Publication Summary

The remnant Gibbons Creek channel, located in eastern Clark County, is a 1-1/2 mile abandoned channel formed when Gibbons Creek was rerouted in 1992. This remnant channel serves as the receiving water body for wastewater from five industrial facilities, and stormwater runoff from many more facilities. Since rerouting, the amount of water available for dilution for these discharges has been substantially reduced, prompting concerns that discharges may be adversely impacting water quality and wildlife from the adjacent Steigerwald Lake Wildlife Refuge.

The remnant Gibbons Creek channel, located in eastern Clark County, is a 1-1/2 mile abandoned channel formed when Gibbons Creek was rerouted in 1992. This remnant channel serves as the receiving water body for wastewater from five industrial facilities, and stormwater runoff from many more facilities. Since rerouting, the amount of water available for dilution for these discharges has been substantially reduced, prompting concerns that discharges may be adversely impacting water quality and wildlife from the adjacent Steigerwald Lake Wildlife Refuge.

Three water and sediment quality sampling surveys were conducted from September 1994 to January 1995 at four receiving water and one storm sewer site. The results show that the remnant channel exceeds state water quality criteria for pH, temperature, fecal coliform, turbidity, and dissolved oxygen. The storm sewer water violates criteria for pH, hexavalent chromium, total chromium, copper, zinc, and arsenic. Metal concentrations are also elevated in sediment samples in the lower channel, including arsenic, chromium, copper, zinc, cadmium, and lead.

Organic compounds detected in surface water samples downstream of the 32nd Street culvert have also been detected in Burlington Environmental′s upper aquifer monitoring wells. The upper aquifer ground water flow direction in the vicinity of the Burlington Environmental Washougal facility appears to be unchanged by the rerouting of the creek.

Recommendations are made to continue to address the contaminated ground water beneath the Burlington Environmental site through their RCRA permit. Further investigations of the lower channel sediments contaminated with high levels of chromium should be addressed jointly by Ecology′s sediment management unit in the Toxics Cleanup Program, and the industrial unit of the Water Quality Program to identify ongoing sources and determine the need for cleanup actions. The two wood-treating facilities need to substantially improve their stormwater runoff controls to reduce the amount of chromium, copper, and arsenic being contributed to the channel. Further source identification is needed for elevated zinc levels found in the 32nd Street storm sewer discharge. It is recommended that the storm sewer be upgraded and connected to the wastewater treatment plant or discharged directly to the Columbia River. If this is not done, all discharges will need to meet water quality criteria at "end-of-pipe" due to the lack of mixing and dilution in the remnant channel.

Link to EIM data for User Study ID KERI0002