The Columbia River Treaty required Canada to build three dams that would provide water storage in Canada that could be used for power generation and flood control benefits downstream in both countries. When Canada built its dams in the 1970s, it chose to construct more water storage than was required by the Treaty.
The additional water storage is termed non-Treaty storage because it is not operated under terms of the Treaty and access to this storage is obtained only through negotiation of operational agreements that provide mutual benefits to the Bonneville Power Administration and BC Hydro. The Treaty Entities ensure that use of this storage does not reduce the flood control and power benefits under the Treaty.
BPA and BC Hydro are negotiating a potential new NTSA to replace the previous agreement, in place since 1990, which expired in January 2011.