Twice a year, Miami experiences extreme high tides, known as "king tides," brought on by gravitational forces. Without any help from rainfall, they can leave streets, yards and driveways under nearly a foot of water. These days, the phenomenon is becoming more of a rule than an exception in the Sunshine State. Experts say it is due to climate change, which is likely to force even higher tides that will push sea-water through storm sewers and back into streets.

"This appears to be occurring frequently, particularly in some parts of Miami Beach," says Jayantha Obeysekera, chief modeler for the South Florida Water Management District and a member of the National Climate Assessment Advisory Committee.

Flooding in southern Florida is just one manifestation of the effects of climate change, environmental experts say. Climate change is rearing its head in the form of parched reservoirs and lakes, widespread flooding in the aftermath of major storms such as Superstorm Sandy and Hurricane Isaac, and the slow erosion of treasured yet vulnerable ecosystems along U.S. coasts.

Many believe the current effects are only going to get worse. "We already have the problem," says Obeysekera, who says the coastal flood-control infrastructure in southern Florida, a system of gates and canals, was built more than 50 years ago and was not designed with sea-level rise in mind. "Although major flooding has not yet occurred upstream of [the gates] due to higher sea levels, there is a potential to cause flooding if there is a big rain event during high tide."

The district built a pumping station near one of the canals to pump out stormwater in case of high tides. "That is probably one of the few adaptation examples in the U.S. to address issues like this," Obeysekera says.

Perhaps no other industry has experienced the effects of climate change as much as the nation's water-wastewater sector. "Climate change primarily affects the water cycle and hits that particular [industry] hardest and first," says Kathy Freas, global director of Englewood, Colo.-based CH2M Hill's water-resources services division. Over the past several years, municipalities and water and wastewater utilities around the country have taken heed of the changing weather extremes, and many are going through a process to help them make informed decisions about how best to adapt to a world of changing temperatures.

Impacts from Sandy, mostly linked to storm surge, caused at least 11 billion gallons of untreated and partially treated sewage to flow into waterways in eight states and Washington, D.C., according to a study by Climate Central, a Princeton, N.J., research and advocacy group.

"Sewage treatment plants are usually placed near water in low-lying areas so that sewage can be piped to the plant via gravity and treated sewage can be easily discharged into receiving waters. These key factors in plant locations make them especially vulnerable to storm surges and coastal flooding," says Alyson Kenward, the group's climate science research manager. The risk, she adds, is compounded by "expansive, underground labyrinths of pipes, holding tanks and pumps that can remain waterlogged and incapacitated long after floodwaters recede" from treatment plants.

Early Adopters

CH2M Hill's Freas says, "The utility community is like any other community, so those that are really at risk …tend to be the leaders." The San Francisco Public Utilities Commission (SFPUC) is one of those out in front. Like southern Florida, San Francisco's wastewater and stormwater infrastructure has been affected by sea-level rise. Over the past four or five years, during high-tide storm events, saltwater has overwhelmed the combined-sewer overflow system and infiltrated the wastewater treatment plants. "We had a very high tide in December 2012, and we had pure saltwater pouring into our system," says Karen Kubick, SFPUC's wastewater enterprise capital program director. "That's a concern because it can really negatively affect the [wastewater treatment] plants" by wasting energy and compromising the biological organisms used for treatment.

SFPUC has identified 27 points where saline bay water is forecast to enter the combined-sewer/waste-water system over the next several years. SFPUC has committed $40 million for a combined-system backflow prevention project, the first phase of retrofits to the system's infrastructure. The project, now under design, is one of the first "climate-justified" projects in the country, says Kubick, meaning that if it were not for climate- change research, the project would not be built.

David Behar, climate program director at SFPUC, adds, "There are very few climate-justified projects that are currently funded and on people's capital plans in part because a lot of people are still catching up in terms of figuring out the vulnerability" of their assets.

Additionally, in the future, all projects SFPUC embarks on will consider climate change, Kubick says. New facilities will be sited to accommodate or adapt to an expected sea-level rise over their lifetime, and officials will evaluate existing infrastructure, she says.

At the other end of the spectrum, extreme drought conditions in the city of Midland, Texas, have caused two of the town's three surface reservoirs to go dry. A third is expected to run dry before the end of the year. In a public-to-public partnership, Midland teamed with the Midland County Fresh Water Supply District No. 1 to address the water-supply shortage. The project—awarded for an undisclosed amount to a joint venture of Overland Park, Kan.-based Black & Veatch and Kansas City-based Garney Construction Inc.—involved drilling a new raw-water well field that has approximately 44 wells and building a 58-mile-long pipeline to convey the water from the well field to the city. The team completed the fast-track design-build project in less than a year. The project, which went on line in May 2013, can deliver 20 million gallons of water a day to Midland.

In California, the Bay Delta Conservation Plan, currently in the planning stages, would provide, if built, a source of water from the Sacramento-San Joaquin Rivers Delta and San Francisco Bay—together known as the California Bay Delta—down to Southern California while striving to protect wildlife and fragile ecosystems. Further, that project is incorporating impacts of climate change related to sea-level rise and snowpack melt into some of its design parameters.

Finding alternative sources of water will become increasingly important as freshwater supplies become more scarce, notes Ben Chou, water policy analyst for the Natural Resources Defense Council.

A Process

Chou says that while some states are moving aggressively to address climate change, others are not, largely due to budget woes.

Cindy Wallis-Lage, president of Black & Veatch's global water business, says, "We've been very slow in the water industry to adopt new technologies. We sometimes move at a snail's pace because … we want to make sure that we're putting the due diligence in place and doing the right things. But when we see some of the extremes that we are challenged with, we need to move faster." Several sources describe a fairly similar process that many utilities undertake to make decisions about enhancing the resiliency of their infrastructure. Initially, they look at the science and work with engineering firms, scientists, consultants and in-house meteorologists to determine how their region might be affected.

CH2M Hill is one firm that works with clients to develop scenarios using global models and weather and other data; it then refines them to apply to specific areas or regions, often with the assistance of its strategic partner, New Zealand-based CLIMsystems.

Then, the utility or municipality must take stock of its assets, using mapping technologies to determine the infrastructure's location. Then, the utility or municipality conducts a vulnerability assessment. "You can't deal with something that's changing if you don't understand the basis of what you have," says Black & Veatch's Wallis-Lage. "We need to be very educated as to what our assets are so that we're very targeted about how we replace them in a manner that's going to maintain the resiliency of the system."

Once a municipality has a good sense of its system's vulnerabilities, it can develop an adaptation plan. "Our governing board wanted us to continue to monitor the science and come back with some actionable science for them to act on," says the South Florida Water Management District's Obeysekera.

Sometimes a city or utility may see big vulnerabilities but decide to take smaller, more achievable steps, notes Michael McMahon, senior hydrometeorologist with Omaha, Neb.-based HDR. For example, HDR conducted a study for an undisclosed client that showed a coastal city could be overwhelmed by sea-level rise by 2100. The only solution to protect the city would be to build a $30-billion seawall, he says. "They're not likely to do that." But what they can do, he adds, is to use green infrastructure to lessen the severity of smaller events of any future sea-level rise or storm surge, he says.

Dealing With Uncertainty

Paul Fleming, manager of climate and sustainability at Seattle Public Utilities, says the uncertain trajectory of climate change creates "a little bit of a barrier" in knowing how to incorporate climate change into facility and system planning and design.