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Water: Watershed Central

Set Goals and Identify Solutions - Develop Indicators/Targets

Once you have established specific management objectives, you will develop environmental indicators and numeric targets to quantitatively evaluate whether you are meeting your objectives. You identified indicators with your stakeholders earlier when building partnerships and the indicators should be reviewed in this step. The specific indicators will vary depending on the designated use of the waterbody and the water quality impairment or issue of concern. For example, multiple factors might cause degradation of a warm-water fishery. Some potential causes include changes in hydrology, elevated nutrient concentrations, increased sediment, and higher summer temperatures. Each of these stressors can be measured using indicators such as peak flow, flow volume, nutrient concentration or load, sediment concentration or load, and temperature. A specific value can be set as a target for each indicator to represent the desired conditions that will meet the watershed goals and management objectives. Targets can be based on water quality criteria or, where numeric water quality criteria do not exist, on data analysis, reference conditions, literature values, or expert examination of water quality conditions to identify values representative of conditions that support designated uses.

If a Total Maximum Daily Load (TMDL) already exists for pollutants of concern in your watershed, you should review the TMDL to identify appropriate numeric targets. TMDLs are developed to meet water quality standards, and when numeric criteria are not available, narrative criteria (e.g., prohibiting excess nutrients) must be used to develop numeric targets. Table 9-2 provides indicators and their associated target values to achieve specific management objectives.

Table 9-2 . Examples of Indicators and Targets to Meet Management Objectives

Management Objective

Indicator and Target Value

Reduce phosphorus loads from cropland runoff and fertilizer application

Dissolved oxygen: Daily average of 7 mg/L (from water quality standards)

Phosphorus: Daily average of 25 µg/L (based on literature values)

Minimize flooding impacts by improving peak and volume controls on urban sources and retrofitting inadequate road culverts

Peak flow volume and velocity: Peak velocity for 1-yr, 24-hr storm of 400 cfs

Reduce sediment loads from upland sources improve riparian vegetation and limit livestock access to stabilize streambanks

Riffle-to-pool ratio: 1:1 ratio (based on literature values)

Percent fine sediment : <10 percent of particles <4 mm (based on reference conditions)

Reduce bacteria loads from livestock operations

Fecal coliform: Geometric mean of 200 cfu/100 mL (based on water quality standards)

Reduce nitrogen loads to limit algal growth

Algal growth: <10 percent coverage of algal growth (based on reference conditions)

Chlorophyll a: <1 µ g/L (based on literature values)

Improve stormwater controls to reduce metal loads from runoff

Zinc: Maximum of 120 µ g/L (based on water quality standards)

Copper: Maximum of 13 µ g/L (based on water quality standards)

 

EPA / Water Science / Great Lakes Initiative - The Final Water Quality Guidance for the Great Lakes System (the Great Lakes Initiative) is a plan agreed upon by EPA and the Great Lake states to restore the health of the Great Lakes.

EPA NPDES Permit Program Basics - This section of this website contains basic information on the major features and elements of the NPDES permit program. The information in this section will be most useful to state and tribal officials, interested citizens, and others with an interest in the details of the NPDES program.

Statistical Considerations for Data Quality Objectives and Data Quality Assessments in Water Quality Attainment Studies - Appendix C (PDF) (94 pp, 1.1MB, About PDF) - Full Appendix is available here.

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