Or. Admin. R. 690-020-0100

Current through Register Vol. 63, No. 6, June 1, 2024

Section 690-020-0100 - Hazard Rating of Dams

(1) The Department shall assign all Dams a Hazard Rating of High, Significant, or Low.

(2) A High Hazard Rating will be based on the Dam breach inundation analysis as described in OAR 690-020-0120 using the following criteria to determine expected loss of life:

(a) An inundation depth of flowing Water of at least two feet over the finished floors of dwellings, other frequently occupied buildings, or road surfaces where a vehicle is likely to be present is likely to result in loss of life. The Department may also consider Water velocity in its determination of inundation depth establishing a High Hazard Rating;

(b) An incremental increase of depth of flowing Water of one foot where recreational or other frequent use occurs downstream is likely to result in loss of life. The Department will also use Water velocity in its determination of inundation depth establishing a High Hazard Rating.

(3) A Significant Hazard Rating will be based on the Dam breach inundation analysis as described in OAR 690-020-0120, using depth and velocity of the flowing Water at affected structures, public infrastructure, and other properties which shows likely damage to property and infrastructure but no loss of life.

(4) Any Dam subject to regulation under these rules that is not rated as High or Significant by the Department will be rated as Low Hazard.

(5) The Hazard Rating of a Dam shall remain in effect until the rating is revised by the Department. The Department may conduct Hazard Rating reviews and dam breach inundation analyses as evidence indicates the impacts to people, property, or infrastructure may have changed since the Hazard Rating was first set. The Dam owner will be notified of the change and have an opportunity to meet with the Department and obtain records of the Department's analyses.

(6) A Dam owner may request that the Department consider revision of a Hazard Rating. The owner may have an Engineer prepare and submit a Dam breach inundation analysis, in support of this request.

Or. Admin. R. 690-020-0100

WRD 7-2009, f. 12-7-09, cert. ef. 1-1-10; WRD 2-2015, f. & cert. ef. 3/17/2015; WRD 3-2020, amend filed 06/29/2020, effective 7/1/2020

Statutory/Other Authority: ORS 536.027, 540.488

Statutes/Other Implemented: ORS 540.443, 540.488