Proper identification and documentation of a water quality problem requires gathering existing data from past or ongoing water quality studies. If adequate water quality data are not available to clearly document the problem and its source, a water quality problem identification and documentation monitoring program should be initiated. Monitoring should include both storm and baseflow sampling of surface water over a 6-18 month period. Ground water monitoring may also be needed. Depending on the pollutant(s) of concern, water quality monitoring may require measurements of chemical, physical, and biological factors.

Clear problem identification and documentation should lead to a water quality problem statement that:

• defines the water resource of concern;
• delineates the water use impairment or threat of impairment and identifies its location and history; and
• states the pollutant(s), the pollutant sources, and magnitude of the sources.

The water quality problem statement provides the basis for a strategy to effectively remediate, or prevent, a water quality impairment and enhance the designated water resource use. The strategy is used to guide the selection and placement of best management practices (BMPs) designed to reduce, remediate, or retard specific pollutants. A well-crafted water quality problem statement is also essential to ensure community consensus about the water quality impairment. Communities are generally unwilling to expend the money and time necessary to combat NPS pollution unless they are convinced that a significant problem or threat exists and that it can be rectified.

The Rural Clean Water Program (RCWP) was a national program that demonstrated the importance of water quality problem identification and documentation to successful agricultural NPS pollution control projects. Lessons learned from the RCWP about problem identification and documentation are presented in this fact sheet.

The Importance of Problem Identification and Documentation

Many of the projects selected to participate in the RCWP had thorough water quality impairment investigations prior to project selection. This allowed project teams to prepare well-crafted water quality problem statements that led to actions that enhanced water quality.

Gathering Existing Data for Water Quality Problem Identification and Documentation

Land use, soils, hydrologic, and climatic data should be compiled. A land use map is one of the most important tools for watershed managers. Land use classifications include agricultural lands, animal operations, residential areas, commercial and industrial facilities, mining operations, parks, forests, and wetlands.

Basic climatic information can be used to evaluate the times of the year when pollutant loads are greatest and when drought or other factors are affecting water resource data.

Data for the watershed analysis may be available from local health departments, county planning departments, state natural resource agencies, USDA - Natural Resource Conservation Service (state or local offices), USDA - Consolidated Farm Services Agency, National Oceanic and Atmospheric Administration, Soil and Water Conservation Districts, or county or regional Extension Service offices.

In cases where existing data are not adequate to identify or document a water quality problem, additional monitoring will be needed.

Monitoring for Problem Documentation

Program Design

The program should employ both ambient and stormwater quality monitoring. Baseflow monitoring of surface water documents ambient water quality conditions and problems. Storm sampling is useful for documenting the magnitude of hydrologic and pollutant impacts. If ground water monitoring is needed, specifically constructed monitoring wells generally yield more reliable data than existing domestic wells.

The categories (physical properties, chemical constituents, biological organisms, and habitat) and individual variables monitored will depend on the water quality impairment and the extent to which the water resource has already been studied.

Physical assessment monitoring includes such variables as water temperature, turbidity, sedimentation, and ground water elevation.

Chemical assessment consists of monitoring inorganic (nitrate, ortho-phosphate, metals) and/or organic constituents (pesticides, benzene).

Biological monitoring should be used to assess impacts on aquatic life, and may include monitoring variables such as coliform bacteria, benthic macroinvertebrates, and fish.

Habitat monitoring is important for characterizing the ecological integrity of the water resource as well as in explaining primary biological variation. Habitat monitoring variables include stream, lake, or reservoir macroinvertebrate and fish habitat.

Depending on the water resource being studied, to determine the water quality impairment and the primary pollutant, and possibly the pollutant source, monitoring stations for surface water may be established at: edge of field; tributaries; main-stem streams; or estuaries, lakes, reservoirs or wetlands. For ground water, stations may be needed: aquifer-wide, in certain portions of an aquifer, at specific sites or locations where particular practices are in use, or at specific intervals within the aquifer.

Tributary stations are often useful for identifying pollutant sources and the magnitude (load) of the pollutant. Simply monitoring the main-stem stream (primary drainage channel or lake) may be inadequate to identify sources of pollutants because the receiving water dilutes and assimilates tributary inputs, making identification of specific sources difficult. Tributary stations should be located immediately above and below suspected NPS pollution discharge areas to facilitate pollutant source identification. For example, in the Oregon RCWP project, tributary stations were used to document the type(s) and magnitude of pollutants entering Tillamook Bay from individual dairy farms.

Data collected at main-stem stream stations provide an aggregate of the water conditions upstream. The water quality variables measured at the main-stem stream station should match those monitored in the tributaries. In the Florida RCWP project, for example, phosphorus, the major pollutant of concern, was carefully monitored in both main-stem streams and tributaries.

Monitoring stations located in reservoirs, lakes, estuaries, or wetlands can provide useful information about the amount and fate of pollutants reaching the water resource. These stations should be strategically positioned to evaluate the impact of the pollutant on the designated water use. For example, in the Oregon RCWP project, estuarine monitoring stations were located in or near shellfish beds so that fecal coliform contamination could be monitored.

Monitoring Duration and Frequency

For continuous streams, monitoring of physical and chemical constituents should occur with sufficient frequency to ensure that water quality changes caused by climatic impacts and watershed activities can be accounted for in the analysis. The timing of biological monitoring should correspond to the type and stage of the organism being documented. Guidance on timing for biological monitoring should be available from the state water quality agency.

The timing of water quality monitoring activities should also be a function of the monitoring objective. For example, timing of storm sampling is critical if the project team is trying to determine load. Water quality samples should be taken during the rise, peak, and fall of stream level during runoff.

Pollutant Budget

The Importance of Preparing a Water Quality Problem Statement

Sometimes the water quality problem statement is written correctly the first time. In other cases, the statement may have to be rewritten as additional information becomes available. In the Illinois RCWP project, for example, the project team originally thought that excess lake turbidity was caused by general erosion (Gale et al., 1993). However, monitoring conducted during the project indicated that a particular type of soil (natric soils) was causing most of the turbidity because saline soil particles from the natric soils do not settle. Once the pollutant source was accurately determined, a new problem statement was written and land treatment efforts were redirected toward the natric soils.

Key Points of Problem Identification and Documentation

• Prioritize problem identification and documentation as a first step to designing a NPS pollution control project.
• Gather existing water quality data. This information should include a physical description of the water resource and the watershed, a designated use of the water resource, and water quality data that indicate a water quality impairment or potential threat to the water resource.
• Water quality monitoring for problem documentation should ensue if existing data are inadequate to identify and document the water quality problem.
• Water quality monitoring for problem documentation should include both storm and ambient flow.
• Variables monitored will depend on the suspected impairment.
• A clear water quality problem statement should be written.
• Well-crafted water quality problem statements should lead the project team toward the selection of the appropriate systems and locations of BMPs.

References

Fredrico, A.C., K.G. Dickson, C.R. Kratzer, and F.E. Davis. 1981. Lake Okeechobee Water Quality Studies and Eutrophication Assessment. South Florida Water Management District (SFWMD), Technical Publication #81-1, West Palm Beach, FL. p. 270.

Gale, J.A., D.E. Line, D.L. Osmond, S.W. Coffey, J. Spooner, J.A. Arnold, T.J. Hoban, and R.C. Wimberley. 1993. Evaluation of the Experimental Rural Clean Water Program. NCSU Water Quality Group, Biological and Agricultural Engineering Department, North Carolina State University, Raleigh, NC, EPA-841-R-93-005, p. 559

NORTH CAROLINA STATE UNIVERSITY
COLLEGE OF AGRICULTURAL & LIFE SCIENCES

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