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Chapter 9
Water Resources
9.1 River Basin Hydrologic Units
Under the federal system, the Savannah River Basin is made up of hydrologic areas referred to as
cataloging units (USGS 8-digit hydrologic units). Cataloging units are further divided into
smaller watershed units (14-digit hydrologic units or local watersheds) that are used for smaller
scale planning like that done by NCEEP (Chapter 11). There are two local watershed units in the
basin, all of which are listed in Table 14.
Table 14 Hydrologic Subdivisions in the Savannah River Basin
Watershed Name
and Major Tributaries
USGS 8-digit
Hydrologic Units
DWQ 6-digit
Subbasin Codes
Tugaloo River
Tullulah River, Chattooga River
Big Creek, Overflow Creek, Scotsman Creek, Fowler Creek
03060102 03-13-01
Seneca River
Toxaway River, Horsepasture River Thompson River, Whitewater
River
03060101 03-13-02
* Numbers from the 8-digit and 14-digit column make the full 14-digit HU.
9.2 Minimum Streamflow
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. One of the purposes of the Dam Safety Law is to ensure maintenance of
minimum streamflows below dams. The Division of Water Resources (DWR), in conjunction
with the Wildlife Resources Commission (WRC), recommends conditions related to release of
flows to satisfy minimum instream flow requirements. The Division of Land Resources (DLR)
issues the permits.
Under the authority of the Federal Power Act, the Federal Energy Regulatory Commission
(FERC) licenses all non-federal dams located on the navigable waters in the United States that
produce hydropower for the purposes of interstate commerce. The license may include
requirements for flows from the project for designated in-stream or off-stream uses.
Under the authority of Section 404 of the Clean Water Act, the U.S. Army Corps of Engineers
issues permits for the discharge of fill material into navigable waters. The permit may include
requirements for flows for designated in-stream or off-stream uses. A 404 permit will not only
apply to dams under state and federal regulatory authorities mentioned above, but will also cover
structures that are not under their authority, such as weirs, diversions, and small dams. Table 15
presents minimum streamflow projects in the Savannah River basin.
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Table 15 Minimum Streamflow Projects in the Savannah River Basin
Name Waterbody Drainage Area
(sq. mi.)
Min. Release
(cu.ft/sec)
Toxaway Dam Toxaway River 7.8 12.5a
Fall Racquet Club Dam Indian Creek 4.8 7.5b
Hogback Dam Little Hogback Creek 1.8 0.7
Cranston Pond Dam Green Creek 0.57 0.24
Upper Ridge Cove Dam Unnamed Tributary of
Chattooga River 0.56 0.19
a April through October the release is to be from the bottom siphon to provide a cold-water release for downstream trout survival b USFWS, NCWRC, NCDWR requested the U.S. Army Corp of Engineers require a cold-water release in the 404 permit to protect trout
downstream.
9.3 Interbasin Transfers (IBT)
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. Also, persons wishing to transfer more than the minimum
transfer quantity allowed by the IBT law (usually 2 MGD) 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, and included as part G.S. 143-
215.22G of the law. These boundaries differ slightly from the 17 major river basins delineated
by DWQ.
In determining whether a certificate should be issued, the state must determine that the overall
benefits of a transfer must outweigh the potential impacts. Factors used to determine whether a
certificate should be issued include:
• 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; and
• 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 support documentation for a transfer petition. Currently, there are no certified or known
potential interbasin transfers in the Savannah River basin.
9.3.1 Local Water Supply Planning
The North Carolina General Assembly mandated a local and state water supply planning process
in 1989 to assure that communities have an adequate supply of potable water for future needs.
Under this statute, all units of local government that provide, or plan to provide, public water
supply service are required to prepare a Local Water Supply Plan (LWSP) and to update that
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plan at least every five years. The information presented in a LWSP is an assessment of a water
system’s present and future water needs and its ability to meet those needs. Currently there are
no LWSP systems that withdraw water from the portion of the Savannah River Basin in North
Carolina.
9.3.2 Registered Water Withdrawals
Large water users are required to register their withdrawals with the Division of Water
Resources. General Statute 143-215.22H requires non-agricultural users that withdraw 100,000
gallons per day or more and agricultural users that withdraw 1,000,000 gallons per day or more
to report their withdrawals. Details of this program can be found on the Division’s website at:
www.ncwater.org. There is currently one registered water withdrawal in the North Carolina
portion of the Savannah River basin (Table 16).
Table 16 Registered Water Withdrawals in the Savannah River Basin
County
1999
Average (MGD)
1999
Maximum (MGD)
Source
Of Withdrawal Facility
Jackson 0.188 0.525 Groundwater Carolina Water Service – Fairfield Sapphire Valley
9.4 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
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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 problems for recreation and difficulty in
water treatment resulting in taste and odor problems in finished drinking water.
9.5 Source Water Assessment of Public Water Supplies
9.5.1 Introduction
The Federal Safe Drinking Water Act (SDWA) Amendments of 1996 emphasize pollution
prevention as an important strategy for the protection of ground and surface water resources.
This new focus promotes the prevention of drinking water contamination as a cost-effective
means to provide reliable, long-term and safe drinking water sources for public water supply
(PWS) systems. In order to determine the susceptibility of public water supply sources to
contamination, the amendments also required that all states establish a Source Water Assessment
Program (SWAP). Specifically, Section 1453 of the SDWA Amendments require that states
develop and implement a SWAP to:
Delineate source water assessment areas;
Inventory potential contaminants in these areas; and
Determine the susceptibility of each public water supply to contamination.
In North Carolina, the agency responsible for the SWAP is the Public Water Supply (PWS)
Section of the DENR Division of Environmental Health (DEH). The PWS Section received
approval from the EPA for their SWAP Plan in November 1999. The SWAP Plan, entitled
North Carolina’s Source Water Assessment Program Plan, fully describes the methods and
procedures used to delineate and assess the susceptibility of more than 9,000 wells and
approximately 207 surface water intakes. To review the SWAP Plan, visit the PWS website at
http://www.deh.enr.state.nc.us/pws/index.htm.
9.5.2 Delineation of Source Water Assessment Areas
The SWAP Plan builds upon existing protection programs for ground and surface water
resources. These include the state’s Wellhead Protection Program and the Water Supply
Watershed Protection Program.
Wellhead Protection (WHP) Program
North Carolinians withdraw more than 88 million gallons of groundwater per day from more
than 9,000 water supply wells across the state. In 1986, Congress passed Amendments to the
SDWA requiring states to develop wellhead protection programs that reduce the threat to the
quality of groundwater used for drinking water by identifying and managing recharge areas to
specific wells or wellfields.
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Defining a wellhead protection area (WHPA) is one of the most critical components of wellhead
protection. A WHPA is defined as “the surface and subsurface area surrounding a water well or
wellfield, supplying a public water system, through which contaminants are reasonably likely to
move toward and reach such water well or wellfield.” The SWAP uses the methods described in
the state's approved WHP Program to delineate source water assessment areas for all public
water supply wells. More information related to North Carolina’s WHP Program can be found at
http://www.deh.enr.state.nc.us/pws/swap.
Water Supply Watershed Protection (WSWP) Program
DWQ is responsible for managing the standards and classifications of all water supply
watersheds. In 1992, the WSWP Rules were adopted by the EMC and require all local
governments that have land use jurisdiction within water supply watersheds adopt and implement
water supply watershed protection ordinances, maps and management plans. SWAP uses the
established water supply watershed boundaries and methods established by the WSWP program
as a basis to delineate source water assessment areas for all public water surface water intakes.
Additional information regarding the WSWP Program can be found at
http://h2o.enr.state.nc.us/wswp/index.html.
9.5.3 Susceptibility Determination – North Carolina’s Overall Approach
The SWAP Plan contains a detailed description of the methods used to assess the susceptibility
of each PWS intake in North Carolina. The following is a brief summary of the susceptibility
determination approach.
Overall Susceptibility Rating
The overall susceptibility determination rates the potential for a drinking water source to become
contaminated. The overall susceptibility rating for each PWS intake is based on two key
components: a contaminant rating and an inherent vulnerability rating. For a PWS to be
determined “susceptible”, a potential contaminant source must be present and the existing
conditions of the PWS intake location must be such that a water supply could become
contaminated. The determination of susceptibility for each PWS intake is based on combining
the results of the inherent vulnerability rating and the contaminant rating for each intake. Once
combined, a PWS is given a susceptibility rating of higher, moderate or lower (H, M or L).
Inherent Vulnerability Rating
Inherent vulnerability refers to the physical characteristics and existing conditions of the
watershed or aquifer. The inherent vulnerability rating of groundwater intakes is determined
based on an evaluation of aquifer characteristics, unsaturated zone characteristics and well
integrity and construction characteristics. The inherent vulnerability rating of surface water
intakes is determined based on an evaluation of the watershed classification (WSWP Rules),
intake location, raw water quality data (i.e., turbidity and total coliform) and watershed
characteristics (i.e., average annual precipitation, land slope, land use, land cover, groundwater
contribution).
Contaminant Rating
The contaminant rating is based on an evaluation of the density of potential contaminant sources
(PCSs), their relative risk potential to cause contamination, and their proximity to the water
supply intake within the delineated assessment area.
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Inventory of Potential Contaminant Sources (PCSs)
In order to inventory PCSs, the SWAP conducted a review of relevant, available sources of
existing data at federal, state and local levels. The SWAP selected sixteen statewide databases
that were attainable and contained usable geographic information related to PCSs.
9.5.4 Source Water Protection
The PWS Section believes that the information from the source water assessments will become
the basis for future initiatives and priorities for public drinking water source water protection
(SWP) activities. The PWS Section encourages all PWS system owners to implement efforts to
manage identified sources of contamination and to reduce or eliminate the potential threat to
drinking water supplies through locally implemented programs
To encourage and support local SWP, the state offers PWS system owners assistance with local
SWP as well as materials such as:
Fact sheets outlining sources of funding and other resources for local SWP efforts.
Success stories describing local SWP efforts in North Carolina.
Guidance about how to incorporate SWAP and SWP information in Consumer Confidence
Reports (CCRs).
Information related to SWP can be found at http://www.deh.enr.state.nc.us/pws/swap.
9.5.5 Public Water Supply Susceptibility Determinations in the Savannah River Basin
In April 2004, the PWS Section completed source water assessments for all drinking water
sources and generated reports for the PWS systems using these sources. A second round of
assessments were completed in April 2005. The results of the assessments can be viewed in two
different ways, either through the interactive ArcIMS mapping tool or compiled in a written
report for each PWS system. To access the ArcIMS mapping tool, simply click on the “NC
SWAP Info” icon on the PWS web page (http://www.deh.enr.state.nc.us/pws/swap). To view a
report, select the PWS System of interest by clicking on the “SWAP Reports” icon.
In the Savannah River Basin, 101 public water supply sources were identified. One is a
groundwater source under the influence of surface water and 100 are groundwater sources. Of
the 100 groundwater sources, one has a Higher susceptibility rating and 99 have a Moderate
susceptibility rating. Table 17 identifies the one groundwater source under the influence of
surface water and its overall susceptibility rating. It is important to note that a susceptibility
rating of Higher does not imply poor water quality. Susceptibility is an indication of a water
supply's potential to become contaminated by the identified PCSs within the assessment area.
Table 17 SWAP Results for Surface Water Sources in the Savannah River Basin
PWS ID
Number
Inherent
Vulnerability
Rating
Contaminant
Rating
Overall
Susceptibility
Rating
Name of Surface Water
Source PWS Name
0188537 H L M Well #1 Toxaway Shores
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