Permitting Your Existing Dam

If your dam meets the following 3 criteria, you are required to obtain permits from the Montana Dam Safety Program:

#1 Storage capacity

Dams with a storage capacity greater than 50 acre feet, measured to normal reservoir capacity, are subject to Montana Dam Safety Act Permitting.  Normal capacity is measured to the crest of the lowest ungated spillway.  For many reservoirs this is the top of the trickle tube or drop inlet.  For others, this is the crest of the auxiliary spillway.  For flood control structures, normal operating pool is always the crest of the auxiliary spillway.  For off stream reservoirs, normal operating pool is determined on a case by case basis.  Dams with a storage capacity of less than 50 acre feet are not required to obtain permits.   

# 2 Ownership of Property Dam is Located On

Dams that are located on non-federal property are subject to Montana Dam Safety Act Permitting.  This includes state, private, irrigation districts, cities, towns and counties.  Exempt are dams subject to the permitting requirements of the Federal Energy Regulatory Commission (FERC) for hydropower generation.  Note there are some dams located on US Forest Service Property that lack Forest Service oversight and therefore default to Montana Dam Safety Act jurisdiction.

# 3 High-Hazard Classification

Hazard classification refers to the potential for loss of life downstream.  A High-Hazard dam could cause loss of life, should the dam fail. High-hazard dams are required to obtain Operation and Construction permits from the Dam Safety Program.  Dams classified as “not high-hazard” are not required to obtain permits.

Notes:

• If a classification has not been done on your dam, and you meet criteria 1 & 2 above, then you should submit an Application for Determination of Hazard Classification.  An engineer from the Dam Safety Program will make an assessment of the potential for loss of life downstream.  Refer to the Hazard Classification web page for more information and instructions on submitting an application.

• Previously classified “not High-Hazard Dams” that are planning repairs or rehabilitation are required to apply for a new hazard classification, even though one has been done in the past.  Recent "red tape reduction" rule changes allow a waiver from the application process if it is obvious that no additional development has occurred downstream.  Refer to the Hazard Classification web page for more information on this waiver option.

High Hazard Dam Defined

A High-Hazard classification is a regulatory definition that dictates whether or not Operation and Construction permits from the Montana Dam Safety Program are required.  Dams classified as High-Hazard are required to obtain Construction and Operating permits.  Dams classified as Not- High-Hazard are not required to obtain Construction and Operation permits from the Dam Safety Program.

Important Note:  A High-Hazard designation does not reflect the safety of the dam, nor is it a statement as to what happens downstream should a dam fail.  During the classification process,  DNRC engineers are required to make many simplifying assumptions including modeling failure during clear weather, ignoring spillway and outlet flows, and only looking a hazards a specified distance downstream.  A High Hazard dam designation is nothing more than a statement that there is potential for loss of life, and therefore additional attention to construction, operation and maintenance is warranted.  A dam owner always has the option to hire an engineer to conduct a detailed engineering analysis of what happens in a dam failure and provide their results to DNRC for consideration.

Normal Operating Level Defined

Normal Operating Pool varies according to reservoir type.  The administrative rules provide a definition:

Maximum Normal Operating Pool - ARM 36.14.101(14)

(a) means the elevation of lowest uncontrolled principal spillway for on-stream reservoirs;
(b) means the elevation of the auxiliary spillway for flood control structures; and
(c) is defined on a case-by-case basis according to reservoir operation for off-stream reservoirs

Does your dam impound less than 50 acre-feet capacity?  Permits from the Dam Safety Program are not required.  However, owners of small dams are required under state law to maintain and operate their dam in a responsible manner.

Resources for Small Dams

Download copy of renewal process

Preparation for Permit Renewal

Advance preparation for the Five Year Evaluation by both owner and engineer is key to an efficient and cost effective renewal.  There are many tasks a dam owner can undertake that reduces their engineer's billable hours.  Advanced preparation by the engineer assures their visit to the dam site is productive. 

Please visit the Five Year Dam Evaluation Page for detailed information and guidance.

Five-Year Dam Evaluation

The Five-Year Dam Evaluation must be completed by a licensed professional engineer.  The evaluation consists of the following:

1. A Visual Inspection of the dam.  This inspection must be done at least once every five years. (36.14.602 (1)) and (36.14.601 (2))
2. A review of the Operation and Maintenance Plan (36.14.602 (d))
   
3. A review of the Emergency Action Plan. (36.14.602 (d))
4. For some dams, a second late summer, early fall Visual Inspection is warranted. (36.14.601 (2)) 
5. A Safety Evaluation of the dam, which consists of an assessment of stability, seepage, instrumentation and hydraulic/hydrologic adequacy. (36.14.602 (c))
   

DNRC has guidance and templates available to assist with the Evaluation. Please visit the Five Year Dam Evaluation Page for more information and resources.

Five Year Dam Evaluation Report

The Five Year Dam Evaluation Report must be delivered to the owner for review 60 days following the most recent Visual Inspection.  This allows the owner time to discuss recommendations made by the engineer before the report is finalized and submitted to DNRC (within 90 days of Visual Inspection).

The Report must contain the following:

1. Documentation of the Visual Inspection (36.14.603 (1)(a))

2. Documentation of the Safety Evaluation (36.14.603 (1) (a) (c) (e))

3. Recommendations (36.14.603 (1) (b) (c) (e) (g))

4. Safe Storage Level (36.14.603 (1) (f))

Five Year Renewal Application

A Five Year Renewal Application includes the following:

1. Five Year Dam Evaluation Report  (36.14.603) (36.14.402 (1) (b))

The Five year Dam Evaluation Report must include documentation of the Visual Inspection and the Safety Evaluation.  The report should be provided to DNRC within 90 days of the most recent Visual Inspection.  Visit the Five Year Dam Evaluation Page for guidance and important information.

2. Updated Emergency Action Plan (36.14.402) (36.14.403)

During the Five Year Evaluation Process, the engineer will review the dam's Emergency Action Plan and make suggestions for improvement.  The owner should discuss these improvements with their engineer and update as appropriate.  The updated Emergency Action Plan should be provided to DNRC as part of the renewal application.  The updated Emergency Action Plan should also be provided to other plan holders.  Please visit Planning for a Dam Emergency for information on developing and updating an Emergency Action Plan.

3. Updated Operation and Maintenance Manual (36.14.402) (36.14.403)

During the Five Year Evaluation Process, the engineer will review the dam's Operation & Maintenance Manual and make suggestions for improvement.  The engineer will also review the methods being utilized by the owner to operate, inspect and maintain the dam.  The owner should discuss suggested improvements with their engineer and either update as appropriate or develop a schedule to update. The updated Operation and Maintenance Manual should be provided to DNRC as part of the renewal application.  Please visit the Operation and Maintenance Manuals Page for more information on developing and updating a dam Operation & Maintenance Manual.

4. Statement of Dam Owner's Intent (36.14.402 (c), (d))

The Statement of Intent is the Dam Owners agreement to follow recommendations made during the Five Year Evaluation Process and a proposed schedule in which to do so.  DNRC has developed an optional form to assist dam owners with this task.  The Statement of Intent can also be provided in a cover letter.

Statement of Owners Intent Form MSWord Form Fillable Document

Statement of Owners Intent Form Adobe pdf Print Version