El Rio Preserve is a 104- acre site that has served a variety of uses for many years. In the 18th century, Juan Bautista de Anza and his followers camped on this site during their journey from Southern Arizona to San Francisco. More recently, the Arizona Department of Transportation used this location as a gravel borrow pit for large infrastructure projects. Over the past several decades, disc golfers have constructed a series of targets throughout the site, and periodically, the flood waters from surrounding neighborhoods have created a seasonal lake, attracting a variety of migratory birds. 

Project Updates have been posted below. Please see "Moving Forward". 


Tucked into a pocket of the upper Tucson Mountains, El Rio Preserve functions as a collecting basin for both run-off from the mountain slopes and overflow from the Santa Cruz River. This confluence of geologic features affords spectacular views of granite and gneiss intermixed with the younger volcanic rocks that produce the vibrantly red hues that distinguish these peaks. To the east is a wide open flood plain of the lower Santa Cruz River, which occasionally becomes a turbulent waterway after heavy rains.


Physical Address: 10190 N. Coachline Blvd; Marana, AZ 85743



El Rio Preserve offers the Marana community a number of benefits which must be considered in any site plan.

  • Rich riparian habitat for nesting and migratory birds. More than 200 species of birds have been observed here.
  • Stormwater retention basin that prevents flooding of nearby neighborhoods.
  • El Rio is one of the links in the chain of preserved riparian habitat along the Lower Santa Cruz River, including sites such as Sweetwater Wetlands and Kino Environmental Restoration Project
  • Natural land features, like mounds and shade trees, that support a variety of land uses and nature viewing.


El Rio Upland Area by J. Spencer.JPG
  • Site is identified as a regionally important wildlife linkage 
  • Any added features must be compatible with the characteristics of natural habitat and wildlife linkage


The Town is developing alternatives for 25-year storm bank protection or a reinforced berm, which will:  

  • Reduce mosquito problems by reducing flood frequencies and standing, stagnant water
  • Reduce the amount of trash and invasive weed seeds that flow in during storm events
  • Reduce concerns of overbank flooding
  • Create an urban oasis for wildlife and residents
  • Preserve and enhance an important riparian area
  • Allow the Town to create an outdoor classroom space for local schools. 
  • Improve the Town’s ability to perform routine maintenance at the site

Snowy Egret Photo © Andrew Core

Snowy Egret Photo © Andrew Core


In the Town's effort to create new amenities that merges community recreation and nature preservation, public feedback is imperative. Thank you to the community survey participants. Your feedback was valuable to help us guide the future of the El Rio Preserve. 

Community SURVEY CLOSEd January 16, 2017

 El Rio Preserve Project Updates

Posted September 28, 2017

  • Preliminary Engineering and Landscape plans have been reviewed by the Town, which are being funded in-part by a Water Infrastructure Financing Authority Grant.
  • Pima County Flood Control District has scheduled the design for bank protection for Fiscal Year 2019 (which starts in August of 2018) and construction for Fiscal Year 2020 (which starts in August 2019). This will reduce the frequency of floods at El Rio, and will reduce mosquitos and standing water issues. Most of the improvements will be initiated after bank protection is in place.
  • A pollinator garden with interpretive signs will be planted near the new Loop Trail parking lot, in coordination with Partners for Fish and Wildlife, Tucson Audubon Society, and Pima County.  
  • The pond at the southeastern corner of the property has been silted in with sediment from the Santa Cruz River during monsoon storms this year.
  • The Town of Marana has been treating mosquitoes at El Rio.


Parks & Recreation Department
Phone: (520) 382-1950
Email: marana.parks@maranaaz.gov

Development Services
Phone: (520) 382-2600


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