2015-28495. Notice of Intent To Prepare an Integrated Feasibility Report and Environmental Impact Statement for the Lower Santa Cruz River Flood Risk Management Feasibility Study, Pinal County, Arizona

AGENCY:

Department of the Army, U.S. Army Corps of Engineers, DoD.

ACTION:

Notice of intent.

SUMMARY:

Pursuant to the National Environmental Policy Act (NEPA), the U.S. Army Corps of Engineers, Los Angeles District (Corps) in partnership with the Pinal County Flood Control District intends to prepare an Integrated Feasibility Report and Environmental Impact Statement for the Lower Santa Cruz River Flood Risk Management Feasibility Study.

DATES:

A public scoping meeting will be held on November 9, 2015 from 6:00 p.m. to 8:00 p.m. Submit written comments concerning this notice on or before December 9, 2015.

ADDRESSES:

The scoping meeting location is: City of Casa Grande Council Chambers, 510 East Florence Blvd., Casa Grande, AZ 85122.

Mail written comments to: Mr. Kenneth Wong, U.S. Army Corps of Engineers, Los Angeles District, CESPL-PD-RQ, 915 Wilshire Blvd., Los Angeles, CA 90017.

FOR FURTHER INFORMATION CONTACT:

Mr. Kenneth Wong, U.S. Army Corps of Engineers, Los Angeles District, CESPL-PD-RQ, 915 Wilshire Blvd., Los Angeles, CA 90017, [phone], [e-mail].

SUPPLEMENTARY INFORMATION:

The Lower Santa Cruz River Flood Risk Management Feasibility Study is authorized by the Flood Control Act of 1938 (Pub. L. 761, 75th Congress) for flood control studies on the Gila River and its tributaries in Arizona and New Mexico. The Santa Cruz River is a major tributary of the Gila River.

The study will evaluate strategies for minimizing flood risks along the Lower Santa Cruz River and its major tributaries within an approximately 1,400 square mile study area in Pinal County. The northern boundary of the study is the Santa Cruz River's confluence with the Gila River near the Maricopa County line. The southern boundary is the Pinal County-Pima County line.

The study will primarily focus on minimizing flood risks associated with large storm events originating from Mexico and Southern/Central Arizona. The study area has long been subject to damaging floods. Since 1887, 34 major floods have occurred on the river, an average of one event every three to four years. Six of the seven most damaging floods have occurred in the last 50 years. Damage has been widespread and devastating, including forced aerial evacuations; the loss of entire buildings; road and bridge closures; destruction of dams, levees, dikes, high-pressure gas lines, and crops; and severe erosion, channel migration, and sedimentation.

The potential for flood related damages has increased with continued population growth within the study area. Pinal County was the second fastest growing county in the United States during the past decade, nearly doubling its population to 375,000, with a projected population of one million by 2030.

Potential alternatives to be evaluated during the course of the study include:

Diversion/Bypass Channels. Capture floodwaters at an upstream location, and divert them away from high damage areas to Tat Momolikot Reservoir.

Channelization. Capture flood flows at an upstream location near Red Rock, and contain these flows in a channel to a point where they could be discharged into the Gila River.

Detention. Detain floodwaters upstream and release at a non-damaging flow rate.

Levees. Construct levees near populated areas and critical infrastructure.

Nonstructural. Prepare floodplain management plans; install flood warning systems and prepare emergency evacuation plans; elevate structures; flood proof structures; and relocate and/or buyout structures.

Additional alternatives that combine elements of those listed above may also be evaluated. In addition, the study would also evaluate the No Action alternative pursuant to NEPA.

The Corps and Pinal County Flood Control District will jointly conduct a public scoping meeting at the date and address indicated above. The purpose of the meeting is to present information regarding the study and receive public comment regarding the appropriate scope, potential alternatives, and environmental resources of concern. Participation of affected Federal, state and local resource agencies, Native American groups and concerned interest groups/individuals is encouraged.

The Draft Integrated Feasibility Report and Environmental Impact Statement is expected to be available for public review and comment in May 2017.

Dated: October 30, 2015.

Kirk E. Gibbs,

Colonel, U.S. Army, Commander and District Engineer.