This is a wonderful area of cliffs, rocky islands, trees, and currents between Hebb County Park and Willamette Park in West Linn just upstream from Willamette Falls (https://www.google.com/maps/@45.3211516,-122.6616025,15z).  It's a favorite paddle spot for many of us.

At lower water you will find currents up to 2-3 knots and a lovely paddle, while at high water it can be a raging, swirling mess and potentially quite deadly.

Here are my observations in different conditions

• River level at Narrows:  http://water.weather.gov/ahps2/hydrograph.php?wfo=pqr&gage=ocuo3
• Flow rates at Narrows:  http://levels.wkcc.org/?D=wr1#Awr1
• Below 55ft and 25,000 CFS - relatively friendly for all levels.  Watch out for exposed rocks and branches, plus motorboat traffic.
  
• Below 57ft and 50,000 CFS - small eddy lines with 3-4 knot currents
• Below 59 ft and 84,000 CFS - moderately strong eddy lines and currents to 5-6 knots.  Also significant boils.  Watch out for debris.
• Below 62ft and 130,000 CFS - strong eddy lines, boils, rapids, standing waves, whirlpools, some currents too fast to paddle, and debris in the water.  Groups of skilled paddlers only.

David had this to say about the Narrows:  I have paddled the narrows from calm water on warm sunny days, to 62' on the gauge above the falls a couple winters ago.  I've found that from 58' to 62' the narrows can be an excellent place to work on ferrying, exiting and entering eddies, and even a little surfing and playing in confused waters.  At 64'+ I wouldn't recommend this for anyone who doesn't have solid skills in fast moving current & rough water.

Don't go downriver from Willamette Park in West Linn - you don't want to get close to Willamette Falls!