Posts Tagged ‘bay’

Guest Speaker: Megan Prelinger 
7pm, Monday April 18th, 2016
FREE Green Apple Books on the Park, 1231 9th Ave, San Francisco, CA 

In 2010, Megan Prelinger and collaborators Rick Prelinger and Stacy Kozakavich were invited by the Exploratorium to develop exhibits for the Museum’s planned Bay Observatory gallery. The Bay Observatory opened to the public in 2013, featuring dozens of research-based exhibits that combine the Museum’s legacy imperative to integrate art and science for the benefit of public understanding with a fresh imperative to explore the waterfront and the natural environment. In response to the Exploratorium’s prompt to “animate the Library in the service of understanding San Francisco Bay,” Megan and her collaborators created a series of graphic atlases that explain that histories of the watersheds and the shorelines, both natural history and the built environment. Watersheds and Shorelines are two of five atlases that also include Islands and the two urban atlases, San Francisco and East Bay. All are installed as permanent exhibits in the Bay Observatory, along with a public access mini library of Bay Area landscape history. In her April 18 presentation, Megan will show slides and discuss the research and outcomes behind the Watersheds atlas and the Shorelines atlas. Watersheds traces the flow of water from the mountains to the mouth of the Bay, and Shorelines traces the landscape of the water’s edge of both San Pablo Bay and San Francisco Bay.

Megan Prelinger is a cultural historian and naturalist. She is co-founder along with Rick Prelinger of the Prelinger Library and architect of its information design. The library is an independent landscape-based research library in San Francisco that has been open to the public since 2004. She is the author of several books, most recently Inside the Machine: Art and Invention in the Electronic Age (W.W. Norton, 2015), and the 2013 and 2014 Watersheds, Shorelines, and Islands historical atlases, all permanent exhibits in the Exploratorium’s Bay Observatory gallery.

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Brenda Goeden of BCDC and Ian Wren SF Bay Keepers joined us on August 19th, 2015 at the Exploratorium to to talk about what gets dredged out of the San Francisco Bay.

Most of the dredging that goes on in the bay is for navigation. This is mostly through mud — 80% of the Bay is fine grain mud, and it is dug out to allow deep draft vessels to come through, and keep waters by marina’s clear. The dredging aka mining of sand is mainly for the construction industry – it becomes cement, asphalt, road-base, sub-base and general fill. The grains of sand are grains (.002 to .08 inches in diameter) bigger than mud, and smaller than gravel. it gets mined on demand, not necessarily day in, day out.

There are two main areas whether the sand comes from: Suisun Bay and the Central Bay. Suisun Bay is a finer grain of sand which is often used for back fill in trenches. The coarser sand of the the Central Bay is used for cement. Sand is only found in the high flow areas of the Bay where the water has enough energy to carry the sand. Mud is taken out to the slow wide sides of the Bay.

Sand Flow in the Bay - Barnard et al. 2013

Sand is important for a number of reasons outside of its commercial uses — it helps build marshes and beach. It provides shoreline protection as it takes more energy to move, it provides a particular kind of habitat, and on the shore provides a place for recreation and having a place for viewing wildlife.

The amount of historical sand, and sand in the Bay is difficult to measure. Most of the sand in the Bay comes from the Delta and the larger watershed (40% of California’s watershed drains into the Bay), and estimated 1.2million cubic yards, with another 300+ thousand cubic yards coming from local streams. Where not blocked, the rivers and creeks, slide and bounce the sand along into the Bay.  Storms and other high flow events are key in moving the sand along and into the Bay and beyond.

The sand also is carried out into the ocean, and large dune field lays under water past the Golden Gate Bridge. This was once a wide delta of sand, but has been slowly growing smaller. This changing shape of this sand has affected how sand flows both inside and outside the Bay. The pattern of sand dispersal on Ocean Beach has meant the northern end of the beach has been gaining sand, and the southern has been losing sand leading to fast erosion of the shore. The bay itself is also losing some protection from ocean waves in this process as well. Crissy field on the other hand has benefited, gaining sand from both flows headed out to sea, and sand coming in along the shore.

There’s not a lot known about the habitat underwater in these sands. The Central Bay sand area is the deepest in the Bay 90′-300′ deep where the water is salty, deep, cold, and fast. Aka difficult to study (there has been some studies monitoring what is brought up by the sand miners). We know there are wondrous things going on down there, like the migration of Dungeness crabs — marching in to lay eggs, and then marching out again — but no one has ever seen it or knows the pathways.

Suisun Bay is shallower, warmer, and less salty. The two areas are pretty different, but in both cases these are deserts compared to the meadows of mud. The organisms living there tend to be smaller, efficient, and highly adapted.

Humans have had a huge impact on these fields of sand — the biggest being the pulse of sand brought down from the Sierra’s by gold miners, and estimated 10x the usual flow of sand. Before that, and before many of the rivers and streams were dammed. The flow might have been around 2 million cubic yards. The sand from mining continued to pulse through the system and is only recently pretty much all gone. Now a large portion of the pool of possible erodible materials is trapped behind dams and the delta tunnels.

We still have sand, and we still have sand coming in, but the question now is how much sand do we have, and how much can we afford to take out. Mining has been happening since the 30s, peaking in the years 1949-79. Much of the sand is used locally shipped to different dispersal points around the Bay.

Dredge mud goes to different places, a lot gets shipped and dumped out at sea, or dumped at certain disposal sites in the Bay itself (inside the bay this can disperse contaminants, cause turbidity). These are not the preferable options — that favored option (by BCDC) is helping restoration efforts, filling land that has sunk below sea level on the other side of levees. This is the unfortunately the most expensive option, which there are not a lot of funds for, and small marinas don’t tend to have funds to support that kind of work, and dredging for ports is an expensive enough business that any additional fees would likely be too onerous.

San Francisco Bay Keeper is involved in the issue, hoping to bring in the perspective of the overall health of the Bay and nearby waters, and the sand being an important part of it. The sand taken is not replenished, there is a net loss, and they want to make sure we keep relic sites, and keep mining more in active parts of the flow. They are also looking to insure there is proper compliance and that companies don’t end up taking more than they should. They are looking through commenting on proposals and active litigation to reduce the amount of sand mining going on — to being sand mining to a sustainable level.

On the flip side, if local industries turned to external sources for sand, there may be equally damaging impacts — leaving aside where the sand is being mined from, the carbon costs of shipping that sand by barge or truck would not be small.

The biggest question we seemed all left with was the complicated nature of the question. A unknown or at least unseen, but super valuable resource here in the Bay below us. How much is there? and how much can we afford to take out?

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Rethinking Invasive Species in San Francisco Bay
Guest Speaker: Michael McGowan
7:30pm, Thursday, May 16th, 2013
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA 

Could a new non-native mud shrimp be good for the sub-tidal ecosystem? Michael McGowan, fisheries oceanographer and aquatic ecologist, will discuss how an invasive species may actually be beneficial.

Michael was a guest speaker last year speaking on Sturgeon. He is a restoration ecologist with 20 years experience in research, teaching, and community-based ecological restoration. He has monitored the impacts of dredge spoil disposal, assessed potential impacts to fishes of runway expansion into the bay, analyzed data on spread of invasive wetlands plants, and evaluated the habitat benefits of native oyster restoration.

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From the Federal Government on down there is a not so virtual alphabet soup (swamp?) of public and private organizations collaborating to protect and restore San Francisco’s wetlands. In fact as of Feb 2nd, it’s become an international concern with San Francisco Bay being named an Wetland of International Importance. Arthur Feinstein, our speaker on February 21st, 2013, has been part of this mix for along time as an Audubon and Sierra Club activist, and as a board member of the San Francisco Bay Joint Venture (SFBJV).

Salt Pond

This Joint Venture is one of 18 that were established by the Migratory Bird Act of 1971 to protect birdlife. The joint ventures originally got off the ground protecting ducks, building on the work of Ducks Unlimited, and their efforts to preserve habitat and species for hunting. These Joint Ventures were so successful that the Fish&Wildlife Service decided to expand the program to in essence save all the birds in the country — and now really goes beyond that to all species in general.

SFBJV — the Joint Venture that is smallest in area of all 18 — has three main areas in restoration: wetlands, riparian habitat, and associated uplands. It works with organizations like Audubon, Save the Bay, Sierra Club and government agencies like the Fish and Wildlife, that have funds. The joint venture’s board and staff work on things like acquiring land, doing evaluation and monitoring, project development and implementation, outreach, and most importantly funding support, looking to get the biggest bang for the buck in these restoration programs.

Arthur spent the rest of his talk walking through the projects up and down the bay looking at the challenges and successes of these projects. One thing that you might not expect is that wetlands restoration is a lot about earth moving. Dyked off areas of the bay begin to sink (think New Orleans). The most famous place locally for this is Alviso in the south bay 16′ below the water line. This means you can’t just breach a dyke, you have to bring in dirt and a lot of it to bring the bottom up.

Happily this leads to a fine talking point — restoration means construction jobs, which is a selling point which reaches past people who are primarily concerned about the environment into a broader community.

These projects can also take a lot of time. This might be negotiating with a land owner, like the Navy at Scagg’s Island (worried about the implications of past contracts with adjacent landowners), others require lots of study — and Army Corps of Engineers studies can take a long time. The South Bay’s wetland restoration program (the largest project in the country outside of the Everglades) will take 50 years, with time built in for study and evaluation. The work is as much art as science, it’s not always certain how things will work. Inshore communities also need to be protected against potential flooding.

There are unintended environmental consequences as well — birds like Canvasbacks like shallow water salt ponds, but with some of these being removed this bird is not coming back in the same numbers. Snowy Plovers have been using dry salt ponds for nesting ground. Some of the restoration projects are now trying to take this into account — leaving a variety ot habitat.

There are all sorts of political & legal battles in this too — elections deciding between development and restoration, at places like Redwood City (46 votes decided one referendum on Bair Island) and Cullinan Ranch (which 20 years ago nearly became a Marina).

All of these things take a lot of effort from a lot of different people and organizations. What we get out of it — the past 30-40 years to make the Bay a better place — includes some intangibles: more resilience against climate change events like rising seas, healthier bay ecosystems, better spawning grounds, and better fisheries, but we also get to see beautiful things like the Clapper Rail returning to San Francisco at Heron’s Head park, and maybe all this effort has also gone to help with the return of harbor porpoises, the otter at Sutro Baths, and the huge herring runs the last two years has brought. I’m looking forward to what the next 30-40 years of restoration might bring.

If you want to play a part — you can look for opportunities in many places, but I will leave it with http://sfbayjv.org today.

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February 21, 2013 – Changing the face of San Francisco Bay
7:30pm, FREE, at the Randall Museum
Guest Speaker: Arthur Feinstein, Chair 

Arthur Feinstein, Chair of the Bay Area chapter of the Sierra Club, examines the largest wetland restoration effort on the west coast – the challenges of sea level rise, saving endangered species, and answering the question as to what we can do about it and how it will make a difference in our lives.

birds in a small wetland of SF Bay

A wetland amidst industry

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An Era of Restoration & Understanding

Sometime in the 70s a murder victim washed up on a bay shore. The police knew to go ask a scientist — where might this body have come from? The answer it turned out was the Golden Gate Bridge. Gangs used to think of it as a good place to dump bodies, thinking they’d soon be carried out to sea, never to be seen again. But our bay waters are more complicated than that. It turns out that the surface water tends to move out to see, but the undercurrents — where a dead body might sink — move inland.

Scientists have spent a good amount of effort and equipment puzzling this out. Not dead bodies per se, but with boats like the Polaris and the Long Fin that are out there collecting and measuring.

The story of our San Francisco Bay is a long one, and for a long time a sad one – impacted as it is by all the hunting, mining, fishing, filling, draining, blowing things up, alien invasions, trash, and dam building that has effected its waters over the last 150 odd years in particular.

Many of those impacts are ongoing and difficult to control (alien species being a good case in point). But the last 50 years has seen an increase in those who would wish to protect, understand, and restore our waters. No longer does the bay stink, and serve as the collective trash dump.

There us still plenty of nature to be found here – the estuary is open ended a mixing bowl of rivers and tides and the bay still serves as a murky nursery to many species of fish. Little fish thrive, there are seals, sea lions, and the only recently returned porpoise. The larger estuary is still a stopover on the Pacific Flyway.

What many people and organizations are working on now is bringing more of that nature back. Bringing us back to a hopefully healthier mix of urban and natural: there are grand 50 years plans to restore salt ponds to wetland, which have has already begun with great signs; plans to restore underwater bay meadows of eel grass — a good habitat for all sorts of creatures and which secures the mud; plans to see if beds of Olympia oysters can be built. We are aiding some species more at risk than others — like for the Clapper Rail — building floating homes where they are safer from all the raccoons and other meso-predators out there.

There are of course risks and additional challenges in all of this — plans for more fill, or the possibility of erosion of the bay bottom which has been securing gold mining mercury for decades. And this is of course, where we hope the science will come in to aid our understanding, help us meet challenges, shift courses, and have a healthy bay for us all to enjoy.

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The lecture below originally scheduled for May 17th, 2012, has been postponed. The speaker, Ariel Rubissow Okamoto, is not able to come speak this month due to unforeseen circumstances.  We hope to have her later in the year. 

The UNnatural History of San Francisco Bay
Guest Speaker:  Ariel Rubissow Okamoto

Date TBD

Journalist and author Ariel Rubissow Okamoto will answer a few burning questions from her new book Natural History of San Francisco Bay: How do you “make” a wetland if you’re not Mother Nature? If you throw a dead body of the GG Bridge where will it end up? Why splashing in the surf off Crown Beach might you give something like poison oak?

Ariel Rubissow Okamoto is a freelance writer living in San Francisco, who has been writing about environmental issues for 25 years, more recently specializing in California water issues. You can find out more about Natural History of San Francisco Bay here.

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picture from Golden Gate Cetacean

Return of the Harbor Porpoises
Guest Speaker:  Bill Keener
7:30pm, Thursday, March 15th, 2012
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA 

Bill Keener, cofounder of Golden Gate Cetacean Research, created to study the porpoise, will tell us of their disappearance by the 1940′s, the mystery of their unexpected return in recent years, and how you can help by reporting your porpoise sightings.

Bill’s experience includes work as a field observer for the harbor porpoise population study in the Gulf of the Farallones National Marine Sanctuary from 1987-1989.  He is an environmental lawyer and the former Executive Director of the Marine Mammal Center.

Read more about Bill and porpoises in Bay Nature magazine, Jul-Sep 2011, Safe Harbor, Welcoming Porpoises Back to San Francisco Bay.

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White Sturgeon in San Francisco Bay

The Sturgeon in San Francisco Bay:
How critical can a 10,000 year old Bay be for a 100 million year old fish?

Guest Speaker:  Michael McGowan
7:30pm, Thursday, February 16th, 2012
FREE at the Randall Museum, 199 Museum Way, San Francisco, CA 

Michael McGowan, fisheries oceanographer and aquatic ecologist, will discuss his research on how the ecology of the green and white sturgeon differ in their life history and in how they use the Bay.

White sturgeon are the largest fresh water fish in North America that can live over a hundred years and can grow to 20 feet long, and weigh 1500lbs. (more info)

Green sturgeon, up  to 7 feet long and 350lbs, seem to be a little more mysterious on the web, they are probably migratory salt water fish that probably spawn in fresh water. (more info)

Michael will fill in the details for us.

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