The Hyla Crossing Pumped Stormwater Discharge project is necessary to preserve the ecology of the Tibbetts Valley basin. Upstream water quality units will treat the stormwater prior to discharge and improve the water quality of Tibbetts Creek and Lake Sammamish. Though much of the stormwater tributary to the pump station receives some level of antiquated water quality treatment, this project will provide a higher level of treatment in line with today’s strict water quality standards.
Protecting Lake Sammamish Water Quality -
The Facts Behind the Hyla Crossing Pump Station
Protecting Lake Sammamish Water Quality: Q&A
Q:
Why is this project necessary?
A:
Issaquah is growing, and this project is a demonstration of responsible growth. This project ensures that water runoff that ultimately reaches Lake Sammamish is managed, treated and monitored properly.
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Q:
What is the environmental/ecological benefit of this project?
A:
The stormwater pump station serves as a public benefit by enhancing public safety, protecting infrastructure and stream habitats, improving water quality, preserving public spaces, supporting sustainable development and demonstrating a commitment to environmental responsibility. These collective benefits contribute to the overall well-being and resilience of the community at large.
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Q:
How much will this cost taxpayers?
A:
The entire project is underwritten by private funds. Rowley Properties is privately funding the Hyla Crossing Pump Station’s development and construction and will deed the project over to the city which will operate and maintain the pump station. In addition, Rowley Properties is financially supporting a WSDOT stream enhancement in their right of way at request of the Tribes.
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Q:
Why are some opposed?
A:
Projects that have an impact to our lakes and streams are always sensitive issues, especially here in the Pacific Northwest where we all have a strong sense of ownership over the natural beauty of our environment. We believe that some have misinterpreted the facts about the project. In truth, this project presents positive outcomes for the environment through water treatment and local fish habitat protection and creation.
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Q:
Will the runoff impact water quality in Lake Sammamish?
A:
The Hyla Crossing Pump Station project uses state-of-the-art water treatment technologies in line with today’s strict water quality standards. The systems implemented may also help remove 6PPD-quinone, a chemical commonly expelled from vehicle tires that poses an immediate and deadly threat to local Coho salmon populations, by filtering runoff through soils.
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Q:
How much water will flow into the lake from the project?
A:
The Hyla Crossing Pump Station project does not add to the lake – it simply treats the water, removing pollutants that currently go untreated and bypasses excess stormwater around the lower reach of Tibbetts Creek. The same areas remain tributary to the lake.
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Q:
Will it affect lake water levels? Will it impact docks or other lake recreation?
A:
No, as proven in a detailed lake level study, the project will not impact lake water levels.
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Q:
Will the project disrupt traffic or cause other problems for residents and businesses?
A:
The development and use of the Hyla Crossing Pump Station does not pose any noticeable impact toward residents.
The local REI Headquarters and Satellite Office on Poplar Way will witness notable disruption from the pump station’s construction. Rowley Properties, the financier and constructor of the Hyla Crossing Pump Station project, leases this specific building. Prior to signing the building’s lease, Rowley Properties informed REI of the future disruptions and will be in communication with businesses and tenants that call Hyla Crossing home as the project proceeds
Construction will follow all City of Issaquah standards including working hours, noise ordinance, traffic safety and public notices.
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What and Where
The Hyla Crossing pump station is designed to collect, purify and pump stormwater runoff from the Issaquah area into Tibbetts Creek. Excess flow is then pumped to an existing pipe under Tibbetts Creek before making its way under Interstate 90 and towards Lake Sammamish to a near shore outfall.
The pump station will be located alongside Interstate 90 on NW Poplar Way, southeast of the Tibbetts Creek bridge within Hyla Crossing and is designed to blend in with the surrounding environment. The construction will not impact vehicle or pedestrian traffic.
Renderings are conceptual
The Details
The Tibbetts Valley Basin and Hyla Crossing Require Improved Water Management Infrastructure
Tibbetts Valley Basin is prone to flooding during heavy rains or snowmelt, which can cause erosion, property damage and put residents at risk. The stormwater pump station will protect and divert excess runoff away from roads, bridges, utilities and other public infrastructure to mitigate flooding and erosion.
The project also plays a crucial role in supporting sustainable urban development within Washington state’s Growth Management Act guidelines and boundaries. It allows the densification of Hyla Crossing within its current footprint and limits urban sprawl. The pump station will also enhance a 0.6-acre wetland buffer with native shrubs and trees and install a soft pedestrian walking trail with seating along Tibbetts Creek.
Beneficial to Fish Habitat and Water Quality
One of the most important contributions from the stormwater pump station is the treatment of stormwater runoff to today’s best available science as it re-enters Lake Sammamish. Filterra® and Modular Wetland® units remove suspended solids, targeted heavy metals and phosphorous from urban runoff by filtering it through a special blend of soils. The National Marine Fisheries Service found that filtering urban runoff through soil-based treatment systems can remove 6PPD-quinone, a toxic chemical found in vehicle tire residue that poses an immediate and deadly threat to local Coho salmon populations.
The project will also provide additional Tibbetts Creek stream habitat and wetland restoration within Sammamish Cove Park.
By managing stormwater runoff and reducing pollutants entering Tibbetts Creek and Lake Sammamish, the pump station contributes to significantly improved water quality for fish and other wildlife in the surrounding area.
Flood Mitigation for Public Safety
One of the primary goals of the stormwater pump station is its role in stream erosion reduction. Unmitigated urban runoff increases flow rates and volumes in streams causing stream bank erosion and sediment transport. The result of this erosion is sediment build up in the lowland and flatter stream sections. This is evident in the lower reaches of Tibbetts creek where the stream bed has risen due to sediment buildup.
Streams can experience increased flooding when sediment buildup gets high enough to reduce their capacity. The project reduces erosion in Tibbetts Creek by sending excess stormwater directly to its next destination, Lake Sammamish. As proven in a detailed lake level study, the project has no effect on lake levels as all runoff in the project area is already tributary to Lake Sammamish.
Public Benefit at No Public Cost
The construction of the stormwater pump station is funded entirely by Rowley Properties, a private commercial and residential realtor. This project will not provide any revenue for Rowley Properties and stands to benefit the greater community.
Upon project completion, Rowley Properties will deed the stormwater pump station and surrounding property to the City of Issaquah who will maintain and operate the station going forward.
In conclusion, a stormwater pump station serves as a public benefit by enhancing public safety, protecting infrastructure and stream habits, improving water quality, preserving public spaces, supporting sustainable development and demonstrating a commitment to environmental responsibility. These collective benefits contribute to the overall well-being and resilience of the community at large.
We want to hear from you
If you have questions or comments about the project, we want to hear from you. We are committed to responding as quickly as possible.