1. (a) A tier 1 stream crossing shall be a crossing located on a watercourse where the contributing watershed is less than or equal to 200 acres.

2. (b) Tier 1 stream crossings shall:

   1. (1) Meet the general design considerations specified in Env-Wt 904.01;

   2. (2) Be sized so as to accommodate the greater of:

      1. a. The 50-year design storm; or
      2. b. Applicable federal, state, or local requirements; and
   3. (3) Be a span structure, pipe arch, open-bottom culvert, or closed-bottom culvert, with or without being embedded with stream simulation.
3. (c) An applicant may propose a design that does not meet the criteria of (b)(1) or (b)(2)a., above, by submitting a request for approval of an alternate design as specified in Env-Wt 904.10. In accordance with Env-Wt 903.01(f)(1)a., a project that includes a request to approve an alternative design for a tier 1 stream crossing shall be a minor impact project.

4. (d) An existing legal crossing that would be classified as tier 1 under (a), above, may be repaired or replaced in-kind as specified in Env-Wt 904.08 pursuant to:

   1. (1) A routine roadway maintenance SPN as specified in Env-Wt 308.04 or registration as specified in Env-Wt 309.03; or
   2. (2) If the crossing is part of a trail, a trail SPN as described in Env-Wt 308.04.
5. (e) Compensatory mitigation shall not be required for any tier 1 minimum impact project.

Source. #12809, eff 12-15-19