LIVING SHORELINES: Linking estuary habitats and building capacity to adapt to rising seas

Millender Park Living Shoreline Project, Florida

A living shoreline is a shoreline protection alternative that relies on the strategic placement of plants, stone, sand fill, and other structural and organic materials to protect the shoreline.  A living shoreline is an alternative to ‘hard’ shoreline stabilization methods like rip rap or seawalls, and can provide numerous benefits such as nutrient pollution remediation, habitat, and buffering of shorelines from storm erosion and sea level rise.  Living shorelines can include any shoreline management system that is designed to protect or restore natural shoreline ecosystems through the use of natural elements and, if appropriate, man-made elements.

At the 2019 State of the Estuary conference, Marilyn Latta from the Coastal Consevancy and Katharyn Boyer from San Francisco State University gave a presentation on living shoreline projects in the San Francisco Bay.


Marilyn Latta manages the San Francisco Bay Living Shoreline Project for the Coastal Conservancy.  The state Coastal Conservancy has been a partner in many of the initial living shorelines efforts in the Bay, either through leading demonstration projects, providing grant funding, or providing training.

She presented a map put together by Rachel Gittman what shows the coastline hardening that has happened around the US coastline.

About 14% of our total shoreline is hardened, and in the Bay Area, that can be upwards of 50% in some areas,” she said.  “This has caused substantial habitat loss, it’s cut off our human access and shoreline uses, and it’s made us less resilient to sea level rise.

Substantial hard infrastructure is the status quo in the Bay Area, and it will be necessary in many locations, but we’ll need to maintain and build larger seawalls at larger scales and at high cost, she said.  Hard infrastructure can affect sediment transport, damage habitat, and doesn’t provide a way for humans to realign their connection to the shoreline.

Nature-based infrastructure has a lot of biological and physical goals.  “There are many possibilities in the Bay Area for sites to have the opportunity to incorporate dynamic designs and reconnect those dynamic biological borders that provide both habitat connectivity as well as shoreline access for people,” she said.

NOAA’s website describes a living shoreline as ‘a protected, stabilized coastal edge made of natural materials such as plants, sand, or rock’ that is meant to grow over time.  This technique has been used mostly on the East coast, with the exception of a few projects in Washington state.  These projects are typically built on the shorelines of bays and rivers and generally not ocean beaches.

Ms. Latta noted that restoration treatments can be strategically sited to have a physical benefit to the shoreline by combining those biological enhancement goals with physical shoreline protection in one multi-objective project.  A living shoreline can include a wide variety of techniques and habitat types, all with the goal of minimizing coastal erosion, maintaining processes, and providing habitat for plants, fish, wildlife, and people.

We’re really trying to achieve multiple goals with these projects,” she said.  “In addition to those that I have mentioned, these types of efforts can also provide outdoor recreation, they may help to sequester carbon, and they may help with buffering against ocean acidification.”

She pointed out that it’s an opportunity to better integrate multiple habitat types up the slope.  Many submerged underwater habitats, such as shellfish beds and eelgrass beds, have been lesser studied, so it’s a great opportunity to think about that full suite of linked gradients along the slope and how they can each play a role in shoreline protection.

Dynamic designs are really part of the path to coastal resilience, she said.  “This slide really shows the synergy between the different goals of sediment accretion, energy attenuation, and wave reduction, as well as habitat restoration and enhancement,” she said.  “If we can really think about the elevational complexity, the habitat contours, and how we can redesign that back into our shorelines by looking at the strength of nature, we may be able to design shorelines that will become stronger over time and also recreate connections.”

These types of projects have been underway on the East and Gulf Coast since the early 2000s; the slide below shows images that have been used, such as stone sills, plantings, refalls, and other techniques.

While we can learn a lot from the East Coast efforts, there are definite regional differences; for instance, there are different species on the West Coast.  There is also a very different physical tidal range; the shorter, smaller tide range on the East Coast really lends itself to smaller projects that are tucked high in the intertidal with the stone sill connected next to the shoreline edge, whereas in the larger tide range on the West Coast and in the San Francisco Estuary, the treatments are sometimes hundreds of meters offshore.

With respect to policies, some states have been progressive, such as the state of Maryland which established their Living Shorelines Protection Act way back in 2008.  The Act requires landowners to prove that a living shoreline wouldn’t work before they can get a permit to construct a bulkhead or a seawall.  Other states have programmatic permit approaches linking joint state, federal, general permits, so that permits can be obtained faster and have standardized conditions.  North Carolina recently got their general permit in place and the National Wildlife Federation is just about to release a report on the regulatory policies of Living Shorelines in 18 different coastal states.

The Army Corps issued the Nationwide Permit 54 for living shorelines in 2017; however, it has fairly limited use in California as it has a cap of 500 of linear feet on the shoreline and treatments can only be 30 feet from the mean tide which doesn’t quite match local conditions.  They are hopeful the Corps can develop special conditions for the West Coast.

There is a lot of policy support in California from the Coastal Commission and many others who are supporting further testing of living shorelines,” Ms. Latta said.  “We have a lot of excellent guidance documents and really now is the time to test in different locations and see what works so we can continue learning and modify.  We’re working hard to build regional capacity and to translate science recommendations into on the ground experimental projects, monitor those heavily, and then feed that science back into the next projects we’re working on and to develop better policies to support this work.


It key to develop collaborative partnerships.  “One agency can’t do this alone and every project is stronger if you involve diverse partners,” said Ms. Latta.  “Our project is much better because we have a great mix of university scientists and graduate students, non-profits, consulting firms, local businesses, conservation corps, and marine contractors, all of whom are working together with the local state and federal agencies toward this common goal, which is really to innovate, experiment, and learn a new paradigm that might work well.”

It’s tough work and it’s difficult to access the project sites; it’s often early morning low tide, very cold conditions, and it takes a lot of resilience even to get out there, she said.

It’s important to design for the future and allowing for habitat connectivity, both above and below the changing water line as sea levels rise.

We want to encourage these nature-based approaches whenever possible, and also encourage local labor and involvement such as with your local Conservation Corps and other groups as this is a fantastic job training opportunity and actually can provide local jobs,” she said.  “We want to encourage better communication between each adjacent landowner because we can’t do this in a box.  We’ve got to make sure that there’s good regional coordination and planning.  We also want to engage the public in new ways on sea level rise and really engage the public in the bottom of the bay as well.”

Permitting multi-habitat projects is certainly complex and challenging.  “It’s exciting to design projects that incorporate multiple habitat types, but when you do that, you also trigger almost every regulatory jurisdiction that you can,” she said.  “This has been challenging.  We are excited about the recent advancement with BCDC’s Bay Plan amendment as well as the BRITT which hopefully increase efficiency and also result in faster timelines for these sequential permits that you must get from each of the agency.

In this age of deregulation, strong environmental laws and policies are important.  “We certainly support and very much respect our regulatory staff partners who are working on this, but it’s challenging for them with outdated at times policies that don’t better recognize sea level rise,” she said.  “So it’s important that each agency as they are doing, water board, BCDC, and others to relook at those policies and work together with applicants to help facilitate this experimental work.”

Another challenge has been fabrication and materials.  The slide shows pictures of the reef structure.  The preferred method is to use clean Pacific oyster half-shells which are bagged and placed into mounds out in the Bay, but there isn’t a local effective shell recycling program yet.  Until one is established with growers and the restaurants, there is a lack of availability of the shell.  For that reason, they are testing hybrid structures called refalls and oyster blocks which provide value as well as help to attenuate waves.  The local conservation corps and others are involved in that work.

Project access and seasonality is also extremely difficult.  Operating a barge and crane in this tidal range is challenging, as well as having to consider the seasonal windows that must be protected.

Finding contractors with the appropriate shallow water equipment is a challenge.  “We have many excellent contractors in the Bay Area who are familiar with Bay conditions who have spent decades working in the Bay,” she said.  “They may not have experience constructing oyster reefs but they are willing to innovate and experiment and we should work with that community.  We recently hired a contractor from Washington State who came down with their shallow water barge and lightweight modular crane, and that is the type of equipment we need to see more of in the Bay Area.”

Getting permission to ground at low tide from the agencies was important as it allowed them to work faster and have less impact then coming in and out on very limited tide cycles.

Their work is informing additional pilot projects in California.  They have been able to increase their reach by sharing designs and lessons learned with other entities.  They want to encourage more local demonstration projects.

We’re really threading the needle between innovation and feasibility,” Ms. Latta said.  “We’ve talked a lot about the institutional barriers that exist to this work, but we really have enough information to act, and if we work together, we can start to experiment and get these projects done.”


Dr. Katharyn Boyer is a Coastal Ecologist and Professor of Biology at San Francisco State where she studies wetland and coastal ecology and restoration, community ecology, biodiversity and ecosystem functioning, nutrient dynamics, trophic interactions, and habitat structure.  She next discussed what they are learning from a scientific perspective from the early living shoreline projects.

There are four categories of recommendations: embedding experimentation in living shoreline projects; finding innovative ways of monitoring to be more effective in gathering data; expecting and planning for climate variability; and communicating the science.

Embed experimentation

First and foremost, embed experimentation.  Key species need to be evaluated before the projects are scaled up.  For example, we may want to plant eelgrass or cordgrass for these foundational habitats,” said Dr. Boyer.  “But first, we need to see if these plants are going to work in these particular sites, and they can tell us by growing there if they like the conditions.  We can put out tiles to see if Olympia oysters will settle.  We can try different substrates to see if there’s a preference for where Olympia oysters will settle.  We can test methods and configurations and substrates and timing first with these species that are our targets for these projects.”

The first project was in San Rafael in 2012.  The basic design was Pacific oyster shells mounded in bags and put in a checkerboard pattern in a large plot; then eelgrass by itself; the shell bag mounds plus eel grass together; and a control plot.  The plots were about 30 by 10 meters in size.

This was a step up in scale from our previous work because we’re not only restoring these habitats and trying to understand the habitat value, but it’s done now at a scale that is large enough for us to look at physical effects, such as wave attenuation and accretion,” said Dr. Boyer.

A lot of lessons learned from the first project in San Rafael.  “We had millions of Olympia oysters settle within a few months of setting out the substrate,” she said.  “We found a lot of other species come to our project, including species like Dungeness crab, economically important, also rare species like the Black Oystercatcher.  We found there were more species that came if we had more eelgrass and oysters present.  We found increased foraging opportunity for birds.  We found a 30% reduction in wave energy at mean tide levels, and we have some initial data suggesting that in this wave shadow, we get enhanced eelgrass growth.”

The lessons learned at the San Rafael project are now informing the next projects.  The most recent project was across the bay from San Rafael at Giant Marsh at the Point Pinole Regional Shoreline.  The project has enhancements that go from the subtidal zone up into the upland.   Dr. Boyer focused on the offshore eelgrass oyster reef and mudflat area in more detail.

There are three offshore oyster reefs about 40 meters wide installed offshore.  There is eelgrass on the bayward side of the oyster reefs, the shoreward side of the oyster reefs, and some distance from the oyster reefs so scientists can determine if there’s a protective effect of those reefs on the eelgrass and if so, how far shoreward does that extend.  There are different densities of plantings so the hypothesis can be tested that greater densities might have positive effects on establishment.  Over time, they will be able to study things such as can eelgrass restoration be used to locally raise pH and can it be used to store blue carbon.

Closer to shore, oyster reefs are placed at different elevations so they can study how oysters and other species perform with depth.  They also have an experiment to see if rockweed, a canopy-forming brown alga, can be added to these reefs to increase the success of oysters by possibly increasing moisture or cooling it down.

Innovative monitoring

These are really difficult places to work, so we have to think about how to monitor in these kinds of conditions.  One could use a scuba tank, perhaps, but visibility can be poor.   So new innovative ways of monitoring are needed that will allow us to work in these environments.

Dr. Boyer said it is hard to know if fish are using these kinds of projects.  She said they could seine but it’s difficult to seine over the physical structure and there’s the poor visibility.  Trapping does dive some information.  At the Giant Marsh project, the monitoring innovation is that they will be using sonar, which has been used effectively at the Sears Point project.

What’s good is it doesn’t need to see, it’s using sonar and it can tell you numbers and sizes of fish and it can even tell you specific species like bat rays if they have a distinctive shape,” she said.

Monitoring birds is challenging because it’s a snapshot in time, so the USGS will be monitoring by using remote cameras on one minute time intervals, and using high school students to look for birds in the thousands of images.  The USGS did this at the San Rafael Living Shorelines project and will be doing it at the Giant Marsh project as well.

Invertebrates can be monitored on exposed surfaces during low tides, but that is difficult, and turbidity makes taking a picture underwater problematic.  An innovative advancement has been the development of a high turbidity underwater camera system which is basically a go-pro with a big piece of plexiglass makes it possible to take a good image which can be evaluated later.

Determining how these kinds of projects affect wave heights is hard to characterize in the shallow water and wave sensors are expensive.  ESA has developed a method using four sensors and an array of PVC pipes that they can focus the cameras on and look at the height of the waves against the PVC pipes and use that to calibrate the wave sensors.  They’ll get a lot more information that way then having a whole array of sensors, she said.

Expect and plan for climate variability

The Bay is already experiencing an increased frequency of heavy storms and low salinity periods.  The graph on the slide is of salinity during the atmospheric rivers of 2017.  There were about four months where the salinity went below 10 parts per thousand.  There were losses of oysters and eelgrass in the Central Bay during this time period, as well as loss of other associated species in the bay which included some that actually eat the algae off the eelgrass and make the eelgrass function better.

There is also an increased frequency of heat waves with climate change which is happening globally.  Locally, there was reduced survivorship of some of the plantings of eelgrass in the heatwave that came in the early summer of this year (2019).

So we have to expect and plan for climate variability as these events are really the new normal,” said Dr. Boyer.  “We can do some things, we can adjust the timing of the restoration to cooler periods, we can identify refuges within the bay.  There may be places during low salinity periods like Richardson Bay where the salinity stays high even when there’s a lot of freshwater coming down.  So if we can distribute our projects across space, we can hopefully maximize the benefits and minimize the different kinds of stressors that would occur.

We need a sustained effort.  Some of these species are going to go and we’re going to have to make some effort to keep them present.”

Communicate science

It’s important that these lessons get out there to inform future projects.  “We’re trying to engage practitioners, we’ve written a book chapter that’s in a new living shorelines book, we speak to the public, we teach in our classes, and we’re trying to find ways of engaging a large array of people so that they learn from us and what we’re learning for our next projects,” said Dr. Boyer.  “We need larger living shorelines projects and we need them quickly in order for them to have the benefits we hope for in the next decade or so.

In conclusion …

The Resilient By Design Bay Area collaborative of 2018 came up with a lot of ideas of how to scale up some of these projects; they are really ideas; they are very large.  These are some reefs that were proposed for the San Rafael shoreline by the Bionic Team, and this is a great idea, but we do need to experiment and learn before we scale up that way.  We need to innovate as we go and find these good ways of monitoring and gathering data.  We need to communicate our findings broadly, and we need to remain flexible and persistent.


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