US Army Corps of Engineers Los Angeles District Paseo de las Iglesias Ecosystem Restoration Final Environmental Impact Statement (EIS) SANTA CRUZ RIVER PIMA COUNTY, ARIZONA July 2005 Cover Sheet Responsible Agency and Lead Federal Agency: U.S. Army Corps of Engineers Title: Paseo de las Iglesias Ecosystem Restoration, Final Environmental Impact Statement (FEIS) Contact: For information on the FEIS and the related public hearings and meetings: Michael J. Fink, Environmental Coordinator, U.S. Army Corps of Engineers, Los Angeles District, Arizona/Nevada Area Office 3636 North Central Avenue, Suite 900, Phoenix, AZ 85012-1939 Phone: 602.640.2001 extension 252 Via E-mail to: [email protected] For information on the overall Feasibility Study: Mr. Kim Gavigan, Study Manager U.S. Army Corps of Engineers, Los Angeles District, Arizona/Nevada Area Office 3636 North Central Avenue, Suite 900, Phoenix, AZ 85012-1939 Phone: 602.640. 2003 extension 251 Via E-mail to: [email protected] Abstract: This environmental impact statement (EIS) analyzes the potential environmental impacts associated with the proposed Paseo de las Iglesias project on the Santa Cruz River in Pima County, Arizona. The primary purpose of the proposed action is ecosystem restoration. The responsible Federal lead agency is the Department of the Army, U.S. Army Corps of Engineers, Los Angeles District. The Pima County Flood Control District is the non-Federal sponsor for the project. The study area for the project consists of a 7.5-mile reach of the Santa Cruz River and adjacent lands, totaling 5,005 acres, in south-central Arizona. More specifically, the study area consists of the Santa Cruz River Valley between Los Reales Road and West Congress Street, immediately south and west of downtown Tucson. Interstate highways 10 and 19 define the eastern boundary of the study area and Mission Road the western boundary. This document addresses the no action, the preferred action and two alternative plans developed to restore and improve native vegetation and overall wildlife habitat values in the project area, and to provide a greater diversity of habitat for threatened and endangered species. Incidental benefits would include both passive and active recreational opportunities, general improvement in the aesthetic quality of the project area, and a slight reduction in the potential for flood damage. Each alternative has been designed to minimize adverse impacts to the maximum extent practicable. The anticipated cumulative effects of implementation of the proposed action have been considered and addressed. Analyses and documentation are consistent with the National Environmental Policy Act and other applicable laws, regulations, and policies, and have been conducted in coordination with the Pima County Flood Control District, the City of Tucson, 2 and concerned resource agencies and members of the public. Information referred to in this document, as well as in the accompanying feasibility report and appendices, is incorporated by reference. Public Comments: In preparing the Draft EIS, the Corps of Engineers considered comments received by letter and formal statements made at public scoping meetings. A 45-day comment period on the Paseo de las Iglesias Ecosystem Restoration, Draft Environmental Impact Statement (EIS) began with the publication of the U.S. Environmental Protection Agency Notice of Availability in the Federal Register on October 8,2004. A public hearing to discuss and receive comments on the Draft EIS was held at the Desert Vista Campus of Pima Community College in Tucson, Arizona on the evening of October 26, 2004. All comments received during the comment period were considered in the preparation of the Final EIS. Comments received during the public hearing or in writing, along with responses, may be found in Appendix 14.5 of the Final EIS. Unless otherwise requested, copies of the Final EIS will be provided on CD-ROM. 3 Summary The Arizona/Nevada Area Office of the Los Angeles District of U.S. Army Corps of Engineers is conducting a feasibility study to assess opportunities for riverine ecosystem restoration for the seven-mile Paseo de las Iglesias reach of the Santa Cruz River in Tucson, Arizona. The study is being conducted in partnership with the Pima County Flood Control District, the non-Federal sponsor. The Paseo de las Iglesias Study Area, as identified in the accompanying feasibility report, consists of a segment of the Santa Cruz River and its tributaries, including the Old and New West Branch, extending downstream from Los Reales Road to Congress Street in the City of Tucson, Pima County, Arizona. The study area boundary encompasses an area approximately seven miles long varying from 0.5 miles to 1.6 miles wide, and contains approximately 5,005 acres. The primary process within the Study Area is systematic and severe ecosystem degradation and loss of riparian habitat that has persisted since the early 20th century. Before 1900, the Santa Cruz channel maintained perennial water flow that supported dense growths of native riparian trees such as cottonwood, willow, and mesquite. Historical accounts of conditions on the Santa Cruz River (circa 1900) describe a tree-lined, river, with dense vegetation, winding throughout a wide flood plain. The river channel formerly provided sufficient water to support rapidly increasing European settlement, increasing uses of the Santa Cruz waters for agricultural irrigation and sustained surface flow. Sustained surface flow has not existed in the Paseo de las Iglesias reach for more than half a century. The once verdant Santa Cruz riparian corridor has been transformed into a deeply incised, ephemeral ditch with either artificially hardened or unstable and eroding banks, that supports flow only briefly in response to storm runoff. These changes came about as a result of the uncontrolled appropriation of surface and groundwater to support expansion of agriculture and nascent industry, acceleration of head cutting resulting from human manipulation of the channel, and transformation of large areas of the landscape to increasingly urban land uses. As a result, native riparian habitat is nearly absent in the Study Area. Historically comprising about 1% of the landscape historically, over 95% of riparian habitat has been destroyed in Arizona. This type of river-connected riparian and fringe habitat is of an extremely high value; a large percentage of wildlife in the arid southwest is riparian-dependent during some part of its life cycle. As a consequence of the loss or degradation of riparian habitat, the area has suffered a concomitant reduction in species abundance and diversity with non-native (exotic) vegetation dominant in the Study Area. Flood damage reduction opportunities were analyzed for the Without-Project Conditions (No Action Alternative). Based on the results of environmental, hydrologic/hydraulic, and economic analyses, flood damage reduction, as a project purpose could not be justified. 4 While the majority of lands in the Study Area are dedicated to residential land use, the majority of lands immediately adjacent to the Santa Cruz River channel are undeveloped. This condition offers an opportunity to accomplish important ecosystem restoration in the Study Area. The Federal planning objective for ecosystem restoration studies is to contribute to National Ecosystem Restoration (NER) through increasing the net quality and/or quantity of desired ecosystem resources. The specific objectives for environmental restoration within the Study Area have been identified as follows: • Increase the acreage of functional riparian and floodplain habitat within the Study Area. • Increase wildlife habitat diversity by providing a mix of riparian habitats with an emphasis on restoration of riparian forests within the river corridor, riparian fringe and historic floodplain. • Provide passive recreation opportunities. • Provide incidental benefits of flood damage reduction, reduced bank erosion and sedimentation, and improved surface water quality consistent with ecosystem restoration goal. • Integrate desires of local stakeholders consistent with Federal policy and local planning efforts. A number of ecosystem restoration measures have been developed based upon those originally identified in Reconnaissance Phase of the study, with additional restoration measures added based upon the results of public input and on other similar studies in the region. Once compiled, potential restoration approaches were evaluated for feasibility, with some screened out and others refined. The initial conceptual alternatives presented in the draft Feasibility Study document (USACE, 2002) were recombined with new restoration approaches and expanded into an array of 14 alternatives that were subjected to more detailed analyses. Through this process, a final array of alternatives was produced consisting of the two “best buy” alternatives (Alternative 2A and 4F), a mid-point water use alternative (Alternative 3E), and the no action alternative. Alternative 2A Alternative 2A uses the basic dry-land restoration practices of water harvesting, soil patterning, mulch and fertilizer amendment, surface grading, a low flow diversion and construction of subsurface water harvesting basins. Implementation of these measures would allow creation of new habitat as well as improvement of existing habitat with plantings in mesquite, scrub/shrub, and river bottom community types. The alternative would require irrigation for establishment and