Operation, Maintenance and Surveillance (OMS) Manuals for Dam Safety are a regulatory requirement in British Columbia and at BC Hydro, they are one of the highest-level governing documents for each dam, trumping Operating Orders and other procedures. The OMS Manuals provide instruction on the requirements for safe operation of the dams which therefore requires that the OMS Manuals be authenticated by a Professional Engineer, in accordance with Engineers & Geoscientists British Columbia (EGBC) Quality Assurance Guidelines. The practice of sealing the OMS Manuals was initiated in 2014. This paper describes the current structure and content of BC Hydro OMS Manuals, the process of updating the documents including review by others, the distinction between design and evaluation information for dam safety, the use of Interim Dam Safety Risk Management Plans, and some examples of interesting findings that were made through the process of rebuilding these documents.