2014-09318. Availability of the Final Environmental Impact Statement for the Moffat Collection System Project, Denver County, Adams County, Boulder County, Jefferson County, Grand County, Summit County, Gilpin County, and Park County, CO

AGENCY:

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

ACTION:

Notice of availability.

SUMMARY:

The U.S. Army Corps of Engineers (Corps) Omaha District has prepared a Final Environmental Impact Statement (EIS) to analyze the direct, indirect, and cumulative effects of a water supply project called the Moffat Collection System Project (Moffat Project or Project) in Denver County, Adams County, Boulder County, Jefferson County, Grand County, Summit County, Gilpin County, and Park County, CO. The purpose of the Moffat Project is to develop 18,000 acre-feet (AF) per year of new, firm yield to the Moffat Water Treatment Plant (WTP) and raw water customers upstream of the Moffat WTP pursuant to the Board of Water Commissioners' commitment to its customers. Denver Water's need for the proposed Moffat Project is to address two major issues: (1) Timeliness—the overall near-term water supply shortage, and (2) location—the imbalance in water storage and supply between the North and South systems. The Moffat Project would result in direct impacts to jurisdictional waters of the United States (U.S.), including wetlands. The placement of fill material in these waters of the U.S. for the construction of water storage and distribution facilities associated with developing additional water supplies requires authorization from the Corps under Section 404 of the Clean Water Act. The City and County of Denver is the Permittee and Applicant, acting by and through its Board of Water Commissioners (Denver Water).

The Final EIS was prepared in accordance with the National Environmental Policy Act of 1969, as amended (NEPA), and the Corps' regulations for NEPA implementation (33 Code of Federal Regulations [CFR] parts 230 and 325, Appendices B and C). The Corps, Omaha District, Denver Regulatory Office is the lead federal agency responsible for the Final EIS and information contained in the Final EIS serves as the basis for a decision regarding issuance of a Section 404 Permit. The Final EIS also provides information for local and state agencies having jurisdictional responsibility for affected resources.

DATES:

Written comments on the Final EIS will be accepted on or before June 9, 2014.

ADDRESSES:

Send written comments regarding the Proposed Action and Final EIS to Rena Brand, Moffat EIS Project Manager, U.S. Army Corps of Engineers, Omaha District, Denver Regulatory Office, 9307 South Wadsworth Boulevard, Littleton, CO 80128, or via email to [e-mail]. Requests to be placed on or be removed from the Project mailing list should also be sent to this address.

FOR FURTHER INFORMATION CONTACT:

Rena Brand, Moffat EIS Project Manager, via phone at 303-979-4120, fax at 303-979-0602, or email at [e-mail].

SUPPLEMENTARY INFORMATION:

The purpose of the Final EIS is to provide decision-makers and the public with information pertaining to the Proposed Action and alternatives, and to disclose environmental impacts and identify mitigation measures to reduce impacts. Denver Water proposes to enlarge its existing 41,811-AF Gross Dam and Reservoir by 72,000 AF to a total storage capacity of 113,811 AF. Gross Dam and Reservoir is located in Boulder County, CO, approximately 35 miles northwest of Denver and 6 miles southwest of the City of Boulder. The enlargement would be accomplished by raising the existing concrete gravity arch dam by 125 feet, from 340 to 465 feet high. The surface area of the reservoir would be expanded from approximately 418 to 818 acres. Denver Water is proposing to raise the dam an additional 6 feet to a total height of 471 feet with a surface area of 842 acres to create 5,000 AF of additional storage for environmental mitigation (“Environmental Pool”). The additional storage would be filled with water provided by the cities of Boulder and Lafayette. Using existing collection infrastructure, water from the Fraser River, Williams Fork River, and South Boulder Creek would be diverted and delivered during average to wet years via the Moffat Tunnel and South Boulder Creek to Gross Reservoir. There would be no additional diversions in dry years because Denver Water already diverts the maximum amount physically and legally available under its existing water rights. In order to firm this water supply and provide 18,000 AF per year of new firm yield, an additional 72,000 AF of storage capacity is necessary. To meet future demands, in most years, Denver Water would continue to rely on supplies from its North and South collection systems. In a drought or emergency, Denver Water would rely on the additional water it would have previously stored in the Moffat Collection System to provide the additional 18,000 AF of yield.

In addition to the Proposed Action (Alternative 1a)—Gross Reservoir Expansion (Additional 77,000 AF with the Environmental Pool for Mitigation), the Final EIS analyzed five additional alternatives: (1) Alternative 1c—Gross Reservoir Expansion (Additional 40,700 AF)/New Leyden Gulch Reservoir (31,300 AF); (2) Alternative 8a—Gross Reservoir Expansion (Additional 52,000 AF)/Reusable Return Flows/Gravel Pit Storage (5,000 AF); (3) Alternative 10a—Gross Reservoir Expansion (Additional 52,000 AF)/Reusable Return Flows/Denver Basin Aquifer Storage (20,000 AF); (4) Alternative 13a—Gross Reservoir Expansion (Additional 60,000 AF)/Transfer of Agricultural Water Rights/Gravel Pit Storage (3,625 AF); and (5) the No Action Alternative, which assumes that Denver Water would not receive approval from the Corps to implement the Moffat Project. The No Action Alternative would require Denver Water to use a combination of strategies to meet the need for additional water supply, including using a portion of its Strategic Water Reserve and imposing mandatory restrictions to reduce demand during drought periods.

Copies of the Final EIS will be available for review at:

1. Arvada Library, 7525 West 57th Avenue, Arvada, CO 80002.

2. Boulder County Main Library, 1001 Arapahoe Avenue, Boulder, CO 80302.

3. Denver Central Library, 10 West 14th Avenue Parkway, Denver, CO 80204.

4. Fraser Valley Library, 421 Norgren Road, Fraser, CO 80442.

5. Golden Library, 1019 10th Street, Golden, CO 80401.

6. Granby Library, 55 Zero Street, Granby, CO 80446.

7. Kremmling Library, 300 South 8th Street, Kremmling, CO 80459.

8. Summit County Library North Branch, 651 Center Circle, Silverthorne, CO 80498.

9. Summit County Library South Branch, 504 Airport Road, Breckenridge, CO 80424.

10. Thornton Branch Library, 8992 Washington Street, Thornton, CO 80229.

11. Denver Water, 1600 West 12th Avenue, Denver, CO 80204.

12. U.S. Army Corps of Engineers, Omaha District, Denver Regulatory Office, 9307 South Wadsworth Boulevard, Littleton, CO 80128.

Electronically at: http://www.nwo.usace.army.mil/​Missions/​RegulatoryProgram/​Colorado/​EISMoffat.aspx.

Rena Brand,

Moffat EIS Project Manager, U.S. Army Corps of Engineers, Omaha District, Denver Regulatory Office.