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Archive for the ‘Lecture Notes’ Category

Kieth Hansen joined us April 29th, 2015 at Green Apple Books. The first of our series’ “wandering era.”

Kieth Hansen has been hooked on birds since he was a kid, when his brother ran into to grab him, and showed him a Cedar Waxwing in the woods of Maryland. Not long after, his family moved to Fresno, where the Sierra Nevada became his backyard, and he went deep into birding, and on to do a 3 week stint on the Farallones with PRBO in 1974 as the youngest person to be allowed on the islands. Since then his birding has taken him all over the world.

He also came from an artistic family, and those two interests were have been tied together since his senior year of high school. His first book was a coloring book about birds of the Sierra, followed by a 4 year project to produce illustrations for “Discovering Sierra Birds” co-authored by my Ted Beedy and Steve Granholm.

His most recent project has been one 14 years in the making — 1400 paintings of 320 species each with their different plumages based on sex, age, seasonality — called “Birds of the Sierra Nevada: Their Natural History, Status and Distribution” with co-authors Ted Beedy and Ed Pandolfino.”

Originally it was planned as one book, but the field guide + life history became too much. The life history book has been published first with example images from the field guide illustrations.

To paint one illustration takes about 2 months from a blank canvas, a slow process of building up the picture of the bird, starting with pencil, measuring out and couting the feathers; wetting the bird and starting with a neutral tint for shadow, then adding color, sheer washes over each other, drawing more while the paint drys, then back to paint; paying attention to the translucency of feathers as they overlap; the full colored bird building up slowly but surely; the final touches in place with colored pencil.

A lot of these images are made up, not directly from a photo or illustration, but trying to get the bird in the perfect pose: pulling from his own years of observation, videos he has taken, specimens, other books, and photos. Consulting with his many birding friends and experts in the birding world to make sure he has gotten it right. This is his 13th book, and for the most part he can block birds out without too much work, it’s the details that take the time and effort. Although he enjoys it, he does not draw as much as he would like in the field.

His love of birds is clear from the beauty of his final exquisite images, and he takes inspiration from his trips out in the field (he showed a great video of birds in the Sierra’s) and also in his backyard in Bolinas. His studio has proved itself an excellent little observatory as well.

His images are fairly small — but this is mostly a factor that he has had to draw so many, and that they will actually be even smaller in the book. He has been pleased to see how well they can be blown up though. One of the most important factors in getting the birds right is their weight and center of gravity — how they carry themselves, and their relation of their legs to the body.

We still illustrate bird guides he says, because they can be drawn in a neutral space, the same generic conditions and lighting to make them easier to compare, and it is easier to highlight and show features. A photo guide has the disadvantage of having a background and the varied lighting, and varied conditions. With an illustration it is easier to show the details and variations that matter.

I hope that he keeps illustrating birds for many years to come. His studio in downtown Bolinas is well worth a visit (he related a funny story about why he has so many hummingbird feeders). He also leads tours through a company called Sacred Monkey. More information can be found on his website at http://keithhansen.com/

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Joel Pomerantz (my partner in this lecture business) talked to us on March 19th, 2015 about his research into the flood of 1862. At first he did not find a whole lot, until he stumbled across the term “freshet”. That opened up a whole new line of research — which led to this wonderful and somewhat unconventional lecture — a “choose your own lecture” adventure: offering a list of topics on which he could speak.

Lithograph with frame K Street A Rosenfeld, SF

He did give some background to start. The term “atmospheric river” is a relatively new one. I hadn’t heard of it myself until I heard a lecture on drought last fall, but it popped up in the news a lot at the start of our winter storm cycle (the threat of which caused more chaos than the actual event this year). These rivers in the sky are actually the delivery mechanism for a lot of moisture from the the equator to landmasses. The moisture isn’t necessarily even visible from space only recently have microwave satellites been able to track them.

One of these rivers pushes up toward the northwest, and under certain circumstances, storms in Alaska (the results of other atmospheric rivers) push these rivers further south into California. The total water in these systems can be huge (10 to 20 Mississippi’s worth), and what fell in California in 1862 was exacerbated by a drought in the prior year, and a hard freeze that followed. What measurements we had: San Francisco saw 24”-37” of rain in January alone (19-20 is the average for the year). In gold country there was 108” in a month.

All this wrought terrible destruction, pretty much every mill, ferry, and bridge were washed out (many many deaths happened with people trying to cross rivers), tens of thousands of dead cattle washed up on beaches, low lying farms inundated, Sacramento flooded.

Newspaper accounts of the time (akin to the blogs of today) had all sorts of accounts of how terrible it was. Every day people thought it could not get worse, and each day it did. A Southern Californian woman recounted how in a 6 week stretch there was not time to dry even a handkerchief.

Given the prior year’s drought, sediment got picked up from the ground rather than the water being absorbed — and given also the blasting going on for mining, a tremendous amount of soil and rock was moved and polished by the high fast moving water.  Water covered 30’ high telegraph poles in some places and steamships were able to go anywhere.

The freeze that followed didn’t stop it. The freeze was a deep one down to sea level, but it didn’t stop the water from moving and ice tsunamis formed — ice piling upon ice, pushing up onto land crushing whatever might be in its path.

San Francisco Bay clocked no flood tides for over a week, raised as it was by 7’, and the water was fresh enough that steam ships didn’t have to trek to their usual freshwater streams to get water.

The effects did not happen all in one go either. Drought followed in 1863 and 600k more cattle died, pretty much the last of the stock that came from the original Spanish settlements. Michael Barber of UC Davis thinks that this is when native grasslands were supplanted, when new cattle was brought in directly from the east. Tree squirrels may have also taken their place at this time — so many ground squirrels were killed into the floods.

The greatest source of information about the floods comes from Sacramento. Governor Leland Stanford was inaugurated on Jan 10th, 1862 and was said to have had to row to the ceremony. Business had to be carried out on the 2nd floor of Sacramento, and 1000s of miners came down from the hills looking for a way back to San Francisco. A fair number of people turned their backs on California altogether.

The story quickly made its way into stories and song: Bret Harte’s Luck of Roaring Camp (the story was very successful, the author himself helped rescue people during the floods), a musician Max Zorer who named his songs after the flood (The California Flood Mazurka Dance), and a minstrel song published in 1863 called Down By the River Lived a Maiden, by H. S. Thompson, about a woman who drowns while chasing her ducks away from the river, which later was the inspiration for a song you are all familiar with Oh My Darlin’ Clementine. Joel gave a fabulous rendition of the original — an “old timey” sounding tune, with its amusing but ultimately sad lyrics (sadly my recording of this event failed entirely).

Down by the river lived a maiden

Joel had us speculate on why this disaster faded into the background, beyond the terminology, until recently there was little to be found on the subject. There is some level of time passing — we would not expect much of a history of Hurricane Sandy in 150 years perhaps, except that we are now building on the places that were designed as flood plains in the 1850s. His hypothesis is that it might be the flood control administrators who did not want to talk about it — the storm was of such a magnitude that it is unlikely we could build to it. It’s only recently that people have begun to think about a response (on such effort referred to as the Ark Storm). 16 million people live in areas which were underwater in 1862.

How long ‘til the next one? It is really impossible to say. There have been 2-5 storms of this magnitude in the last 2000 years (measuring from sediment layers taken from lakes). Ultimately, it is up to us citizens to remember, research, pass on, and act on this kind of knowledge.

At the end of the lecture, I am sure that Joel could have gone on much longer. Keep an eye on http://thinkwalks.org for updates and future talks on his flood research.

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John Wick came to us on February 19th, 2015 to talk to us about soil. It turns out that our millenias of farming & ranching have left us, overall, with some pretty wretched soil. Soil that is also conspicuously devoid of carbon.
Source: Intergovernmental Panel on Climate Change (IPCC)

Source: Intergovernmental Panel on Climate Change (IPCC)

John’s route to having a potential fix for capturing carbon back from the atmosphere started in a deceptively simple desire to turn his land back to nature, to re-wild a bit of California. They had 540 acres, three valleys of land. It was not so easy as he had imagined — left to its own devices, the ecosystem fell into chaos and a riot of invasive plants took over.
They turned to Dr. John Creque, an scientist and expert in land management, who suggested a controlled application of cattle might help nudge their system back towards native systems. And nudge it did, by 2007 their rented cattle, brought in in April when the swallows came and moved 67 times through 5 weeks, had results. Native perennials began to show up, meadowlarks showed up in great numbers, eagles arrived, and the quail population exploded.
Over time, they became interested in whether this was possibly sequestering C02. They turned to another scientist, Dr. Silver who was skeptical, who didn’t think it was likely, and who didn’t think it would be possible to measure, but she was wanted to do the research.
Grassland it turns out are big carbon stores, and rangeland now covers more of the earth than forests, so it had potential – if this proved out, there was a lot of possibility to sequester a lot of carbon. And do the Marin Carbon Project was started. They took samples before they began trying to get an idea of what carbon was already there, and then they began with a series of experimental plots both on his land and in the Sierra Nevada.
One aspect of this was grazing, another aspect was putting compost down… half an inch. And they began taking weekly readings. And the results were amazing — 30-70% increase in forage compared to control, more water retention in the solid, and an additional ton of carbon per hectare sequestered. Even more interesting was that no additional compost needed to be added (and 96% of the carbon ended up stored), each year and additional ton/hectare was stored, and perennial grasses dominated — and that result happened in both areas.
The same experiment was then duplicated on other farms and dairies, with different grazing practices. There still had to be good grazing management, and there had to be compost. Manure and other fertilizers do not work as well, fertilizer is the big can of coke of agriculture, lots of empty calories that don’t do a lot for the system as a whole.
And the most important thing in all of this is the soil, and how the plants interact with it… the plants take in CO2 produce oxygen and, but they also exude sugars — carbon, which get taken up by the microbes in the soil… and this is where the magic of carbon sequestration happens.
The two big questions are cost and scale. Additional testing showed that only a quarter inch of compost is really required. Some of the cost is covered by selling carbon credits, and tests are being designed to take it to scale, including a million acre project on BLM land. None of this depends on new technology, just good practices that have been developed with silence.
The increased water retention is also a big draw to Western farmers and ranchers who are now deep in drought. But the most important news for our long term future, is that even including the full life-cycle of Carbon costs to this project (transporting cattle, and compost, creating compost, and burping cows), the potential level of carbon sequestration is astounding.
They’ve worked out a strong protocol that requires good grazing practices, and not allowing the disturbance on intact systems, no increase in stocking, and no noxious weeds.
The project’s focus on rangelands is based on the fact that there are so many, and that with enough land devoted to this practice C02 in the atmosphere could be brought under the 350 mark. So much land has been leached of its carbon by bad grazing practices, 60-70% of solid C02 lost over the last 10,000 years, there is a lot we could do to recover that.
They are working on many ways to provide the compost required, composted manure, and chicken manure (compost piles that are hot enough destroy pathogens and deactivate other dangerous chemicals), and the potential to use human waste as compost (using something like Gary Anderson’s fiber chips).
The only challenges are perhaps convincing people to use it, and on that front their seems to be great interest from governments around the world (they recently hosted a big delegation from China) and it is the UN Year of Soil.
It seems incredible, but this management of soil, this management of the microbes within our soil, could go a long way to bringing our carbon back under the line, and with renewables and efficiency, could do way better.
To find out more details about the project and their original science (any incorrect details above are due to my poor note taking abilities), visit the http://marincarbonproject.org

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Joe Jordan led us on a glorious tangent filled romp through the sky — chasing rainbows and other phenomena with photos, chalkboard drawings, and props.

Joe, former physicist NASA, current director of the Sky Power Institute (http://www.sky-power.org) talked to us at the Randall on November 20th, 2014 about all manner of sky phenomena and the physics behind them: the complexities of rainbows, sun dogs, sun pillars, moonbows, haloes, glories, contrails, green flashes, castles in the air, the directionality of meteor showers, and more!

A lot of what we see looking up, or what we see downwards looking out of a plane is the result of ice crystals in the air, their orientation to the sun, and the observers particular perspective.

Sun pillars for instance — where a column appears to rise from the setting sun — is sunlight reflecting off the undersides of ice crystals. It is the same effect as the sun reflecting off the waves toward you, just in the sky. Other effects depend on the angle that light is hitting the crystal, and where that crystal is in relation to the light and you.

A more complicated phenomena, but one of my favorites, are glories. Sitting on the shadow side of the aircraft — as you are coming into land and passing over clouds, you might see a glory in the clouds, a circular rainbow. At the center of that you might be able to make out the shadow of the aircraft.
(If you are a SCIAM subscriber you can read more at http://www.scientificamerican.com/article/the-science-of-the-glory/)

Joe talked a fair amount about the appearance of sun rays fanning out. Sun beams are essentially parallel given the distance the travel from the sun. The fanning out is an optical illusion akin to how train tracks look when we look down them.

We spent the longest time with the intricacies of rainbows, the bending of light through raindrops and how that gets to our eyes. Multiple bounces leads to double and triple and more rainbows (in the lab, this has been done up to the 15th order, but in nature you’d be lucky to see a 5th order rainbow).

My favorite factoid of the night is that although what we see a rainbow as a static thing up in the sky, what that rainbow actually is is an animated mosaic projected onto our eyes — millions of rain drops bending light in our direction, changing colors until they fall “out of the picture.” followed and replaced by the raindrops above.

Double Rainbow!

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(notes by Joel) Geologist and plate tectonics animator Tanya Atwater spoke to us October 16, 2014. She gave us her presentation called Living in the Plate Boundary and Through the Ice Ages.

The presentation was largely based on diagrammatic animation videos which these notes cannot describe. But you can see them yourself on Atwater’s website  (or you can Google Atwater animations). I apologize that I wasn’t as able to take notes as usual since my eyes were up on the video screen a lot.

The surface of the earth is made of plates floating on (and diving down thousands of miles into) the earth’s molten mantle, which is always flowing.

When you look at the animation of the continents coming into their present formation, India seems to move faster than the rest. This is partly due to the size. Smaller means it can move faster. Of course the speeds are all pretty slow, taking many millions of years. (Speeds are similar to how quickly a fingernail grows, according to Julian’s talk back in July.)

The Himalayas are uplift (crumpling and wrinkling of the plate that pushes the surface up). This is due to the direct-hit crunching of the Indian plate against the plate to its north.

The Pacific Plate is the largest plate, taking up almost 1/3 of the surface of the earth. It’s being dragged past the North American Plate to the NW, scraping against it and at the same time leaving bits behind along the edge.

The area west of North America has been for a long time (until recently) made up of three ocean plates. Ocean plates are formed by spreading mid ocean rifts where mantle magma wells up in the gap. (Continental plates are formed by uplift, by volcanos, by wind and glacial deposits, etc.) The two plates on the east side of the rift zone have flowed under the Americas now (a process called subduction). There’s a tiny bit left of one (Juan de Fuca Plate) in Oregon and North California Coastal waters and a little (of the Farallones Plate) near Central America.

As the rift spreads, the Pacific Plate gets bigger on its east side faster than it moves northwest. That means it grows and seems to come closer while in fact it is moving away. The direction of movement is not directly away, but scraping NW along our coast, pulling our coast out and stretching the North American continent. That’s why the high areas that used to be Utah and Nevada had room to collapse and fall over becoming the basin and range provinces with lots of gaps between high ridges. It’s also why the Gulf of California has opened up.

The San Andreas

Tanya’s graduate thesis was to try and figure out the San Andreas Fault, which turns out to be a unique fault over the whole earth.

If a slipping fault is a perfect line in the direction of slip, it has no gaps or places that push against each other (forming wrinkles, i.e. hills). But in reality, all places have some kinks, so there are hills and gaps formed.

Pinnacles Park in California has a very different kind of volcanic rock. Rocks the same have been found hundreds of kilometers away so we know that one side of the slipping fault moved that far since the eruption.

Bodega Head has granite that has moved up from Southern California, 500 km, as do a few other spots on the Northern California coast.

About 25% of the motion of the fault’s energy is spread into the Tahoe region in smaller stresses. In 10 million years, there will be an ocean alongside Las Vegas, because the Pacific Plate will have dragged what is now California away, probably.

Subduction

Before the San Andreas, we had a subduction zone as the ocean rift pushed plates under us. The mid ocean ridge where the spreading areas were is now mostly under us. A subduction pretty much has to be along a straight line. When the subduction hits the melting point (not from friction but from the internal heat of the earth) it bubbles up through the plate above it. That is why there are volcanos in the Cascade Mountain Range. It’s the Juan De Fuca Plate coming back up. Some is trapped under and that becomes granite. Some makes it to the surface and is lava. That lava flowed to the coast and was crumbled and tossed into a mixer of rocks, seawater, etc, some of which was dragged back down by the subduction to enter the whole cycle again and again. Meanwhile, some of the rubble of this cycle is left on the edge of the North American Plate. This is the accretionary wedge.

Other geographical features

The Great Valley (a.k.a Central Valley, San Joaquin Valley, etc.) is the collected debris of the volcanos and cycles of subduction at the edge of the continent. The land west of it (the coast range) is the uplifted part of that debris (cause by bends in the slipping fault pushing mountains up) mixed with melange of things dragged along from elsewhere. The melange is blue schist and chert and all sorts of stuff.

The Transverse Ranges (Tehachapies) that curl toward the coast are granite like the Sierra Range, but the farther south you go the more deeply eroded it is, so the farther under the formation you are looking. The granite in places like Joshua Tree Park are not smoothed into canyons like the Sierra’s because there were no glaciers to scrapes and smooth them. They formed rounded boulders instead.

The L.A. basin is deep and filled with mud.

Between Santa Barbara and San Diego there was a break and a gap opened. The land that was there got pulled and rotated. It is now the block of material that the Channel Islands and Santa Barbara sit on. It tumbled and was rotated to its current position by the two plates grinding past one another within a gap where the coast was pulled out allowing for rotation. Geologists can tell this is so, even though it is unlikely, because the rocks formed with their magnetism lining up with the poles. Now it points east in all those areas, so they know by paleomagnetism studies that the whole section pulled apart and rotated.

Ice Age

The present sea level is about as it has been since the last ice age ended 6,000 years ago. It’s melt from the ice age glaciers. The maximum of the ice age was about 17,000 years ago after tens of thousands of years of ice age. We are now in an interglacial period. The previous one was about 100,000 years ago, and they happened in the past about every 100,000 years. Ice ages always come on slowly and end quickly.

As the glaciers melt quickly, the sea level rises a lot. (For the most recent, between 300 and 400 feet all around the world at once.) Each place where a sea level remained a while, the wave action cuts a terrace on the edge of the continent. By the time the sea level goes gradually down and then quickly back up the next time, the continent has risen some distance, so the next wave terrace is below the old ones. This eventually forms a stair-step coast line. The older steps are more eroded but they are highly visible even to the untrained eye.

If there is a lot of sand in the waves, it takes up the wave energy, but if not, the energy cuts new terraces.

There was so much more she said!

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(Notes by Joel)

John Scarpulla talked to us September 18th, 2014, about the Living Machine at the Public Utilities Commission (PUC) building SF Headquarters. John is a project manager, not an engineer. Very informative.

PUC headquarters: a well built building. Safe place in a quake. Command center for emergency operations. Features: Rainwater harvesting in preschool play area made of spongey material that’s permeable. Collects the water there and uses it to irrigate street trees.

The system called the Living Machine, a million and a half gallons per year. Not a large project compared to the 65 million gallons per **day** that the SF sewage treatment plants treat, but an example, a demonstration site. And a chance to test processes, including permits and ordinances. Wastewater treatment out in the open. Integrate technology into the neighborhood providing green in tenderloin.

Building is separately “dual plumbed” for potable water from the Hetch Hetchy system and wastewater internal system.

Water flows from primary tank to flow equalization tank to wetlands to building in a 48 hour loop. Flows from 7 to 7; none at night or weekend. Wetlands are in sidewalk, lobby and then the water cycles through the basement systerms.

Primary treatment tank is called and looks like a big “hotdog” and they needed a permit for that because it goes under the sidewalk.

First, a trash chamber separates things that shouldn’t have been flushed.

Second, a settling chamber removes a lot of the settleable and floatable solids. The solids are processed elsewhere. They don’t manage solids on site because the site’s too small.

The cycle is in waves, sending batches into the system with a 3000 gallon equalization tank. Recirculating tank for water available to go back to toilets is 6000 gallons. Wastewater treatment of 5000 gallons a day.

Nature wetlands, etc. process water by slowing the flow and cleaning the water but this speeds it up while cleaning it.

One way they do that is with “tidal” action. Water fills and then goes down like a tide every 58 minutes. Process quickly because the plant roots and soils are exposed to an influx of oxygen when water is low and organic microorganisms when the water is up. Most of the solids that were suspended in the water are removed by this process. Both aerobic and anaerobic bacteria involved. Self sustaining.

Ramped up population at the beginning, two years ago: Plants got inoculated then synthetic wastewater (milk solids and ammonia) were fed to it until real nutrients came into the system when building opened. Gradually reducing synthetic wastewater as human use increased so microorganisms kept stabilized.

Off gassing of nitrogen tells what population of microorganisms is like.

Department of Public Health (DPH) required wastewater to stay six inches below topsoil, so there are overflow vents to the sewer system preventing sidewalk overflows. Four inches under there’s a mesh to keep people from digging into the wastewater. No odors because subsurface vent sucks in and odors are emitted through a rooftop carbon filter scrubber.

Reasons particular plants were picked: Marsh plants can stand water in their roots all day every day. Must be tolerant of high nutrient levels. North side gets no sun. Plants have to be able to survive those conditions.

Landscape architect new to this but experienced engineer that has done this system before.

Batch sizes depend on whether it’s raining and day of the week. People are not in the building weekends.

Golden Gate Avenue side is the tidal flow wetland. Polk is the vertical flow wetland: one pass through of the water there first to cell 2a, then down hill to cell 2b. Light tan tint to the water after going through the wetlands. The filtering is then complete so it goes into the interior lobby plants which are a different plant pallet with species that like more sun.

“Acre Café” is in the lobby area twenty feet from the treatment.

There are pumps in addition to gravity. Twenty percent of California’s electrical and 30 percent of natural gas in the state is used for water systems. Living machine uses 75 to 90 percent less power than other systems available because they all use force through a membrane and this does not.

The water gets disinfected with UV light and a little chlorine in tablet form like a pool before it goes to the toilets again. There is one building in Toronto trying something similar that decided not to do chemical treatment and the mold growth became a public health and operational concern.

The system is entirely operated by computer from control room or from desktop computer or smartphone. Fully automated.

Aqua Nova specializes in wetlands.

DPW (Public Works) was involved because it was a large public building being built. Permits: No regulatory rules existed for this so they had to create some. DPH and DBI (Department of Building Inspection) and PUC signed letter of agreement. Will test yearly and inspect plus send results to DPH. Choloform, Turbidity, Oxygen load, etc. In the system itself, sampling is the biggest time draw. Otherwise little for humans to do to maintain it, oh except: Maintenance is big because warmth attracts sleeping, then there’s vandalism. People steal the plants and they have to be replaced.

Inreach wasn’t done as well as they wanted. For an agency of 2300 only about a dozen people came to the one inreach meeting. Outreach was good though.

Project purpose: help ask How can we get other building designers to rethink? In large residential, about half is nonpotable. 95 % in commercial buildings.

City ordinance introduced: Now any building in SF can reuse blackwater, graywater, stormwater (hits ground), rainwater (hits roof), or groundwater.

Amended an ordinance: Buildings can now share non-potable water between them but only by contract, whether paid or free.

If you go into the sidewalk you need a “minor encroachment” permit and it street then “major encroachment” permit.

PUC’s nonpotable guidebook is available from John. Grants from PUC are available for certain sized buildings to encourage development of more such systems or similar. If you expect to offset enough per year you get the grant.Moscone and Transbay and others will use from groundwater systems on sumps. Sump water doesn’t need all the plant cycle stuff, just filter and UV.

The Bullet Center and two military systems in San Diego are using black water, otherwise most systems that exist now are sump (groundwater) or storm water.

John Todd is the inventor of the living machine and calls himself an ecological engineer.

AAA Clifornia Automobile Association building had a groundwater system but was a failure due to high iron in the water. (Different locations have different minerals in groundwater.) gave them orange toilet stains so they only operated it a month. Redid building and took the system out.

In PUC building graywater and blackwater both treated combined, so it all is called black water.

Gray water reuse for homes was allowed as of last year by state law changes. Became okay for using indoors in January 2014.

Airport has a hidden and fenced-in staff building that does the same full system for blackwater but only 475 people work there.

Solar panels produce 12 percent of the buildings energy and the wind turbines 1.5 percent so easily covers the system pumps and UV.

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Spreck Rosekrans came to us August 21st, 2014 to make the case for restoring Hetch Hetchy from reservoir to valley. The dam just passed its 100th anniversary in 2013, but what was hugely controversial at that time (more than 200 newspapers opposed, and John Muir famously broken-hearted by the decision) is now something of which most San Franciscans are proud.

Spreck spent only a little of his time on the “why” of making the effort. We lost this special place, and many people regretted the choice to dam it at the time, and today we have a chance to correct that mistake and restore an iconic place. To do that would show not just values, but also show that we can make meaningful water reform (not something that seems to come easily to Californians). The arguments (which Spreck also layed out) against it are many — people feel that the water is SF’s birthright, that Hetch Hetchy was a swamp, that we are actually protecting the valley, and there’s hydro power from the dam, the cost of removing it, and that we need more storage not less.

The main thrust of the talk was on the practical question of: if we removed the dam, how would we actually supply the water coming into the pipes of the 2.4 million people? It is not a pie-in-the-sky, wishy-washy notion as one might first think. EDF hired 2 mainstream engineering firms, and one law firm to look into what it would take (this resulted in a publication called Paradise Regained — the summary on this page gives a pretty good idea of what is proposed).

The amount of water involved is not the biggest. Of 5 big water projects over the last 22 years, Hetch Hetchy would involve less water than 4 (Delta ESA work, Central Valley wetlands, Trinity River, and rivers in the Central Valley). It would mean juggling water from various sources, doing what is known as “water banking”, taking more from the Cherry reservoir. Looking at the dry years, that kind of work (with the removal of the dam) would get is to around 80%.

The last 20% would take working to be more efficient with the water we have, from farming practices, to recycling, to just plain using less. These are things that of course are not easy, but they are things that we can do — and given current state of our reservoirs maybe things we will have to do anyway. At the end of the day though, we could have our cake and eat it too.

Hetch Hetchy left alone will be with us a long time – unlike other dams, silt does not seem to be a great problem there. Choosing to restore the valley to its former glory would no doubt have its complications and difficulties, but that choice is not just a fantasy.

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