Siuslaw River near Mapleton

1. 32.50 ftthe flow at this level is about 62,000 cfs and has a 1 percent chance of happening in a given year (aka 100-year flood).
2. 30.60 ftthe flow at this level is about 56,000 cfs and has a 2 percent chance of happening in a given year (aka 50-year flood).
3. 28.00 ftexpect major flooding along Riverview Avenue area and numerous homes and businesses in Mapleton. Flooding of roads adjacent to the Siuslaw River in the vicinity of Mapleton is likely. Flooding of Highways 126 and 36 will be significant.
4. 26.00 ftthe flow at this level is 42,000 cfs and has a 10 percent chance of happening in a given year (aka 10-year flood).
5. 25.00 ftexpect widespread flooding, including several homes and structures in low areas of Mapleton. Many sections of Highway 126 from Tiernan to Mapleton, along with Hwy 36 north of Mapleton begin to flood. Flooding may be exacerbated during high tide.
6. 23.20 ftthe flow at this level is about 35,000 cfs and has a 20 percent chance of happening in a given year (aka 5-year flood).
7. 22.00 ftexpect widespread flooding of low-lying land. Several homes and structures in low areas of Mapleton start to flood. Numerous rural roads along and near the Siuslaw River will likely be flooded, and water begins to cover the lower sections of Hwy 126 at this stage. Flooding may be exacerbated during high tide.
8. 20.00 ftexpect water over East Mapleton Road. Flooding of some low-lying homes and structures begins. Flooding may be exacerbated by high tide.
9. 19.10 ftThe flow at this level is about 24,600 cfs and has an annual chance of 50 percent (aka 2-year flood).
10. 18.00 ftexpect minor flooding of low lying dairy land along with some structures right along the banks of the Siuslaw River in and near Mapleton.

Chance of flooding, September to November

The three-month chances are the River Forecast Centers’ long-range flood outlook, issued September 20, 2026.

Most recent crests

• December 19, 2025: 21.60 ft
• March 16, 2025: 18.87 ft
• April 8, 2019: 19.73 ft
• December 18, 2015: 22.36 ft
• December 7, 2015: 18.36 ft
• December 21, 2014: 22.80 ft
• February 12, 2014: 18.02 ft
• November 19, 2012: 18.27 ft
• March 30, 2012: 20.39 ft
• January 19, 2012: 28.07 ft

• Big Creek of Lane Co. at Florence
• Yachats River at Yachats
• E Fk Lobster Creek at Alsea
• Alsea River at Tidewater
• Long Tom River at Noti
• Umpqua River at Reedsport
• Drift Creek of Lincoln Co. at Waldport
• Smith River at Drain

Forecasts by the Northwest River Forecast Center. Forecasts are issued routinely year-round.

Stage, flood stages, impacts and crest history from NOAA’s National Water Prediction Service. Streamflow and the daily record from the U.S. Geological Survey.