The Dam Safety Technical Notes are guidance manuals provided by the Montana Dam Safety Program to help engineers in their evaluation of high hazard dams throughout Montana. The methods found within these technical notes are accepted by the Montana Dam Safety Program and are common in engineering practice.

Technical Note 1 - Analysis of Spillway Capacity in Montana *REVISED Jan. 2019

Technical Note 1 (TN1) provides guidance to engineers engaged in the analysis and design of spillways for Montana high hazard dams. TN1 is intended for analyses related to high hazard dams regulated by the Montana Dam Safety Program, but the guidance provided can be used on other dams.
  • References and Additional Information
    • Spreadsheets to assist with calculations, guidance for verification/calibration and modeling, USGS documents used to estimate extreme storm precipitation, hyetographs and unit hydrographs

Technical Note 2 - Loss of Life Determination for Spillway Capacity Analysis *REVISED January 2019

Montana spillway standards are risk based. As the potential for loss of life downstream of a dam increases, the spillway standard increases. Technical Note 2 (TN2) is provided to assist and guide engineers in estimating the potential loss of life downstream of Montana high hazard dams.

Technical Note 3 - Evacuation Mapping for Emergency Action Plans (Update Pending)

Evacuation maps are a necessary component of emergency action plans.  The first version of Technical Note 3 (TN3) has been retired, as it no longer reflects industry practice.  An update is planned.  In the interim, please reach out to Dam Safety Program staff to discuss evacuation mapping.

Technical Note 5 -Simplified Seismic Analysis Procedures for Montana Dams UPDATED 2020!

Technical Note 5 provides an updated step-by-step procedure for evaluating embankment dams for seismic stability. Methods for determining liquefaction potential and estimating soil strengths are included.

Technical Note 6 - Downstream Hazard Classification Procedures for Montana Dams

Technical Note 6 documents methods and procedures used by the Montana Dam Safety program to conduct a downstream hazard determination.

Technical Note 7 - Guidelines for conducting a Potential Failure Mode Analysis for Montana Dams

Failure Mode Analysis is a useful tool for comprehensively looking at a dam. Results from a Failure Mode analysis can be used to direct future monitoring and identify repair priorities. A Failure Mode Analysis is not another engineering study….the dam owner/dam tender play a big role. Technical Note 7 describes how to conduct a cost effective simplified Failure Mode Analysis. Read how a Failure Mode Analysis can benefit you!

Technical Note 8 - Specifications Guidelines for Dams

Technical Note 8 (TN8) is provided to assist and guide engineers in preparing construction specifications for Montana high hazard dams.

Technical Note 9 - Design Review Procedures for a Dam Construction Project

The purpose of this Technical Note is to establish guidelines and procedures for the design review process for a dam construction project. The process includes all project stakeholders, including the owner, engineer, and the Montana Dam Safety Program, but could also include others if their involvement is important for the success of the project. The goal of this document is to provide guidance on advancing a project from concept through construction efficiently and to provide a clear understanding of the various stages of the process.

Technical Note 10 - Analysis of Dam Instrumentation as part of a Five-Year Dam Evaluation - Working Draft

During the Five Year Dam Evaluation, the Engineer is required to review all available instrumentation and monitoring data for the dam. The purpose of Technical Note 10 is to summarize expectations of the Montana Dam Safety Program regarding the analysis and reporting of instrumentation data.

Note:  Technical Note 10 is considered to be a working draft, allowing comment and feedback from the Dam Safety Community.

Technical Note 11 - Montana DNRC Rainfall Runoff Guidance Manual

The purpose of this manual is to provide guidance on how to model rainfall-runoff inflow events that have a relatively high probability of occurrence so that Dam Safety can make appropriate level restriction decisions based on best-available information.

This manual can also be used to model frequent storm inflows for the purpose of determining the effects during construction projects. Nearly all construction projects on dams require reservoir level restrictions to maintain the safety of the dam. Since these restrictions are essentially the same as the restrictions for dam safety concerns, this manual is appropriate for use during construction projects.