HomeCommunityCarmel Wastewater Treatment Plant facing move due to potential impacts of sea level rise

Carmel Wastewater Treatment Plant facing move due to potential impacts of sea level rise


Built in the 1930s and tucked off of Highway 1 just 2,500 feet from the ocean, the Carmel Wastewater District Treatment Plant is surrounded by cottonwood trees. In the year since the California Coastal Commission told the district they may have to relocate due to sea level rise, a threat many districts up and down the coast are facing, the agency has been evaluating potential options which mitigate cost to the community and maximize efficiency.

Wastewater District general manager Barbara Buikema explains that most of the community may not be aware of what the Wastewater District does, much less the fact that they are considering moving due to the impacts of climate change.

“This community may not have developed in the way that it has were it not for the Wastewater District,” Buikema explains. “We made some of the development possible… We’re critical to public health and safety.”

The facility reclaims roughly 1.2 million gallons per day and 1,000 acre feet of water annually, about one-tenth of the total water used by the Monterey Peninsula. The major components of the Wastewater District include maintenance of sewer lines and reclamation of wastewater from their service area, which extends as far as Quail Lodge in Carmel Valley and as far south as Carmel Highlands, though they are looking to expand.

The majority of water treated at the plant is pumped to Pebble Beach to irrigate the community’s golf courses, which, as Buikema points out, are a significant asset to the economy of the Carmel/Pebble Beach Area. The salty water left over after each step of treatment is pumped into Carmel Bay, and the health and biodiversity of the site are closely monitored.

According to plant engineer Patrick Treanor, the plant was built to withstand fluvial flooding from the Carmel River, the last occurrence of which took place during the ‘90s. The projected intensity of future floods due to sea level rise could be more than the site can handle. As Treanor explains, the plant was not engineered to sit in water.

Due to its proximity to the Carmel River Lagoon, the facility could potentially be facing three types of flooding over the next few decades as sea levels continue to rise. There is a threat of backwater lagoon flooding, closed lagoon storm flooding and fluvial flooding, when extreme weather events cause the river to overflow. To avoid these possibilities, Buikema says, the district and the California Coastal Commission have agreed on a three-part plan.

“We will submit within one year a short-term coastal hazards plan that will identify all the hazards that we see at our location,” Buikema explains. “We are going to monitor conditions like lagoon levels, sandbar levels, river flow, all the things that could potentially have an impact. And we have to come up with a plan or a solution.”

Part of the primary stage of wastewater treatment at the Wastewater Treatment Plant in 1955. Courtesy of BARBARA BUIKEMA

As of now, the solution looks like it involves relocating the plant in some way or another, the timeline of which is around 40 years. Even so, for a project of this scale, planning and research have already begun.

The Wastewater District is looking at three potential options: connect Carmel’s underground infrastructure with Monterey One, the wastewater treatment plant that serves the majority of Monterey Peninsula and is located in Marina; relocate Carmel’s treatment plant to higher elevation; or break up the treatment plant into “package plants,” which are smaller and located throughout the community. The current treatment plant is gravity-fed, and all of these alternatives would involve installing more pumps throughout the community to move the water uphill.

According to Buikema, Morro Bay is currently in the process of relocating their wastewater treatment plant, a project which has cost about $175 million. If Carmel were to relocate, she says the total cost would be similar. Of the three options, Buikema estimates that nothing would cost under $100 million to fund. The immense cost is the primary reason for the Wastewater District’s meticulous analysis of coastal conditions and safety.

“I want to be sure that this district makes the right decision that’s best for the community,” Buikema says. “It has to be a science-based decision.”

She says the Wastewater District would look for grant money to help fund the project down the line, but some of it would be financed by increased user rates. Buikema and Treanor emphasize that the plant is in no immediate danger, and that, according to a sea level rise study, the plant still has roughly four decades to come up with funding and a plan to move.

In upcoming years, the Wastewater District plans to seek input from the community and open up the issue to public comment. Buikema emphasizes that agencies similar to the Carmel Wastewater District are dealing with similar obstacles due to climate change.

“Sea-level rise is going to happen,” Buikema says. “You can Band-Aid it for a little while…but I don’t think you can ignore it.”

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