This rule defines zones based on wells expected to pump at least 28% of their water from an adjacent stream over a 40-year period (Nebraska DNR, 2004). As stream depletion increases with both time and proximity to a stream, all else being equal, the 10/50 rule is more stringent than the 28/40 rule and will cover a large area adjacent to streams where stream depletion is a concern. In Nebraska, numerical methods have been used in the Republican River Basin and the Big Blue River Basin (MODFLOW-based), and in the Platte River Basin (COHYST-based).