Areas of Concern: Polycyclic Aromatic Hydrocarbons (PAH) Source Tracking in Milwaukee River

Science Center Objects

Project objectives are to identify potential Polycyclic Aromatic Hydrocarbons (PAH) sources and quantify PAH loading to the Kinnickinnic River Great Lakes Legacy Act (KKGLLA) Estuary from 2009 through 2014.

Sampling pipe under bridge

A sampling pipe for PAH placed under a bridge. 

(Public domain.)

The goal of the project is to develop management strategies that reduce PAHs in the Milwaukee Estuary and other AOCs.

The objectives are:

  • Quantify PAH loads from urban runoff for the project area by modeling with Source Loading and Management Model for Windows (WinSLAMM).
  • Develop an ACCESS database incorporating all of the nonpoint studies collected by Wisconsin Department of Natural Resources (WDNR) in cooperation with the USGS Water Science Center located in Wisconsin. The databases name is WI-Urban.
  • Determine the importance of PAH loads in urban runoff compared to other sources including incidental input, direct air deposition, and loading from upstream of the project area based on mass balance approach for the PAHs in sediment of the KKGLLS project area.
  • Assist in developing a future cost-effective mitigation plans to reduce PAH input to the project area, including the source areas within the drainage watershed.
  • Provide a methodology to analyze PAH sources for the entire Milwaukee Estuary AOC and other AOC with PAH concerns.

Data availability is a critical component of the modeling assessment and integration of management strategies. Previous studies in Wisconsin and throughout the country have collected PAH concentrations in runoff from a variety of urban landuses. The USGS will collect and review urban runoff PAH and perform a literature review for PAH data available in other parts of the country.

Data compilation includes:

  • Gather existing source area PAH concentration data from previous studies. The USGS - Wisconsin Water Science Center has previously studied several nonpoint source projects that measured flow, solids, and PAH concentrations on source areas integrated with different landuse types and management practices. Data from other PAH studies may exist that could be used as input to WinSLAMM.
  • Assess the quality of all data compiled. Statistical and graphical of summaries of existing solids and PAH data will be used to select the appropriate values to incorporate into WinSLAMMs parameter files. Apply the appropriate site characteristics for solids and pollutant parameter files. Determine if default initial winter load to include in WinSLAMMs for spring street-dirt loading parameter is valid for this project.
  • Compile existing data in a usable format for WinSLAMMs and landuse load evaluation. This includes Wisconsin Urban Studies Monitored (Fig. 3) studies done by USGS, WDNR, and other cooperators to improve WinSLAMM capabilities to accurately predicting sources of runoff pollutants and flows for a measured watershed. Stakeholder can use products from this study for future results assessments and integration of management plans on other watersheds.
Collected samples for PAHs

Samples of water collected to be tested for PAHs from the Milwaukee River AOC. 

(Public domain.)

Significant events and experiences

  • WinSLAMM results were presented at the WI-AWRA annual conference March 2019 by Judy Horwatich
  • Updates presented at WDNR at monthly staff meetings

Synopsis and analysis of collected data

  • Continuous runoff samples were collected at the 29th Street pipe – so far 16 samples were collected, processed, and analyzed for sediment and PAHs
  • Combined sewer overflow samples were collected for two grab samples at 4th Street deep tunnel overflow in cooperation with MMSD
  • The WI-Urban database has over 7,500 rainfall (8,500 volume and 7,700 water-quality) These records are being used to develop equation to enhance stormwater runoff and loads models such as WinSLAMM.
  • Nine source areas equations to predict volume are now in WinSLAMMs runoff coefficient parameter file. Modeled volume comparisons to the observed values were compiled for 20 sites for calibration and 45 sites for validations These results have been present to WDNR staff and at various conferences.

Anticipated outputs

  • The Wi-Urban ACCESS Database
  • WinSLAMM Rv Parameter file (Runoff coefficient file)
  • Summary of goodness of fit indicators and six plots for each of the 65 sites used in the calibration and validation of volumes in WinSLAMMs


  • Wisconsin Department of Natural Resources
    • WDNR staff has gathered funding to collect additional sediment cores in the KKGLLA estuary

Contributions to the Great Lakes Restoration Initiative

  • Update WinSLAMMs parameter files for runoff coefficients, particulate solids, and concentrations that include PAHs.
  • Environmental managers can develop a plan to reduce loadings in their watersheds using WinSLAMMs with the updated parameter files.
  • The predicted landuse outputs as river inputs into a mass balance model or a transport model will be used in a second phase for this project if funded.