SMA DSNDING OVER ASSIGNED RPTING POINT HAS NMAC WITH 2 HANG GLIDERS.

Narrative

I WAS PLTING MY SMA ON A VFR FLT FROM TORRANCE; CA; TO SALT LAKE CITY; UT; AND HAVING JUST CLOSED MY FLT PLAN WITH CEDAR CITY RADIO I WAS LETTING DOWN INTO THE SALT LAKE AREA. AFTER PASSING FAIRFIELD VORTAC WE NAVIGATED TO THE E OF THE INTERSTATE IN ORDER TO AVOID THE RESTR AREA (R-6412 A/B) WHICH WAS HOT. I CONTACTED SLC APCH AND AFTER RECEIVING A SQUAWK WAS TOLD TO NAV VIA THE E SIDE OF THE HIGHWAY; RPT OVER THE 'POINT OF THE MOUNTAIN' AND DSND VFR TO 6000. THE MENTIONED RPTING POINT CORRESPONDS CLOSELY TO THE VFR RPTING POINT FOUND ON THE SECTIONAL WHICH IS CALLED 'STATE PRISON.' AS WE DSNDED THROUGH 7000 AT 'POINT OF THE MOUNTAIN' I AND MY 3 PAX SAW AT LEAST 3 NON PWRED HANG GLIDERS IN OUR CLOSE VICINITY. THE CLOSEST WAS AT OUR ALT AND ESTIMATED TO BE NOT MORE THAN 200 FT FROM OUR FLT PATH. I PASSED OVER ANOTHER BY NOT MORE THAN AN ESTIMATED 100 FT. WE RPTED OUR POS AND TOLD APCH CTL OF THE PRESENCE OF THE GLIDERS. THEY WERE UNAWARE OF THEIR PRESENCE AND OF COURSE DID NOT HAVE ANY RADAR ON THEM. ON LNDG A LCL PLT REMARKED THAT THESE GLIDERS WERE KNOWN TO USE THIS AREA AND THAT SHE FLEW WELL TO THE E OF THE AREA TO AVOID THE POSSIBILITY OF ENCOUNTERING THEM. ON TALKING TO FLT SVC A FEW DAYS LATER; THEY SEEMED UNAWARE OF THIS ACTIVITY AND CONFIRMED THAT HANG GLIDERS WERE NOT A NOTAM EVENT. BECAUSE IT IS NOT ASSOCIATED WITH AN ARPT IT WOULD NOT BE RPTED IN THE ARPT FACILITIES DIRECTORY; OR ANYWHERE ELSE FOR THAT MATTER. IT SEEMS TO ME THAT THIS IS AN ACTIVITY THAT SHOULD SOMEHOW BE ANNOUNCED SO THAT PLTS OTHER THAN THE 'LCLS' ARE AWARE OF. THIS IS A STANDARD RTE THAT VFR TFC USES TO NAV TO SLC. THE GLIDERS USE THE UP SLOPE WIND FOR THEIR FLT AND ARE WELL ABOVE GND IN CTLED AIRSPACE. THEIR RIGHT TO BE THERE; ALTHOUGH OF QUESTIONABLE JUDGEMENT; IS NOT DISPUTED. I FEEL THAT THIS IS AS SERIOUS HAZARD AND HOPE THAT SOMETHING CAN BE DONE ABOUT IT BEFORE A TRAGIC EVENT OCCURS.