Climate Change and Water Supply

According to many concerned with future water supply, whether as municipal utility officials or as developers, real estate professionals, and citizens, we need to pay close attention to climate change projections. “Most of the really important impacts of climate change are not going to come directly from temperature increases but because of changes to the water cycle,” says Brad Udall, director of the Western Water Assessment at the University of Colorado and a member of a family known for its political and environmental achievements.

Udall and others say that as a result, the West is likely to see less snowpack, which states in that region now rely on to melt gradually and provide a steady water supply in the spring and early summer. The result could be more drought at times and more flooding at others. Already, more precipitation is coming as rain instead of snow, and droughts are longer and more severe. Because water in the Colorado River, for instance, has been designated to places ranging from Southern California to southern Nevada, “we can’t just draw water out of the river,” says Linda Romer Todd, owner of Associated Brokers and Consultants, Grand Junction, Colo., and water activist. “If we don’t have snow, we don’t have water.”

But the effects of climate change won’t be felt only in the West, according to the Government Accountability Office. A 2008 GAO report stated that at least 36 states would see water shortages by 2013, including eastern states such as Georgia and Florida. Higher temperatures result in greater evaporation, which puts a strain on water supplies. A forecast of continued population growth in major metropolitan areas adds to the pressure.

Part of the challenge in dealing with water supply and climate change is the lack of predictability, says Heather Cooley, co-director of the water program at the Pacific Institute. The need to plan for different scenarios makes it all the more urgent for utilities to work closely with scientists who are closely tracking climate change patterns.

The other problem in state planning is resources, says Will Hewes, associate director for climate policy at American Rivers. All states are short on money now, and climate change and water infrastructure programs are often the first to be cut. “It’s about realigning resources,” says Hewes, “providing incentives to reduce vulnerability” to the effects of climate change.

As for the uncertainty, we do at least know the outlines of what future climate patterns will hold, Hewes says: “greater volatility, more extreme droughts and floods, melting snowpack in the West.” He suggests flexible solutions that deal well with volatility.

For instance, a city can promote green infrastructure by embedding green space throughout its landscape to absorb water. Such small, decentralized approaches can control more extreme floods. Philadelphia is investing heavily in green infrastructure as a cost-effective way to control its combined sewer overflows. It didn’t add the green spaces as a way to deal with climate change and water supply, but they will have made it easier to withstand some of the predicted volatility.

What are water utilities and other suppliers to do? Every community would need to increase its available water supply through a combination of conservation, recycling, new water sources (which will be covered in more depth in the next section of the toolkit) and, in some cases, rationing. Each municipality has to decide on the degree to which it will depend on each of those measures. That in turn will depend on what’s practical in an individual situation, and what the local politics will allow.

The politics and policy issues can be controversial. New water sources for one area usually have to come from another community, which may want the water for its own citizens, even if there are fewer of them. The population centers have the need for the water and often have the political clout to claim the water source. “About 80 percent of the water in Colorado is on the west slope, but 85 percent of the population is on the east side,” says Stacy Chesney of Denver Water, the city’s water utility. So the city is already transporting water from the west slope, on the other side of the Great Divide, and will probably bring more.

Here’s a closer look at what a few communities and states are doing to ensure they have the water supply they need as climate change occurs.

Denver Plans for Warming

Matt Waage, manager of water resources planning for Denver Water, deals with uncertain climate change forecasts every day. For Colorado, “almost as many models say it’s going to get wetter as say it’s going to get drier,” he says.

But it’s clearly going to get warmer, he adds, which will mean more runoff from snowmelt and more streamflow in the fall. The hotter temperatures will also result in more evaporation and more consumption of water by plants. Combined with continued population increases, the upshot is this: “We will need more water, like every western state,” says Waage.

Working with the utility’s climate change policy analyst Laurna Kaatz, Waage is planning for a 5-degree warming in the state by 2050, with no change in precipitation--what he calls a middle of the road projection. That means Denver Water will be pushing hard in all three areas of recycling, conservation, and new water sources. Its board is working on a plan, due out in early 2012, which will determine the right mix for future water supply.

For new water sources, the utility has conditional water rights for several reservoirs that haven’t been built yet. In Colorado, any entity that wants to draw water from a piece of land must own the water rights, which are not necessarily associated with the property rights. The owner with the oldest rights has priority. Denver Water is keeping hold of water rights it acquired decades ago so it can build new reservoirs if they’re needed.

Based on the board’s 2012 plan, the utility will also consider trying to draw more water from the west slope in cooperation with local communities, water rights groups, and environmental groups. The board’s policy is that all future drawdown of water from the west should be done in cooperation with western slope interests.

Needless to say, there would be many conflicting interests in such a project. “We want to try to build a multipurpose project that’s going to give not only the water supply benefits to Denver, but the local water supply benefits and environmental benefits,” says Waage. Any time a reservoir is built in Denver,
it can cause low flow for the rivers.

One solution is to store some of the peak flows of runoff in the reservoir to use for municipal purposes, then augment the stream flow when it’s low. Storage could help shift the timing of the water flow. When the utility artificially releases water from the reservoirs, it has to work with the state Division of Wildlife to assure minimal environmental consequences.

With water supply always a potential problem in Colorado, a state law requires developers to demonstrate that any new development has a source of water, such as aquifers or wells, that will last 100 years. “So there’s been a lot of effort to find renewable supplies for those communities,” says Waage. Renewable supplies could include snowmelt, but not groundwater, which could not be replenished unless it’s connected to a stream.

What about recycling? “Because of the obligations we have to deliver water to states downstream, and the scarcity of supply, every drop of water is already spoken for,” Waage says. “So we’re looking at projects that would reuse water from wastewater plants.” But not all of it is reusable.

That’s one reason Denver Water is pushing a conservation plan that aims to cut overall water use by 22 percent from 2001 levels (before the drought of 2002 to 2004) in 2016. Some parts of the plan are mandatory, such as year-round restrictions on the time of day and number of days that irrigation is allowed. The utility is generally working to create a “culture of conservation” among residents with measures that include rebates for high-efficiency toilets.

Under the 2016 target, overall use would be 165 gallons per person per day, including residential, commercial, industrial, and institutional. It’s hard to compare that figure with use in other parts of the country because other figures may cover only residential use. The U.S. Geological Survey, for instance, estimates national average household use at 80 to 100 gallons a day. However it’s measured, western states like Colorado are in a semi-arid climate and may naturally use more water.
San Francisco’s East Bay Finds New Water Sources

The East Bay Municipal Utility District (EBMUD) in Oakland, Calif., was dealing with the same problem of unpredictability as Denver. So the utility decided to look at the commonly expected effects of climate change and honed in on decreased precipitation as the factor most likely to affect that region. “We expect more droughts, so there would be more times where we would be unable to provide enough water to our customers,” says Mike Tognolini, EBMUD’s manager of water supply improvements.

When drawing up future water supply sources, “we tried to maximize water conservation and recycling,” says Tognolini. The district’s Water Supply Management Program 2040 sets goals of saving 39 million gallons a day through conservation and 11 million through recycling (up from 9 million now). Rationing would be capped at 15 percent, meaning customers would be told to use 15 percent less water than they normally would. EBMUD already asked for rationing during a previous water supply emergency, and water rates were adjusted to promote rationing (customers paid proportionately more as they used more water).

New water sources would account for 43 million gallons a day under the plan, through water transfers, groundwater storage, and regional supply projects. EBMUD is pursuing multiple water supply sources to be assured of a robust plan, says Tognolini. For the near term, it completed work in early 2011 on the Freeport Regional Water Project, which will allow EBMUD to take water from the Sacramento River during a drought.

Water transfers from the Sacramento Valley make up one of the biggest pieces of the 2040 plan. Under contracts through the Freeport project, EBMUD could potentially buy water from agricultural users of the Sacramento River. Water transfers are generally less expensive than other options such as groundwater banking or desalination because the infrastructure is already in place.

EBMUD has been working on groundwater banking for a long time and has recently completed construction of a single well to be used for testing. The idea is to store water in local aquifers in the East Bay and pump it out during dry periods. The amount of water that could be stored is limited by the capacity of the groundwater basin. The cost of groundwater banking is a little higher than water transfer because it requires drilling and monitoring wells, building a treatment facility, and storing the water in the aquifer and pumping it out.

Expanding surface water reservoirs is another possibility, but policy issues make it problematic. To expand the existing Pardee Reservoir, a new dam would likely have to be built. There could be permitting problems and local concerns about whether whitewater rafters could continue to use the stream, says Tognolini.

Farther in the future, desalination of seawater remains a possibility, but an expensive and energy-intensive one. For now, EBMUD is monitoring the technology closely, participating in a study with other Bay Area utilities that are discussing a possible joint future project. (The next chapter addresses the above and other new water sources in greater detail.)

With all of the possible new water sources, “there are stakeholders that feel there could be harm,” says Tognolini. “That’s why we haven’t built them yet.” The water transfers from the upper Sacramento River could cause job losses in the farming community. Some endangered species rely on the wet fields created by rice farming, which could be limited.

With groundwater banking, overlying landowners feel they should have first rights to the groundwater basin. San Joaquin County prohibits export of groundwater outside county lines. “Even though we’d be putting water in to the ground, we wouldn’t be able to take it back out,” says Tognolini.

It took more than 30 years and several lawsuits to reach agreement with the Sacramento County Water Agency on diverting water from the Sacramento River to the East Bay. A deal was finally struck in 2002, and construction was completed nine years later.

Maryland: Dealing with More Flood, More Drought

As in the West, eastern states are planning for unpredictability. The Maryland Department of Natural Resources’ Comprehensive Strategy for Reducing Maryland’s Vulnerability to Climate Change, published in early 2011, offers suggestions for dealing with the risk of both more floods and more drought. American Rivers’ Hewes, who participated in the state’s Water Resources working group, calls the Maryland plan unusual in offering concrete strategies for reducing vulnerability in the short term.

For instance, the report recommends protection of source waters and measures that promote conservation by raising the per-unit water rate as more water is used, as EBMUD does. The plan also suggests adjusting funding to promote green infrastructure (the placement of green spaces throughout metropolitan areas to absorb water, as in the Philadelphia example earlier in this paper).

As a coastal state bordering both the Atlantic and the Chesapeake Bay, Maryland is preparing for, and already seeing, sea level rise and changing water patterns in the Bay. The expected increase in precipitation would add to stormwater runoff. That in turn would affect water quality and infrastructure for stormwater, water, and wastewater. To help prepare, the state plan recommends reducing paved surfaces that contribute to runoff in developed areas and removing barriers such as dams.

With the increased threat of drought, regional cooperation becomes more important. “During times of drought,” says the report, “the three major utilities of the D.C. area follow water allocations given to them by the Interstate Commission on the Potomac River Basin (ICPRB), independent of the management of any of the utilities.” The ICPRB also routinely conducts drought preparation exercises to strengthen regional coordination.


For More Information

Western Water Assessment

American Rivers’ work on climate change

Denver Water

EBMUD Water Supply Management Program 2040

Maryland’s climate change adaptation plan

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