Many concrete infrastructures in Canada are aging and many of the most important condition indicators occur in locations that are difficult, hazardous, or costly to inspect using traditional methods. This paper presents a drone-based condition assessment and digital modeling program completed for a reinforced-concrete hydropower structure. The structure includes concrete exterior surfaces over water as well as multiple shafts for maintenance and operating gates and for flow of air.  A DJI Pro drone was used to inspect the exterior surfaces and an Elios 1 confined-space drone was used to review interior chambers and shafts. The field program was planned to include approximately 8 to 10 hours of drone flights over 2 to 3 days. The recorded imagery supported development of digital twin models for the exterior surfaces and interior chambers and were used for measurement models. The remote assessment facilitated visual review of areas that are difficult to access, reduced the need for high-risk entry and supported estimation of repair quantities to advance rehabilitation planning. The work also established a digital baseline for future inspections of the aging asset where repeatability and traceability of changes over time are essential for lifecycle decision making.