City plans to clear ditch to lower flooding risk

July 27, 2010

By Warren Kagarise

Pickering Place drainage ditch

The city plans to clear a silt- and weed-choked ditch in Lake Sammamish State Park to protect city streets and sidewalks — as well as Pickering Place businesses — from flooding.

The former agricultural ditch near the park’s soccer fields handles storm water runoff from Pickering Place and the retention pond behind Costco corporate headquarters.

Blockages in the ditch have caused water to back up into the pond and inundate area sidewalks. Rainfall last winter caused the water level to rise and nearly swamp nearby electrical equipment.

City Surface Water Manager Kerry Ritland said deferring maintenance on the ditch could cause worse flooding in the future.

Though the ditch runs through the state park, the city, state and Pickering Place Owners Association agreed last year for the city to maintain the waterway.

Ritland has requested $90,000 to complete the project by late summer. The property owners group provided $150,000 for the project.

Because the city had already earmarked $60,000 for the effort, Ritland asked to steer the additional $30,000 from a city storm water fund.

Though the city had budgeted $60,000 for ditch maintenance, King County — the permitting agency for the project — required native plants to be added to the site as a condition for approval. Permitting costs also mounted.

Moreover, Lake Sammamish State Park has restrictions on access to the ditch, and King County has strict rules outlining construction in environmentally sensitive areas — both factors in the cost increase.

City Council members approved the expense July 19.

Crews from Pacific Northwest Earthworks, a Fall City company, should start work by late August. Ritland said workers plan to rip out reed canary grass and plant willows along the ditch to shade the area and prevent the invasive grass from taking root in the future.

Crews updated the old agricultural ditch in the 1980s as part of the Pickering Corporate Park project. The development had responsibility for maintaining the ditch. In 2002, water backed up from the ditch to 11th Avenue Northwest and into the Costco pond.

But a dispute ensued as to whether the Pickering Place Owners Association — the successor to Pickering Corporate Park — should be responsible for maintenance.

In the end, the city, state park and property owners group agreed the city should handle maintenance, because the flooding from the ditch puts public roads at risk. City Council members approved the agreement last September.

Warren Kagarise: 392-6434, ext. 234, or Comment at

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