In accordance with Chapter 791, Government Code, the district and the Rio Grande Regional Water Authority may enter into a contract under which the Rio Grande Regional Water Authority may provide administrative or any other contract activities for or with the district. The district may enter into interlocal cooperation contracts with any public or private entity, request any necessary regulatory approval required, and charge fees and rates adequate to generate revenue sufficient to cover all expenses of the district based on cost-of-service principles. For purposes of Chapter 791, Government Code, performance under a contract is a governmental function or service.