The US Bureau of Reclamation (USBR), which is implementing the project, cites no-bid contracts and low estimates for the bulk of the cost overruns. Construction on the dam began in the spring when limited site work began on the southern edge of Durango, where Ridges Basin Dam and the 120,000-acre-foot reservoir are to rise over 10 years. Officials attributed most of the cost overrun to sole-source contracting with the Ute tribes. The Indian Self-Determination and Education Assistance Act requires the government to give contracts to tribes when work is done on their reservation, without a bidding process.