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Surface Water Monitoring Program

Ambient Surface Water Monitoring | Outside Agency Data Requirements | SCECAP Coastal Monitoring
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The biological, water quality and shellfish monitoring program are accomplished by the Aquatic Biology Section (ABS), the Water Quality Monitoring and Modeling Section (WQMMS) and the Shellfish Sanitation Section (SSS), respectively.

Within the WQMMS, one of the major programs is the Ambient Surface Water Monitoring Program. “Ambient” refers to immediate surroundings, especially pertaining to the environment about a body but undisturbed or unaffected by it, as in ambient water quality.  The Ambient Surface Water Monitoring Program coordinates a network of monitoring stations located across the State of South Carolina. In addition to physical parameters measured at each station, surface water samples are collected and analyzed for chemical specific parameters on a periodic basis.

In addition to the Ambient Surface Water Monitoring, the Section provides technical support within the Department, Quality Assurance (QA) training for Central Office and district personnel, and conducts special studies specific to water quality. Enabling authority for activities conducted by the Section are granted by the  Pollution Control Act (48-1-50)  and through the Department's implementation of Water Classifications and Standards (R.61-68)  and  Water Pollution Control Permits (R.61-9) . For general information regarding the activities of the Section, contact  David Graves , 898-4398.

Ambient Surface Water Monitoring

Common Water Quality Indicators 

Ambient Surface Water Monitoring Map (Interactive map downloadable for Google Earth)

The Ambient Surface Water Monitoring Program is directed toward assessing attainment of water quality standards (R.61-68), identifying locations in need of additional attention, determining long-term water quality trends, and providing background data for permitting, modeling, planning, and evaluating stream classifications (R.61-69) and standards (R.61-68). For more information see the State of South Carolina Monitoring Strategy Watersheds and Common Water Quality Indicators .

Ambient Surface Water Monitoring data are also used in the process of formulating permit limits for wastewater discharges with the goal of maintaining State and Federal water quality standards and criteria in the receiving streams in accordance with the goals of the Clean Water Act. These standards and criteria define the instream chemical concentrations that provide for protection and reproduction of aquatic flora and fauna, help determine support of the classified uses of each waterbody, and serve as instream limits for the regulation of wastewater discharges or other activities.

Section 106 of the Federal Water Pollution Control Act (Clean Water Act or CWA) provides for federal funding to States to administer programs, “ for the prevention, reduction, and elimination of pollution, including enforcement directly or through appropriate State law enforcement officers or agencies.” This includes, and in fact requires, monitoring for the purposes of developing the report to Congress required under §305(b) of the CWA. The 305b Report - State of South Carolina Integrated Report Part II: Assessment and Reporting summarizes State-scale water quality with respect to attainment of classified uses by comparing the statewide probability-based monitoring data to the State Water Quality Standards (R.61-68). Ambient surface water monitoring data are also used in the preparation of the §303(d) List - State of South Carolina Integrated Report Part I : Listing of Impaired Waters of impaired waters, also required by the CWA. The Ambient Surface Water Monitoring data are stored in the USEPA STORET Data Warehouse and can be downloaded from the EPA website. 

There are currently two major components to the Ambient Surface Water Physical & Chemical Monitoring, including ongoing fixed-location monitoring and statewide probability-based monitoring; each designed to provide data for water quality assessment of major water resource types at different spatial and temporal scales.

The fixed-location component of the monitoring network is comprised of Base Sites that are generally sampled every other month, year round.  Probability-Based Monitoring Sites are typically sampled once per month for one year and moved from year to year. 

Base Sites

Base Sites represent the base network of 245 permanent, fixed-location, monitoring sites.  Base Sites are sampled bi-monthly, year round, over an extended period of time, in a uniform manner to provide solid baseline data.  Some of the probability-based locations may correspond to existing fixed Base Site and, because of the increased sampling frequency for random sites, may be used in place of the Base Site for that year.  Base Sites were chosen to target the most downstream access of each of the National Watershed Boundary Dataset (WBD) 10-digit watershed units (WSU) in the state, as well as the major waterbody types that occur within these WSUs.

The result is consistent data from all WSUs in the state that can be used in tracking standards compliance and long-term trends.

Probability-Based Monitoring Sites

A Probability-Based, or random, monitoring design is a type of a survey in which the population of interest is sampled in a fashion that allows statements to be made about the whole population based on a subsample, and produces an estimate of the accuracy of the assessment results.  The advantage of the probability-based sampling design is that statistically valid statements about water quality can be made about large areas based on a relatively small subsample.  Probability-based water quality data can be used to make inferences, with known confidence, about the condition of the water resources of the State.

A statewide probability-based, or random sampling, component is part of the Ambient Surface Water Quality Monitoring Network.  Separate monitoring schemes have been developed for stream, lake/reservoir, and estuarine resources to represent the entirety of each resource type.  Each year a new set of approximately 30 probability-based sites is selected for each waterbody type.  Each random site will be sampled monthly for one year.  Some of the random locations may correspond to existing fixed Base Sites.

Taken together the probability sites can be used to make statistically valid statewide statements about the condition of each water resource type.  The compilation of data from multiple years increases the confidence and accuracy of the statements about water quality condition.  An additional advantage of the probability-based approach is that it presents the opportunity to collect data at previously unsampled locations.


Streams of different sizes may be more or less sensitive to different types of environmental perturbations.  Because of this, three stream sizes have been specifically targeted to ensure they are represented in the selected random sites.


Eligible lakes/reservoirs are restricted to “significant lakes”, which refers to those freshwater lakes/reservoirs with at least 40 acres surface area that offer unrestricted public access.  The size of significant lakes/reservoirs varies immensely; therefore two size classes of lakes/reservoirs have been specifically targeted to ensure that the smaller lakes/reservoirs are represented in the selected random sites.


The coastal estuarine probability-based monitoring scheme has been developed jointly by SCDHEC, Bureau of Water, and the South Carolina Department of Natural Resources (SCDNR), Marine Resources Research Institute (MRRI).  This effort has been dubbed the South Carolina Estuarine and Coastal Assessment Program (SCECAP, see below) and sampling of the probability-based coastal estuarine sites is a cooperative venture between SCDHEC and SCDNR-MRRI. 

To ensure inclusion of a variety of estuarine ecosystems and habitats, the coastal estuaries have been divided into two discrete categories: Tidal Creeks and Open Water areas.  Each year there will be approximately 15 Tidal Creek sites and 15 Open Water sites.

SCDHEC personnel sample sites monthly for one year for water column physical and chemical parameters. SCDNR-MRRI samples annually for sediment chemistry, sediment physical characteristics, sediment toxicity, benthic infaunal community composition, 25-hour hydrolab deployments, and fish trawls. SCDHEC Water Quality Monitoring and Modeling Section staff collects one set of water column samples in conjunction with SCDNR-MRRI sampling.

For further information regarding Ambient Surface Water Monitoring, or water quality monitoring data, contact David Chestnut at (803) 898-4066.

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Accessing DHEC Water Quality Data From USEPA STORET

The USEPA Legacy STORET database contains data through 1998.  The SCDHEC Organization Code for Legacy STORET surface water quality data is 21SC60WQ.

The USEPA Modernized STORET database contains SCDHEC data from 1999 forward.  When looking for SCDHEC surface water quality data in Modernized STORET look under the Organization Name 21SC60WQ_WQX.

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Outside Agency Data and Quality Assurance Requirements

SCDHEC has developed a guidance document to help outside entities understand and meet the appropriate data quality requirements when monitoring water quality in South Carolina.  The guidance document outlines the following:
Examples of the different uses SCDHEC may make of water quality data collected by outside entities, and
The data quality assurance requirements associated with those uses.
Outside Agency Data & QA Requirements

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Basic Parameters Collected for Ambient Surface Water Monitoring

The following table is a list of the most common, basic parameters that may be routinely sampled by SCDHEC as part of the Ambient Surface Water Monitoring network.  This list also contains the reference for the analytical methods used by DHEC and the typical reporting limits for each parameter.
Routine DHEC Ambient Surface Water Monitoring Parameters

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The South Carolina Estuarine and Coastal Assessment Program (SCECAP)

In 1999, the South Carolina Department of Natural Resources (SCDNR) and the South Carolina Department of Health and Environmental Control (SCDHEC) initiated a major new collaborative coastal monitoring program entitled the “South Carolina Estuarine and Coastal Assessment Program” (SCECAP). The goal of SCECAP is to monitor the condition of the state’s estuarine habitats and associated biological resources on an annual basis. This program significantly expands ongoing monitoring efforts by each agency and draws upon the expertise of both in a cooperative effort. SCECAP integrates measures of water quality, sediment quality and biological condition at a large number of sites throughout the state’s coastal zone. It also expands historical monitoring activities that have primarily focused on open water habitats (e.g. bays, sounds, tidal rivers) to include an assessment of conditions in tidal creeks, which serve as important nursery habitat for most of the state’s economically valuable species. Many of these tidal creeks are also the first point of entry for non-point source runoff from upland areas and therefore provide an early indication of anthropogenic stress. For more information and SCECAP reports, visit the SCECAP website at or contact David Chestnut at (803) 898-4066.

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Related Reports

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Related Links


Environmental Protection Agency Links

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Bureau of Water . Phone: (803) 898-4300 . Fax: (803) 898-3795 . Contact Us