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HomeMy WebLinkAboutchapter 32 water resources Chapter 32 Water Resources, Minimum Streamflows and Interbasin Transfers 32.1 River Basin Hydrologic Units Under the federal system, the Cape Fear River basin is made up of hydrologic areas referred to as cataloging units (USGS 8-digit hydrologic units). The Cape Fear River basin is made up of seven whole cataloging units. Cataloging units are further divided into smaller watershed units (14-digit hydrologic units or local watersheds) that are used for smaller scale planning. There are 2,819 local watershed units in the basin. Table 33 compares the three systems. A map identifying the hydrologic units and subbasins can be found in Appendix I. Table 33 Hydrologic Subdivisions in the Cape Fear River Basin Watershed Name and Major Tributaries DWQ Subbasin 6-Digit Codes USGS 8-Digit Hydrologic Units Onslow Bay Masonboro and Middle Sounds Topsail and Stump Sounds 03-06-24 03030001 Haw River and Jordan Reservoir Upper Haw River Reedy Fork, Stony Creek and Haw River (middle) Big and Little Alamance Creeks Haw River (lower) New Hope Creek and Jordan Reservoir Morgan Creek and University Lake 03-06-01, 02, 03, 04, 05, 06 01 02 03 04 05 06 03030002 Deep River Deep River (upper) and Muddy Creek Deep River (middle) and Richland Creek Deep River (middle), Cabin Creek and McLendons Creek Deep River (lower) Rocky River 03-06-08, 09, 10, 11, 12 08 09 10 11 12 03030003 Upper Cape Fear River Cape Fear River (upper) Upper Little River Little River Rockfish Creek and Cape Fear River 03-06-07, 13, 13, 15 07 13 14 15 03030004 Lower Cape Fear River Cape Fear River Town Creek, Brunswick River and Cape Fear River (extreme lower) 03-06-15, 16, 17 16 17 03030005 Black River South River Great Coharie Creek, Six Runs Creek and Upper Black River Black River 03-06-18, 19, 20 18 19 20 03030006 Northeast Cape Fear River Upper Northeast Cape Fear River Middle Northeast Cape Fear River, Goshen Swamp and Rockfish Creek Lower Northeast Cape Fear River 03-06-21, 22, 23 21 22 23 03030007 Chapter 32 – Water Resources, Minimum Streamflows and Interbasin Transfers 290 32.2 Minimum Streamflow One of the purposes of the Dam Safety Law is to ensure maintenance of minimum streamflows below dams. Conditions may be placed on dam operations specifying mandatory minimum releases in order to maintain adequate quantity and quality of water in the length of a stream affected by an impoundment. The Division of Water Resources, in conjunction with the Wildlife Resources Commission, recommends conditions relating to release of flows to satisfy minimum instream flow requirements. The Division of Land Resources issues the permits. The Federal Energy Regulatory Commission (FERC) licenses all dams associated with hydropower that meet the conditions of the Federal Poser Act. FERC-related dams are exempt from DLR authority, and flow requirements are included in the federal license. Flow requirements were also requested by agencies in the Certification of Convenience and Necessity (CPCN) that is required for public utilities and issued by the NC Utility Commission. 32.2.1 Deep River Hydroelectric Projects Coltrane Dam is unlicensed and will be inundated by the Randleman Reservoir project. Worthville Dam has no minimum release requirement according to their FERC license. This dam operates in a run-of-river (non-peaking) mode and has no bypass reach. The dam is located near Ramseur. Cox Lake Dam is required by FERC to provide a minimum flow of 42 cfs. The dam is located near Asheboro and has a 506-foot bypass reach. Cedar Falls Dam is required by FERC to provide a minimum flow of 32 cfs. The dam is located near Asheboro and has a 2,112-foot bypass reach. The license has been transferred to Piedmont Triad Regional Water Authority. The possible removal of the dam is being studied. Franklinville/Randolph Mills Dam was deemed non-jurisdictional by FERC and is unlicensed. This dam operates in a run-of-river (non-peaking) mode and has no bypass reach. There is a 46cfs minimum flow requirement in its CPCN. The by-pass reach is 480 feet. The dam is located near Franklinville. Ramseur Dam is required by FERC to provide a minimum flow of 45 cfs. The dam is located near Ramseur and has a 1,430-foot bypass reach. Coleridge Dam is required by FERC to provide a minimum flow of 35 cfs. The dam is located near Coleridge and has a 500-foot bypass reach. High Falls Dam is required by FERC to provide a minimum flow of 108 cfs. The dam is located near Robbins and has a 2,844-foot bypass reach. Carbonton Dam has no minimum release requirement according to their FERC license. This dam operates in a run-of-river (non-peaking) mode and has no bypass reach. The dam is located upstream of Sanford. Chapter 32 – Water Resources, Minimum Streamflows and Interbasin Transfers 291 Lockville Dam is required by FERC to provide a minimum flow of 70 cfs. The dam is located near Sanford and has a 2,300-foot bypass reach. The upper 700 feet is subject to project operations and lower 1,600 feet is the backwater of the Buckhorn Dam 32.2.2 Haw River Hydroelectric Projects Altamahaw Dam is unlicensed and has no minimum release requirements. The dam is located near Altamahaw and has an 800-foot bypass reach. Glencoe Mills Dam is required by FERC to provide a minimum flow of 57 cfs. The dam is located near Glencoe and has a 1,815-foot bypass reach. Swepsonville Dam is unlicensed and not operational. The dam is being considered for removal. Saxapahaw Dam is required by FERC to operate in run-of-river non-peaking mode. The CPCN states that 10 cfs or one-quarter of the reservoir inflow, whichever is less, is required in the west channel below the dam. The dam is located near Saxapahaw and has a 5,200-foot bypass reach. Bynum Dam is required by FERC to provide a minimum flow of 80 cfs. The dam is located near Bynum and has a 3,000-foot bypass reach. 32.2.3 Rockfish Creek Hydroelectric Projects Raeford Dam has no minimum release requirement according to their FERC license. This dam operates in a run-of-river (non-peaking) mode and has no bypass reach. The dam is located near Raeford. 32.2.4 Rocky River Hydroelectric Projects Rocky River Dam has no minimum release requirement according to their FERC license. This dam operates in a run-of-river (non-peaking) mode and has no bypass reach. The dam is located upstream of Sanford. 32.2.5 Lake Mackintosh (Big Alamance Creek) Burlington Water Supply The Town of Burlington’s water supply, Lake Mackintosh, has a tiered release with a maximum flow release of 9 cfs at full pool. The recommendation was based on a wetted perimeter study done by Division of Water Resources (DWR). 32.2.6 Back Creek (Graham-Mebane Reservoir) Graham-Mebane Water Supply DWR requested, following the review of the environmental assessment for the expansion of the Graham-Mebane water treatment plant from 6 to 12 MGD, a tiered release with a maximum low flow release of 5 cfs at full pool from Graham-Mebane Lake. The flow recommendation was based on a wetted perimeter study by DWR. Chapter 32 – Water Resources, Minimum Streamflows and Interbasin Transfers 292 32.2.7 Bones Creek (Lake Rimm) Lake Rim is used by the NC Wildlife Resources Commission as a fish hatchery storage pond. DWR requested a minimum flow as a stipulation for dam repair. The Division assisted the Commission in determining a tiered release of 18 cfs from the impoundment in all months except July, when the release is 10.5 cfs. The releases are based on a hydrologic desktop investigation. A calibrated gage is required to monitor releases. 32.2.8 Bransom Creek (Forest Lake Dam) A stipulation for repairs to Forest Lake Dam in Fayetteville was a minimum flow requirement of 3.4 cfs. The recommendation is based on a NC Wildlife Resources Commission habitat evaluation and a hydrologic desktop investigation. 32.2.9 Little Cross Creek (below Glenville Lake) DWR participated in an aquatic habitat assessment of Little Cross Creek below Glenville Lake (Fayetteville’s reserve water source) with the NC Wildlife Resources Commission and DWQ. A minimum flow of 3.6 cfs, based on a hydrologic desktop investigation, was established. 32.2.10 Deep River (Randleman Dam) The proposed Randleman Reservoir will serve the cities of Greensboro and High Point. The reservoir will have a tiered minimum release ranging from a high of 30 cfs at full pool, 20 cfs when below 60 percent full pool, and 10 cfs when below 30 percent full pool. The minimum flow recommendations are based on a wetted perimeter study. The project will divert up to 30.5 MGD (47.1 cfs) that will reduce the average annual flow. The natural low flows in the lower Deep River will be increased by the minimum release. There will be some interbasin transfer. Randleman Reservoir will impact hydropower generation in the Deep River. The Coltrane Mill project will be inundated by the impoundment. DWR estimates that hydropower generation will be reduced by 5 to 15 percent depending on the amount of withdrawal from the reservoir, proximity of the generation facility to Randleman, and the minimum flow requirement at each project. 32.2.11 Mill Creek (Reservoir Park Dam Southern Pines) Reservoir Park Dam in Southern Pines has a minimum flow requirement of 0.5 cfs based upon consultation with the NC Wildlife Resources Commission and a hydrologic desktop investigation. 32.2.12 Nick’s Creek (Town of Carthage Water Supply) Based on an instream flow study, the Town of Carthage was granted permission for an increase of its run-of-river withdrawal from 0.5 MGD to 1 MGD with no flow requirement. Carthage received temporary permits to reconstitute the breached dam upstream of the water supply intake. A flow requirement is under consideration. Chapter 32 – Water Resources, Minimum Streamflows and Interbasin Transfers 293 32.2.13 Reedy Fork Creek (Lake Townsend) Lake Townsend in Greensboro has a minimum flow requirement of 7.1 cfs at full pool as a stipulation for expansion of the water treatment plant from 20 to 30 MGD. The recommended flow is based upon a wetted perimeter study done by DWR. 32.2.14 Rocky River (Rocky River Reservoir) The Town of Siler City has a tiered release at their water withdrawal structure based on an instream flow study performed by DWR. The minimum release from December through May is 3.5 cfs when the town’s reservoir is at 40 percent capacity or greater. The town has installed gages to monitor the release. The Siler City is proposing to build a new dam 105 downstream of the existing lower dam that would increase storage from 24.1 to 162.5 acres. Instream flow requirements are being developed based on requirements in the 401 permit. 32.2.15 Haw River (Greensboro Emergency Intake) Greensboro has an emergency intake on the Haw River that can only be used during drought conditions. Based on previous studies a minimum instream flow of 22 cfs is recommended below the intake at all times during pumping. 32.2.16 Little Rockfish Creek (Hope Mills Dam) The Hope Mills dam was destroyed during high flow events in 2003. Based on existing studies DWR recommends a minimum instream flow of 38 cfs after dam reconstruction. 32.2.17 Juniper Branch (Forest Creek Golf Club) The Forest Creek Golf Club irrigation impoundment provides a 0.15 cfs minimum instream flow. 32.3 Interbasin Transfers In addition to water withdrawals (discussed above), water users in North Carolina are also required to register surface water transfers with the Division of Water Resources if the amount is 100,000 gallons per day or more. In addition, persons wishing to transfer two million gallons per day (MGD) or more, or increase an existing transfer by 25 percent or more, must first obtain a certificate from the Environmental Management Commission (G.S. 143-215.22I). The river basin boundaries that apply to these requirements are designated on a map entitled Major River Basins and Sub-Basins in North Carolina, on file in the Office of the Secretary of State. These boundaries differ from the 17 major river basins delineated by DWQ. Table 60 summarizes interbasin transfers within the Cape Fear River basin. In determining whether a certificate should be issued, the state must determine that the overall benefits of a transfer outweigh the potential impacts. Factors used to determine whether a certificate should be issued include: Chapter 32 – Water Resources, Minimum Streamflows and Interbasin Transfers 294 • The necessity, reasonableness and beneficial effects of the transfer. • The detrimental effects on the source and receiving basins, including effects on water supply needs, wastewater assimilation, water quality, fish and wildlife habitat, hydroelectric power generation, navigation and recreation. • The cumulative effect of existing transfers or water uses in the source basin. • Reasonable alternatives to the proposed transfer. • Any other facts and circumstances necessary to evaluate the transfer request. A provision of the interbasin transfer law requires that an environmental assessment or environmental impact statement be prepared in accordance with the State Environmental Policy Act as supporting documentation for a transfer petition. For more information, visit the website at http://www.ncwater.org/ or call DWR at (919) 733-4064. Water users in North Carolina are required to register their water withdrawals and transfers with the Division of Water Resources if the amount is 100,000 gallons per day or more, according to NCGS §143-215.22H. In addition, transfers of two million gallons per day or more require certification from the Environmental Management Commission, according to NCGS §143-215.22I. The river basin boundaries that apply to these requirements are designated on a map entitled Major River Basins and Sub-Basins in North Carolina that was filed in the Office of the Secretary of State on April 16, 1991. Within the Cape Fear River basin, six subbasins are delineated: the Haw River, the Deep River, the Cape Fear River, the South River, Northeast Cape Fear River and the New River. (Note: The New River is not considered part of the Cape Fear River basin under the basinwide management approach which utilizes basin definitions adopted by the Department of Water and Air Resources in 1974. The New River will be addressed as part of the White Oak River Basinwide Water Quality Plan in 2001.) Table 34 lists all potential transfers within the basin. Unless otherwise noted, the transfer amounts are 1992 average daily amounts in million gallons per day (MGD) based on Local Water Supply Plans and registered withdrawal/transfer information. Many of the transfers can not be quantified due to undocumented consumptive losses (examples: septic, lawn irrigation). Note: Under a provision of Senate Bill 1299 (ratified by the General Assembly on September 23, 1988), all local water systems are now required to report existing and anticipated interbasin transfers as part of the Local Water Supply Planning process. This information will be available for future updates of this management plan and will allow an assessment of cumulative impacts. There are two permitted transfers in the Cape Fear River basin. The first permit is for Cary/Apex’s 16 MGD transfer from the Haw River subbasin to the Neuse River basin. The EMC granted an increased transfer to 24 MGD effective July 2001. The certificate requires that any water used in the Neuse basin in excess of 16 MGD shall be returned to the Haw River subbasin or into the Cape Fear River by 2010. Water used for consumptive purposes in the Neuse basin is not subject to this condition. The second permit, for Piedmont Triad Water Authority’s 30.5 MGD transfer from the Deep River subbasin to the Haw and Yadkin River subbasins, covers anticipated transfers for the operation of the proposed Randleman Dam. Beginning in 1999, North Carolina General Statute 143-215.22H requires all persons who withdraw or transfer 100,000 gallons per day or more of surface or groundwater on any day to register with the Division of Water Resources (DWR). Table 34 lists the registered withdrawals in the Cape Fear River basin as of January 1, 1999. Chapter 32 – Water Resources, Minimum Streamflows and Interbasin Transfers 295 Table 34 Interbasin Transfers in the Cape Fear River Basin Source System Receiving System Source Subbasin Receiving Subbasin Estimated Transfer (MGD)1,2,3 Permitted Transfers Cary/Apex Cary/Apex Haw Neuse 16.04 Piedmont Triad WA Piedmont Triad WA Deep Haw, Yadkin 30.55 Other Transfers Graham Orange-Alamance Haw Neuse Emergency Greensboro Jamestown Haw Deep 0.09 Greensboro Greensboro Haw Deep Unknown OWASA Hillsborough Haw Neuse Emergency Reidsville Reidsville Haw Roanoke Unknown High Point Greensboro Deep Haw Unknown High Point Thomasville Deep Yadkin Emergency High Point High Point Deep Yadkin 3.5 Lower Cape Fear WSA Brunswick County Cape Fear Shallotte Unknown Carthage Carthage Cape Fear Deep Unknown Dunn Benson Cape Fear Neuse 1.0 Dunn Dunn Cape Fear South Unknown Dunn Benson Cape Fear South Unknown Harnett Fuquay-Varina Cape Fear Neuse Unknown Harnett Angier Cape Fear South Unknown Harnett Coats Cape Fear South Unknown Harnett Dunn Cape Fear South Emergency Sanford Chatham County East Cape Fear Deep Unknown Sanford Sanford Cape Fear Deep Unknown Sanford Lee County - Tramway Cape Fear Deep Emergency Wilmington Wilmington Cape Fear New Unknown General Electric General Electric NE Cape Fear Cape Fear 0.75 Southern Pines Southern Pines Lumber Cape Fear Unknown Archer Daniel Midland Archer Daniel Midland Shallotte Cape Fear 1.89 Durham OWASA Neuse Haw Emergency Durham Durham Neuse Haw 18.06 Goldsboro Wayne WD Neuse NE Cape Fear Emergency Hillsborough Orange-Alamance WS Neuse Haw Emergency Orange-Alamance WS Mebane Neuse Haw Emergency Orange-Alamance WS Orange-Alamance WS Neuse Haw Unknown Raleigh Holly Springs Neuse Cape Fear 0.8 Davidson Archdale Yadkin Deep Unknown Davidson Davidson Yadkin Deep Unknown Montgomery County Montgomery County Yadkin Deep 1.0 North Wilkesboro Broadway Yadkin Cape Fear Unknown Winston Salem Kernersville Yadkin Haw Unknown Winston Salem Winston Salem Yadkin Deep Unknown Winston Salem Winston Salem Yadkin Haw Unknown Asheboro Randleman Uwharrie Deep Emergency Asheboro Asheboro Uwharrie Deep 4.7 1 Transfer amounts are based on average daily water use reported in 1992 Local Water Supply Plans, and the 1993 Water Withdrawal and Transfer Registration Database. 2 "Unknown" refers to undocumented consumptive use. 3 "Emergency" refers to emergency connections. 4 Transfer amount for Cary/Apex are based on its permitted transfer. Chapter 32 – Water Resources, Minimum Streamflows and Interbasin Transfers 296 5 Transfer amount for Piedmont Triad Regional Water Authority is based on its permitted transfer, but will not become effective until completion of Randleman Dam. 6 The estimated transfer amount for Durham is based on information in their Jordan Lake allocation application. 32.4 Water Quality Issues Related to Drought Water quality problems associated with rainfall events usually involve degradation of aquatic habitats because the high flows may carry increased loadings of substances like metals, oils, herbicides, pesticides, sand, clay, organic material, bacteria and nutrients. These substances can be toxic to aquatic life (fish and insects) or may result in oxygen depletion or sedimentation. During drought conditions, these pollutants become more concentrated in streams due to reduced flow. Summer months are generally the most critical months for water quality. Dissolved oxygen is naturally lower due to higher temperatures, algae grow more due to longer periods of sunlight, and streamflows are reduced. In a long-term drought, these problems can be greatly exacerbated and the potential for water quality problems to become catastrophic is increased. This section discusses water quality problems that can be expected during low flow conditions. The frequency of acute impacts due to nonpoint source pollution (runoff) is actually minimized during drought conditions. However, when rain events do occur, pollutants that have been collecting on the land surface are quickly delivered to streams. When streamflows are well below normal, this polluted runoff becomes a larger percentage of the water flowing in the stream. Point sources may also have water quality impacts during drought conditions even though permit limits are being met. Facilities that discharge wastewater have permit limits that are based on the historic low flow conditions. During droughts these wastewater discharges make up a larger percentage of the water flowing in streams than normal and might contribute to lowered dissolved oxygen concentrations and increased levels of other pollutants. As streamflows decrease, there is less habitat available for aquatic insects and fish, particularly around lake shorelines. There is also less water available for irrigation and for water supplies. The dry conditions and increased removal of water for these uses further increases strain on the resource. With less habitat, naturally lower dissolved oxygen levels and higher water temperatures, the potential for large kills of fish and aquatic insects is very high. These conditions may stress the fish to the point where they become more susceptible to disease and where stresses that normally would not harm them result in mortality. These are also areas where longer retention times due to decreased flows allow algae to take full advantage of the nutrients present resulting in algal blooms. During the daylight hours, algae greatly increase the amount dissolved oxygen in the water, but at night algal respiration and die off can cause dissolved oxygen levels to drop low enough to cause fish kills. Besides increasing the frequency of fish kills, algae blooms can also cause difficulty in water treatment resulting in taste and odor problems in finished drinking water. Chapter 32 – Water Resources, Minimum Streamflows and Interbasin Transfers 297