1. (a) A tier 4 stream crossing shall be a crossing located on a tidal watercourse.
2. (b) A tier 4 stream crossing shall be a span structure or a culvert specifically designed for the geomorphic and habitat conditions of the tidal environment.
3. (c) The applicant may propose an alternative design by submitting a request as specified in Env-Wt 904.10.

4. (d) Compensatory mitigation shall be required for any new tier 4 stream crossing unless the crossing:

   1. (1) Meets the general design criteria in Env-Wt 904.01 and the tier-specific criteria in Env-Wt 904.07;
   2. (2) Is self-mitigating;
   3. (3) Improves aquatic organism passage, connectivity, and hydraulics; and
   4. (4) Is not an alternative design or any design for which a waiver is needed.
5. (e) In addition to meeting Env-Wt 903.07(c) and (d), plans for a tier 4 stream crossing shall be dated and bear the signature and seal of the professional engineer who prepared or had responsibility for and approved them, as required by RSA 310-A:18.

Source. #12809, eff 12-15-19