Stymied Steelhead

by Sandy Guldman

The information in this article was condensed from a draft report prepared by Michael Love and Associates, as part of work funded by a grant to Friends from the California Coastal Conservancy.

Abundant steelhead trout (Oncorhynchus mykiss) and coho salmon (Oncorhynchus kisutch) spawned in the creeks of the Ross Valley during the 1940s and 50s. Over the years, these creeks were degraded as fish habitat by hardened banks, culverts, and dams for swimming holes and stock ponds. Fewer and fewer fish returned to spawn. The final insult was the construction of the concrete channel in Kentfield and Ross, built by the US Army Corps of Engineers (USACE) in the 1960s with the intended purpose of reducing flooding. Making it through that barrier is something only the most robust fish can accomplish. About 10 years after its construction, coho salmon were extirpated from the watershed. A very small population of steelhead trout, now listed as threatened under the Federal Endangered Species Act, lingers on.

A postcard dating from about 1900 promotes the Ross Valley for fishing.

The section of concrete channel upstream of the College of Marin campus is the primary barrier to fish passage within lower Corte Madera Creek. Although two streams that historically supported salmonid species, Larkspur Creek and Tamalpais Creek, can be reached without passing through the concrete channel, both of them are seriously impaired: neither supports coho or steelhead populations.

The concrete channel reaches from Kentfield, downstream of Kent Middle School (KMS) to near the Ross post office. Below College Avenue, adjacent to the KMS campus, the channel provides poor fish habitat, but they can move through it. Then, as spawners attempt to move upstream, they encounter higher water velocities and the trip becomes even more challenging.

Two features to aid migrating salmonids were included in the design. The 33-foot-wide concrete channel has a v-shaped bottom that provides a low-flow zone for fish, and the upper part of the channel includes small depressions, intended to serve as resting “pools” for fish during higher flows.

In 1972, a wooden bulkhead, about five tall, was built at the upstream end of the concrete channel as a “temporary” structure to prevent erosion upstream. The bulkhead includes a wooden Denil fish ladder intended to facilitate fish passage. Although the USACE had planned to continue the concrete channel through Ross, local opposition stopped construction. The bulkhead and Denil fish ladder were originally intended to be in service for only one season; unfortunately, their flood-damaged remnants are still in place, about 50 years later.

With a grant from the National Fish and Wildlife Foundation, Friends hired Michael Love & Associates and Jeff Anderson and Associates (MLAJAA) to conduct a detailed passage assessment for steelhead in the upper part of the concrete channel. The Marin County Flood Control and Water Conservation District and the USACE made in-kind contributions.

As part of this effort, volunteers with Friends, directed by MLAJAA, made videos at several locations during the fall of 2005 and winter of 2006. The videos showed what appeared to be a Chinook salmon (likely a stray from the Sacramento River system) in early December attempting to pass through the Denil fish ladder. Two steelhead were attempting to enter the fish ladder and one was resting in one of the resting pools in the concrete channel.

In addition to these four salmonids observed in 2005–2006, several steelhead kelts (fish that had spawned and were returning to the ocean) were observed together in a pool immediately upstream of the fish ladder in February 2006, reluctant to move down the ladder. These sightings confirmed that steelhead can occasionally ascend the Denil fish ladder.

The assessment (MLAJAA 2007) used detailed modeling that covered variable water depths and velocities and how far fish can swim before becoming exhausted. Passage conditions were evaluated for six flows from 14 cfs (cubic feet per second) to 177 cfs. Each flow was analyzed for three tidal conditions: mean low low water (MLLW), mean tide level (MTL), and mean high high water (MHHW). The table above shows the results from the channel modeling.

Generally, satisfactory fish passage means that more than 90–95% of fish can move through the area during flows considered appropriate for spawning. The assessment found that during most of this period the proportion of fish able to pass through the concrete channel ranges from low to negligible. Because the lower portion of the concrete channel does not include any resting pools, at low tide nearly all the fish become exhausted attempting to swim through this lower reach.

Even for the fish who succeed in swimming the length of the concrete channel, the fish ladder at the bulkhead lacks an entrance pool downstream, so steelhead struggle to swim through a fast and shallow jet of water just to reach the entrance. The fish ladder often catches debris, creating yet another barrier to fish trying to reach upstream spawning grounds.

Are There Solutions? As part of their 2007 study, MLAJAA also evaluated the use of new larger resting pools to improve passage success within the concrete channel. The analysis focused on three different pool shapes, to identify a configuration that would provide low velocity zones suitable for steelhead to rest at all fish passage flows. An additional objective was to develop a pool shape that would minimize sedimentation. They developed three designs, with one better for straight reaches of the channel and another in curved reaches. Now, an additional complication has been added: more water needs to be accommodated in the concrete channel to reduce flooding. Unfortunately, features to aid fish passage often reduce the channel’s water capacity.

MLA and engineers from GHD, consultants working with the Flood Control District on the project, are designing measures to meet all three objectives. Alternatives being evaluated include:

  • installing much larger pools in the bottom of the channel;
  • total or partial removal of the concrete channel upstream of the Kentfield Rehabilitation Hospital;
  • raising channel walls;
  • lowering part of the channel, and/or
  • installing setback walls.

One size does not fit all. Each section of the creek requires a different combination of measures. But whatever project is implemented, it will include removal of the bulkhead and fish ladder. There are alternative means to handle the elevation change between the bottom of the concrete channel and the natural creek bottom upstream of the bulkhead.

The Flood Control District has begun preparation of an Environmental Impact Report (EIR) that will cover proposed changes to the concrete channel. The public scoping meeting for the EIR is tentatively scheduled for August 2020. Check the Ross Valley Watershed website for more information as work proceeds. We are confident that a project that meets with public approval will be developed and that it will include improvements to fish passage—everyone can agree on that.

A Native Basketry Garden in Ross

by Charles Kennard

In an out-of-the-way corner of Ross, the Basketry Garden lies on an eastern slope of the Marin Art and Garden Center, with a view to lofty Bald Hill. It covers about half an acre adjacent to the Barn Theater, and features over seventy species of plants—most of them Californian natives—traditionally used in basketry or cordage-making. Woven fences, big baskets, and basket beehives (skeps) punctuate this semi-wild area.

The garden is intended to display a variety of plants used by Native basket weavers, demonstrate traditional cultivation and harvesting practices, and to be a minor source of basketry materials. It also attracts hummingbirds, juncos, phoebes, and many other birds and insects. Red-shouldered and red-tailed hawks are often wheeling overhead.

Craft and nature are blended in the Basketry Garden. In the foreground is a Romanian-style fence woven with sycamore shoots, capped with a mat of Harding grass straw. Photo by Charles Kennard.

I was inspired to create this garden by the discovery of a patch of whiteroot sedge (Carex barbarae), a grass-like plant used by the Pomo and other central Californian tribes in making extremely fine basketry. This small patch was hemmed in by thistles, dense broom and, on the downhill side, Bermuda grass stretched down to the gravel parking lot. A MAGC gardener at the time used the area as an orphanage for unwanted specimen plants. Beginning in 2004, as a volunteer, I pulled, dug, or smothered undesirable plants and replaced them with fiber plants that I propagated, begged for, or bought.

From the small patch of sedge, plants were propagated to fill a large area of the garden. In designated beds, the heavy soil has been amended with large quantities of sand and of chippings from tree services, and every two years each bed is cleared of plants and the underground rhizomes. The hundreds of removed plants are donated to STRAW for creek restoration on Lagunitas Creek, while many of the rhizomes—a prized weaving material up to six feet long—are given to Native and non-Native weavers.

Other prominent basketry plants are seven species of willow, coppiced or pollarded (i.e., cut above deer grazing height) annually to produce long shoots. The native grey willows (Salix exigua) growing here are clones from the last tree of the species growing in the Ross Valley, on Lagunitas Road. The mother tree died in about 2005, and I have planted cuttings at several locations in the valley. Marsh plants grow in and around a group of water tubs: two species of tule, narrowleaf cattail, common reed, threesquare (Schoenoplectus americanus), river bulrush (Bolboschoenus fluviatilis), and several species of Juncus. Deer grass, looking like 3feethigh fountains, has flowering stems that are used for the foundation of coiled baskets. Redbud and creek dogwood have reddish stems and attractive flowers. Dogbane, milkweeds and leatherroot (Hoita macrostachya) are used for string-making. There is also a section reserved for conifers, and one for desert plants used in basketry.

Each plant used for basketry or string-making has an optimum time for gathering, relating to its growth stage or benefit to the plant’s growth or for pest control. So, redbud—valued for its reddish bark—is cut in winter when the bark adheres to the wood, whereas grey willow is typically cut in late February when the bark can be slipped off and discarded. After gathering, plants are processed to a stage convenient for storing and seasoning, and only later, trimmed for use.

As a basket-weaver interested in many different kinds of traditional techniques from around the world, I use many of the fiber plants in the garden, and also provide them to my students.

The Basketry Garden, as a part of MAGC, is open and free to visitors at all times, although, as of this writing, the parking lots are closed to cars. A plant list and map are available by request to charleskennard@comcast.net

DO or Die: Dissolved Oxygen Testing in Ross Creek

All animals and insects need oxygen to live and they acquire it in a variety of ways. They use it to convert nutrients into the energy they all need for life itself. Getting this oxygen is easy for terrestrial creatures, including humans. The air that surrounds us contains abundant oxygen (about 20% is oxygen) and we are well adapted for extracting what we need.

Board member Parker Pringle (left) and Drake High student Logan Smith with a DO logger inside its protective casing, just before it was installed. Every effort is made to hide the loggers to prevent vandalism and theft. Photo by Sandy Guldman

Getting essential oxygen is much harder for fish. Oxygen is not very soluble in water and fish can only access dissolved oxygen (DO). Worse, as temperatures rise, oxygen solubility goes down and fish requirements for it go up. DO is always an important factor in aquatic habitat quality for fish and in summer, when temperatures rise, it can become the critical factor in determining fish survival.

How does oxygen get into the water? Oxygen enters water from air or as a plant byproduct. From the air, oxygen slowly diffuses through the water surface or is mixed in quickly through aeration. DO is also a byproduct of photosynthesis from aquatic plants. As a result, DO levels can fall at night, when there is no photosynthesis, and rise during the day. Winds contribute to DO by aerating the water when they blow over it. Waterfalls and riffles also aerate water. Abundant, well-aerated groundwater inputs can both cool the water and directly contribute more DO.

Why measure dissolved oxygen? We measure DO because it is so critical to the health, and the very survival, of fish. We measure DO as milligrams per liter (mg/L). DO levels and how they vary throughout the day are important in monitoring environmental quality and determining needed management actions. DO requirements vary with fish species, stage of development, temperatures at which prior acclimation occurred, and activity level. As noted above, DO levels and fish metabolic rates both depend on temperature: as temperature increases, the saturation level of DO in the water decreases, but fish become more active and their DO requirements increase. The table below summarizes information about steelhead trout in our watershed.

In general, salmonids incubated at low DO levels are small with slower development, are weak, and abnormal structural growth is more common. For juveniles and adults, low DO can result in reduced fecundity and even prevent spawning. (Salmonids are also affected by many other factors: water depth, pH, velocity, turbidity and gravel characteristics for spawning. Assessments of streams for suitability consider all these parameters.)

Friends has been measuring temperature and DO in the watershed since 2008. While we have logged the temperature at 15minute intervals, we measured DO only a few times a year when we installed and downloaded the temperature loggers. DO measuring equipment is expensive and challenging to maintain, which is why we used it infrequently. However, the amount of DO in creek water is as important as temperature as a measure of habitat quality.

Structures such as this log, installed in Ross Creek, do triple duty: provide shelter for fish, protect the creek bank from erosion, and are convenient places to attach temperature gauges. Photo by Sandy Guldman

On March 7 of this year Friends installed three loggers in Ross Creek that record both temperature and DO. We set them to record every 15 minutes. These instruments are fitted with a pre-calibrated optical sensor that will last 6 months. Collecting these data will greatly improve our DO records. We also installed three loggers that record only temperature, continuing our long-term temperature monitoring. Sadly, over the years we have had three temperature loggers stolen and several removed from the water.

Measurements of DO, taken during the March day when we were installing temperature loggers, showed very low levels of DO in the water that emerges from the release valve at the base of Phoenix Lake, with generally higher levels downstream, the result of natural aeration. However, as the summer progresses, water levels fall and temperatures rise, leading to generally lower DO levels throughout the creek. The continuously monitored DO at three separate locations will provide more detailed information and perhaps suggest ways to improve conditions for fish in Ross Creek.

We extend our thanks to the Marin County Fish and Wildlife Commission for funding the purchase of our new DO loggers and, over the years, half of our temperature loggers.

Much of the technical information came from Fondriest Environmental, Inc. 2013. Dissolved Oxygen. Fundamentals of Environmental Measurements.