San Francisco Chronicle - (Sunday)
The lucky witness the Muir Woods miracle
One of the small natural miracles in this part of the world is just an autumn rainstorm away.
The first good rainstorm is the beginning of the salmon spawning season in Redwood Creek, a tiny stream that runs through Muir Woods National Monument. It is a natural pageant that has been going on in coastal streams for thousands of years when the seasons make their turn from autumn to winter. The salmon, first coho then steelhead, return from the Pacific Ocean to the stream where they were born to spawn and then die. The eggs they leave behind produce another generation of fish, and the cycle repeats.
Though Redwood Creek is nothing like the mighty salmon rivers — the Columbia, the Klamath, the Eel — it is important in its own way. Its watershed covers only 8.7 miles of small creeks and springs on the southerly side of Mount Tamalpais, but the creek flows through Muir Woods, a world-famous grove of ancient redwoods. It’s so popular that visits are by reservation only, and there are limits. In a busy year, a million people come to see Muir Woods.
National Park Service ranger Jace Ritchey is concerned that visitors to Muir Woods are so impressed by the mighty trees they fail to see the rest of the park. “It’s more than that,” he said. “The big trees depend on an ecosystem.” And right down the middle of the canyon where the redwoods grow is the creek, with water to bring life to the forest. The water is full of life itself.
Because of their great age, the redwoods seem eternal. But nature is always changing, and when the rains come, the great forest and the small creek will change as well.
The stage was set a few days ago, when fall rains produced enough water for the creek to open the sandbar at Muir Beach so that Redwood Creek is now connected to the ocean. It’s only a trickle now, but the next big rain will make it possible for the fish to cross the bar and start up past the 13acre Big Lagoon at Muir Beach and up Frank Valley 3 miles into Muir Woods.
And the fish will find changes in Redwood Creek as well. The park service and its contractors have been working to rework the creek in the woods, a project that took all summer and much of the fall. It was just finished a few weeks ago.
The park service calls it “an enhancement,” “designed to make a more natural creek, to improve the habitat for the seasonal salmon,” said Carolyn Shoulders, the project manager.
This wasn’t the first time Redwood Creek had seen major changes. During the Great Depression in the 1930s, government crews working with the Civilian Conservation Corps built an extensive flood control project on Redwood Creek. There had been big rains in Marin in the 1920s, and the little creek in Muir Woods had flooded, threatening visitor facilities like restrooms and snack bars. The ’30s were an era of dams and flood control projects, and Muir Woods got its share: Redwood Creek was straightened and channeled. Big rocks were used to build flood walls. There was less meandering, more asphalt. The creek was made to behave.
It became clear over the years that this flood control approach was doing damage to the ecology of Muir Woods. At the same time, the salmon run on Redwood Creek went into a steep decline. It appeared that the condition of the creek was a factor.
So park service research decided on the project in several stages. “We are doing this work in part to undo the work of past generations,” Ritchey said.
For a while this summer, Muir Woods looked like a construction zone. Heavy equipment was used to tear out tons of big rock. Fallen trees were moved and put into the creek to make something that looks like beaver dams, or log jams.
More dramatically, the creek was rerouted, and the creatures who live in the summer creek were removed temporarily, even fish and giant Pacific salamanders who normally come out only at night. It was a bit of a surprise to find out how many creatures lived in the creek.
It was a surprise too to see that the project left so little visible trace. I needed a guided tour to see it on a walk in the woods on a fall afternoon: Here, a rock wall gone; there, a collection of small snags; here, a pool, a restored creek, a small jewel, inches deep.
It all had a natural purpose, Shoulders said, pointing to a small, dark pool near a fallen tree. “Fish like places like this,” she said. “They are deep, dark and dense. In a word, messy. There are also hiding places for small fish to keep away from predators.”
She said in the spawning season, bridge No. 2, not too far upstream from the visitor center, is a good place in the season. “If you are lucky, you can come out and watch the fish spawn,” Shoulders said. “It’s very dramatic too,” she said. There are also life lessons. The salmon are careful about where they spawn and where they deposit their eggs. “Coho are very picky, very territorial,” she said. Big fish in a small stream.
I asked ranger Ritchey when he thought the run might start. “I don’t know,” he said. “You’ll have to ask the fish.”