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Paseo de las Iglesias Ecosystem Restoration


Study status:  Phase One has competed design and is under construction

 

Paseo de las Iglesias logoThe Paseo de las Iglesias Environmental Restoration Feasibility Study was undertaken by the US Army Corps of Engineers and the Pima County Regional Flood Control District, with input from the City of Tucson and other stakeholders.

The study, completed in 2005, evaluated ecosystem restoration, flood control improvements, and river park trail development along a 7-mile reach of the Santa Cruz River from Congress Street upstream 7 miles. Planning objectives include increasing riparian wildlife habitat acreage and diversity, providing erosion protection where necessary, and providing passive recreation opportunities. 

In 2007 the study was authorized by the House and Senate as part of the Waster Resources Development Act, enabling future federal fund appropriations for design and construction of the project.

Paseo de las Iglesias Phase I: Santa Cruz River Bank Protection, Ecosystem Restoration, and Linear Parkway project between Ajo Way and Silverlake Road is currently under construction. This project will connect the existing bank protection and linear park south of Ajo Way with the existing bank protection and linear park north of Silverlake Road.

Project Features

Historical photograph of the Santa Cruz River near 'A' MountainThe Recommended Plan includes 1,100 acres of mesquite bosques on river terraces and floodplain, bordered by palo verde woodland and desert shrubs on both banks. Implementation will consist of land re-contouring to enhance passive water harvesting. Supplemental irrigation will be provided to aid in establishment and as needed to maintain healthy plant communities.

Flood control improvements included erosion protection that will be limited to at-risk areas. Recreation elements will include trail linkages to complete the Santa Cruz River park trail throughout the study area. Trails will also link to the existing Julian Wash Trail.

The plan features are consistent with the desires expressed by public involvement work groups. Implementation of the plan is supported by the U.S. Fish and Wildlife Service, Arizona Game and Fish Department, Center for Biological Diversity, Santa Cruz River Alliance, Tucson Herpetological Society, and others.

Project Costs

Per federal guidelines, the ecosystem restoration features are a 65% federal/35% local cost share. Recreation elements are a 50/50 cost share. Total project construction cost will be about $92 million. Of the $32 million non-federal share, $26 million is accounted for by the sponsor’s land contributions, leaving $6 million as the local sponsor's cash commitment. Existing local funds include $14 million in dedicated 2004 bonds. The project was recently authorized as part of the federally approved Water Resources Development Act (WRDA) 2007 bill, enabling future federal funding requests.

The Pima County Regional Flood Control District has begun preliminary design on the Phase One, Ajo to 29th street reach.

Restoration Approaches

Xeroriparian Restoration Approach

Xeroriparian habitats are associated with streams that flow in response to rainfall (ephemeral streams). Plant species present are similar to those in upland areas, but in greater densities due to the extra water.

Restored mesquite and palo verde trees would provide limited shade to the channel invert and would be bordered by Sonoran desertscrub species. Vegetative stabilization of the riverbanks, and an increase in flood retention and incidental recharge would result. Mostly small trees and shrub-sized vegetation would provide improved habitat for native wildlife and a setting for passive recreation. Irrigation would be needed for vegetation establishment, with planned delivery via water trucks. No irrigation system would be installed. After establishment, only water captured by water harvesting techniques would be used to sustain vegetation. An increase in abundance of ~65 native wildlife species would be expected. Project goals are harmonious with the Sonoran Desert Conservation Plan (SDCP).

Mesoriparian Restoration Approach

 Mesoriparian habitats are associated with areas with shallow groundwater and or intermittent flow. Dense mesquite forest (bosque) is characteristic of this habitat type.

Restored and irrigated mesquite-hackberry bosques would provide shade to the channel invert and would be bordered by mesquite and palo verde woodland and Sonoran desertscrub species. The outcome of this approach is expected to be most similar to the historic vegetation communities in this river reach. Vegetative stabilization of the riverbanks, and an increase in flood retention and incidental recharge would result. Both tree and shrub vegetation would provide improved habitat for native wildlife and a pleasant setting for passive recreation. Permanent irrigation would be needed to accomplish design goals, and an irrigation system would be installed. An increase in abundance of ~80 native wildlife species would be expected. Project goals are harmonious with the SDCP.

Hydro-meso Riparian Restoration Approach

 Hydro-mesoriparian habitats are associated with perennial watercourses where plant species such as cottonwoods and willow are present.

Restored and irrigated cottonwood-willow galleries would shade the intermittently flowing channel and be bordered by both mesquite bosques and Sonoran desertscrub species. Vegetative stabilization of the riverbanks, and an increase in flood retention and incidental recharge would result. Both tree and shrub vegetation would provide improved habitat for native wildlife and a pleasant setting for passive recreation. Permanent and extensive irrigation would be needed to accomplish design goals, and an irrigation system would be installed. Depending on period of stream flow; roughly one-third to two-thirds of all irrigation water would be used to maintain intermittent to perennial flow in the main channel. An increase in abundance of ~95 native wildlife species would be expected. Project goals are harmonious with the SDCP

Reports

For additional information regarding design and future implementation of the first phase resulting from the feasibility study, please visit the Phase I: Santa Cruz River Bank Protection, Ecosystem Restoration, and Linear Parkway, Ajo Way to Silverlake Road.

The following reports and brochures are available:

US Army Corps of Engineers Reports and Resources

Supporting and Supplemental Resources

Maps

For additional information regarding maps, design and future implementation of the first phase resulting from the feasibility study, please visit Phase I: Santa Cruz River Bank Protection, Ecosystem Restoration, and Linear Parkway, Ajo Way to Silverlake Road.


Click image to enlarge image and expand coverage area of map.

Public Outreach and Meetings

For additional information regarding future implementation of the first phase resulting from the feasibility study, please visit Phase I: Santa Cruz River Bank Protection, Ecosystem Restoration, and Linear Parkway, Ajo Way to Silverlake Road.

News Releases


Public Presentation Slide Shows

  • January 31, 2006 - "Paseo de las Iglesias Ecosystem Restoration Feasibility Study Update and Design Input Meeting"
    • Provides a overview of study results and a summary of the Recommended Plan, plus options for beginning the Design Phase. Presentation given by Jennifer Becker.
  • November 16-19, 2004 - "Paseo de las Iglesias Ecosystem Restoration Feasibility Study"
    • Provides a study overview and a summary of the Recommended Plan and Feasibility Study results as of November, 2004. Presentation given by Jennifer Becker at the Association of State Floodplain Managers Conference
  • January 22, 2004 - "Paseo de las Iglesias Environmental Restoration Feasibility Study"
    • Provides a overview of the Feasibility Study progress as of January, 2004. Presentation given by Thomas Helfrich.

Meetings


Contacts

Kim M. Gavigan

U.S. Army Corps of Engineers
Phone: (602) 640-2033 or (602) 640-2015, ext. 251
Fax: (602) 640-5383
Kim.M.Gavigan@sp101.usace.army.mil

Jennifer Becker

Pima County Regional Flood Control District
Phone: (520) 724-4600
Fax: (520) 724-4621
Jennifer.Becker@pima.gov

Tom Helfrich

Pima County Regional Flood Control District
Phone: (520) 724-4600
Fax: (520) 724-4621
Tom.Helfrich@pima.gov