Walking on Water: Creating Parks over Reservoirs

Mobile Workshop

Explore Seattle’s innovative transformation of open-air reservoirs into stunning parks, a trend initiated in the early 2000s, downstream of Cedar River and Tolt River source water treatment facilities. These unique spaces provided the opportunity for interdepartmental collaboration, giving rise to four remarkable parks, with more in the works.

This tour will explore two of the four sites, offering picturesque views and insights into the development processes. Cal Anderson Park is the site of the city’s first major lidded reservoir park project was originally designed by the Olmsted brothers and today is the neighborhood epicenter of Seattle’s Capitol Hill.  In 2020, it was the site of a controversy occupied by protestors during the height of the country’s movement for Black Lives. Lessons learned from this project informed the lidding of Jefferson Park. 

Jefferson Park, the decommissioned reservoir that had been surrounded by barbed wire for decades, creates a framework forming a lattice of Olmsted-inspired walkways and dramatic city views of the Olympic Mountains. The resulting 35 additional acres of parkland both preserve the utility function and provide space for a community gathering space, a skate park, and an expansive stormwater feature, much of which is constructed over a six-acre lidded reservoir. The re-purposing of this space adds 35 acres of new parkland while maintaining utility function.


  • Outline a successful series of interdepartmental collaborations resulting in a significant net increase in public open space.
  • Identify the technical constraints and resulting design and construction challenges of parks built on reservoir lids.
  • Discuss how local communities were crucial in fundraising and shaping park design, influencing amenities like off-leash dog areas and community gardens.
  • Discuss with colleagues about interdepartmental partnership opportunities for expanding urban open space.