This spring (2013) I was using the SART to help rehab my Fx hip.
I started there in late April riding pretty slow. On Saturdays, when entering the trail near GG Blvd (southbound) twice I encountered a well organized team that dispatched a pair of riders out in front of me at about 15-17 MPH. At that time I was pretty weak and didn't try to pass them. They stopped at Fifth Street, turned and faced me. Naturally, this seemed strange and the feeling stuck with me.
As I got faster, their tactics changed and they got more riders involved, using a 'block and swarm' technique to try and control my speed. I never tried to talk to them, photograph them, etc, but simply did my ride.
After reading this thread below, I believe that OCParks officially recognizes an entity they call the 'SART Safety Patrol Team'
Nobody on this forum has mentioned any encounters with such a SART Patrol Team, so I will be the first. They are out there
Tuesdays and Saturdays and they are well organized, using headsets, texting, and hand signals to coordinate members.
Except for the rude behavior and disrespectful tactics, there was only one incident where they showed illegal behavior. Back in mid-July there was a boatload of punctures in this area between Orangewood and Fifth Street (Santa Ana). I had one, I saw 3 other roadies over 2 days fixing flats, and on Mr Beanz site he mentioned 2 punctures on Saturday, July 13.
Shortly before I punctured (small piece of glass) I had one of the SP team riders pop-up in front of me south of GG Blvd, on a day that I entered the trail at Orangewood. I clearly saw him reach into his back mid-pocket and make a dusting action, fanning his fingers. So I claim this team member was dusting the trail with glass in order to harass fast Roadies.
Since I was riding the SART regularly I had the chance to see day-to-day action in a detailed way. This team is not law enforcement and they may be all volunteers, but they are bad for cycling. They have a mix of joggers, single riders, riding couples, and pedestrian lookouts. I can get into much more detail if anyone is interested, since I ran into them more than 10 times.
Take a look at the above link and you will see a reply from OCParks.com where they mention this team.