According to a U.S. Army Corps of Engineers report released late last week, the price tag to address floodplain issues, wetland and creek restoration and habitat enhancement projects at Mountlake Terrace’s Ballinger Park is approximately $5.4 million, up almost 10 percent from the estimated cost five years ago. 

But the report is also a harbinger of what is coming for the 55-acre park space located on the north shore of Lake Ballinger.

City officials asked the Corps of Engineers to study the area and determine a plan of action that would benefit the entire watershed made up of Ballinger Park, Hall Creek (that runs north to south through the park) and Lake Ballinger itself. The finished report spells out a plan that “would include wetland, stream channel and riparian zone restoration, benefiting fish and wildlife in and around Hall Creek and in Lake Ballinger.”

The report provided seven alternatives that could be pursued for park improvements, ranging from taking no action at all to an elaborate plan that would include invasive plant removal, creek improvements and additional creek channels throughout the site, including to the far north reaches of the park where a tennis court and playfield now sit. 

The alternative chosen by the report as the desired plan-of-action is Alternative 5. It includes invasive plant removal, extensive creek and channel improvements — among them the addition of a second parallel channel to Halls Creek but none in the north sector of the park — plus pond enhancements and the planting of wetland vegetation.

The $5.4 million cost to pay for the implementation of Alternative 5 would be split, with the Army Corps of Engineers covering 65 percent and the City of Mountlake Terrace the remaining 35 percent.

The biggest modification to Ballinger Park spelled out in the preferred plan may be the digging of an additional channel for Hall Creek just west of the creek’s current path. A new channel would be dug out starting near the Mountlake Terrace Senior Community Center building. The soil removed for the new channel would be repurposed into hummocks — raised mounds in the park that would “provide a place for upland plants to thrive as well as help control movement of people around the site to protect sensitive vegetation.” 

The new channel would be approximately 925 feet long and would follow “natural lowland contours of Ballinger Park.” The report cites the need for the new channel as Hall Creek, due to “decades of degradation,” has lost almost all of its “hydraulic diversity.”

Other major changes that would come with a new channel for Hall Creek include the plugging of the current creek where it flows into Lake Ballinger and the construction of a new pedestrian bridge over the creek to support pedestrians and emergency vehicles.

The report also emphasizes a plan to build a pedestrian boardwalk along the north shoreline of Lake Ballinger running east to west in the park. The boardwalk would be 400 feet long, set on top of wood or concrete footings and would be elevated in some  portions. “The use of boardwalks to control access and protect native riparian communities is a common activity and will greatly enhance the survivability of the restoration site,” the report stated.

The preferred Alternative 5 plan also calls for large scale removal from the park of invasive plants such as scotch broom, blackberry, knotweed and canary grasses; the eradication of the unwelcomed vegetation will likely require use of herbicides, the report warns.

With the Corps of Engineers report now completed, design and engineering planning is expected to ramp up according to a timeline previously released by City of Mountlake Terrace officials. Construction on aspects of the Hall Creek restoration and rechanneling could begin as early as summer of 2021.

The full 130-page Corps of Engineers report titled “Lake Ballinger Aquatic Ecosystem Restoration Project Draft Feasibility Report/Environmental Assessment” can be viewed at www.nws.usace.army.mil/Missions/Environmental/Environmental-Documents/. Comments on the report can be made to Michael Scuderi, US Army Corps of Engineers Environmental Coordinator, at michael.r.scuderi@usace.army.mil by May 26.

— By Doug Petrowski