South Platte River & Tributaries Project, now the Water Resiliency Program (WATR)

Mile High Flood Control District, City and County of Denver | Denver, CO

As Denver grew into the booming metropolis it is today, the South Platte River slowly degraded over time. In 1965, the biggest and costliest flood in metro Denver’s history occurred along the South Platte River, taking 21 lives and destroying thousands of businesses and homes. The damage caused by the flood equates to nearly $4 billion dollars today. In the aftermath of the flood, the U.S. Army Corps of Engineers (USACE) undertook construction of the Chatfield and Bear Creek dams and reservoirs. However, flooding along the river continued to occur.

The Merrick team led an alternatives analysis study for the Mile High Flood Control District and the City and County of Denver for a seven-mile stretch (6th Avenue to 58th Avenue) of the South Platte River to document the development of alternatives for the Water Resiliency Program—the second largest USACE river restoration project ever undertaken, next to the LA River project. This approximately $700 million project is one of the largest urban integrated ecosystem and recreational river improvement projects in the country.

The alternatives analysis has three primary goals:

  • ecosystem recreation
  • flood risk reduction
  • recreational improvements.

Our team developed and evaluated over 30 alternatives based upon costs and a detailed aquatic, wetlands, and riverine habitat analysis. The analysis included FACWet and FACStream methods, as well as computer analysis. Alternatives vary but include enhancement of existing riparian, wetland, and aquatic habitat and addition of new riparian and wetland area within adjacent parks and developments. Improvements also include narrowing the low flow channel and laying back banks to improve bank stability, floodplain connectivity, and flood conveyance capacity. The project utilizes existing parks and City property and includes acquisition and infrastructure relocations to increase potential for restoration and flood risk reduction. This reach of the South Platte River corridor is in a highly urbanized area in the City of Denver and creates opportunities for significant recreational enhancements – including new river access points, drop structure rehabilitation, viewing terraces, trails and trailheads, wetland boardwalks and educational signage. Coordination with on-going development and infrastructure projects is a key focus.


Surveying; 1D and 2D hydraulic modeling; alternatives analyses; cost estimates; conceptual design; assessment of aquatic and riverine habitat; sediment transport evaluation; and urban river restoration
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