New treatment plant increases Alaska community’s climate resiliency

In Sitka, Alaska, accelerated glacial melt and record-setting rain events are creating an unprecedented climate challenge: increasingly turbid source water. This cloudiness is intensified by the glacial silt that rising and falling water levels draw into Blue Lake Reservoir, the city’s primary source of water.

The small coastal city of about 8,500 people receives an average of nine feet of rainfall per year. Because turbidity can harbor harmful bacteria and other contaminants, an increased level can pose a serious threat to public health.

To address this challenge, Sitka’s water department has built a new treatment plant designed to adapt to climate change. The plant has a microfiltration membrane system with a series of tiny pores to trap contaminants, including turbidity. This allows Sitka to maintain its filtration avoidance waiver and not have to filter its surface water source year-round, saving a significant amount of money in operating costs.

“We were dangerously close to losing our filtration avoidance waiver,” said Shilo Williams, environmental superintendent with the City and Borough of Sitka. “The new membrane plant allows us to put filtration into service during times when source water turbidity is elevated. This helps us to protect the health of our community and ensure that we have access to clean water, even in the face of climate change.” (Pictured from left, inside the facility, glacial silt impacting turbidity, Blue Lake Reservoir.)

The plant also uses an onsite sodium hypochlorite generation system, which is a safer and more environmentally friendly way to disinfect the water than the previous chlorine gas disinfection system. The new system eliminates the risks associated with transportation and storage of hazardous chemicals and reduces the plant’s environmental footprint.

Community engagement key to project success

Public outreach and community engagement played a crucial role in the success of the Sitka water treatment plant project. The city conducted public meetings, presentations and work sessions to ensure the community was informed and engaged, especially given the impact of the project on water rates.

“Beyond public meetings, we also posted presentations and fact sheets online, avoiding technical jargon to ensure our message was accessible to everyone,” Williams said.

To fund the project, Sitka raised water rates by 22%, which translated to an $8.62-per-month increase for customers. The city also took advantage of a low interest loan program through the Alaska Department of Environmental Conservation State Revolving Fund to help finance the project.

“Overall, the treatment plant ensures that we can consistently provide our community with high-quality drinking water, even during times of elevated raw water turbidity, which might have been a challenge in the past,” Williams said.