The City of Greeley, Colorado (near Fort Collins) wanted to increase the holding capacity of the Milton Seaman Reservoir to support the growing population in dry years. In order to support this effort, the city needed a detailed and highly accurate survey of the outlet tunnel. SAM accomplished field data collection by utilizing 3D terrestrial laser scanning in conjunction with conventional survey techniques conducted with robotic total stations. SAM began by establishing a project control network, and then scanned the 340-foot tunnel under the dam and reservoir to produce a 3D LiDAR point cloud. Using the point cloud, SAM then built a 3D model of the tunnel and slide gate equipment and delivered the completed dataset to the client.