Willamette River at Portland streamflow

USGS gage 14211720 sits on the Willamette River at Portland, at the Morrison Bridge, near the bottom of a valley that drains about 11,200 square miles between the Cascades and the Coast Range. Thirteen federal dams sit on its tributaries, operated by the Corps of Engineers for winter flood control and for summer flow augmentation in the mainstem.

The Willamette is a rain river rather than a snowmelt river, so a normal year is dominated by winter storm peaks between November and March and settles into a low, stable, largely reservoir-supported summer. Storm peaks arrive and pass within days. The gage sits close enough to the Columbia that its record is tidally influenced at low flow, which is worth knowing before reading small day-to-day movements as hydrology. Low summer readings are the ones that matter locally, for temperature and dissolved oxygen in the reach through the city and for the fish using it.