Follow the Pollution
Amendments to the Clean Water Act identified urban stormwater runoff as a source of water pollution, while recognizing the need for more
information on exactly what contributes to water pollution. Indiana State Rule 13 is a similar measure which applies to utilities with
sewer systems that discharge stormwater. The challenge was to meet State and Federal compliance requirements, and develop a long-term
water quality analysis plan.
Using Geographic Information Systems (GIS), the Monroe County Planning Department developed a stream assessment
which gives an overview of water quality.
The first step was to determine the amount of runoff produced by different areas. Planners developed a unique process
which uses zoning classifications to calculate both current and future impervious surface estimates. Those areas with
more impervious surfaces, like parking lots and driveways, generate more runoff. Next came the lengthy process of
reviewing and classifying parcels according to land use. Finally, benchmarks were used in calculations to provide a
snapshot of long-term water quality impacts in a given area.
The completed assessment shows where runoff originates, indicates land use on each property, and determines which water
bodies are affected by the runoff. This combined data provides a baseline for future comparison, and is a
key component in analyzing the effects of land use on water quality over time.
Results
- Monroe County planners developed a highly-effective water quality analysis tool
- Planners can see which bodies of water are most heavily affected by pollution from stormwater
- The impact of future development can be seen before it is approved
- Investigative and corrective resources can be prioritized based on quantifiable needs
- The evaluation process was designed to be easily replicated for use by all levels of government
Printable Version