Phase I Municipal Stormwater Permit Monitoring: Stormwater Monitoring (S8.D)

2007-2012 Results

  • Full Report: Contains detailed analyses and conclusions, including trends and concentration estimates.
  • Dataset: All 45,000 individual records available for review or download on

Program Details

Special Condition S8.D of the 2007-2012 Phase I Municipal Stormwater Permit required permittees to collect and analyze data to evaluate pollutant loadings of stormwater discharged from different land uses: high density (HD) residential, low density (LD) residential, commercial, and industrial.

To meet the S8.D requirement, Phase I Permittees collected water quality and flow data, sediment data, and toxicity information from stormwater discharges during storm events.

The intent of the outfall monitoring program was to gather baseline stormwater discharge quality data and to determine whether stormwater management programs reduced pollutants discharged to Washington's Waters and thus protected water quality.

Some permittees have either elected to, or been required to, continue stormwater discharge monitoring under the 2013-2018 permit; specifically, Clark County and the City of Tacoma.

Sample Concentrations by Parameter and Land Use

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Each dot represents a single storm event (for water results) or a yearly composite sample (for sediment results).

Gray dots represent non-detect samples.

Parameters monitored:

  • Conventional Parameters
  • Organics
  • Metals
  • Pesticides
  • Nutrients

For detailed parameter lists, see S8.D of the 2012-2013 Phase I permit.

Reporting and Data Sharing
Phase I S8.D outfall data gathered under the municipal stormwater permit are submitted to Ecology’s Environmental Information Management Database (EIM). To access data reports or obtain more information about Ecology’s EIM database go to:

Quality Assurance Project Plans
Phase I Permittees were required to develop Quality Assurance Project Plans (QAPPs) for review and approval by Ecology. The QAPPs below contain detailed information about each Permittee’s S8.D monitoring program from 2007-2013:



Stormwater Monitoring Report Guidance-Phase I

EAP Quality Assurance

Phase I Permit

QAPP Guidance for S8.D

Phase I S8.E Monitoring

Phase I S8.F Monitoring