I'm not sure if you're in a hydrology/hydrogeology program but they're fairly structured so you have a competent background to call yourself a hydrologist/hydrogeologist. Soils classes are not 'wasted' credits. Look at the NRCS- they're mostly older guys that are retiring soon and they need to fill those jobs with people who have a few courses of soils. The more advanced maths with help you understand the derivation of equations. If they scare you, you can always take them pass/fail. I had to take Physics II, Calc II, Calc III and differential equations for my masters deficiencies and still got out in two years. Stats would be beneficial too.
I'm in a PhD program now.