Irrigation systems are vitally important for economic development on a number of reservations in this Country. Often these systems benefit both Indian and non-Indian communities. There are over 100 irrigation systems across Indian Country that are owned and managed by the Department of Interior. These systems range in size, the smallest may focus on only subsistence farming while some of the larger projects can span tens of thousands of acres of critical components for the tribal economies that they serve. All together, these irrigation systems reach about 1 billion acres. A smaller set of revenue-generating irrigation projects make up the bulk of that acreage, and BIA estimates that the projects lead to about $300 million worth of agricultural crops grown each year. While these irrigation projects are important to reservation economies, they have been allowed to deteriorate for decades. In 2006, a GAO study found that these projects had hundreds of millions of dollars in deferred maintenance needs. More recent estimates by the BIA place the maintenance needs at about $600 million.