Willamette River Basin – Streamflow, Reservoir & Tide Gages

About the Willamette River Basin

The Willamette River drains about 11,500 square miles of northwest Oregon between the Coast Range and the Cascades, flowing north about 187 miles from the confluence of the Middle and Coast forks near Eugene to the Columbia River at Portland. It is home to about 70 percent of Oregon’s people, and the Willamette ranks among the largest rivers in the United States by average flow. Cascade tributaries such as the McKenzie, Santiam and Clackamas are fed by rain, snowmelt and cold High Cascades springs, while Coast Range and valley streams such as the Long Tom, Marys, Luckiamute, Yamhill, Pudding and Tualatin are rain-fed with low summer flows. Thirteen U.S. Army Corps of Engineers dams of the Willamette Valley Project regulate the Middle Fork, Coast Fork, McKenzie, Long Tom and Santiam rivers for flood control, hydropower, irrigation, fish and recreation, and the lowest 26 miles of the Willamette below Willamette Falls are tidal. River Flow Planner covers 155 gages here: USGS streamflow gages such as the Willamette River at Albany (record since 1892) and the McKenzie River near Vida, river stage and dam tailwater gages, the reservoir levels of Detroit, Green Peter, Lookout Point and the other project lakes, Oregon Water Resources Department and Bureau of Reclamation gages in the Yamhill and Tualatin basins, Henry Hagg Lake, and NOAA tide stations at Portland, the Multnomah Channel and St. Helens.

What River Flow Planner shows for each gage

Each gage page turns the agency’s full daily record into planning tools for fishing, rafting, kayaking, swimming, boating, irrigation and in-stream work:

• Summary hydrograph of typical flows, river stages or lake levels through the year
• Percent of time flows fall within a range you choose
• Likely range of flows on future dates you pick
• How a recent period compares with normal, plus a year-by-year spaghetti plot
• Flood frequency statistics for USGS gages with peak-flow records
• Tide forecasts, a tide calendar and tide statistics for the NOAA stations
• CSV downloads and links to current real-time data and short-term forecasts

Middle Fork Willamette River

Listed upstream to downstream, including Fall Creek and the dam tailwater gages.

Coast Fork Willamette & Row River

Listed upstream to downstream.

McKenzie River

Listed upstream to downstream, including the South Fork McKenzie and Blue River.

Willamette River Mainstem

Listed upstream to downstream, from Eugene to Portland.

Long Tom, Marys, Calapooia & Luckiamute Rivers

West-side and valley-floor tributaries of the upper Willamette.

North Santiam River

Listed upstream to downstream.

South Santiam & Santiam Rivers

Listed upstream to downstream, including the Middle Santiam and Quartzville Creek.

Yamhill River

Molalla & Pudding Rivers

Tualatin River

Listed upstream to downstream.

Clackamas River

Listed upstream to downstream.

Portland Area Streams

Urban streams in the Portland metropolitan area.

Lake & Reservoir Levels

Daily reservoir water-surface elevations (feet). The 13 U.S. Army Corps of Engineers Willamette Valley Project lakes are USGS gages; Henry Hagg Lake is a Bureau of Reclamation Hydromet site.

Canals & Diversions

Tide Stations (NOAA)

The lower Willamette River, the Multnomah Channel and the Columbia River at St. Helens are tidal. Tides here are small and are strongly affected by Columbia and Willamette river flows, which NOAA tide predictions do not include. Heights are in feet above mean lower low water (MLLW) unless you choose another datum.

Other basins

Rogue River Basin · Klamath River Basin · Deschutes River Basin · North Coast Basin · Mid Coast Basin · Umpqua River Basin · South Coast Basin · Sandy River Basin · Hood River Basin · John Day River Basin · Umatilla River Basin · Grande Ronde River Basin · Powder River Basin · Malheur River Basin · Owyhee River Basin · Malheur Lake Basin · Goose & Summer Lakes Basin