Your alternator is air cooled on the 3.0, however coolant entering the alternatr housing can lead to failure later on. That exact issue occurred on the CEO's 325i after a pin hole in the upper radiator hose sprayed coolant directly into the alternator.

The fact you have no power steering is a strong indicator of belt slippage which is probably resulting from coolant residue, or a failing belt tensioner. This could also be causing reduced alternator output. I'd check the belt and tensioner first, then address the alternator if there's no change.

2002 X5 3.0 260,259 miles
2004 325i 115,000 miles