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Part 5. Environmental Indicators for Stormwater Programs
Although you are required to develop measurable goals for each BMP, identifying overarching goals for your entire stormwater management program is also useful. Establishing objectives for each of the minimum measures can help put each program component into perspective within the framework of your overall program. One way to evaluate program success at either the minimum measure- or overall program-level is through the use of environmental indicators.
Useful indicators are often indirect or surrogate measurements where the presence of the indicator points to a likelihood that the program area was successful. Indicators can be a cost-effective method of assessing the effectiveness of a program because direct measurements sometimes can be too costly or time-consuming to be practical. A well-known example is the use of fecal coliform bacteria as an indicator of the presence of human pathogens in drinking water. This indicator dates back more than 100 years and is still in widespread use for the protection of public health from waterborne, disease-causing organisms.
| Environmental indicators are measurable features which alone or in combination provide managerially and scientifically useful evidence of ecosystem quality, or reliable evidence of trends in quality. (Intergovernmental Task Force on Monitoring Water Quality, 1995) |
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Environmental indicators are relatively easy-to-measure surrogates that can be used to demonstrate the actual health of the environment based on the implementation of various programs or individual program elements. Some indicators are more useful than others in providing assessments of individual program areas or insight into overall program success. EPA has developed a hierarchy of indicators to illustrate this issue, which is shown below.
Figure 1. Environmental Indicators Pyramid (USEPA, 1998).
The indicators at the base of the pyramid are more general and might be most useful for limited statements about specific program areas, such as establishing a relationship between the use of BMPs and loadings reductions. As one advances to higher levels on the pyramid, the environmental indicators reflecting improvements in instream biota could be linked to overall program success.
In a similar fashion, the indicators shown on the lower boxes of Figure 2 reflect administrative or programmatic measurements while actual indicators of environmental change are encompassed by the upper boxes. Both figures depict the hierarchy of indicators where administrative or programmatic indicators are relatively easy to determine but are generally not as useful as the environmental indicators.
Figure 2. Hierarchy of Environmental Indicators (USEPA, 1998).
Table 1 presents environmental indicators that have been developed specifically for assessing stormwater programs (Claytor and Brown, 1996). Note that some of the water quality indicators, physical and hydrological indicators, and biological indicators (indicators 1 through 16) can be integrated into an overall assessment of your program and used as a basis for the long term evaluation of program success. Indicators 17 through 26 correspond more closely to the administrative and programmatic indicators as well as the practice-specific indicators for which you are establishing measurable goals.
Table 1. Stormwater Indicators
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Category
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# |
Indicator Name |
| Water Quality Indicators |
1 |
Water quality pollutant constituent monitoring |
| 2 |
Toxicity testing |
| 3 |
Loadings |
| 4 |
Exceedance frequencies of water quality standards |
| 5 |
Sediment contamination |
| 6 |
Human health criteria |
| Physical & Hydrological Indicators |
7 |
Stream widening/downcutting |
| 8 |
Physical habitat monitoring |
| 9 |
Impacted dry weather flows |
| 10 |
Increased flooding frequency |
| 11 |
Stream temperature monitoring |
| Biological Indicators |
12 |
Fish assemblage |
| 13 |
Macroinvertebrate assemblage |
| 14 |
Single species indicator |
| 15 |
Composite indicator |
| 16 |
Other biological indicators |
| Social Indicators |
17 |
Public attitude surveys |
| 18 |
Industrial/commercial pollution prevention |
| 19 |
Public involvement & monitoring |
| 20 |
User perception |
| Programmatic Indicators |
21 |
Number of illicit connections identified/corrected |
| 22 |
Number of BMPs installed, inspected & maintained |
| 23 |
Permitting & compliance |
| 24 |
Growth & development |
| Site Indicators |
25 |
BMP performance monitoring |
| 26 |
Industrial site compliance monitoring |
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