Water Quality Monitoring In Tennessee
The Division of Water Resources has developed a monitoring strategy based on the need to collect data for various program responsibilities. Biological, chemical, bacteriological, and physical data are collected to supply information for the activities listed below.
Additional information concerning the monitoring strategy can be found in the in the Division of Water Resources Monitoring and Assessment Program Plan posted on the publications webpage.
Consistent with the division’s watershed approach, as many additional stations as possible are monitored in order to collect information on waterbody segments that have not previously been assessed. If possible, sampling locations are located near the mouth of each tributary. Minimally, macroinvertebrate biorecons, habitat assessments, and field measurements of DO, conductivity, pH, and temperature are conducted at these sites.
If impairment is observed, and time and priorities allow, additional sites are located upstream of the impaired water reach to define the impairment length. Chemical samples are collected as needed to determine pollutant causes. Bacteriological samples are collected to determine recreational use support.
During each watershed cycle, 303(d) listed streams are monitored. At a minimum, 303(d) stations are sampled three times for the pollutants of concern and a macroinvertebrate biological sample is collected. Additional monitoring is required for confirmation if water quality appears to have improved.
Approximately 60 long-term trend stations are monitored quarterly for chemical and bacteriological quality. These data are used to check for changes in water quality over time.
Before activities that degrade water quality can be authorized, a stream’s proper status under the antidegradation policy must be determined. The division uses a standardized evaluation procedure for this purpose. These activities are difficult to plan, because waterbodies are evaluated as needed - generally in response to requests for new or expanded NPDES and Aquatic Resource Alteration Permit (ARAP) permits. The type of monitoring utilized for this purpose is the more intensive biological survey since the biological integrity of a stream is an important consideration.
Established reference stations are monitored in conjunction with the watershed cycle. Each station is sampled quarterly for chemistry and pathogens as well as in the spring and fall for macroinvertebrates. Semi-quantitative single habitat and biorecon samples are collected to establish biocriteria and biorecon guidelines. In 2007, the division also began collecting periphyton at these sites. If watershed screening results indicate a potential new reference site, more intensive reference stream monitoring protocols are used to evaluate potential inclusion in the reference database.
Monitoring is undertaken each year to insure that facilities or other entities are in compliance with permit conditions. These monitoring efforts typically have one of the following designs:
- Above/Below Surveys – Samples are collected above and below an activity to determine the immediate effect the activity is having on the stream.
- Trend Determination – Samples are collected over time downstream of an activity to document if conditions are getting better or worse.
- Reference Approach - Data collected below an activity are compared to a suitable reference stream. This technique is particularly helpful when the activity is in a headwater reach or where the stream is also impacted upstream of the activity.
Additionally, the department receives numerous water quality complaints each year from citizens. These are handled as a priority activity and any data collected at these streams can be used to assess the waterbody.
Statistical survey designs have been used for many years to characterize the condition of large populations based on a representative sample of a relatively few members or sites within the population. The ability of these designs to provide accurate estimates, with documented confidence levels, of the condition of populations of interest is well documented. These surveys are used in a variety of fields including election polls, monthly labor estimates, forest inventory analysis, and the national wetlands inventory.
In 2001, the division began incorporating probabilistic survey design into its monitoring strategy. Probabilistic monitoring means that sites are selected using a random sample design. Every site in the target population has an equal chance of being selected for sampling can be extrapolated to the entire population of waterbodies represented by the subsample. Because of its consistent methods and sampling framework, probabilistic monitoring is useful as a baseline for trend analysis.
Fish tissue samples are often the best way to document chronic low levels of persistent contaminants. Discovery of elevated levels of certain contaminants in fish tissue can lead to use advisories.
Fish tissue monitoring in Tennessee is planned by a workgroup consisting of TDEC staff (Water Resources and DOE-Oversight), TVA (Tennessee Valley Authority), TWRA (Tennessee Wildlife Resources Agency), and ORNL (Oak Ridge National Laboratory). The workgroup meets annually to discuss fish tissue monitoring needs for the following year. Data from these surveys help the division assess water quality and guide the issuance of fishing advisories.
TVA routinely collects fish tissue from reservoirs they manage. ORNL collects fish tissue samples from rivers and reservoirs that receive drainage from the Department of Energy Property in Oak Ridge. TWRA provides fish tissue samples to TDEC that are collected during population surveys.
TDEC contracts other needed fish sampling and analyses to the Aquatic Biology Section, Tennessee Department of Health. Targeted fish are five game fish, five rough fish, and five catfish of the same species. Samples are generally composited, although large fish may be analyzed individually. Only fillets (including belly flap) are analyzed for routine monitoring, however whole body fish may be used for special projects.
Although, not commonly collected, sediment at the bottom of a creek or lake can be sampled to determine the presence of harmful amounts of metals or carcinogens. One of the reasons this type of monitoring is not frequently a part of monitoring plans is that few criteria exist to reliably assess the degree of harm to the waterbody.
As with all monitoring, field and laboratory staff use standardized procedures for the collection and analysis of sediment samples. Although Tennessee has no numeric sediment criteria, EPA literature and guidance developed by the National Oceanographic and Atmospheric Administration (NOAA) are used to assist in data interpretation.