In the mid-west of the United States, getting enough water for crops and people is an ever-increasing problem. For seven US states, a crucial source is the Colorado River, for which each has a set allocation laid down in rules called the Law of the River or the Colorado River Compact that have existed since 1922. Because Arizona doesn’t use all its allocation, it has begun to store the part that it doesn’t immediately consume in underground aquifers against future need. This technique, called water banking, is starting to reshape water policy in the area, especially since Nebraska plans to use the same storage as Arizona for a similar purpose; Bruce Babbitt, the US Interior Secretary, approved draft regulations in January 1998 for such transfers. California has for some time relied on unused allocations by upstream states to supply part of its needs, but the new system, called the Arizona Water Bank, means it will have to find other sources of supply.