by: Jonathan House, Spencer Finnan, center, and Jason Nelson of Henderson Land Services move dirt while crafting a new tributary that will flow to Tryon Creek.

Repairs to a series of outdated pipes are part of the latest upgrades to Lake Oswego's surface water system, made in part to improve the health of local rivers, lakes and streams.

The projects, funded by bonds against the city's surface water utility, are part of a continued effort to shift work in Lake Oswego's surface water system from flood prevention to water quality.

The utility carries water away from streets and buildings to one of three waterways locally: Oswego Lake, the Willamette River and the Tualatin River. It is a significant contributor to phosphorus buildup in Oswego Lake, where the nutrient causes algae growth.

Through a $345,000 contract with Henderson Land Services, work recently began on nine outdated pipe outfalls that funnel water in the system - typically rainwater - through the city to local tributaries.

The pipes are located in backyards or in natural resource areas and emerge from the underground system into either Springbrook or Tryon creeks or their upland tributaries.

The aging outfalls are causing soils around the pipes to erode, forcing dirt to travel downstream, which brings with it nutrients and other materials that can be harmful to waterways and aquatic life.

'The overall goal is facility stabilization because what is happening is many of these were built back in the 70s when these developments were built,' said Rob Amsberry. 'What we're seeing now is a failure to the systems installed in the 60s and 70s.'

To improve those, crews will restore the water outfalls to mimic natural stream behavior. In doing so, they will grub out nonnative plants, clear stream channels, excavate and define those channels, then stabilize them using rock material and fabric. Native plantings will ultimately hold the new streambed in place.

'They will be back in the end of October, early November to do all of the plantings and get those in as the rain season picks up,' Amsberry said.

On most projects, neither the summer nor the wet-season work will garner much attention. Most will occur in wooded areas or on private property upstream of Springbrook and Tryon creeks.

But work on Country Club Road will cause big changes, requiring removal of 51 trees to make way for improvements to an outfall on a tributary of Springbrook Creek. It will also involve installation of new pipe along the road, as well as curbs and a sidewalk on both Country Club and Boones Ferry roads. Bike lanes will be unchanged by the construction but the project is expected to cause traffic delays. It will be constructed in tandem with a median on Country Club Road.

On Kerr Parkway, replacement of an underground pipe near the road's intersection with Grotto will also close one lane of traffic.

Projects will also stabilize outfalls off Hide-a-way Lane, two behind Briercliff Lane, one at the north end of Bonniebrae Drive and one on Atwater and Woods Drive. A tenth project near the Hope Community Church is also in the planning stages.

The repairs complete a series of upgrades prompted three years ago by an assessment of outfalls in the Tryon Creek and Springbrook Creek basins. At that time, about 35 of approximately 90 outfalls warranted repairs in those basins. Twenty-five have been completed over the last two years.

As the final 10 projects move forward, about 300 outfalls outside the Tryon and Springbrook creek basins are also scheduled for assessment. Additional repairs are likely as upgrades to the surface water utility move forward. Details on related traffic delays will be posted at the project locations.

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