why does my 1998 malibu spray water from resivour when trying to start?

This don't sound good. There is no way coolant should be blowing out the reservoir when trying to start the engine. Probably a blown head gasket. If it is this bad you can check compression in the cylinders, it should show up as low compression on a cylinder or two. Head also could be cracked.

That is probably his problem I would check the oil cap and the oil itself if it looks tan milky you have either two things blown intake gasket or blown head gasket those exhaust gases and pressure from the exhaust it's pushing the water back out either has one of those too.