Cannon Hill Park may be a beloved and classic example of an Olmsted Brothers park on Spokane’s South Hill, but the pond at its center has quickly become a point of contention for its neighbors.
This summer, the pond became muddy and opaque, leading local residents to question why. Some of them blamed swales along nearby Lincoln Street, said Park Director Leroy Eadie.
A recent report from AHBL, a green infrastructure firm, said this isn’t true. Treated stormwater from Lincoln Street accounts for less than 2 percent of the pond’s entire volume on an average year. In 2013, that amounted to 390,000 gallons, said Marlene Feist, the city utilities spokeswoman. A really wet year will bring that total up to about 8 percent.
Len Zickler, a landscape architect with AHBL, told the Spokane Park Board last week that treated stormwater was not muddying the pond water.
“I’d like to dispel that perception,” he told the board. AHBL was involved in landscaping the swales. The city’s utilities department paid AHBL about $3,000 for the Cannon Hill pond study.
The swales, or storm gardens, are part of the city’s integrated effort to divert stormwater from entering, and overwhelming, the city’s treatment plant. The swales, which were built in 2010, take in rain water, filter it through organic matter and put some of it into the pond.
Shallow water and recent extreme temperatures are more likely the culprit, Zickler said. The park was designed by the Olmsted Brothers, a New York landscape architecture company that laid the groundwork for much of the city’s park system. The Cannon Hill pond has historically been used as a skating pond in the winter, due to its 18-inch depth. For comparison, the duck-filled Mirror Pond at Manito Park is more than 6 feet deep. Zickler also pointed to a cold winter and hot summer as factors. February was a cold month, and this past summer was one of the hottest Spokane’s had in a decade.
Still, the Cannon Hill pond has long been lauded as fresher than its peer in Manito. Part of the reason for that is its leaky nature, causing the loss of so much water that every year it must be refreshed with millions of gallons of water. Last year, almost 18 million gallons of domestic water went to the pond. In 2009, 28 million gallons were used.
In his presentation, Zickler recommended a number of solutions, which included making the pond deeper to increase aeration and lining it with Bentonite to prevent water loss. He also suggested letting treated stormwater continue going to the pond.
“We just want cleaner water,” Zickler said, noting that it was still unclear what was causing the muddy water at Cannon Hill Park. Even without a definitive answer, Eadie was thankful for Zickler’s work.
“You busted the myth that it’s a stormwater concern,” he said.
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