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El Rio Preserve Bank Protection Project

Study Status:  Anticipated construction to begin December, 2019



The El Rio Open Space Preserve is owned and managed by the Town of Marana.  The Preserve is 104 acres, comprised of parcels 226-01-0170, 226-03-0130, and 226-03-0120. It was an active gravel pit in the 1960s and 1970s to provide materials for the construction of I-10. It is located adjacent to the Santa Cruz River and an earthen berm protected the gravel mining operation from typical river flows. It is within an area of rich riparian habitat for nesting and migratory birds.  In fact, around 240 bird species have been observed within the Preserve.  Marana has a series of improvement projects planned for the Preserve. For current information on what Marana has planned and their schedule, please see Marana’s Website at: http://www.maranaaz.gov/elrio.

In the past, high flows in the Santa Cruz River would occasionally overtop the earthen berm and flood the pit. In 2014 the earthen berm protecting the Preserve breached, causing more frequent influxes of water, sediment and trash into the pit.  This compromised some of Marana’s earlier efforts to restore the site.

flood trash
To protect the Preserve from frequent flooding, allowing for restoration and further enhancements, the Pima County Regional Flood Control District (District) has been asked by Marana to design and construct bank protection along the northern side of the Preserve at the Santa Cruz River.  This would replace the eroded earthen berm that previously protected the lakes.  The intent of the bank protection is to help minimize the damage from frequent flooding.  This includes reducing the amount of trash and invasive species that flow in during a storm event.  The bank protection will be constructed from soil cement and is being designed to protect the Preserve from receiving flows up to the 25-year event. 

The El Rio Preserve Bank Protection project construction plans are currently under design. The District anticipates construction will being in December 2019.

Located south of the Town of Marana’s El Rio Open Space Preserve, the Pima County Los Morteros Conservation Area and Heritage Trail received enhancements in June 2019 to improve the educational opportunities of the site that embodies the major traditions of the region, including Native American, Spanish, Mexican, and the American Territorial.


The following design documents are currently available:

*It is important to note that these are not final construction documents and some details may change.


Information related to Construction will be placed here as it becomes available.


Information related to Funding will be placed here as it becomes available.

Public Outreach

Information related to Public Outreach will be placed here as it becomes available.