In some cases, entire watersheds are given a designation of connectivity, but in others, a combined spatial and temporal definition is used. For example, the Nebraska Department of Natural Resources (DNR) has implemented the “10/50 rule" (Nebraska DNR, 2007) which defines separate zones, and therefore potential regulations, for wells based on whether or not groundwater pumping over a 50-year period will include at least a 10% contribution from an adjacent stream. In some cases, Nebraska has also applied a 28/40 rule.