The Tier II classification identifies the State's high quality waters, where existing conditions are better than necessary to meet the Clean Water Act's "fishable/swimmable" goals. State law requires MDE to protect high-quality Tier II waters.
Please stay tuned to MDE’s High Quality Waters webpage for emerging information on Maryland high-quality (Tier II) waters designation and protection. Maryland has over 235 listed Tier II stream segments. Development proposals within designated Tier II watersheds, which cover extensive land areas in several local jurisdictions, may require additional environmental review and may need to meet additional requirements depending on the nature of the proposal and the associated potential impact to water quality.