Is desalination the answer? Local parties sound off.
The city of Santa Cruz plans to build a desalination plant to offset water deficits during the worst summer droughts—the kind that hit once every 10 to 30 years. Models predict that if Santa Cruz continues to grow, and UC Santa Cruz expands, we will be left bone dry—at least if current water use trends continue during the driest of all summers.
When Santa Cruz doesn’t need the water, the Soquel Creek Water District will run the desalination plant, supplementing underground water reserves that have dipped dangerously low due to prior over-use. Soquel aquifers now face the danger of saltwater intrusion from the Bay, which could damage water quality indefinitely. This is why the district needs to find an alternative water supply, or perhaps heighten conservation and the regulation of pumping from competing private wells, depending on who you ask.
The desalination plant may be one of the biggest controversies in the county’s history. It will remove 5 million gallons of seawater each day from the Monterey Bay to produce 2.5 million gallons of drinkable water. The remaining brine will be trucked to a water plant, mixed with treated wastewater, and put back into the Bay.
Desalination is one of the most energy-intensive methods of producing water. And as the city of Santa Cruz has implemented successful water-saving strategies during past droughts, environmental leaders say water needs could be met by maintaining restrictions during non-drought years. “If we use less during the years before a drought, we will enter the dry spell with more water in Loch Lomond,” says David Stearns, a community activist who organized two seminar forums on the issue last winter.
Santa Cruz city leaders say that water conservation alone won’t solve the problem. “We need to conserve water as much as we can, but we will still need to increase supply,” says Toby Goddard, water conservation manager for the Santa Cruz City Water District.
The plant’s energy use will be offset by conserving electricity elsewhere in the city, and by installing solar panels on city buildings, according to Mayor Mike Rotkin. Yet carbon calculations have yet to be completed, raising questions about whether offsets will account for the additional energy used by the plant, or just go toward offsetting the city’s current carbon footprint.
The water district’s energy report has yet to be published. Originally slated for release this summer, the report totals the plant’s energy demand under different design and use scenarios.
“We had some contract difficulties and will be resuming work soon, but the report won’t be done this summer,” says Linette Almond, deputy water director for the city of Santa Cruz.
Also delayed are two environmental reports, one outlining options for brine discharge, and another indicating the impacts of ocean water intake on sea life. Both reports were originally slated for release this spring, but remain incomplete.
Despite these unknowns, officials are moving full speed ahead. On March 23, the Santa Cruz City Council unanimously endorsed the desalination plant, giving the green light for design and planning. In April the results of a 14-month pilot desalination plant were released. Competing proposals for the plant’s design were received on May 27. Built at the Long Marine Lab, the pilot plant made 72,000 gallons of water a day using four different methods of desalination. Two achieved desirable water quality products, but consumed 9.7 and 10.5 kilowatt hours per 1,000 gallons—a little less than the final plant’s energy demand, which will be higher as large-scale operations are less efficient. In contrast, it takes three kilowatt hours to remove and treat river water from the San Lorenzo.
If all goes smoothly, Mayor Rotkin says the Santa Cruz plant could be up and running by 2015.
To help readers understand more about the desalination plant, Good Times posed the following key questions to a selection of community activists, city officials and water district representatives.
Q: HOW MUCH WATER CAN SANTA CRUZ SAVE?
If more water can be conserved, deficits in the worst summer droughts will be much smaller—perhaps even non-existent. Can Santa Cruz meet its water needs through conservation?
MIKE ROTKIN, MAYOR: We looked at how much we could save during drought years. The possibility of saving 10, 15 and 30 percent of our current use are all scenarios we explored. After a lot of discussion we decided 15 percent was what we could do. This is how much we can curtail use during drought years. Last summer we saved 14 percent. If you try to save more than this, businesses start failing and people can’t afford to have veggie gardens. Trees start to die. Even if we could do more, the public is probably not willing. They would end up recalling everyone in public office.
DAVID STEARNS, COMMUNITY ACTIVIST: Elected officials don’t like telling people to conserve or use less of something. Yet we, the residents of the city of Santa Cruz, cut our water use by 15 percent last summer by simply restricting sprinkler systems to twice per week, and limiting automatic watering. I don’t recall it being an arduous task, and with our leaders reinforcing the importance of conservation, we could easily do more.
There is a consensus among our policy makers that conservation will not be sufficient and that desalination is our only option to maintain public health and quality of life. If that is the case then how do Australians live on 30 gallons per day? The average user in the Santa Cruz and Soquel Creek districts consumes about 75 gallons per day.
We don’t live in a climate where we can use as much water as we want, and growth needs to be contingent on people understanding and respecting this fact.
Water capturing option: Buildings that capture rooftop water still use H20 from the city. They just use less water overall, as toilets are flushed and gardens are watered with rainwater. Two tanks this size can store 3400 gallons of water.
BILL KOCHER, WATER DIRECTOR, CITY OF SANTA CRUZ: We have already done the easy stuff, like help people install low-flow toilets and efficient washers and dryers, and we have seen some significant benefits from this. But market penetration for more stringent measures is very low, industry tells us. We aren’t discouraging people from conserving, but we can’t count on this to solve the problem. We just won’t get high enough market penetration—not enough to meet the 2.5 million gallons of water per day that the desalination plant would provide during a drought cycle.
In the final analysis, it comes down to the cooperation of our customers. Are they willing to face periodic drought restrictions, occasionally very severe, while at the same time investing heavily in water conservation on a day-in-day-out-basis?
RICK LONGINOTTI, COMMUNITY ACTIVIST: With Soquel Creek, water conservation is the simplest solution. Here the district is divided between two aquifers. In the north, use of the Purisima aquifer needs to be cut by 15 to 20 percent to allow for sustainable recharge. If use could be cut by this much, there would be no need for desalination. Last year Soquel Creek demonstrated this was possible—they cut 14 percent of water use during the summer months. They would only need to cut by 17 percent all year round to reach the sustainable yield of the aquifer.
In the south, the Aromas Red Sands Aquifer is shared with the entire Pajaro Valley, and this is in a critical state of overdraft. Pumping from agricultural wells has done a lot of damage, and saltwater intrusion is beginning to be seen. The remedy here isn’t desalination, it’s the reduction and regulation of pumping from agricultural wells.
In Santa Cruz we face the problem of supply during drought years. If we conserved water during the years prior to a drought, we would enter the dry season with more water in Loch Lomond. Last summer the city said we could only water the yard twice a week, and the lake was at 90 percent capacity at the end of the summer—this is pretty good. If we go into the winter with 90 percent capacity, there is a good chance the Loch will fill up. This means that if we hit a severe drought this summer, we will have enough water.
Q: IS WATER STORAGE AN OPTION FOR SANTA CRUZ?
How much room is available for water storage in Loch Lomond? How high would the Loch need to be kept in order to prepare for a drought year?
TOBY GODDARD, WATER CONSERVATION MANAGER FOR THE SANTA CRUZ WATER DISTRICT: The problem is that we have no place to store the water we save. Most of our water is taken from surface sources, like the San Lorenzo River, with some taken from Loch Lomond during the summer. In wet years the Loch is so full that it spills over, so saving water during wet years wouldn’t necessarily provide us with more water during drought cycles. There is no reason to make people restrict water use during wet years.
LONGINOTTI: Currently, the reservoir does not fill up in three out of 10 winters. In those three years, the Water Department is hoping that the following year will not be a drought year. That’s a big gamble.
If instead the reservoir were managed with a priority for drought security, there would be another 500 to 700 million gallons available in year two of the critical drought. That’s more than the expected output of the desal plant.
In wet years we might be able to send water to Soquel Creek in exchange for their well water during droughts. The city dropped this option from consideration in 2000 due to the fear that getting a revised water rights permit from the state would require the city to allow more stream flow for native fish. This concern may no longer be an obstacle, since the city is currently in negotiation with the state and federal agencies to provide habitat for endangered fish.
How Desalination Works
1 SEAWATER SUPPLY From the Pacific Ocean.
2 PRETREATMENT SYSTEM To protect the reverse osmosis membranes from fouling, incoming seawater is screened and clarified to remove solids and its pH is adjusted.
3 REVERSE OSMOSIS PROCESS Seawater is pumped into a series of closed containers and forced through membranes which inhibit the passage of salts while permitting the fresh water to pass through.
4 CONCENTRATED SALTY WATER DISPOSAL
5 STABILIZATION Product water is adjusted for pH (acidity/alkalinity).l
6 FRESH WATER STORAGE
7 FRESH WATER
Q: CAN CAPTURING ROOF WATER WORK IN SANTA CRUZ?
Los Angeles is currently considering a law that requires developers to capture 100 percent of rainwater from a three-quarter inch rainstorm. The water would be kept in storage cisterns, or directed to permeable pavement or bioswales—not just to provide H20 for the home and office, but also to prevent toxic runoff, a major source of water pollution.
Buildings that capture rooftop water still use H20 from the city. They just use less water overall, as toilets are flushed and gardens are watered with rainwater. Based on real-world examples, 250,000 gallon cisterns can be installed—these usually fill up after three to four days of rain.
Imagine that an office building repeatedly fills its cistern during the spring, using the water as it goes along. It will enter the summer with 250,000 gallons. If the cistern fills only three times during the late spring, this could spare 750 gallons of San Lorenzo and Loch Lomond water. If 300 buildings installed a cistern of this size, more than 225 million gallons of water would be saved. As the water deficit during the worst drought ranges from 300 to 375 million gallons, rainwater harvesting could meet as much as 75 percent of the need—assuming the water saved could be stored in Loch Lomond.
There is no doubt rainwater harvesting would offset our use of city water, but by how much?
ROTKIN: Larger storage cisterns might work for the campus—it’s possible UCSC could store water from the rooftop. We haven’t looked into it. But this won’t work for the people of Santa Cruz. It just costs too much for the average home—you have to install a pump, buy the tank, burry the tank, and dig up the backyard.
Also, roof water capture is premised on situations back east where you get rain all year. Santa Cruz has a Mediterranean climate, this means you can only capture water during the winter—but this isn’t when the shortages occur.
MIKE WILSON, ASSOCIATE ENGINEER, SOQUEL CREEK WATER DISTRICT: Roof water capture is not in our jurisdiction, but it does reduce water usage. We just sell ground water that is pumped up and treated and put in distribution system.
STEARNS: Even if rooftop capture only offsets a month or two of water use, this will have a huge cumulative impact. Even if it’s not practical for every home, encouraging offices, schools and city buildings to collect water would be huge.
LONGINOTTI: After I installed my home rooftop rainwater harvesting system, I became painfully aware of every drop I used. It made me a water miser. The same might happen for other people.
KOCHER: A lot of folks have suggested rainwater catchment, greywater and composting toilets—these are about the only things we haven’t invested in. These are not likely to catch on. They require too much effort, and if a water conservation effort requires a lot of thought, the majority of people won’t do it.
Rainwater catchment may provide a small alternative water source for a homeowner at times when the city is imposing water restrictions, but it does not provide enough water to eliminate the need for the city to augment its water supplies for severe drought events.
Again, we won’t discourage these, but when looking at the amount of adoption we will realistically get, we will almost surely still need the desalination plant.
Q: CAN GREYWATER HELP OFFSET OUR WATER DEFICIT IN PLACE OF DESALINATION?
Greywater systems direct wastewater from clothes washers to landscaping. New state rules make greywater legal, but only when systems are designed appropriately. As the average washing machine uses 30 to 45 gallons of water per load, this can save a lot of water. If we install more greywater systems, will we still need desalination?
ROTKIN: Small systems in people’s yards are feasible, but greywater makes the most sense when you are building new subdivisions. The c ity of Santa Cruz is 95 percent built out.
HEATHER COOLEY, PACIFIC INSTITUTE, OAKLAND: If you combine greywater and rainwater harvesting with drought tolerant landscapes, you can save a considerable amount of water. The activist community needs to evaluate water district standards and do this analysis independently.
GODDARD: Greywater standards were liberalized to facilitate laundry water, but this was a recent development. We are gong to look at it, but there may be changes to the rules that limit the legal uses of greywater.
Q: CAN THE CLIMATE IMPACT OF DESALINATION BE ADDRESSED?
From a climate change perspective, desalination is the worst possible source of water. How will this impact the future of desalination?
KOCHER: While I understand your point referred to carbon impact, I would also point out that desalination is a drought-proof source like no other addition to the city's water portfolio would be. There is nothing in our lives more important than water. While I totally appreciate the concept of peak oil, I would urge people that if we have to make choices about how to spend our energy, I think it’s a reasonable discussion to have as to whether this is a valid use.
We also need to understand the dramatic effect a severe drought will have on our community. Desalination, even in a severe drought, will only supply 20 percent of the total water supply, but this is not just drought resistant, it is drought proof. We must reduce our reliance on stream flows and there are few alternatives to that.
LONGINOTTI: State law Assembly Bill 32 set a greenhouse gas reduction target of 1990 levels by the year 2020, and a further 80 percent reduction by 2050. If the desal plant is built, the Soquel Creek Water District will more than double their emissions.
ROTKIN: Desalination plants probably won’t fall under AB 32. I don’t foresee any conflict with AB 32. We can probably make the plant work within this framework anyway.
STEARNS: The desal plant will not be powered by renewable energy. The city’s Integrated Water Plan is very clear about that. The majority of the power that it will take to run this thing will likely come from out-of-state coal plants and other non-renewable sources. This is because California imports more brown energy from other western states as energy demands increase. Even though energy producers in state are incorporating renewable sources as a result of AB 32, our demand is exceeding what we can produce. If we start running a desalination plant, the additional energy will likely come from conventional fossil fuel installations in bordering states with less stringent environmental regulations.
Our climate in Santa Cruz is particularly vulnerable to climate change—our redwood forests don’t get as much water as those up north. Researchers at UC Berkeley recently found that climate change is reducing and thinning fog up and down the western seaboard. The coastal redwoods only span from the Oregon Boarder to our lovely stretch of coast and we need to be enacting water policies that reduce greenhouse gas emissions, and protect and enhance this vulnerable ecosystem, not the opposite.
Q: HOW CAN WE OFFSET THE ENERGY USED FOR DESALINATION?
Offsets can include carbon saving-measures like solar panels, as well as carbon sequestration measures like reforestation. How does the city plan to offset the desalination plant’s energy consumption?
KOCHER: If the desalination plant can’t be built as a carbon neutral facility, it probably won’t be built. It won’t be energy neutral, but we can minimize energy use. We might be able to make it carbon neutral with offsets. We are installing solar panels on city buildings—even though the desalination plant can’t be run on solar, we will put up solar in other places. We are also installing a hydro turbine in the Graham Hill Water Treatment plant to capture energy on Graham Hill Road. Curtailing water use will also offset our energy use, as providing city water from surface sources like the San Lorenzo also takes energy. As people use less water, this will reduce our total energy use.
The energy plan is in the works. We haven’t concluded anything, but it won’t be hard for Santa Cruz to offset our needs. We won’t be using the plant that much, so not as much of the energy use will be our responsibility. Soquel Creek’s needs will be different, and they will need to consider different measures to offset their energy demands.
ROTKIN: We will offset the actual energy use by building solar arrays on the roofs of city buildings. The plant may have a zero carbon impact. We don’t have reports back yet on the energy use, but we can calculate how much energy the plant will use.
STEARNS: We need to be installing solar and saving energy anyway. We can’t implement clean energy changes that are already overdue and then claim them as offsets for a new, power intensive desalination plant. This isn’t how offsets are supposed to work. The two districts are scrambling to come up with offsets, but they're realizing that changing the light bulbs in the Water Department offices and installing solar panels will fall woefully short of mitigating the plant's tremendous impact on the climate. Renewable energy should supplant fossil fuel energy for existing electricity loads in order to reduce greenhouse gasses, not offset increases in emissions.
Also, whether Santa Cruz or Soquel Creek uses the plant, it will release the same amount of greenhouse gasses.
Q: WHAT ROLE DOES UCSC EXPANSION AND OTHER GROWTH PLAY IN THE PROJECTED WATER DEFICIT?
Plans for desalination are based on the worst of past drought cycles. They are also based on development models. If development was curbed, would we need desalination?
ROTKIN: We would need desalination whether UC expands or not. The issue is growth and population size, not whether UCSC expands.
GODDARD: The model that predicts drought outcomes assumes that Santa Cruz will grow by about 11,000 people by 2030. This number includes the 4,000 additional students UCSC plans to enroll, and the faculty and staff needed to support university expansion. Yet as part of a settlement agreement with the city over their long-term development plan, the university has also agreed to purchase water at fair market rates. They have also gone through and retrofitted many campus buildings, and have surpassed our expectations for campus conservation.
STEARNS: UCSC is a great asset to our community and I embrace the university’s existence as much as anyone. But having them pay for their water use is not a huge victory. Why should they need pressure to conserve and pay for their use when we’re all dependant on the same water?
Campus growth is the elephant in the room when it comes to desal. Were campus growth not part of the equation, the case for desalination would lose much of its gusto. If growth were only predicted to be 6,000 people, and more stringent conservation goals were implemented, the potential drought deficit would be much lower. Still, Water Department officials say that the desal plant is not needed solely because of university growth.
LONGINOTTI: Any new growth should be water neutral by offsetting new water demand with conservation retrofits in existing buildings.
UCSC could be self-sufficient in water from shallow wells on the upper campus without adversely affecting neighbors’ wells or coastal streams, according to UCSC emeritus professor of geology, Robert Curry.
Q: HOW MUCH WILL DESALINATION COST?
At least 15 agencies will need to give approval for the desalination plant, including health regulators and regional water quality boards. The permitting costs alone will be expensive, not to mention the list of contractors, and even the contractors hired to manage the contractors. In March the City Council renewed a $300,000 contract for Kennedy Jenks—a San Francisco-based environmental firm—charged with soliciting plant designs. Who will pay for all this, and how will it impact water rates?
ROTKIN: There are no final cost figures yet, but it will definitely come out of rate increases and water system hook-up charges.
COOLEY: Because desalination is one of the most energy inefficient options available, it’s vulnerable to energy prices. Energy use accounts for about half the cost of the water. For every one-cent increase in the price of electricity, the cost of water goes up by about $50 per acre-foot. It’s hard to say how much energy will increase over the next few years, but it will go up. Not only is the price of oil expected to go up, but renewables are also a little more expensive. As we move the grid to cleaner options, energy will get more expensive.
written by Chris Morrow, June 10, 2010
|< Prev||Next >|