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  • El Rio Preserve offers rare sanctuary for birds, native species

    Oct 22, 2020 | Read More News
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    An old gravel pit that many rare winged and crawling creatures call home will enjoy additional protection thanks to a partnership with the Pima County Regional Flood Control District and the Town of Marana.

    The District recently completed a bank protection project at the El Rio Preserve that will protect the open space preserve, which has become a sanctuary for many rare and native species and a host of migratory birds. 

    The project to construct bank protection along this section of the Santa Cruz River was done in cooperation with the Town of Marana, which owns the El Rio Preserve and maintains it as a public amenity. 
    El Rio Preserve
    “The District worked closely with the Town of Marana and the Friends of the El Rio Preserve stakeholder group to develop a project which could provide protection to the Preserve while still preserving floodplain functions,” said Deirdre Brosnihan, Project Manager with the District.  

    The El Rio Preserve, located at Coachline Boulevard and Lambert Lane in Marana, was previously a gravel pit in the 1960s and 1970s. An earthen berm was built at the pit to protect it from flooding. When quarry activities ceased, the area evolved into a sort of sanctuary for birds and other wildlife. 

    The former earthen berm that protected the Preserve was often breached by the Santa Cruz River, which while providing water and attracting plant and animal life, also created maintenance issues for Marana officials. Each time the berm was breached, it scoured out areas and washed in plumes of trash.    

    Originally El Rio had two ponds, however, the eastern-most pond was damaged from the last breach of the Santa Cruz. By building bank protection, the District safeguards the Preserve from receiving the full force of the Santa Cruz and instead allows for a slower and more controlled connection to the river.  

    “The Town of Marana had expressed concerns regarding making future investments to the Preserve if the Santa Cruz River continued to flow directly into the Preserve and repeatedly damage the area,” Brosnihan said.  

    That provided the impetus for the District to assist Marana with the future of the El Rio Preserve.  

    The newly constructed soil-cement bank protection will prevent the Preserve from being overtaken by frequent flood events while allowing reduced and slower flows to enter the area. This was done by placing a permanent opening in the bank protection wall that allows water to flow into the preserve but also to flow back out into the river. 

    A low-flow drain pipe also was installed, which allows Marana to further drain down the Preserve to do maintenance to the ponds. Future pond grading within the Preserve is in Marana’s master plan for the El Rio Preserve.    

    Prior to construction, sediment removed from the river channel was moved to the El Rio Preserve to create habitat for wildlife and native vegetation and to construct bird viewing islands. The sediment also was used in the material mix in construction of soil cement bank protection.
    Los Morteros
    The project prioritized wildlife rescue efforts. Prior to construction, herpetologists worked with the County to relocate hundreds of reptiles away from the construction areas. 

    Among the animals trapped and removed were a rarely seen species of desert iguana (Dipsosaurus dorsalis). Since 2004, the Pima County Regional Flood Control District has worked with local biological experts to save toads and lizards in key habitat areas prior to larger construction projects. 

    A benefit of wildlife trapping is that it conveys what type, and how many, of a given species exist in an area. These efforts also protect species from becoming endangered as a result of habitat loss.

    The El Rio Preserve is part of a multi-jurisdictional plan to protect and enhance cultural, historical, and environmental heritage. 

    Just south of the El Rio Open Space Preserve, at Pima County’s Los Morteros Conservation Area and Heritage Trail, staff beefed up educational opportunities at the site, which embodies the major traditions of the region, including Native American, Spanish, Mexican, and the American Territorial. The work included a new trail, interpretive signs, and erosion repair.