Comments Period: April 21, 2016 – May 5, 2016
SUBJECT: The U.S. Army Corps of Engineers, Sacramento District, (Corps) is evaluating a permit application to construct the City of Durango’s Municipal Water Intake Maintenance project, which would result in impacts to approximately 1 acre of the Animas River, a waters of the US. This notice is to inform interested parties of the proposed activity and to solicit comments.
AUTHORITY: This application is being evaluated under Section 404 of the Clean Water Act for the discharge of dredged or fill material in waters of the United States.
APPLICANT: City of Durango, Utilities Department, Attn: Mr. Matt Holden, 105 Sawyer Drive, Durango, Colorado 81301
LOCATION: The project site is located within approximately 600 linear feet of the Animas River at Santa Rita Park immediately above the Whitewater Park, Latitude 37.263966°, Longitude -107.881024°, Durango, La Plata County, Colorado and can be seen on the CO-DURANGO WEST USGS Topographic Quadrangle.
PROJECT DESCRIPTION: The applicant is proposing to construct four cross channel grade control structures. The proposed structures will insure continual water supply to the City of Durango Water Intake, mitigate erosion and channel incision, and provide fish and recreational navigational passage. Based on the available information, the overall project purpose is to insure sufficient water for the water intake, prevent continual head cutting and channel degradation, and provide a recreational navigational feature. The applicant believes there is a need to increase the water elevation at the Santa Rita Water Intake structure to insure the City can continually meet water demands, stabilize the river channel, and allow for navigational passage of recreational boats. The attached drawings provide additional project details.
PROJECT DETAILS: The proposed project involves the placement of 4063 cubic yards of material, including the placement of recycled dredged material, rocks, boulders, and grout, the excavation of 394 cubic yards of river rock from the channel, permanently impacting 0.49 acre of stream channel, and temporarily impacting 1.01 acre of stream channel. The project includes the total of four structures in addition to a few small habitat rocks and deflectors. The project also includes the installation of a temporary cofferdam within the river to dewater the site during construction. Structure 1 which will be located immediately upstream of the water intake, will be constructed with 4-foot diameter boulders individually placed with grout filling the voids between the boulders. The grout will be held back 6” from the surface to minimize the visual impact, while providing structural integrity necessary to mitigate damage during flooding. Structure 1 will raise the water elevation at the location of the water intake to compensate for the historic incision that has caused the current dewatering of the intake. Following construction of Structure 1, there will be an 8 feet of drop between structure 1 and the downstream crest of the Smelter Rapid drop within the Whitewater Park. To control the grade, minimize erosion, and insure navigational safety, the project includes the construction of three boulder sills. The sills will also control flows allowing for the creation of a fish passage channel and additional habitat areas. The sills will be installed without grout. The project also includes the maintenance of three existing boulder deflectors located upstream of Structure 1.
As part of this project, the City proposes constructing two fish passage channels. The first will be created in the existing side channel at the most upstream structure in the Whitewater Park, known as Smelter Rapid. The channel was intended to provide fish passage around Smelter Rapid, however it is currently dry at lower flows. The proposed project will modify the slopes and elevations to introduce water into the channel during low flows. The second passage is part of the proposed Structure 1, which is to insure that this structure does not create a fish barrier. This fish passage will roughen portions of the structure and increase the slope to at least 20:1. The goal of this fish passage is to create lower flow velocities, flow complexity, sufficient depth at low flows, and appropriate velocity refuges.
Environmental Setting. The project is located within the Animas River immediately upstream of the City’s whitewater park and the City’s municipal water supply intake. The area is heavily used by recreational floaters, kayakers, and area visitors. All work will be conducted within the river and it has been identified that there are no wetland areas located within the area of construction.
Alternatives. The applicant has considered three on-site alternatives. These alternatives include bulldozing a rubble pile, creation of a cross vane, and creation of a multi-use structure. Additional information concerning project alternatives may be available from the applicant. Other alternatives may develop during the review process for this permit application. All reasonable project alternatives, in particular those which may be less damaging to the aquatic environment, will be considered.
Mitigation. The Corps requires that applicants consider and use all reasonable and practical measures to avoid and minimize impacts to aquatic resources. If the applicant is unable to avoid or minimize all impacts, the Corps may require compensatory mitigation.
OTHER GOVERNMENTAL AUTHORIZATIONS: Water quality certification or a waiver, as required under Section 401 of the Clean Water Act from the Colorado Department of Public Health and Environment is required for this project. The applicant is aware of this requirement but has not indicated that they have applied for certification.
HISTORIC PROPERTIES: Based on the available information, no cultural resources were identified within the project's area of potential effect. The Corps will initiate consultation with the State Historic Preservation Officer under Section 106 of the National Historic Preservation Act, as appropriate.
ENDANGERED SPECIES: The project would not affect any Federally-listed threatened or endangered species or their critical habitat that are protected by the Endangered Species Act.
ESSENTIAL FISH HABITAT: The proposed project would not adversely affect Essential Fish Habitat (EFH) as defined in the Magnuson-Stevens Fishery Conservation and Management Act.
The above determinations are based on information provided by the applicant and our preliminary review.
EVALUATION FACTORS: The decision whether to issue a permit will be based on an evaluation of the probable impacts, including cumulative impacts, of the described activity on the public interest. That decision will reflect the national concern for both protection and utilization of important resources. The benefit, which reasonably may be expected to accrue from the described activity, must be balanced against its reasonably foreseeable detriments. All factors which may be relevant to the described activity will be considered, including the cumulative effects thereof; among those are conservation, economics, aesthetics, general environmental concerns, wetlands, historic properties, fish and wildlife values, flood hazards, floodplain values, land use, navigation, shoreline erosion and accretion, recreation, water supply and conservation, water quality, energy needs, safety, food and fiber production, mineral needs, consideration of property ownership and, in general, the needs and welfare of the people. The activity's impact on the public interest will include application of the Section 404(b)(1) guidelines promulgated by the Administrator, Environmental Protection Agency (40 CFR Part 230).
The Corps is soliciting comments from the public, Federal, State, and local agencies and officials, Indian tribes, and other interested parties in order to consider and evaluate the impacts of this proposed activity. Any comments received will be considered by the Corps to determine whether to issue, modify, condition, or deny a permit for this proposal. To make this decision, comments are used to assess impacts on endangered species, historic properties, water quality, general environmental effects, and other public interest factors listed above. Comments are used in the preparation of an Environmental Assessment and/or an Environmental Impact Statement pursuant to the National Environmental Policy Act. Comments are also used to determine the need for a public hearing and to determine the overall public interest of the proposed activity.
SUBMITTING COMMENTS: Written comments, referencing Public Notice SPK-2014-00221 must be submitted to the office listed below on or before May 5, 2016.
Kara Hellige, Project Manager
US Army Corps of Engineers, Sacramento District
1970 E. 3rd Ave, #109
Durango, Colorado 81301
The Corps is particularly interested in receiving comments related to the proposal's probable impacts on the affected aquatic environment and the secondary and cumulative effects. Anyone may request, in writing, that a public hearing be held to consider this application. Requests shall specifically state, with particularity, the reason(s) for holding a public hearing. If the Corps determines that the information received in response to this notice is inadequate for thorough evaluation, a public hearing may be warranted. If a public hearing is warranted, interested parties will be notified of the time, date, and location. Please note that all comment letters received are subject to release to the public through the Freedom of Information Act. If you have questions or need additional information please contact the applicant or the Corps' project manager Kara Hellige, 970-259-1604, Kara.A.Hellige@usace.army.mil.
Attachments: 13 drawings