Arguments continue about what exactly is causing global climate change, but evidence that it’s happening now is undeniable. One only needs to look at evidence like retreating glaciers, the decline of polar ice caps, and the effects of rising seas on low-lying communities.

Climate change and its impacts are a significant concern for water, wastewater and stormwater utilities. One utility taking a proactive approach to the issue is the Portland (Oregon) Water Bureau, which is modeling for the effects of warmer temperatures and has created a comprehensive climate resiliency plan.

The Portland Water Bureau is a member of the Water Utility Climate Alliance, a collaborative effort involving 12 of the largest water providers in the United States that together supply drinking water for more than 50 million people.

The bureau delivers drinking water at retail and wholesale to more than 950,000 Oregon residents, almost one-fourth of the state’s population. In 2016-17, the bureau directly served more than 584,000 people in 153,500 single and multifamily residences along with nearly 20,000 commercial and industrial customers.

The bureau’s climate resiliency plan is designed for the long term to protect the quality of its water and to safeguard the infrastructure by which it is delivered. Leading that effort is Kavita Heyn, climate science program manager, who spoke about the effects of climate change on water, stormwater, and wastewater agencies in an interview with Treatment Plant Operator.

TPO: What would you say to someone who would deny that the climate is changing?

Heyn: Warming is happening right now, and we’re seeing the impacts in many parts of the country. Climate change is not something in the far-off future. It is affecting us right now, and it puts at risk our ability to ensure a future of reliable and safe water for our communities.

TPO: How resilient is your water utility?

Heyn: We are quite resilient because we have two supply sources, a surface watershed called the Bull Run and a groundwater system as an emergency backup and secondary source. That helps us with both short-term and long-term climate resiliency. So we’re very different from the typical arid western systems that are the focus of most climate change stories.

TPO: What specific climatic changes do you see affecting Portland’s water system?

Heyn: The loss of snowpack and earlier snowmelt will change the natural way our watershed responds during the seasons. The timing of rainfall, especially the return of fall rains, is important because our reservoirs fill primarily from those rains. We want to know at the end of the summer season that we will get the return of the rains. If those assumptions are changing, significantly, that can be problematic for how we manage our reservoirs and treatment plants.

TPO: To date, have you actually experienced any of these types of impacts?

Heyn: Extreme years like 2015, which was a snow-drought year in the Pacific Northwest, are important indicators of what a warmer future will mean for the region and our drinking water system. Ski resorts and mountains in the Northwest had no snow through most of that winter. Temperatures were high from winter to fall, and stream flows in the spring and summer were historically low, leading to hydrologic drought conditions. While our system and reservoirs are not solely dependent on snow and refill from fall rains, we still experienced our earliest and longest reservoir drawdown. However, because of the resiliency of our supply, we used our groundwater source as a supplement in that year.

TPO: What other kinds of impacts can a warming climate have on water systems?

Heyn: Something many people don’t think about as much is what happens to water quality. When you have warmer water, treatment processes can become more complicated. You can have an increased risk of nitrification and algae blooms in reservoirs and disinfection byproducts in the distribution system. If your treatment systems haven’t been designed to account for those things, that can be costly and challenging.

TPO: Apart from supply and quality concerns, what about potential effects in physical infrastructure?

Heyn: Pump stations, conduits, pipes, and treatment plants could be exposed to higher sea level storm surges, stronger hurricanes, bigger wildfires, and heavier floods. Those assets could be damaged, so thinking about the risks is very important. There are lots of ways to adapt to a changing climate.

TPO: What would be some examples?

Heyn: A water district in Texas was seeing record air temperatures and lake temperatures in 2011, and their pump motors were overheating. They installed new cooling systems that don’t require lake water for cooling. The new cooling systems can operate at higher temperatures. New York City is another example. After Hurricane Sandy, they redesigned some wastewater pump stations that failed because the electrical components were underground. The new design raised those components so they are not inundated in future floods or storms.

TPO: What is the history of your climate resiliency program?

Heyn: We’ve been planning for climate change for over 20 years. The water industry is really the canary in the coal mine for climate change because climate affects water resources so directly. So we have to think about the changes and plan for a long time in the future. We’ve spent a lot of time building internal capacity to do this work. As challenges and surprises affect our systems, are there people in the utility thinking about the vulnerabilities and planning for and responding to them? An important part of our history is that we’re a member of the Water Utility Climate Alliance. In that capacity we’re helping to develop resources and tools for the whole water sector to plan and prepare for climate change.

TPO: What specific actions have you taken so far to address climate resiliency?

Heyn: To date we haven’t undertaken any on-the-ground concrete projects solely because of climate change, but we’re preparing in different ways. One is to plan for multiple futures, which means planning for potential drought as well as floods, and to make sure our infrastructure and systems are flexible to deal with those conditions. We’re integrating climate change into our state-mandated water supply plan, and we’re trying to understand through modeling how climate change will affect variables like water supply, water temperature, and extreme rainfalls.

TPO: Do you see a good level of awareness across the industry about climate change and the need for resiliency?

Heyn: A lot of larger water systems are addressing the issue in very progressive ways. For smaller systems, resiliency can be challenging because they don’t have secondary backup supplies, and they may not have the staff resources to really think about the issue. That’s why we advise operators and engineers in those systems to look to groups like the Water Utility Climate Alliance for advice. Other water utility groups like the American Water Works Association can also be good resources to learn from.

TPO: What kind of timeline should utilities be thinking about in addressing climate change resiliency?

Heyn: If you’re building infrastructure to last many years, then you want to consider the longer-term changes that are likely to occur. If you’re building things now and you don’t know exactly what is predicted, then the important thing is to build some flexibility and modularity into those systems so you can deal with a variety of conditions that may occur.

TPO: What would be a couple of examples of building in flexibility? 

Heyn: Speaking hypothetically, you could build a pump station with a certain amount of capacity but with the ability to add more capacity later if you’re worried about bigger rain events. Another option would be to plan for another source of supply even if you don’t need it right now. Know what alternative sources are available, and keep those options open in case you should have to bring them online.

TPO: How can a utility model for its needs in the face of so much uncertainty about the precise challenges climate change may bring?

Heyn: We’re basically carrying out an unprecedented experiment on our planet. We can’t know for sure exactly what will happen. Models are useful and can indicate a range of changes that might occur. That’s where it goes back to planning for multiple futures and multiple conditions. It’s also helpful to know the vulnerability of your system. What has made it fail in the past? Was it a flood? Or a storm surge? That will help in assessing what increased risk might exist in the future.