25 October 2004
Nitrate + Nitrite
NO2 + NO3
5-5.2.4 Biological Monitoring. Pollutants in stormwater runoff have a direct effect
on the biological integrity of the receiving waters. The effectiveness of water quality
controls can therefore be evaluated by assessing the biological health of the receiving
waters in the vicinity of the stormwater outfall. The EPA has developed Rapid
Bioassessment Protocols (RBP)13 that can be used to characterize the existence and
severity of impairments to streams, and help to identify sources and causes of
5-5.2.5 Monitoring Program. There are four phases to develop a monitoring
1. Determine the objectives and scope of the monitoring program
2. Develop the monitoring plan in view of the objectives
3. Implement the monitoring plan
4. Evaluate and report the results
Monitoring programs are shaped by the site characteristics, the goals of the
project, regulatory requirements, and available funds.
5-5.2.6 Variability. The high variability of stormwater flows and pollutant
concentrations at any location makes it difficult to obtain useful monitoring results.
Typically, facilities must collect a large number of samples to adequately characterize
how a device is functioning under natural conditions. The monitoring approach used on
any given site will depend on regulatory requirements, the pollutants of concern, the
physical characteristics of the runoff management features, and the availability of funds
and personnel for planning, sampling and analysis.
5-5.2.7 State and Local Program Conformance. Water quality monitoring
programs should be undertaken to conform to state and local protocols. A detailed
guidance manual for water quality data collection, management and interpretation is
available from the Environmental Protection Agency15 and the Department of
Transportation.16 The guidelines, which are primarily concerned with meeting the
national stormwater BMP database requirements, can be easily adapted for use in a
variety of monitoring activities.
5-5.2.8 Sampling Locations. An effective monitoring effort for decentralized runoff
management requires a judicious selection of sampling locations as well as sampling
times and techniques. The challenge is often to complete the monitoring effort
Barbour et al., 1999.
DOT, 2000; EPA, 2002.