Conn. Gen. Stat. § 25-46: Interstate waters used for drinking water supply.

For the purpose of protecting the purity of interstate waters used or intended for use by any municipality, public institution or water company of this or of any adjoining state or states as sources of drinking water supply, and with a view to reciprocal action by adjoining states for the benefit of this state, the Department of Public Health is authorized, at the request of the Department of Public Health, or the official body having similar powers and duties, of an adjoining state, to provide in the Public Health Code regulations for the protection of the purity of the waters of any lakes, ponds, streams and reservoirs, within any specified drainage area in this state, tributary to any such drinking water supply of an adjoining state.