NPDES Permit Monitoring and Inspection

Coastal Resources, Inc. (CRI) is providing field support for annual data collection in compliance with Charles County’s National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit over a 7-year period. Field efforts to date have included geomorphic assessment, biological monitoring, watershed assessments, and Illicit Discharge and Detection Elimination (IDDE) monitoring. Five years of data collection under this contract has been completed.  The continuation of these monitoring tasks will allow for year-to-year comparisons of data, which will help the County demonstrate progress and maintain compliance with the permit. CRI assisted with monitoring efforts at two long-term stream monitoring sites and various other locations across the County.

As part of the County’s efforts to evaluate the health of County streams to satisfy the requirements of the NPDES Permit Update, long term monitoring is conducted annually at a site on a tributary of Mattawoman Creek known as the Acton Hamilton site.  Baseline geomorphic and biological conditions were established at this site through monitoring conducted by others in 2005 and 2006, and these conditions are re-monitored annually to assess the tributary’s biological and physical condition over time. The geomorphic assessment includes cross section surveys, longitudinal profiles, and particle size analysis. Spring bioassessment monitoring involves the collection of water quality data, sampling and analysis of the benthic macroinvertebrate community, assessment of physical and habitat characteristics, and photo documentation of site conditions throughout the study reach.  Each year’s data is then compiled into an annual report comparing current and previous conditions against baseline data and long-term trends.

Since 2003, Charles County has also been conducting stream monitoring on a tributary to Piney Branch to evaluate the effectiveness of stormwater management, designed under the stormwater design regulations in the 2000 Maryland Stormwater Design Manual, to adequately provide channel protection. CRI assisted with approximately 5,000 linear feet of longitudinal profile and cross-section survey and development of the stormwater assessment report, which compared geomorphic data from several years. The evaluation involved the annual survey of permanently monumented cross sections and longitudinal profiles of the tributary and outfall to detect channel degradation or aggradation.

The pond outfall was selected for additional study in 2011 due to the presence of channel erosion and potential sediment load entering the tributary to Piney Branch. Monuments were established and the initial longitudinal profile and cross section survey of the pond outfall was completed on April 26, 2011. Annual surveys of the longitudinal profile and cross sections established on the pond outfall channel occurred from 2013 through 2019. The cross sections and longitudinal profile of the pond outfall channel are compared over time to detect channel degradation or aggradation.

CRI assisted with IDDE monitoring, including illicit discharge outfall inspection and commercial and industrial visual surveys. One hundred major outfalls were inspected for signs of deterioration and dry-weather discharge, where present, was tested using a Hach Storm Drain Test Kit. In addition, suspicious practices and evidence of possible sources of pollutants found on commercial and industrial sites within the watershed selected for the IDDE screening were recorded.

Watershed assessments included synoptic sampling at the subwatershed level and visual watershed inspection of upland and lowland areas. Lowland areas were evaluated using the Stream Corridor Assessment (SCA) protocol. Approximately eight miles of stream were assessed using the SCA protocol. Upland reconnaissance included the use of Neighborhood Source Assessment (NSA), Hotspot Site Investigation (HSI) and Pervious Area Assessment (PAA) protocols.


Charles County, MD


Charles County Planning and Growth Management

Key Services:

  • Watershed Assessments
  • Biological, Physical, and IDDE Monitoring
  • Report Preparation