Water Supply Storage Reallocation Report Reallocation of Storage at Greers Ferry Lake, Arkansas, for Mid-Arkansas Water Alliance
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US Army Corps US Army Corps Engineers Engineers Little Rock District Southwestern Division Water Supply Storage Reallocation Report Reallocation of Storage at Greers Ferry Lake, Arkansas, for Mid-Arkansas Water Alliance DRAFT REPORT FOR REVIEW – NOVEMBER 2017 THIS PAGE IS INTENTIONALLY LEFT BLANK DEPARTMENT OF THE ARMY LITTLE ROCK DISTRICT, SOUTHWESTERN DIVISION CORPS OF ENGINEERS P.O. BOX 867 LITTLE ROCK, ARKANSAS 72203-0867 Water Supply Storage Reallocation Report Reallocation of Storage at Greers Ferry Lake, Arkansas, for Mid-Arkansas Water Alliance DRAFT REPORT FOR REVIEW– NOVEMBER 2017 THIS PAGE IS INTENTIONALLY LEFT BLANK DRAFT FINDING OF NO SIGNIFICANT IMPACT ENVIRONMENTAL ASSESSMENT – WATER SUPPLY REALLOCATION OF STORAGE AT GREERS FERRY LAKE, ARKANSAS, CLEBURNE AND VAN BUREN COUNTIES (NOVEMBER 2017) The U.S. Army Corps of Engineers (Corps) has prepared an Environmental Assessment (EA) to assess the potential environmental consequences resulting from implementation of a proposed reallocation of 25,360 acre-feet of storage (approximately 20.75 mgd) at Greers Ferry Lake, in accordance with the National Environmental Policy Act of 1969. Greers Ferry Lake is a 40,463-acre lake located in north- central Arkansas within Cleburne and Van Buren counties, with portions of Searcy and Stone counties contributing to its watershed. The communities of Greers Ferry and Heber Springs are located upstream of the dam on the lake, while Clinton, Arkansas sits approximately six miles northwest of the lake. Little Rock, Arkansas is 65 miles to the south, and Memphis, Tennessee is 130 miles to the east. The primary inflow of the lake is from the Little Red River with discharges from the lake flowing into the White River below the dam. The Water Supply Act of 1958 (43 United States Code § 390b), as amended, provides for storage and makes it available for municipal and industrial water supply. The purpose of the Proposed Action is to address future water supply needs for the central Arkansas region. Increased demand is due to population growth, which is driving the need for additional water. Alternatives evaluated in the reallocation study include: groundwater; purchasing wholesale; water supply from a local river or stream; reallocation from either the conservation, flood or inactive pools at Greers Ferry Lake; reallocation from another existing reservoir and the “no action” alternative. As a result of evaluation and comparison of the alternatives, the Proposed Action would be to reallocate approximately 25,360 acre-feet of hydropower storage from the conservation pool in Greers Ferry Lake to water supply storage. The proposed reallocation would not require any construction or modifications to the dam. Anticipated Environmental Effects: Implementation of the Proposed Action would not impact any biological, geological, or cultural resources, land use, hazardous and toxic substances, environmental justice, recreation, transportation, or noise. There would be no impact to any proposed or listed species, or critical habitat, protected under the Endangered Species Act. Groundwater quality and quantity would benefit from the Proposed Action due to less reliance on groundwater for municipal and industrial water supplies. Insignificant adverse impacts are anticipated to socioeconomic resources due to lost hydropower revenue by Southwestern Power Association. This lost revenue would be offset by credits to the U.S. Treasury. Minor adverse impacts could occur to air quality and climate change if lost hydropower energy production were replaced by coal-fired energy sources. Any impacts would occur due to increases in annual levels of sulfur dioxide (0.02% increase), nitrous oxide (0.03%), and carbon dioxide (0.01%) in the United States. These extremely minor increases are likely unmeasurable, and therefore are considered insignificant. Implementation of the Proposed Action would not require a 404 permit or Arkansas State Water Quality Certification. Facts and Conclusions: Based on a review of the information contained in the EA, it is determined that the implementation of the Recommended Action is not a major federal action which would significantly affect the quality of the human environment within the meaning of Section 102(2)(c) of the National Environmental Policy Act of 1969, as amended. Therefore, the preparation of an Environmental Impact Statement is unwarranted and a “Finding of No Significant Impact” (FONSI) is appropriate. The signing of this document indicates the Corps final decision of the proposed action as it relates to NEPA. Date ROBERT G. DIXON Colonel, EN Commanding EXECUTIVE SUMMARY The following document is an integrated reallocation report and environmental assessment completed by the U.S. Army Corps of Engineers (Corps), Little Rock District (SWL) that presents the results of a water supply storage reallocation study. The overarching purpose of the study is to evaluate a request for storage in Greers Ferry Lake to provide municipal and industrial (M&I) water supply for the Mid- Arkansas Water Alliance (MAWA) made up of nine water utilities in central Arkansas. MAWA members have requested that the Corps reallocate reservoir storage at Greers Ferry in amount necessary to produce additional water supplies totaling 20.75 millions of gallons (mgd) per day of water supply (approximately 25,360 acre-feet of storage). This study evaluates and compares an array of potential water supply storage alternatives including reallocation of storage from other authorized uses of the lake and recommends a preferred alternative. In addition, the report documents possible impacts to regional environmental, socioeconomic and cultural resources of implementing the recommended plan pursuant to requirements of the National Environmental Policy Act (NEPA). Initially, the study team qualitatively assessed measures and a preliminary array of alternatives based on factors including financial costs, environmental impacts and effects to authorized uses of reservoir storage (i.e., flood risk management, hydropower, and recreation), dam safety considerations, and the ability of a measure to yield comparable amounts of water. After screening a preliminary array of nine alternatives, the team selected three final alternatives for a quantitative analysis: . Alterative 3: No Federal Action (Future without Federal Project): In the absence of Federal action in developing water supplies, the alternatives analysis assumes that the designated water users (requesters) would build a new reservoir providing a yield of 60 million gallons per day. Alternative 5: Conservation Pool Reallocation from Greers Ferry Lake: This alternative would reallocate storage from hydropower to water supply. Alternative 6: Flood Pool Reallocation from Greers Ferry Lake: This alternative would reallocate storage from the flood pool to the conservation pool for supply. Hydrologic and hydraulic studies were performed to determine, frequency and duration for pool elevation, lake-outflow, river stage, and river discharge for each of the respective reallocation alternatives. Reallocation of 25,360 acre feet of storage for water supply would provide firm yield of 20.75 mgd. Hydrologic analysis showed minimal impact if reallocated from conservation storage. However, reallocating from the flood pool would increase damaging releases and downstream impacts during flood events. Reallocating from the flood pool would also adversely affect recreational uses of the lake and require additional land acquisitions due to the associated increase in lake level and shoreline inundation. Table E-1 displays National Economic Development (NED) costs that include both financial costs to implement, maintain, and operate an alternative, and forgone economic benefits of implementing an alternative. NED financial costs include project capital costs including real estate, and operations, maintenance, repair, rehabilitations and replacement (OMRR&R) costs. Forgone benefits in this case consist of hydropower, flood risk management, and recreation benefits. As shown in Table E-1, the alternative that minimizes NED costs is Alternative 5 (reallocate storage from conservation pool). Additional criteria as they related to other accounts including Environmental Quality, Regional Economic Development Benefits, Other Social Effects and Corps planning feasibility criteria (i.e., acceptability, completeness, effectiveness and efficiency, were also considered.) Table E-1: National Economic Development Costs for Evaluation of Final Array of Alternatives Alternative 3 Alternative 5 Alternative 6 (No Federal (Conservation pool (Flood pool Cost or Forgone Benefit (2) Action) 1 reallocation) reallocation) Hydropower energy benefits forgone $0 $117,000 $101,000 Hydropower capacity benefits forgone $0 $60,000 $ 57,000 Revenue forgone $0 $51,000 $44,000 Real estate costs $0 $0 $105,000 Recreation benefits forgone $0 $0 $587,000 Flood risk management $0 $0 $6,000 Capital costs $14.0 M $ 285,000 $ 274,000 OMRR&R Costs $ 1.0M $ 2.5 M $ 2.5M Total $15.0 M $ 2.75M $ 3.6 M 1. In the absence of Federal action to reallocate water supply storage from the Greers Ferry Project, the only viable option identified would be the construction of a single purpose reservoir by the water users. Based on the analysis summarized above, the preferred alternative is reallocation of 25,620 acre-feet of reservoir storage from the conservation pool at Greers Ferry Lake for M&I water supply as requested by the MAWA. The Corps has completed an Environmental Assessment