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Horsetail Creek Cold Water Refuge

View upstream through diversion, after project 

Project Number



Lower Columbia Estuary Partnership


Horsetail and nearby Oneonta creeks had severe thermal loading problems due to the creation of a gravel pit turned pond during I-84 construction. Oneonta’s flow was diverted through the pond, raising its’ water temperature to at/above the Columbia mainstem temperature. The culvert connecting Horsetail Creek to the Columbia River under I-84 was impassable to fish at a variety of stream flows. Instream habitat complexity was low and lacked overhanging riparian vegetation.

Project Overview

The Horsetail Creek Floodplain Restoration Project was undertaken by Lower Columbia Estuary Partnership in 2013. Restoration activities focused on improving fish access to the site, increasing the quality and quantity of instream habitat, restoring riparian vegetation and reunifying Oneonta Creek to its natural course along the floodplain. Restoration activities in the Horsetail Creek floodplain are helping to maintain summer site water temperatures below levels that can be dangerous to salmonids, in contrast to the Columbia River mainstem where summer temperatures often exceed these levels.

To learn more please visit:

For more information, please search OWEB's Grant Management System(OGMS) for Project Number 218-7000--17238.