Along the river from Vaseux Lake to just south of Road 22 are 19 dams, a handful of which also serve as road bridges. Spread along the Okanagan River between Oliver and Osoyoos Lake are 17 smaller man-made dams known as
Vertical Drop Structures, all spanned by narrow vehicle or pedestrian bridges. Each of these dams raises the water level of the river one metre, thereby increasing the storage capacity of the river. Designed to regulate the flow of water as it gradients downhill, these dams had to be built when the river was channelized, preventing the water from flowing too quickly and posing a downstream threat to habitat erosion, fish migration and human safety.
The dams, or Vertical Drop Structures, are numbered VDS 1 to VDS 17 from south to north, beginning north of Osoyoos Lake. VDS 1, this is the southernmost of the Vertical Drop Structures. All are of about the same dimensions, about 28 metres, or 93 feet, in length. Situated about 510 metres (1,680 feet) south of Road 22, it is easily reached via a dirt roadway from Road 22 down the east side of the channel. Like all the Vertical Drop Structures that don't also serve as road bridges, VDS 1 has a pedestrian walkway running along its top.
An ambitious irrigation scheme, the South Okanagan Lands Project, begun in 1918 by then Premier John Oliver would soon turn the southern Okanagan from a desert wasteland to a highly productive farming, market gardening and wine producing area. The area became so productive so quickly that, in 1920, the CPR deemed it necessary to begin construction of a spur line, the Osoyoos Subdivision, south from Penticton, eventually to reach Osoyoos at the U.S. border.
The irrigation scheme consisted of 2 major parts:
- Channeling the Okanagan River which flows south from Okanagan Lake.
- Creating a canal, known locally as The Ditch, coming off the river south of Vaseux Lake to irrigate areas downstream which were higher the the river.