The Carson City Freeway drainage system was designed and constructed in coordination
with major off-site drainage improvements by Carson City. The resulting drainage system provides a coordinated and functional 100-year drainage system to detain, intercept, and convey storm drainage within the freeway
corridor to the Eagle Valley Creek channel that ultimately discharges to the Carson River. This coordinated system includes three major detention basins (Shenandoah Heights, Eagle Canyon Creek, and Silver Oaks
areas), three sediment basins (Shenandoah Heights, Eagle Canyon Creek, and Silver Oaks), and one large regional water quality basin (Lompa Ranch area) at the downstream terminus of the project. The
drainage system includes a series of channels, box culverts, and pipes within the freeway corridor to intercept and convey those flows to the water quality basin that provides water
quality treatment of the stormwater discharging from the Carson City Freeway as well as the surrounding areas before it reaches the Carson River. The facilities located within
the NDOT right-of-way were constructed by NDOT. The remaining off-site facilities were constructed by Carson City.
The drainage system within NDOT right-of-way was completed in
two phases. Phase 1A (Advanced Bridge Contract) completed conveyance facilities from Northgate Lane to just south of College Parkway, drainage facilities needed for the re-alignment of
Arrowhead Drive, and a temporary water quality treatment facility to collect sediment produced from Phase 1A construction activities. The temporary water quality basin was replaced by a permanent facility within the Lompa Ranch area.
The drainage system is the result of years of cooperative planning
between NDOT, Carson City, the U.S. Army Corps of Engineers, U.S. Fish and Wildlife Services, Nevada Division of Environmental Protection, Nevada Division of Wildlife, and many other agencies.
The resulting system not only provides for the drainage associated with the Carson City Freeway to provide adequate protection of the freeway improvements but also provides
substantial flood control benefits for Carson City and a substantial reduction in limits of flooding as currently shown on the FEMA Flood Insurance Rate Maps. It also reduces peak flows
throughout the entire drainage system and reduces the cost of drainage facility construction now and in the future. 
Drainage - Phase 1
Carson City Floodplain
Carson City Freeway Drainage System
