Note: the information presented below was prepared with the help of SRA’s professional wetland biologist, Suzanne Tomassi of The Watershed Company.
What’s going on at the Sammamish Rowing Association facility?
SRA is building a new boathouse in Marymoor Park. It will replace the existing boathouse, which has been used by rowers for three decades. It will be located just behind the existing boathouse, but on higher ground. Utilities for the new boathouse will be routed underneath the gravel path leading to the boathouse. The footprint of the new construction is slightly more than 17,000 square feet.
The new boathouse will not disturb any of the wetlands on the property; it is being built completely within the wetland buffer. A significant amount of mitigation will be done as part of this project. The mitigation includes more than 88,000 square feet of wetland buffer improvement, nearly 74,700 square feet of wetland restoration and improvement, and almost 5,000 square feet of wetland reestablishment. That’s more than three acres of mitigation!
A temporary trail through an area vegetated with invasive reed canarygrass provides access to the existing boathouse during construction. This and any other area that is temporarily disturbed for construction purposes will be restored to native habitat.
What’s mitigation and what can I expect to see after it’s complete?
Mitigation is compensation for unavoidable impacts to critical areas and their buffers.
What’s the extent of the mitigation?
Mitigation measures will remove invasive species from the property and replace them with native trees and shrubs. This will restore areas disturbed by previous land uses to wetland or functional wetland buffer.
For example, a raised berm that was part of a sewage treatment plant that used to be on this site artificially separates two wetlands. This berm will be removed as part of the mitigation effort, restoring the hydrologic connection between the two wetlands. The berm area will be planted with native wetland trees and shrubs.
Today, the wetland north of the berm and its buffer are almost entirely infested with the invasive species reed canarygrass and Himalayan blackberry. Once these are removed, the whole area, all the way to the property boundary and west to the pond, will be densely planted with western red cedar, Sitka spruce, black cottonwood, Oregon ash, red alder, twinberry, Pacific ninebark, and other native species as appropriate for the wetland and buffer conditions. No native vegetation will be destroyed in these areas.
To ensure maximum survival rates, the whole area will be irrigated until the plants are established, and monitoring will occur for at least 5 years (longer if the site has any trouble meeting the stringent performance standards). By that time, a dense thicket of wetland and buffer will cover about 1.5 acres in this part of the site. A few years after that, young forest will blanket the area where presently there’s very little cover or forage for wildlife. The whole area will be contiguous with the Sammamish River and birds and other wildlife will be able to travel through it unhindered and undisturbed.
In addition to this completely reclaimed area, another approximately 2 acres of wetland and buffer will be improved on the property. All invasive species will be removed and replaced with native trees and shrubs. The enhanced areas include the wetland and buffer area along the Sammamish River, as well as other small wetlands that are separate from the large Sammamish River wetland. Debris placed behind the existing boathouse many years ago will be removed and the area will be restored. The road will be lined on both sides with very dense native vegetation. All of the restored and improved areas will be bordered with split-rail fencing and “Native Growth Protection Area” signage.
How is the mitigation going to be maintained?
New plants will be watered with a temporary irrigation system for at least two years, and longer if needed. At least twice a year, crews will remove all resprouting invasive species by hand and add mulch around plants where needed. Dead or dying plants will be replaced as necessary. Twice-yearly summaries of maintenance efforts and recommendations will be submitted to the City of Redmond. All mitigation areas will be required to meet maintenance goals until they are established.
All mitigation areas will be monitored yearly to make sure that they are making acceptable progress toward performance standards. Yearly mitigation reports to Redmond will include measures of vegetative cover, survival and health; extent of any non-native and invasive species; hydrology in the root zone; and wildlife use. The site must demonstrate progress toward written performances standards for each of these parameters; if yearly milestones are not met, additional actions (increased maintenance, more planting, contingency plans, etc.) will be taken. Only when the site has met year-five performance standards, regardless of whether this takes place in year five or requires additional time, will it be considered complete and successful. However, maintenance will continue as needed beyond the five-year monitoring period.
What will it look like when they’re finished?
The Sammamish River wetland and buffer will be expanded so that the property becomes home to a large, high-quality wetland and forested buffer, contiguous with the river across to south Marymoor Park and to Lake Sammamish. The most noticeable difference from the present state will be the conversion of a great expanse of blackberry and invasive grass to a young stand of native trees and shrubs. This is the area north of the access road. What might be less noticeable to people, but certainly not to wildlife, are improvements to the areas that are already forested, primarily the wetlands and buffers south and east of the road. All invasive species will be removed from these areas and replaced with native trees and shrubs. Large woody debris (LWD) will be scattered throughout to provide additional habitat value.
The open water ponds will be unchanged except for the addition of some LWD. The pond edges will be enhanced with native species where appropriate.
The new building and adjacent turn-around apron will be along the existing road and entirely surrounded by native vegetation. The road will be densely lined with native shrubs. All of the restored and enhanced area will be separated from areas of human use, including the building and the road, with wildlife-passable split-rail fence.
In the end, wetland buffer vegetation will be improved so that natural protection of the wetlands is greater than what is there today. In additional to improving the buffers as storm water control and water treatment features, the additional vegetative diversity and complexity will improve habitat. The overall area of available native habitat will be much greater than what is there today.
How many trees are being cut down? Will they be replaced?
Of approximately 590 trees originally on the site, 116 or 20 percent have been removed. Redmond allows the removal of up to 65 percent of significant trees, and more in some cases. Redmond regulations originally required that we remove many more trees, but we hired an arborist who examined every tree and recommended the removal of only those trees which would actually be damaged by construction. Cut trees will be replaced at a replacement-to-removal ratio of nine new trees for every removed tree. This is well above Redmond’s requirement of a one-for-one replacement.
No landmark trees will be removed. In total, 1,045 trees, 3,104 shrubs, and 3,480 live stakes will be planted.
What are you going to do with the cut trees?
The trees will remain on-site for wildlife use. A few large trees have been placed in the pond and are already very popular with wildlife – the green herons began hunting frogs from them almost immediately! All of the other large trees will be used as habitat features in the mitigation areas. Small trees and some branches will be chipped and used as mulch in the planting areas.
How and why was the building site selected? Why can’t the new boathouse be located elsewhere?
Our original site for the new boathouse was going to be just to the southeast of the existing boathouse. However, it turned out that we would have intruded on the wetlands on this location. We then looked at three other possible locations:
- Across the path, to the north-west of the existing boathouse. There was a relatively clear meadow on this location. However, we would have had to somehow carry boats across a Category I wetland in order to reach the dock. This would have required building a large and unsightly footbridge that was wide enough to handle carrying down an eight-person boat. We would have also had to build an entirely new road from the boathouse to the parking lot; a significant additional disturbance given that a road already existed.
- Near the parking lot. There is land outside of the wetland buffer between the pond and the parking lot. However, this location is simply too far from the river; it isn’t practical to carry boats that distance.
- Behind the existing boathouse, just up the path. This turned out to be the best location. The existing road can be used, there is plenty of space to build the boathouse and not intrude on the wetlands, and it is close enough to the river to be viable as a boathouse.
Isn’t the entire area by the river a wetland? It gets pretty wet in winter…
The largest wetland is contiguous with the Sammamish River, but not all of the area is wetland. Wetlands must meet specific scientific criteria in the areas of hydrology, soils and vegetation. Areas not meeting these criteria are not wetlands and do not perform the same functions as wetlands. On the project site, they do serve to protect wetlands and this is why SRA is implementing so many improvements to these “buffer” areas.
Sometimes non-wetland areas have standing water. This can be due to any of a number of conditions, including excessive rains, compacted soils, and past disturbance. Standing water alone does not signify a wetland.
What else did you do to avoid and minimize impacts, and what are you doing during construction to protect habitat?
After selecting the building location, we made certain that all wetlands, whether regulated by Redmond or not, were completely avoided. The building is designed with two stories to minimize the footprint and is placed as close to the road as possible to minimize buffer intrusion. Required fire safety features and utilities are to be placed within the existing road footprint and minimized to the greatest extent legally permissible. All construction materials are inert and non-leaching.
No wetlands are directly impacted by the construction, apart from the enhancement and reestablishment that will occur. Wetlands were carefully delineated by a team of qualified professionals, and the delineation was reviewed and approved. Wetland boundaries were marked by a surveyor, and clearing limits are tightly protected with storm water protection features. An approved back-up plan is in place, just in case an unseasonal storm event provides more water than expected. As a further protection measure, no exposed earth will remain on the site – any bare ground will be covered to prevent sedimentation when not actively being worked on. No earth will be disturbed by clearing or construction during the rainy season, and the site will be visited regularly to make sure that all protective measures remain in place and functional. As well, a biologist and a building inspector will be on-site during site preparation, construction, and mitigation implementation to make sure that all work is properly conducted.