L30 TRACON Controller reported LAS published procedures are unsafe and do not ensure separation between aircraft on the CHOWW RNAV arrival and departing aircraft.

Narrative

Aircraft X on the GIDGT departure. Aircraft Y on a non-RNAV arrival route from the northeast gate at or below 12;000 feet. The arrival sector pointed out Aircraft Y. The non-RNAV route crosses courses with the GIDGT departure. It requires an immediate vector to avoid intruding too far into MED airspace. The course design allows Aircraft Y to go on a southwest track west of AIRRO. AIRRO is the last fix on the GIDGT departure with an altitude and speed restriction. This restriction is at or above 11;500 feet and 250 knots. LAK arrival sector did vector the Aircraft Y east of AIRRO. However; the climb rate of Aircraft X with the descent rate of Aircraft Y was not going to work. An 'immediate' heading of 030 to Aircraft X was issued to avoid a loss or possible near midair collision. The northeast gate altitude should be 10;000 feet for prop aircraft. Also; the GIDGT departure requires an addition fix beyond AIRRO. This fix should be at least 15;000 feet with a speed of 250 knots. Aircraft X was vectored for Aircraft Y. However; that was just the closest aircraft. Vectors would have been necessary to miss the CHOWW arrival behind the Aircraft Y. The CHOWW arrival must be lowered to at least 17;000 feet at CHOWW. Trying to leave the airspace at 19;000 feet and enter our airspace at 19;000 feet is a very unsafe practice. The arrival and departure tracks converge.