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Rillito River-Swan Wetlands Ecosystem Restoration

Project status:  Complete 

Pima County Regional Flood Control District in cooperation with the U.S. Army Corps of Engineers has undertaken an environmental restoration project called the Rillito River at Swan Wetlands Ecosystem Restoration Project. The project area encompasses approximately 60 acres along the south bank of the Rillito River from Craycroft Road to just west of the Columbus Boulevard alignment. For planning purposes, the project area was divided into four areas. The project utilized a modified design-build process where design of Areas 2 and 3 was completed during construction of Area 1. The U.S. Army Corps of Engineers began construction of Area 1 in September 2006 and completed project construction in April, 2008. The total estimated project cost is approximately $4 million.

Project Plan

The project plan consisted of land recontouring to enhance passive water harvesting (collection of rain water) and planting of native vegetation. Passive water harvesting is expected to occur during storm events in small, created basins and along drainage channels. A mix of plant species, grading from Mesoriparian (i.e. Mesquite type) to upland species (i.e. Mesquite/Palo Verde type) was planted. After planting, each area was hydroseeded with a seed mix of local native plants. Supplemental irrigation with reclaimed water was provided to vegetation during the establishment period. Design documents and other information are available in the Reports and Brochures tab. The design for Area 2 and Area 3 was completed during the construction of Area 1.

Area 1

Small water harvesting basins were created in Area 1, near Craycroft Road north of the Hill Farm subdivision. Nonnative plants and some invasive plants were removed to allow planted native species to become established. The entire area was hydroseeded with a native seed mix. Restoration of plant species is expected to increase habitat value. During construction, a biologist was on site to direct construction equipment so as to avoid damaging existing vegetation.

Area 2

In Area 2, a small basin adjacent to Alamo Wash, minor surface recontouring of the basin will result in small water harvesting basins. Native vegetation was planted in the basin and irrigation with reclaimed water will be provided during the establishment period. The area was hydroseeded with a native seed mix after planting was completed.

Area 3

In Area 3 at the north end of Columbus Boulevard, cement lining in the existing drainage channels was removed and the channels were recontoured to create a more sinuous alignment. This is expected to decrease the water velocity, which will allow more time for the water to move into the banks increasing soil water available to vegetation. The channel bank slopes were flattened and native vegetation was planted along the newly constructed channels. The channels were designed to convey the same amount of water as before construction. In the area away from the channels, small water harvesting basins were created to capture rain water and native vegetation will be planted. The area was hydroseeded with a native seed mix after planting was completed. Irrigation with reclaimed water will be provided during the establishment period. The Work Plan and drawings of the new channel alignments can be found under the Reports and Brochures tab.

Area 4

The current maintenance path along the bank protection, will receive additional vegetation plantings as part of a separate river park project that will be completed by Pima County Parks and Recreation Department.

Project Schedule

The project was completed in phases beginning with Area 1. Construction in Area 1 began in September, 2006 and was completed in December, 2006. Design of the second phase, Areas 2 and 3, ran concurrently with construction of the first phase. Construction of the second phase began with Area 3 in May, 2007 and was completed in January, 2008. Construction in Area 2 began in December, 2007 and was completed in April, 2008.

Project Funding

Current estimated project cost is approximately $4 million. This type of ecosystem restoration project utilizes a cost sharing of local sponsor (Pima County) 25% and U.S. Army Corps of Engineers 75%. An estimated total project cost of $4,000,000 would result in a cost to Pima County of $1,000,000.

Maps

The following maps are available:

  • Location Map
    Location Map
  • Area 1 and 2
    Area 1 and 2 map
  • Area 3
    Area 3 Map

Reports

The following reports and brochures are available:

Area 1

Area 2/3

Public Outreach

The following public outreach information is available:

Dedication Ceremony

The Pima County Regional Flood Control District held a dedication ceremony for the Rillito River/Swan Wetlands Ecosystem Restoration Project at 11:00 A.M. on October 17, 2008. The project restored approximately 36 acres of riparian habitat along the south bank of the Rillito River between Craycroft Road and Columbus Boulevard.