Mealey's ( November 22, 2021, 12:18 PM EST) -- WASHINGTON, D.C. — The doctrine of equitable apportionment applies to the use of groundwater from aquifers that lie beneath more than one state, the U.S. Supreme Court held Nov. 22 in deciding for the first time that an aquifer is an interstate water resource that must be shared equitably, just like water from lakes, rivers and streams....