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 March 3, 2017

  • The 25-year bank protection proposal for El Rio Preserve scored highest of the projects proposed to the Pima Regional Flood Control District Committee. Whether this project will be funded, and in what year is not yet known.
  • The berm should reduce the frequency of floods at El Rio, which will allow the Town to begin site improvements and will [CN1] reduce mosquitos and standing water issues
  • If the Pima Regional Flood Control District does not fund the bank protection proposal, the Town contracted an engineering firm [CN2] to evaluate alternative flood control measures.
  • Seven Sandhill Cranes were spotted at El Rio Preserve last fall – a welcome resting spot.
  • The Town was awarded $35,000 by the Water Infrastructure Financing Authority (WIFA) to develop a design and grading plan. The design process will begin in mid-March after the regulatory agencies have submitted responses to the proposal.
  • The site has been surveyed for cultural resources and received a concurrence letter from the State Historic Preservation Office.
  • A Biological Assessment/Evaluation has been submitted to the US Fish & Wildlife Service and AZ Game and Fish Department for environmental clearance.
  • The temporary berm was breached again on Jan 21, 2017, and the Santa [CN3] Cruz River water currently flows into the site intermittently.
  • Over 400 people responded to the online survey. The objectives that were rated as most important were ranked as follows:                     
    • 1- Riparian rehabilitation/flood control
    • 2- Environmental education
    • 3- Mosquito prevention and trash prevention
  • Bird- and wildlife-watching were rated as the most common activities enjoyed at El Rio, with nature appreciation second and walking/running third.
  • The Town is working with other entities to create a new disc golf course nearby, where   flooding is not as frequent.
  • Although not part of the El Rio Riparian Restoration Project, the Loop Trail extension to    Avra Valley Road should be completed by the spring of 2017.


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

Planning Department
Phone: (520) 382-2600


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