Conveyance provides the means of moving water to connect the supply to the demand. Conveyance systems are a necessary and critical link in the water management chain, as water supplies are of no use without the means to distribute that water to end users or to put it into storage for future use.
Conveyance infrastructure can include combination of natural watercourses such as streams and rivers, human-engineered structures such as canals and pipelines, and associated infrastructure such as pumping plants, diversion structures, and fish screens.
California has an extensive system of conveyance facilities that move water throughout the state, the two largest being the State Water Project and the federal Central Valley Project. Other conveyance systems such as the Mokelumne Aqueduct, the Hetch Hetchy Water & Power System, and the Los Angeles Aqueduct deliver water to large urban areas. (For more on California’s water systems, click here.)
Across regions and in cities and communities, on a smaller scale, local and regional conveyance systems move water from sources such as rivers and streams, groundwater, reservoirs, imported water systems, recycled water, stormwater, and/or desalination plants and then treat and distribute that water to end users or put it into storage for later use.
Improving conveyance can potentially provide multiple benefits, such as maintaining or increasing water supply reliability, protecting water quality, and providing water system operational flexibility. Some examples include:
- By widening bottlenecks that constrict the movement of water in the system, more surplus or stormwater can be moved into a conjunctive use or groundwater recharge project.
- Water supply reliability can be increased by conveyance improvements that increase the operational flexibility to move water between storage and points of use, or connect to other local or regional water systems.
- Improving conveyance capacity to capture high river flows and move them into surface storage or groundwater storage projects can provide water for beneficial uses later in the year and reduce the pressure to divert water in the drier months when river flows are lower.
The costs for conveyance vary significantly and generally depend on how far the water needs to be conveyed, the timing, and the topography; these costs can be substantial. It costs far less to move water by gravity through natural channels than through a constructed conveyance system with pipelines and pumps. However, the additional flexibility may be able to offset some costs, such as being able to move water during off-peak energy demand periods when power costs are lower.