Everyone told me to focus on the adjudicated water rights attached to the parcel — senior priority date, acre-feet, the usual checklist. What nobody warned me about was checking whether the state had filed instream flow reservations on the creek running through the property. In Montana, those reservations protect minimum flows for fish habitat, and they can legally outrank junior agricultural rights during low water years. I nearly bought a 40-acre parcel assuming I could develop a small stock pond fed by that tributary. Turned out the instream flow reservation effectively locked that water during late summer — exactly when I'd need it most. The seller wasn't hiding anything. He genuinely didn't know. My realtor didn't flag it. The title company didn't flag it. I only caught it because I personally called the DNRC and asked the right question. If you're buying any parcel with a named creek, check instream flow reservations before you get emotionally attached to the land. Most buyers never think to look, and that oversight will cost you in ways a soil test never could. Has anyone else run into this in other western states with similar reservation systems?