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Stormwater Monitoring

The Environmental Protection Agency (EPA) delegates authority to the Washington State Department of Ecology (Ecology) to issue WSDOT our NPDES Municipal Stormwater Permit (pdf, 5mb)(WSDOT permit). Discharges in the WSDOT permit S7 include stormwater runoff from state highways, rest areas, ferry terminals and maintenance facilities. Stormwater quantity and quality information is gathered from the continuous monitoring of stormwater runoff.  BMP at Pilchuck Creek

Stormwater Monitoring in WSDOT’s NPDES Municipal Stormwater Permit

The NPDES Municipal Stormwater permit requires WSDOT to:

  1. Produce scientifically credible and representative data.
  2. Provide information that WSDOT can use for designing and implementing effective stormwater management strategies for WSDOT’s highways and facilities.
  3. Provide information WSDOT can use to refine requirements, guidelines, and procedures contained in Stormwater Pollution Prevention Plans (SWPPPs) and the Highway Runoff Manual (HRM).

In order to accomplish this, WSDOT created a stormwater monitoring program to monitor stormwater runoff from our highways and maintenance facility sites and evaluate the effectiveness of Best Management Practices (BMPs) in the treatment and hydrologic management of stormwater runoff.

A stormwater BMP is a structural device, maintenance procedure, management practice, or activity used to prevent or reduce the harmful effects of stormwater runoff. Some of the BMPs assessed by the WSDOT stormwater monitoring program include:

  • Vegetated Filter Strip (VFS)
  • Compost-Amended Vegetated Filter Strip (CAVSF)
  • Modified Vegetated Filter Strip (MVFS)-a modified version of a CAVFS

To evaluate these BMPs, WSDOT establishes and maintains monitoring stations to continuously record environmental conditions and collect samples from both untreated and treated stormwater runoff.

WSDOT continuously seeks opportunities to conduct stormwater research, both on existing and novel BMP types, to gather information on stormwater managements systems that are currently being used and may be used in the future.

WSDOT also participates in the Puget Sound status and trends monitoring component of the Regional Stormwater Monitoring Program (RSMP) with annual financial contributions to the RSMP collective fund.

Information collected at Stormwater Monitoring Sites

Environmental:

WSDOT continuously monitors and records environmental conditions at each of our stormwater monitoring stations allowing us to determine when storm events occur and sample the runoff in accordance with the permit. Environmental data collected includes:

  • Rainfall - continuously measures the amount of rainfall each of the monitoring stations receives.
  • Temperature - measures air and runoff water temperature at each station.
  • Hydrology - measures the instantaneous water level of stormwater runoff (or stage) during rain events. These stage measurements are used to calculate stormwater runoff volume.

Stormwater Runoff Samples:

WSDOT collects stormwater samples from runoff events following the criteria in the permit. Each site has separate parameter requirements for samples analysis. Some common parameters WSDOT samples for include:

  • Total Petroleum Hydrocarbons
  • Total Suspended Solids (TSS)
  • Total and dissolved metals (Cu, Zn, Cd, Pb)
  • Total phosphorus and orthophosphate
  • Hardness
  • Polycyclic Aromatic Hydrocarbons (PAHs)

Additional Guidance Documents

Technology Assessment Protocol-Ecology (TAPE) (2011)

Urban Stormwater BMP Performance Monitoring Manual (2009)

Summary Reports

WSDOT NPDES Municipal Stormwater Permit BMP Effectiveness Monitoring Status Report (S7.C and S7.D) Water Years 2012-2015 (pdf 5 mb)

WSDOT NPDES Municipal Stormwater Permit BMP Effectiveness Monitoring Status Report (S7.C and S7.D) Water Years 12-14
(pdf 6 mb)

WSDOT NPDES Municipal Stormwater Permit Final Highway Runoff Characterization Report (S7.B) Water Years 12-14
(pdf 7 mb)

WSDOT NPDES Municipal Stormwater Permit Highway Runoff Characterization Report (S7.B) Water Year 2013
(pdf 2 mb) Appendices A-F (pdf 5 mb)

WSDOT NPDES Municipal Stormwater Permit BMP Effectiveness Monitoring Report (S7.C and S7.D) Water Year 2013 (pdf 4 mb)

WSDOT NPDES Municipal Stormwater Permit Highway Runoff Characterization and BMP Effectiveness Stormwater Monitoring Status Report (S7.B, S7.C, and S7.E) (pdf 358 kb)

WSDOT NPDES Municipal Stormwater Permit Rest Areas, Maintenance Facilities, and Ferry Terminals Stormwater Monitoring Report (S7.D) Water Years 2012 and 2013 (pdf 5 mb)

WSDOT NPDES Municipal Stormwater Permit Highway Runoff and BMP Effectiveness Stormwater Monitoring Report (S7.B, S7.C, and S7.E) Water Year 2012 (pdf 5 mb)

WSDOT NPDES Municipal Stormwater Permit Rest Areas, Maintenance Facilities, and Ferry Terminals Stormwater Monitoring Report (S7.D) Water Year 2012 (pdf 4 mb)


Quality Management Plan (QMP)

COMING SOON!


Quality Assurance Project Plans (QAPPs)


Data Validation Guidance and Criteria

WSDOT Stormwater Monitoring: Chemical Data Validation Guidance and Criteria 2014 (pdf 1 kb)


Standard Operating Procedures (SOPs)

COMING SOON!

Contact Information

For more information on WSDOT NPDES stormwater monitoring, contact Fred Bergdolt at 360-570-6648 or by e-mail BergdoF@wsdot.wa.gov .