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Sandy River Delta Dam

From Oregon Hikers Field Guide

The Sandy River Delta Dam before its removal (Steve Hart)

Description

The Sandy River Delta was formed by mudflows originating on Mount Hood and flowing down the Sandy River to the Columbia. The most recent of these mudflows was about the year 1800. By 1900, the delta had been reworked by floods on the Columbia, as well as a constant stream of sediment coming down the Sandy River as the river cleared its channel. The larger part of the river flowed under the railroad and highway bridges and about a half mile north. At that point, it veered east and entered the Columbia River almost two miles east of where it does today. A secondary, smaller channel existed where today's current channel exists.

In 1904, a large flood partially blocked the secondary channel and it began to run dry during the fish runs. In an effort to help fish runs, a dam was built in 1931 that completely blocked the main eastern channel. In this way the river was forced in its entirety into the former secondary channel. The original dam was a 750 foot wide, five foot high barrier constructed of piling. In 1938, the dam was improved to a 10 foot high structure filled with riprap. In time, continuing erosion filled the old river channel with sediment.

In 2013, after much discussion, the dam was removed and the old east channel of the Sandy restored. Hikers can no longer access Sundial Island or the mouth of the Sandy (west channel).

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Oregon Hikers Field Guide is built as a collaborative effort by its user community. While we make every effort to fact-check, information found here should be considered anecdotal. You should cross-check against other references before planning a hike. Trail routing and conditions are subject to change. Please contact us if you notice errors on this page.

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