Stormwater Wetlands


Stormwater runoff from downtown Arlington, approximately 286 paved acres, discharges into Arlington’s Stormwater Wetland Park where it is naturally treated through four wetland cells before entering the Stillaguamish River.   And while the Stormwater Wetland appears well developed and may look as though it has been here forever, there is a history that precedes the construction of the Stormwater Wetland Park.  

The Stormwater Wetland Park location was a village of the local Stoluck-wa-mish River Tribe (Stillaguamish Tribe of Indians) called Skalbalko prior to European settlement. The Stillaguamish Tribe had many camps and villages along the river and in the Arlington area. This location was used as a hunting and trading camp when traveling up and down the river to other villages. In 1855, the Stillaguamish Tribe signed the Point of Elliott Treaty and some members moved to the Tulalip Reservation while many stayed along the Stillaguamish River. In 2014, the Stillaguamish Reservation was established northwest of the former Skalbalko village.

In 1851, settlers of European descent (prospectors) began exploration of the future Arlington area; this was soon followed by construction of a U.S Army trail in 1856. The first store opened up by the forks of the Stillaguamish River in 1888 in what was then Haller City, the opening of a hotel followed several months later.

With the proximity to the river and the booming logging industry, the Stormwater Wetland property became the site of two Haller City shingle mills in the 1890’s. The shingle mills operated until the 1920’s when the logging industry declined.

Records indicate that the Hammer family started to actively farm the land in 1927. In 1945, Curtis Hammer acquired the property from his parents and established a dairy farm on the property which had 34 head of Holstein milking cows and produced 250 gallons of milk a week for Darigold.  The farm facilities included a barn, milking parlor, tool shed, and pump house.  The Hammer family ran the farm until Mr. Hammer retired in 1965. In 1970 the family built what was known as the “roundhouse” using the original shingle mill incinerator foundation.  The Roundhouse has recently been removed; the shingle mill incinerator foundation has been preserved and will now remain a part of the Stormwater Wetland Park.

In 1965, after retirement, the Family began to lease the property to other farmers until 1990. From 1990 to 2000 little is known about what the land was used for, but aerial images show that it was farmed for agricultural purposes. In 2000, the City purchased the Stormwater Wetlands Park property from the Hammer/Butler family with the intent of creating a natural Stormwater Wetland Treatment Facility.  Design and permitting of this facility began in 2008 with construction completed in 2011.   

What Does the Wetland Do?

The 10-acre constructed stormwater wetland provides outdoor recreation opportunities for the public and enhanced wildlife habitat, while naturally treating stormwater runoff. The constructed wetland treats stormwater from Arlington’s “Old Town” Downtown drainage basin and reclaimed water from the City’s Water Reclamation Facility before it is discharged to the Stillaguamish River. The wetland will serve as an ecological connection between the existing Washington State Department of Transportation wetland mitigation area and the Stillaguamish River corridor. 

The wetland is designed with four cells that provide various stormwater treatment ranging from nutrient uptake to temperature cooling. As the wetland vegetation grows and matures, it begins to provide an urban habitat for birds and other wetland wildlife. A 4,200-foot trail network includes three pedestrian bridges over the weir structures and provides a relaxing area for hikers to walk. Wayside exhibits and viewing areas will inform visitors of the environmental benefits of an urban stormwater wetland.

WETLAND CELL 1 ​Wetland Cell 1 provides a short-term holding area for newly collected stormwater. Stormwater will be detained in this initial storage cell, allowing suspended solids and associated nutrients and toxicants to drop out of the stormwater.​

WETLAND CELL 2 ​Wetland Cell 2 provides storage and increased retention time for interaction with soils and vegetation for nutrient cycling. Increased stormwater storage in this cell will help to reduce peak flows to the Stillaguamish River, as well as provide relief from periodic river flooding during storm events.​

WETLAND CELL 3 ​Wetland Cell 3 provides additional storage and treatment. Increased retention time improves water quality by allowing more time for sediment to be filtered out and deposited. This cell will offer a mixture of shade trees and exposed areas. Light exposure, through the sun’s ultraviolet radiation, helps to reduce bacteria, shade is beneficial for temperature moderation.​

WETLAND CELL 4 ​This wetland cell will serve primarily as a conveyance of naturally treated stormwater to the river corridor. Stormwater in this cell will splash over rounded cobble channel which will aerate the water and raise the amount of dissolved oxygen before discharging to the Stillaguamish River. Dissolved oxygen is crucial for fish and aquatic organisms.​

Upcoming Projects

  • TBD - Repairs to bridges and weirs.

Completed Projects

  • 2021/2022 Maintenance - The Arlington Stormwater Wetland Park had a number of projects to maintain, restore and improve functionality of the wetland and to enhance the experience for public activities.  The projects included the removal of sediment in Cell 1, the removal of invasive species and planting of native species and replanting of a Native Growth Protection Area.
  • Roundhouse Demolition - Due to continued vandalism over the years the roundhouse had become unsafe and needed to be removed for the safety of the community.  The roundhouse demolition began on Monday, July 24th and was completed by August 4th. The city was able to save the foundation of the roundhouse which was the original incinerator foundation for the shingle mills located in Haller City (circa 1890’s). The city has reached out to the Arlington Arts Council for ideas on how this foundation can be preserved and incorporated into an art exhibit or Stormwater Park feature.