Leroy H. Hemmingway was born in Evanston, Illinois, in 1946. In 1968, he earned a degree from Stanford University. In 1972, he earned a law degree from Yale University. He was involved with the Oregon Environmental Council during the early 1970s, and in 1976, he worked as a lawyer for the Oregon Public Utility Commission. He served as deputy public utility commissioner under Commissioners Charlie Davis and John J. Lobdell, during both the administrations of governors Bob Straub and Vic Atiyeh. He represented Oregon on the Northwest Power Planning Council, now known as the Northwest Power and Conservation Council, from 1981 to 1986. From 1995 to 2001, he was a policy advisor to Oregon Governor John Kitzhaber. From 2001 to 2003, he served as chair of the Oregon Public Utility Commission. From 2003 to 2006, he served as New Zealand Energy Commissioner. He then returned to Portland, Oregon, and worked as an energy consultant.

The Northwest Power Planning Council is a four-state regional planning body formed by Congress through the Northwest Power Act of 1980 to develop and maintain regional conservation and electric power plans and a fish and wildlife program. The council is composed of two representatives from each member state: Oregon, Washington, Idaho, and Montana. The mission of the council is "to preserve the benefits of the Columbia River for future generations." The body was originally known as the Pacific Northwest Electric Power and Conservation Planning Council; the name was shortened to Northwest Power Planning Council in October 1981, and in 2003, the name was changed to the Northwest Power and Conservation Council.