Tacoma’s Surface Water Utility Earns National Award for Improving Stormwater Quality in the Thea Foss Watershed - February 2011

Type: 
Award
Contributor: 
City of Tacoma

The City of Tacoma’s stormwater management program received a 2011 Operations and Environmental Performance Award from the National Association of Clean Water Agencies for their work to improve the quality of stormwater discharged into the Thea Foss Waterway.

NACWA’s environmental awards recognize agencies that have made outstanding contributions to environmental protection and wastewater management. The Operations and Environmental Performance Award is presented for outstanding initiatives in wastewater treatment, wastewater conveyance, stormwater management, and/or environmental enhancement.

Tacoma’s Surface Water Utility was one of five honorees in this category in 2011. Awards recognize innovative and effective projects that have been developed and successfully implemented in a cost-effective manner while achieving environmental compliance objectives.

The utility’s aggressive stormwater management program, launched in 2001, includes source control, maintenance, rehabilitation, treatment and education. To track progress, the City undertook extensive monitoring of stormwater, baseflow and sediment throughout the watershed.

Monitoring data showed subtle improvements in the early years of the program. City staff began new targeted programs based on the data collected and with the intent of increasing the levels of water quality improvement. Those programs include:

  • Studying effective treatment of phthalates
  • Cleaning 100-year-old storm pipe to eliminate legacy contaminants
  • Rehabilitating 15,000 feet of pipe where it traverses through contaminated soils
  • Installing a system of 226 canisters to tackle chronic PAH levels in an industrial area

Over a ten-year period, 26 trends show decreasing contamination in stormwater discharged into the Foss. After 1,140 samples were collected at seven outfalls (points where stormwater enters the waterway), some of the most improved outfalls show:

  • 44 to 57 percent reduction of total suspended solids
  • 44 to 49 percent reduction of lead
  • 40 percent reduction of zinc
  • 81 to 97 percent reduction of some PAH compounds
  • 57 to 81 percent reduction of the plasticizer DEHP