This is a convenient run close to Lincoln City that follows Highway 18.
The first mile from the Treat River to the Highway 18 bridge is creeky, with small ledges and chutes. Widow Creek enters from the right through a culvert a short way below the Zeller's Riverside Bar and Grill, the next rapid is the largest on the run and forms a small horizon line at 'Widowmaker'. This rapid can be scouted from the right bank, and is a narrow turbulent chute along the left bank that is easy to portage on the right.
Below the Highway 18 bridge there are lots of beginner friendly surf waves in the next mile down to Slick Rock Creek. The best set of waves ends below a private bridge. There is an access point at the confluence with Slick Rock Creek where a fun class III rapid is best run along the right bank.
The last 3.5 miles is more open, with more water. Surf waves still exist, but are further between. The whitewater eventually ends and there is about a mile of easy floating to the take out at the fish hatchery. The best take out is above the low head dam on river right, where a trail through the hatchery leads back to the visitor vehicle parking area. If that trail is closed, there is also access near the downstream end of the hatchery near the Sitka Spruce.
The gauge for the run is found here (change the dataset from 'mean daily flow' to 'instantaneous flow'):
SALMON R BL SLICK ROCK CR AT ROSE LODGE, OR
500 cfs is a nice friendly flow, it could be run lower.
1,000 cfs is a good medium flow.
It can be run at twice that without the difficulty increasing much, but it can be challenging to get swimmers and gear to shore, and some parts can get squirrely for beginner kayakers.
The following videos are from before the gauge was reporting, so flows are estimated.
Video : ~1,100 cfs
Video: ~1,300 cfs
Video: ~1,500 cfs
Video 4: ~2,000 cfs
The put in is a short way above the Zeller's Riverside Bar and Grill at a small roadside pullout: 45.02168014704719, -123.84695898632742
The take out is at the Fish Hatchery. It says visitors are only allowed until 4:30 but the people there didn't seem bothered by kayakers using it later than that, remember to be respectful because some of the employees live there too: 45.01713632300631, -123.93705814651344