AN S80 DEPARTING SNA ENCOUNTERS WAKE TURB BEHIND A B757. WAKE EFFECT IS LIGHT CAUSING VERY SLIGHT ROLL. NO CTL PROBS OCCURRED.

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XX10Z. ATC FACILITY: SNA DEP. LOCATION: RWY 19R 1 DME FIX SNA. APPARENTLY ENCOUNTERED THE FRINGES OF WAKE TURB OF COMPANY B757 FLT DEPARTING SNA AT THE RWY 19R 1 DME FIX FOR THE NOISE ABATEMENT TURN. WE WERE MAINTAINING V2 PLUS 10 KTS PER THE SPECIAL NOISE ABATEMENT PROCS. AT THE TURNING FIX; WE ENCOUNTERED THE B757'S WAKE; WHICH CAUSED THE ACFT TO WANT TO ROLL TO THE L. ADDED TO THIS WAS MODERATE CHOPPINESS. LOWERED THE NOSE SLIGHTLY TO ATTAIN ADDITIONAL ACFT CTL AND ATTEMPTED TO TURN L AT APPROX 13- 15 DEGS OF BANK PER THE DEP. I WAS VERY CONCERNED THAT A LARGE ROLL MOMENT MAY BE ENCOUNTERED AT ANY TIME. ACFT CTL WAS PRUDENT IN THIS SIT. THE L TURNING BANK WAS LIMITED BY ME; PF; BECAUSE OF THE ACFT WANTING TO ROLL L DURING THIS DEP. HAD WE EXECUTED A 20 DEG BANK TURN; THE STALL MARGIN WOULD HAVE BEEN LOWERED TO A VERY UNCOMFORTABLE AND UNSAFE LEVEL. I WOULD LIKE TO CLARIFY THAT THE MODERATE CHOP WAS APPARENTLY CAUSED BY THE B757 AND NOT AN ATMOSPHERIC CONDITION; AS IT WAS SMOOTH OTHERWISE.