As used in sections 25-32 and 25-37a to 25-37e, inclusive, “critical components of a stream belt” means (1) the watercourse of a defined stream including banks, beds and water; (2) land subject to stream overflow; (3) associated wetlands, and (4) shorelines of lakes and ponds associated with the stream. “First-order stream” means a stream which directly enters a reservoir; “purity and adequacy of public drinking water supply” means the quality and quantity of public drinking water as determined by the Commissioner of Public Health under subsection (d) of § 25-32; “water company” means any water company as defined in § 25-32a, and “commissioner” means the Commissioner of Public Health.