I ran about 2 miles of this trail (each way, out and back) from the southern end of the construction closure in Riverside. At least in this section, the trail is built alongside or on top of a sewer main, and my run was punctuated by regular mouthfuls/lungfuls of sewer gas. For almost a mile just north of Van Buren the trail runs a gauntlet between two high chain link fences protecting a sewage treatment plant on one side and the section of the river that the plant dumps into on the other. I'm hoping another section of the trail is better; I won't be on this one again.
Beautiful day for a walk along the Santa Ana River Trail. The trail will be closed Monday through Friday until 2017 for the 2 miles between Martha McLean Park and Ryan Bonaminio Park but is still open on the weekends all the way from Norco to Colton. Lots of bicyclists, walkers, and dog walkers share the trail. It is paved all the way.