California Code of Regulations
Title 23 - Waters
Division 2 - Department of Water Resources
Chapter 1 - Dams and Reservoirs
Article 6 - Inundation Maps
Section 335.4 - Downstream Hazard Potential Classification

Universal Citation: 23 CA Code of Regs 335.4

Current through Register 2024 Notice Reg. No. 38, September 20, 2024

(a) The department classifies the downstream hazard potential of all state jurisdictional dams based on a sunny-day loading condition as follows:

(1) Low Hazard Potential. No probable loss of human life and low economic and environmental losses. Losses are expected to be principally limited to the owner's property.

(2) Significant Hazard Potential. No probable loss of human life but can cause economic loss, environmental damage, impacts to critical facilities, or other significant impacts.

(3) High Hazard Potential. Expected to cause loss of at least one human life.

(4) Extremely High Hazard Potential. Expected to cause loss of at least one human life and one of the following:
(A) Result in an inundation area with a population of 1,000 persons or more, or

(B) Result in the inundation of facilities or infrastructure, the inundation of which poses a significant threat to public safety as determined by the department on a case-by-case basis.

(b) A dam owner may request a re-evaluation of hazard potential classification in accordance with the following:

(1) If a dam owner contends that their dam should be assigned a different hazard potential classification, the dam owner may request a re-evaluation by submitting a complete request, which includes the following:
(A) A justification letter that explains why the initial classification is not applicable and the reasons that warrant a different classification based on the classification criteria contained in section 335.4(a), and

(B) Supporting documentation, which may include aerial imagery, topography data, or inundation studies.

(2) The department will complete the re-evaluation and notify the dam owner within 60 days of receiving a complete request.

(3) The existing classification assigned by the department shall remain in effect until a different classification, if any, is assigned by the department.

1. New section filed 10-19-2017 as a deemed emergency pursuant to Water Code section 6162; operative 10-19-2017 (Register 2017, No. 42). A Certificate of Compliance must be transmitted to OAL by 4-17-2018 or emergency language will be repealed by operation of law on the following day.
2. New section refiled 4-16-2018 as a deemed emergency pursuant to Water Code section 6162; operative 4-18-2018 (Register 2018, No. 16). A Certificate of Compliance must be transmitted to OAL by 7-17-2018 or emergency language will be repealed by operation of law on the following day.
3. New section, including amendment of section heading and section, refiled 7-12-2018 as an emergency pursuant to Water Code section 6162; operative 7-18-2018 (Register 2018, No. 28). A Certificate of Compliance must be transmitted to OAL by 10-16-2018 or emergency language will be repealed by operation of law on the following day.
4. Certificate of Compliance as to 7-12-2018 order, including amendment of subsection (a)(4), new subsections (a)(4)(A)-(B), amendment of subsection (b) and new subsections (b)(1)-(3), transmitted to OAL 10-16-2018 and filed 11-29-2018; amendments effective 11-29-2018 pursuant to Government Code section 11343.4(b)(3) (Register 2018, No. 48).

Note: Authority cited: Sections 6078 and 6162, Water Code. Reference: Sections 6002.5, 6009, 6160 and 6161, Water Code.

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