo Leopold said, saving all the pieces. Save them for what they mean to our heritage. Save them to show that we can be good stewards of this world. That way, in theory at least, we can pass these fish on to the next generation.