Restored wetlands defend Lake Tahoe from human disturbance
By Teresa Crawford, Outpost staff
Calm, clear water
reflects boulders at Sand Harbor. Photo by Teresa
Crawford
But in reality, it's a wetland restored in 1989 by the
California Tahoe Conservancy under the direction of erosion
specialist Steven Goldman.
The damp one-third acre is a hard-working soldier in the ground battle to rescue Lake Tahoe's astonishing clarity from degradation by human impact. The battle so far has failed to halt the lake's decline. The tangle of plants includes several species of wetlands specialists. They efficiently filter sediment and nutrient from rain and snowmelt running off impervious surfaces: the roofs, roads and driveways of human habitat.
It's that runoff, thick with fine clay particles and fertilizer-rich with phosphorus, that scientists blame for damaging the lake's optical qualities and causing algae to grow.
"I wanted to create an urban wetlands that would drain and filter a nearby section of Highway 50 and the adjacent neighborhoods," Goldman said. "We call these entrapment basins. A good cover of native vegetation is the key. The plants provide rough surfaces that trap large quantities of sediment, especially the fine particles that do the lake the most damage."
Goldman and his staff manage more than 70 such projects that dot the California portion of Lake Tahoe's watershed, but he said such piecemeal efforts hardly match the magnitude of human disturbance.
"The parcel-by-parcel approach will put balance back into the natural system," he said. "But it hasn't been implemented fully. We need to do ten times as much."
Fixing nature is expensive
The money needed to revive natural processes adds up quickly. According to its 1997 progress report, the conservancy has spent $35 million for the grants to local municipalities for water quality improvement, acquisition of properties like this one and site improvements, an understated term for major restoration projects.
The golden little half-acre on Chris Avenue brings to life the concept of biological diversity espoused by conservation biologists like Peter Brussard, University of Nevada, Reno professor. Intact systems of plants, soil, water and wildlife are essential to the global life support system, he said, and provide direct economic benefits that most people don't appreciate.
One who does is Goldman, erosion control and stream restoration program manager for the conservancy and a principal warrior on the lake's behalf. He helped plan and direct the lot's transformation from a bulldozed surface to a damp pocket meadow.
Before the subdivision, the area probably featured a small stream and meadows, Goldman said. After the construction, water pooled on the street and flooded basements during heavy rains and the spring snowmelt. The project aimed to replace some of the lost wetlands' beauty and function.
Steven Goldman
designed an urban wetland. Photo by Teresa
Crawford
"Just throwing in grass seeds isn't enough," he said.
"Without good veg, I've seen water emerging from a basin
dirtier than what went in."
What a bulldozer driver wiped out in a single swipe three decades ago took a summer of painstaking attention to detail and more than $350,000 to repair, of which the conservancy spent $66,300 to acquire three vacant lots.
California Conservation Corps crews helped out. They dug up the native wetlands sod and willows, tended them on a nearby lot with shade screens and daily watering, then replanted the site.
The sod, containing the community of microscopic organisms that defines wetlands, sprouted the kind of grasses that thrive on damp roots within a year. They filter the water percolating through, trapping sediment and consuming phosphorus that would fuel algal growth in the lake. Finally, Goldman directed crews to replant the willows around the basin's margins where they've grown into a screen that attracts songbirds.
The system is working, Goldman said. He pointed to the turbid, gray water, drainage from the neighborhood, that entered the lot through the inflow pipe on the east. A few hundred feet away on the lot's west side, clear, odorless water, cleaned by the wetland, trickled through the outflow pipe, bound for the Upper Truckee River, the lake's largest watershed.
It would help reduce the basin's burden, Goldman said, if owners of some of the surrounding houses handled their own runoff, but nearby properties have no water-absorbing vegetation or infiltration trenches to catch the rain and snowmelt dripping off roofs. Some still have unpaved driveways, which are considered a major preventable source of erosion into the lake.
Compliance with the Tahoe Regional Planning Agency erosion control program, called Best Management Practices is voluntary (except for new building permits), according to an agency brochure about the process. However, the target date for property owners in the most erosive areas, known as Priority One watersheds, to take action is Oct. 15, 2000.
Priority One watersheds have dense development, steep slopes and improperly drained roads. The South Lake Tahoe neighborhood with the restored wetland is in a Priority Two watershed.
Goldman said he believes most homeowners have not done the necessary work.
"A big part of the problem (with low compliance) is public education," Goldman said. "TRPA should be investing much more money in informing the public. If people understand the significance of the requirements, they will want to do the right thing."
Pam Drum, a spokesperson for TRPA, said she agreed that people need more assistance in understanding the problem and more hands-on help in making corrections, but she said the agency had plans to increase outreach.
"We have pockets where compliance is very poor that you can see just by driving around," she said. "But a recent phone survey showed that people have a high awareness that there are things they can do to control soil erosion and storm water runoff.
"It's a matter of getting the technical help out in the field. TRPA has received grants from the federal Clean Water Act through California and Nevada to work with the Natural Conservation Resource Service to bring technical helpers to neighborhoods."
Nature is the best planner, erosion expert says
Goldman said the irregular contours of the basin mimic nature's undulating shapes. An interesting lesson in this fledging field of reconstructing nature, he said, is that the most aesthetic solution is often also the most functional.
"I learned erosion control on the job," he said. "It's not taught in school. It involves several disciplines: hydrology, ecology, botany and engineering."
It also involves common sense, something Goldman said many projects lack.
"It is arrogant to try to control nature without understanding natural processes," he said.
"What distresses me is throwing money at problem drainages without figuring out the best solutions for the lay of the land.
"We shouldn't be building stuff that doesn't make sense."
To make his point, he stopped the conservancy's truck next to a basin flooded with dishwater-gray standing water at the bottom of a steep street. Engineered by the city of South Lake Tahoe, the basin had never been revegetated. An unsightly corrugated pipe stuck out of the muck, a drainage method that wasn't necessary at the conservancy site. With its perfectly regular grading cuts, it looked like an abandoned construction project, nothing like the mini-wetland on Chris Avenue.
"It's cut too deep, into the subsoil, so vegetation won't grow," he said. "When the fines (smallest clay-like soil particles) wash in and mix with the subsoil, a brick layer will form that won't drain and won't grow plants."
A creek is resurrected
The premier project on Goldman's watch is the Cold Creek stream restoration. Once a small creek meandered through a broad meadow that is now stranded between two subdivisions. It was probably Comstock-era loggers who diverted the stream into a sluice channel, he said. One hundred years later, developers dug out a lake for their subdivision that promptly silted up behind a dam later deemed unsafe by South Lake Tahoe officials.
The new creek
diverts silt from Lake Tahoe. Photo by Steven
Goldman
The conservancy teamed up with the city and a federal
agency, the Natural Resources Conservation Service, to
create a reasonable facsimile of the original landscape.
That's where the design process got so complicated it
consumed nearly half of the $1.2 million total costs,
Goldman said.
But the burbling little stream has already repaid its makers by functioning exactly as planned. During the heavy spring runoff of 1997, it overflowed its banks and deposited tons of silt that were bound for Lake Tahoe.
Root balls
stabilized new stream banks. Photo by Steven
Goldman
"The more runoff, the better it will work as it adjusts
itself," Goldman said.
It took a lot more than digging out the creek bed. Under the guidance of David Rosgen, a University of Colorado expert on building streams, crews studded the creek's walls with dried up root balls still attached to 7-foot sections of tree trunks. This stabilized the freshly cut bed. Excavated sod was replaced on the creek's margins. Finally, middle-school children planted hard-working willows all over the meadow.
"Their rough surfaces really enhance sediment deposition," Goldman said. "In an area without enough coverage, we wove willow branches between the plants to form a silt-catching lattice. Some of the branches even rooted."
Because of the way rocks are arranged in the creek bed, the water drops naturally, with the familiar sequence of riffle, pool and shady bend that anyone who has waded or fished a meadow stream knows. The creek sparkled on a warm October afternoon.
Trout stocking has succeeded and neighborhood kids play there. But predation by domestic and feral dogs and cats has prevented waterfowl from making a strong comeback in the meadow, Goldman said.
Saving Lake Tahoe means more gutters, drains and wetlands
Goldman has been on the job since voters established the California Tahoe Conservancy in 1985. The conservancy's mission is to protect and restore the natural environment of the Tahoe Basin, especially the watersheds, increase public access to the lake and enhance wildlife habitat. Goldman said the difficulty of communicating with scientists on one side and engineers from two counties on the other is taking its toll, along with the magnitude of the task.
Goldman says the
meadow collects tons of sand that would have washed
into the lake. Photo by Teresa
Crawford
"I used to be more energetic and write comment letters to
the county planners," he said. "Now I choose my battles
carefully. What have we learned after all this time? Why
aren't there changes? Construction permits for 300 new
residences are issued every year."
Back at the conservancy offices, Goldman laid out some slides that illustrated his frustrations.
One transparency after another showed the sediment plumes discharged by each of the 63 streams that flow into the lake. Another series of slides showed where a lot of that sediment comes from, the unlined ditches that drain many of the basin's roads. Only a tiny fraction of the roads have the curb and gutter system that would divert runoff into absorbent meadows. Goldman said.
After attending the Adaptive Research Symposium on Oct. 20 and 21 where leading Tahoe researchers discussed their findings, Goldman said he walked away feeling some of the Tahoe Basin's needs weren't addressed.
"The scientists need to do research that will help us get to solutions," he said. "I wanted to give them a tour like this one, but they weren't real interested. I suggested that the scientists help us teach the county agencies and their engineers the best designs to infiltrate fine particles."
"An Indian mystic said Westerners like to name things instead of understanding relationships," he said. "When you do that, you are just describing parts and simplifying what nature really is."
At the symposium, a parade of scientists named the causes of the Tahoe Basin's declining health in great detail and they talked of monitoring restoration efforts and building computer models of how the lake responds to human and natural changes.
But Goldman and two erosion managers for Nevada, Kathy Jordan and Meri McEnery, said they have gotten little help for their work from the existing body of research.
"Researchers need to understand how to tailor research to managers' needs," Goldman said. "I would love it if the Tahoe Research Group would monitor Cold Creek's sediment carrying capacity for us."
Posted Dec. 9,
1998
Copyright 1998 Nevada Outpost
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