I would check for other wells in the area at http://mbmggwic.mtech.edu/. The account is just an email and password no money or anything required. Hopefully there are a few wells in the general area to give you an idea on depth to water and geology. Also be sure you file with DNR once you have the well to protect your water right. Even if your property is on the Rez you will need to file. Once the water compact is done they may grandfather the existing filings. Any new wells after that most likely will have to be approved by a committee. I am down by St Ig and my well is 140 Ft deep and yields 25 gpm. I am a professional geologist and will say that I believe dowsing by the right dowser can be helpful. Sediment geology is highly variable in glaciated areas but the reality is your water could be much deeper than the reach of an excavator.