Use caution & common sense when you visit the LA River. Play in your comfort zone. Play during the day as a general rule. Most sites along the LA River are not lit or patrolled.
Whenever you visit the LA River, obey posted signs & play next to the river. You can only 100% legally enter the river (including the channel & sloped embankments) in the two summer LA River Recreation Zones.
Above all, stay out of the river during & for at least 24 hours after a rain—& whenever the summer rec zones are closed. ALWAYS, ABSOLUTELY, NO EXCEPTIONS. FLASH FLOODS ARE EXTREMELY DANGEROUS.
Check out the Play the LA River Quik-Guide for more tips & info.