Full Exclusion Guide Nets 

Pacific Netting Products designed a full depth barrier net to guide down-stream migrating smolts to a Floating Collector System at Puget Sound Energy’s Upper Baker Lake. In 1985, the Skagit River annual adult sockeye returns had plunged to a low of just ninety-nine fish, imperilling the stock. For the next twenty years, Puget Sound Energy invested in habitat, hatchery and other methods to support the watershed’s fish populations and to improve downstream fish passage. In 2011 a survey showed a contributing reason for poor fish passage collection results was material and design failures of their existing partial depth barrier net. Pacific Netting provided a temporary fix and then worked with PSE engineers and their engineering firm MWH, as well as fish biologists, regulators, contractors and others. We helped them understand the benefits of advanced material and technology in meeting their goals, concerns and downstream migration objectives. Working under tight schedules with multiple stakeholder interests, PNP custom designed flexible exclusion and guidance screens that were built of high molecular weight polyethylene fibre. These screens had structural features to allow strength, shape and fish passage service during periods of high pool fluctuations. It went into service in 2012, in time for the outbound spring migration.

KEY FEATURES

  •  Full exclusion guide nets
  •  2,000 ft long x 300 ft deep, about 500,000 sq ft
  •  Built with 1/8” x 1/8” and 1/4” x 1/4” Dyneema® netting
  •  Designed for extreme pool fluctuations (50 to 70 ft)
  •  Helped PSE achieve record downstream fish passage
  •  Designed for single direction water flow velocities 0.1 – 0.5 fps
  •  Secured by shore-side embedment anchors
  •  Deployed year round