Big Fish on the Move

Following the heavy October rain, Friends was delighted to receive several reports of big fish, positively identified as Chinook salmon, in Corte Madera Creek, Ross Creek, San Anselmo Creek, and even as far upstream as Cascade Creek. Spawning fish detect the flush of fresh water in the estuary and follow it upstream, normally to their natal streams.

The best spawning habitat in our watershed is in the Cascades, where Morgan Cantrell photographed this Chinook salmon.

This year, as very high flows generated by the big storm dropped, conditions seemed right for the spawners to navigate the many barriers to their passage in our watershed. Steelhead don’t begin to spawn until mid-December or January and the fish we have seen so far are all Chinook salmon. Eric Ettlinger, Aquatic Ecologist at Mar-in Municipal Water District, recently reported on the abundant fish in Marin’s creeks this fall. Referring to the Chinook salmon, he stated: “Many, if not all, of these fish were the survivors of the millions of juvenile Chinook Salmon that were bred in hatcheries and released into San Francisco Bay in recent years. These fish don’t have a natal stream to re-turn to, so will follow the scent of rain-water to the nearest stream.”

Although the chances are high that these returning Chinook are from the recent hatchery releases, this is still encouraging news. A small percentage of salmon are genetically programmed to “stray” from their natal streams, enabling them to recover populations that may be lost even in natural conditions, like a volcanic eruption or large wood dam. We are hopeful the strays entering Corte Madera Creek will be plentiful and successful in re-establishing a small sustainable population of Chinook in the lower watershed.

According to fish biologist Andrew Bartshire, “there is very little competition between steelhead and Chinook for spawning habitat. Chinook are [in-migrating] Sept–Nov. (typically) and steelhead are anywhere from Oct.–Apr. but peaking closer to Feb./Mar. Typical hatch timing for Chinook is about 12 weeks so most of those juveniles should be out of the streambed by the time steelhead are in the system. Also, Chinook typically spawn in much larger gravel than steelhead. There also isn’t an issue with rearing carrying capacity because Chinook juveniles move, almost immediately, down to more estuarine environments so they will likely be getting big and fat down by Hal Brown Park!

The success of these fish is directly dependent on the health of the stream, and this is a great reminder to keep our watersheds clean, support restoration efforts, and limit diversions of water from the creek.”

Let’s hope for more rain this winter to promote spawning steel-head trout as well.

Did Phoenix Lake Avert Flooding During the Big October Storm?

by Erik Stromberg

Add the October 24th 2021 storm to the list of storms that have caused flooding in Ross Valley. Water escaped the banks of San Anselmo Creek and flooded houses at known trouble spots including Nokomis and Madrone avenues in San Anselmo. We now know that it could have been worse.

Every large storm is unique. This is partially what makes managing flood risk in Ross Valley tricky. Large downpours following a few days of steady rain are usually what overwhelm the creek and cause flooding. The downpours don’t need to last long. If the hillsides are saturated, and the creek has a strong base flow, the creek can spill over into our neighbor-hoods with as little as 30 minutes of heavy rain. This makes predicting which incoming atmospheric river will deliver the next disaster to Ross Valley difficult. It is also why adding detention basins into the valley can reduce flooding. The runoff from these intense downpours can be stored in the basins and slowly released in the hours following the peak rainfall.

What made the October 24th storm unusual was that heavy rain persisted for hours. Typically flooding is not a concern when hillsides and creeks are dry at the start of a storm. However, after 12 hours of steady rain the hillsides were saturated, and the creek was rising fast. By 3 p.m., after more than 15 hours of constant rain, the storm moved on and Corte Madera Creek and all the tributaries began to recede. The water levels crested right at flood stage in downtown San Anselmo and Fairfax, just as officials ordered the flood sirens to sound. Once again, we escaped a large-scale disaster.

Phoenix Lake spillway. Photo by Charles Kennard

According to MMWD storage data and observations by community members, Phoenix Lake rose 27 feet during the storm. This provided approximately 311 acre-feet of storage prior to spilling between 2 and 3 p.m. Sunday afternoon. Prior to the storm, Phoenix Lake held an unusually low volume of 99 acre-feet of water. This had me wondering, did Phoenix Lake prevent flooding in Ross Valley?

To help answer this, I analyzed the discharge data for Ross Valley to estimate the discharge that would have occurred if Phoenix Lake had been full prior to the peak discharge. The analysis indicated that Phoenix Lake likely prevented flooding in Kentfield, Ross, and San Anselmo by reducing the peak discharge by about 17% and lowering water surface elevations on the order of a foot at the Corte Madera Creek gauge near the Lagunitas Road bridge. Considering the creek peaked at the top of bank, this extra foot of rise if Phoenix Lake had been full would have instead flooded streets and homes in our neighborhoods and businesses in San Anselmo, Ross, and Kentfield.

We can’t count on Phoenix Lake to save us during the next storm— after all every storm is different and the lake is not usually drawn down. But we now have a real example of how detention basins in the Ross Valley can make the difference between inconvenience and disaster.

Moving Forward with Flood Risk Reduction in Kentfield and Ross

by Sandy Guldman

The Corte Madera Creek Flood Risk Management Project is making big strides forward, albeit with some modifications. The project currently consists of components to reduce flood risk and improve fish passage. Flood risk reduction in the Granton Park neighborhood will be accomplished by installing flood walls along the left bank (looking downstream) and constructing a pump station to remove local drainage that accumulates on streets during heavy storms. To aid maintenance of the concrete channel, a ramp allowing vehicles to drive into the channel is proposed near Granton Park. Some low walls will probably be needed along the left bank near College Avenue to reduce the flooding of homes and businesses in that neighborhood. Fish passage will be improved by removing the fish ladder at the upstream end of the concrete channel, creating a smooth transition from the concrete channel to the natural channel, and enlarging the small fish-resting pools in the upstream half of the concrete channel.

Although removing the fish ladder will provide some reduction in flood risk for Ross residents, the Town of Ross opted to preserve the concrete channel and chain link fence in Frederick Allen Park, rather than restore the riparian corridor and further reduce the flood risk in Ross, especially for homes between the park and Sir Francis Drake Boulevard. This is ironic because residents of Ross have prided themselves on stopping construction of the concrete channel since the 1970s; now they are champions of its preservation?

The riparian corridor at Allen Park in Ross would have provided major environmental benefits—another requirement, in addition to flood risk reduction and fish passage, of both the fee passed after the 2006 flood event and a grant from the Department of Water Resources. Although some habitat enhancement will take place upstream of the concrete channel, the significant habitat benefits of the overall project will come from restoring 1.5 acres of creek, riparian, and upland habitat with the Lower College of Marin (Lower COM) Project. This project will lower much of the concrete wall downstream of Stadium Way, in Kentfield, and restore tidal wetland and nearby transition zone and upland habitats. It is designed to be resilient to climate change and adapt to rising sea level, a living shoreline so to speak. It will also create an outdoor classroom where students and faculty can study hydrology, geomorphology, biology, and more.

The future scientists, technology developers, engineers, and mathematicians of Ross School could have had a new, outdoor classroom and laboratory in Town, across the street from their campus, as well. Fortunately, they will still be able to use the one at the downstream end of the concrete channel, at College of Marin, when it is restored. Maybe in the coming years, the next generation of Ross students and residents will be able to revisit creek restoration at Allen Park and pride themselves once again as leaders in creek preservation and restoration.

Funding for construction of the flood risk reduction and fish passage projects is being provided by the Ross Valley Stormwater Fee and the Department of Water Resources. Friends of Corte Madera Creek and the Flood Control District are seeking funding for the Lower COM Project.

Projected calendar:

In process         Prepare complete designs for the entire project

Feb or March    Release request for bids and let contract

April                 Begin construction of pump station and access ramp

June                  Begin construction of in-channel work in Ross and Kentfield

September         Begin construction of Lower COM Project (if funding available)

October            Complete all instream work

Winter 2022-23 Finish planting of native vegetation

Surfing Daydream

by Gerhard Epke

I’m always daydreaming about surfing. Riding some kind of smooth-bottomed craft as it glides across a smooth face of water is somehow good recreation. There is something special about leaning your body into a vortex of energy right below the curl, right at the edge of chaos. Recently I have been thinking about surfing in the context of my own watershed. Local surfing opportunities abound if you know where to look.

Waves occur in water when an energy drop creates what is called a hydraulic jump. The clean face of a wave is water accepting energy that pillows up behind. With increasing energy, the wave breaks and energy is released into turbulence. Sometimes the water is moving and the energy is stationary, as in a standing wave. Other times the water is stationary and the energy moves, as in an offshore swell hitting the coast. Different surfing styles have evolved to match these different kinds of waves.

We have traditional stand-up Hawaiian surfing down where all the tributaries to San Francisco Bay reach the ocean. Just past the mouth of the Golden Gate, our local estuary mouth and surfing spot is Rodeo Beach at Fort Cronkhite. By surfing standards, “Cron” is very often a challenging, unforgiving, short, and treacherous ride. Swell from all directions enters the cove and hits a steep beach of Franciscan cobbles. Like Ocean Beach in San Francisco, it is impossibly huge above two or three feet but occasionally affords beautiful days and smooth rollers.

Farther upstream in the bay, kayakers can go after standing waves in Raccoon Strait. Tidal flow and runoff from our watershed, and from the Sacramento and San Joaquin valleys, is focused between Tiburon/Belvedere and Angel Island. A strong ebb tide, combined with ocean swell and wind coming in, creates standing waves in the mid-to-west end of the strait off the end of Belvedere Island. This can also be treacherous and requires some safety precautions.

Even farther upstream in the Corte Madera Creek estuary, wind-surfers and kite surfers launch for surf without waves. There are apocryphal accounts of surfing the wake of the ferries coming out of Larkspur Landing once they get far enough out to speed up and create significant water displacement. This kind of wave moves laterally off each side of the ferry and, if you catch the smooth face, it would boost you along.

On its way to the ocean, the waters of our watershed are replete with waterfalls, rapids, standing waves and breakers. Photo of Westbrae dam. Fairfax, by Charles Kennard

Upstream even farther, the freshwater stream has standing waves that are prone to set up with sufficient flow and a good hydraulic jump. Looking at our stream in the summer, it is hard to imagine that kind of power, but at high enough flow—say above 500 cubic feet per second—one can see waves setting up in various places as the discharge changes.

I haven’t seen it, but the mouth of the concrete channel where it opens up to the earthen channel at College of Marin must have a good standing wave at some high flows. It even is configured to have a good slack-water eddy to take a break and get back in. However, within the concrete channel itself is a truly dangerous place to try to do any surfing since there is no escape but down-stream. This also happens to be the reason it is a barrier for migratory fish.

Creek surfing and whitewater boating is possible at high flows in San Anselmo Creek anywhere upstream of Ross. The rapids are primarily concrete drop structures beneath bridges like Pastori and Saunders avenues. These drop structures are also fish passage barriers that we hope to someday remove.

As we work on restoring the creek for migratory fish, consideration should also be given to aligning our goals with the recreational opportunities that can also be improved. For instance, in many other places whitewater parks have intentionally designed standing waves for surfing. In the meantime, the surfing will remain catch as catch can—or in my dream, unlimited.

Best Practices for Riparian Corridors

by Laura Lovett and Sarah Phillips

A riparian corridor is the vegetated area next to a creek channel. If you are lucky enough to have one on your property, it comes with wonderful benefits and some added responsibilities.

Riparian habitats are vital biological systems that provide irreplaceable functions for water purification, flood control, fish and wildlife movement, and native habitat. Healthy waterways and their natural habitats are an essential environmental, economic, social, and community asset. They provide access to lands for recreation, protection against potential flood damage, soil stabilization, ground-water recharge, stormwater pollution filtration, and aesthetic benefits. Riparian woodlands along perennial creeks also tend to have low ignition potential. In locations where the plants are hydrated year-round, riparian vegetation may inhibit ignition, diminish fire intensity, and halt or slow the spread of fire.

Creeks need space to perform naturally. Photo by Charles Kennard

The Marin Countywide Plan sets goals for conservation of vegetation corridors along existing streams in order to protect and, where possible, restore their natural structure and function. Unfortunately, large portions of existing riparian systems have been eliminated by stream channelization and urban development. Corte Madera Creek is among those that have been channelized for lengthy portions.

A stream conservation area (SCA) is a buffer established to protect the active channel, water quality and flood control functions, and associated fish and wildlife habitat values along streams. There are designated SCAs along perennial, ephemeral and intermittent streams and they include the waters within the channel as well as the stream banks and adjacent uplands. There are limits on what you can do within an SCA. Marin County has had a Stream Conservation Ordinance since the early 1970s. Last revised in 2007, the county is currently in the process of updating this major planning tool, pertaining to the County’s unincorporated areas.

If you have native vegetation along your creek, you should retain at least 75 percent of the overstory and 50 percent of the understory canopy of native riparian vegetation within the riparian habitat. The vegetation needs to be in a well distributed, multi-storied stand composed of diverse species that are similar to those that would grow there naturally. Limit your vegetation treatment to the removal of invasive, dead or dying vegetation and trimming/limbing of woody species to reduce ladder fuels. Avoid any vegetation removal that could reduce stream shading and increase stream temperatures.

Avoid removing large, native riparian hardwood trees, e.g., willow, ash, maple, oak, alder, and box-elder. These trees are difficult to replace and provide essential erosion control and habitat for wildlife. Fell hazardous trees away from adjacent streams or waterbodies and pile the debris outside of the riparian zone.

Do not use herbicides or pesticides in the riparian zone unless they are approved for use in aquatic environments; use those only during low stream flow.

Limit ground disturbance within riparian habitats to the minimum necessary to implement effective treatments that will reduce hazardous fuels. Any bare ground exposed needs to be revegetated immediately with native species. Use biodegradable erosion control measures (no plastic) to keep banks intact and sediment out of the creek channel until the native plants grow in.

Revegetate with native plants. Plant species native to California, which need no fertilizer, and once established, are tolerant of dry summers. They are established when they have put down a deep root system. For the first couple of years, they will need watering. Less frequent, deep watering is preferable to a surface wetting as it encourages roots to grown down. It is best to plant in fall to reduce watering. Regular weeding and protection from deer will increase survival rates.

Creeks need sufficient width and unobstructed flow to carry the runoff from a heavy storm and to prevent flooding on your property. Work with your neighbors to ensure that your stretch of waterway is well maintained and doesn’t contain obstructions. With proper care, the riparian zone on your land can be a source of habitat for wildlife, a buffer against erosion, a potential help in wildfire, and of great benefit to our region’s salmon and steelhead populations, as well as a wonderful place to enjoy.

Resources:
If you are in unincorporated Marin, the regulations that apply to your property are set forth in the Marin Countywide Plan. Most actions carried out within or near the creek channel will require a creek permit, which can be obtained through Marin County’s Department of Public Works.
If you live in an incorporated area of the Ross Valley—within the town limits of Corte Madera, Larkspur, Ross, San Anselmo, or Fairfax—contact your town’s Department of Public Works.
If you have dead, invasive, or exotic vegetation, or plants on the fire-prone list, they can be removed without a permit.
If you have native vegetation, follow the creek care rules above. Removing natives is highly discouraged and may trigger the need for a tree removal permit. A permit is not needed to plant natives.
Helpful information can be found through MCSTOPPP, Marin Resource Conservation District, and the Marin chapter of the California Native Plant Society.

MCSTOPPP publications
https://mcstoppp.org/2020/03/public-resources then choose Creek Care, or Gardening
Creek Care, Repairing Streambank Erosion, Erosion Control for the Weekend Warrior, and more
The county’s creek restoration and permitting guide https://mcstoppp.org/2020/03/creek-restoration-and-permitting/

Marin RCD

RESOURCES


Resources for plans and permits, bank stabilization, vegetation, erosion control and more
RCD Stream Maintenance Guide

Marin chapter, California Native Plant Society
Fire Smart Landscaping: cnpsmarin.org/native-plants/fire-smart-landscaping
Lists of Native Plants for various growing conditions, including riparian habitat: https://cnpsmarin.org/native-plants/how-to

Marin County offers free creek permitting assistance at monthly project coordination meetings to review and guide projects through the environmental and regulatory permit process.
http://www.marinrcd.org/wp/wp-content/uploads/2015/02/MPC_flyer_2016-1.pdf

Contacts for creek permits and information:

Fairfax
(415) 458-2370
Mark Lockaby mlockaby@townoffairfax.org

San Anselmo
(415) 258-4616, 415-258-4646
Sean Condry, scondry@townofsananselmo.org

Ross
(415) 453-8287; (415) 453-1453, ext. 117
Eric Robbe, erobbe@townofross.org

Corte Madera
(415) 927-5057
Cymantha Baroy, cbaroy@tcmmail.org

Larkspur
(415) 927-5017
Julian Skinner, jskinner@cityoflarkspur.org

Marin County Dept. Public Works
Land Development Division, (415) 473-3755

Sarah Phillips, is the Urban Streams Program Manager for the Marin Resource Conservation District. Contact her at sarah@marinrcd.org for advice on creek care if you live in unincorporated Marin County.