City completes four years of water reservoir improvements

MI to receive Puget Sound Energy grant.

By Andy Nystrom • September 29, 2025 8:30 am
Workers survey the scene during the city’s water reservoir improvements project. Photo courtesy of the city of Mercer Island
Workers survey the scene during the city’s water reservoir improvements project. Photo courtesy of the city of Mercer Island

A four-year city of Mercer Island project in the water reservoir improvements realm is in the books.

At the Mercer Island City Council’s Sept. 16 regular meeting, City Manager Jessi Bon announced that in August, crews put the finishing touches on four years of continuous construction and reinvestment at the reservoir.

The facility — which features two, four-million-gallon steel tanks containing potable water from Seattle Public Utilities — is located between 88th and 89th avenues southeast at Southeast 44th Street.

“We’re really proud of this work and we thank you, council, for your leadership and investment in this critical infrastructure over the last four years,” Bon said during her report.

Crews constructed a chlorination booster station; replaced the emergency power generator and all electrical panels; recoated the inside and outside of both tanks (needs to occur every 20 years); installed new stairs and safety railings; and replaced the five main pumps and installed two new and smaller jockey pumps.

Both tanks stand approximately 32 feet high and reach about 150 feet in diameter. Crews constructed the north tank in 1962 and built the south tank in 1975, and both tanks were seismically enhanced in 1999, according to the city’s website.

Mercer Island’s Public Works team will give a complete rundown of the capital project program at city council’s Oct. 20 regular meeting.

SUSTAINABILITY SCENE

On the sustainability front, the city of Mercer Island will receive a $10,000 Puget Sound Energy (PSE) grant for reaching — and exceeding — its 100-resident/business signup goal by notching 108 enrollments in PSE’s Green Power Program.

The grant will contribute to a new community solar panel project, which has yet to be determined, according to Bon. She noted that a discussion regarding the project will take place soon with city council.

For the last couple of months, Bon said that the city’s sustainability program manager Alanna DeRogatis worked on the PSE Green Power Challenge that matches electricity use with renewable wind and solar energy.

These actions help advance the city’s Climate Action Plan goals of reducing greenhouse gas emissions 50% by 2030, 75% by 2040 and 95% by 2050 (compared to 2007 levels), according to city documents.

“Be an inspiration as a leader in sustainability and environmental stewardship. The city of Mercer Island and its residents will serve as a model and set an example for other communities to follow,” reads the PSE website’s Green Power Program page.