Case Study

Stormwater Pond Vegetation Clearing Restores Compliance in Bothell, Wash.

Bothell, Wash.

Commercial

Pond Management Services

A commercial property in Bothell, Wash. experienced overgrown vegetation and accumulated debris that restricted access and water flow within its three-cell stormwater pond system, prompting a city maintenance order. The property owner contacted AQUALIS to clear the pond, restore the hillside drainage path feeding the system and inspect critical stormwater infrastructure.

Overgrowth Restricts Access and Stormwater Flow

During an inspection, the City of Bothell found the pond banks heavily overgrown with saplings and invasive blackberry bushes. The city issued a maintenance order, sometimes called a notice for corrective action, requiring the property owner to clear the vegetation and maintain proper stormwater flow, with civil penalties possible for continued noncompliance.

Once onsite, AQUALIS stormwater experts found that the property likely had not been maintained or inspected in years. Manholes were buried beneath dense brush, downed trees had accumulated within the pond and logs, sediment and debris associated with beaver activity were blocking the hillside drainage path.

This hillside channel, also known as a conveyance path, carries stormwater runoff into the ponds. When the channel becomes blocked, water cannot move through the property as designed. Dense vegetation can also bury manholes and other infrastructure, making routine inspection and maintenance more difficult.

manhole before and after vegetation removal

Clearing the Pond and Restoring Drainage

AQUALIS began by locating the buried manholes and clearing the drainage line. Crews used a vacuum and jetter truck to remove accumulated material and flush the pipe with high-pressure water. Clearing the line lowered water levels within the ponds and provided better access for the remaining work.

Crews removed invasive blackberry bushes and saplings from the pond banks and winched downed trees from the water. Trees and vegetation were chipped on site before being hauled off for disposal.

As clearing progressed, crews identified the overgrown hillside above the ponds as the drainage path feeding the system and shifted their focus uphill. They removed logs, sediment and debris that restricted the movement of stormwater. Wattles, rolls of natural fiber placed along the ground, were installed to help keep loose soil from washing downhill and entering the ponds during the work.

AQUALIS inspected the pond’s control structure, the concrete chamber that controls how quickly water leaves the pond. The structure was in good condition and did not require repairs.

After clearing was complete, crews repaired areas affected by beaver activity, seeded exposed soil and installed erosion control matting along the hillside. These erosion control measures help keep newly exposed soil in place while vegetation becomes established, reducing the potential for erosion and additional sediment buildup in the ponds.

AQUALIS also coordinated directly with the City of Bothell throughout the project to support the property owner’s compliance efforts.

Restored Flow and Improved Maintenance Access

The completed work satisfied the city’s maintenance order and restored access throughout the stormwater system. Pond banks were cleared and stabilized, and previously buried manholes are now accessible for future inspections and maintenance. Obstructions were also removed from the hillside drainage path.

With the drainage path open, stormwater once again moved down the hillside and into the ponds as designed. Soon after, water levels in the ponds began to rise, showing that stormwater from the hillside was reaching the system again.

With the system restored, the focus now shifts to keeping it that way. Routine stormwater inspections and vegetation management will help the pond stay accessible, functional and compliant long term.