Environmental Services to Clean Out CS Gas Residue from Storm Drains in Effort to Protect Willamette River

News Article
In an effort to prevent tear gas residue and other pollutants from reaching the Willamette River, the City of Portland Bureau of Environmental Services is planning today to clean six storm drains around the Multnomah County Justice Center and the Mark O. Hatfield federal courthouse.
City workers take storm drain samples.

The action follows weeks of deployment of tear gas and other crowd-dispersal agents. Environmental Services has received reports from the public, and documented several instances of power washing that flushed contaminants into the street and to storm drains.

It is against City Code to flush any material into the City’s storm system, which is for rainwater only. In some parts of the city, including portions of downtown, rainwater is sent through sewer pipes to the City’s wastewater treatment plant. In other areas, such as the blocks surrounding the courthouse and justice center, stormwater pipes flow directly to the Willamette River.

Typically, rainwater mixes with dirt, motor oil residue, and other debris as it washes over city streets and to the stormwater system.  But the sustained use of CS gas and other agents by Portland Police and federal authorities poses a new and unknown pollution source. 

 “Our primary goal is pollution prevention,” said Matt Criblez, Environmental Services’ compliance manager. “We know that a certain amount of these chemicals have settled into the City’s storm drains. We are going to remove as much as possible to prevent that material from being flushed into the Willamette River.”

Crews will vacuum out the drains, and send the sediment to a commercial landfill. Crews will clean out six storm drains and are working on getting permission to access a seventh, which is behind the courthouse fence.

Additional actions Environmental Services is taking include: 

Map of storm drain cleanout areas.
  • Sampling. An Environmental Services team already has taken samples from the storm drains for analysis. The samples are being analyzed for levels of zinc, lead, copper, and chromium -  contaminants found in crowd control agents but also commonly found in stormwater due to motor vehicle and other sources. The samples also will be analyzed for substances specific to CS gas use: hexavalent chromium, perchlorate, barium, and cyanide. The results, expected to be available later this month, will help inform the City’s ongoing evaluation and response.
  • Preventing additional discharges to the stormwater system. Environmental Services is working closely with City bureaus, the community, and local contractors to prevent wash water from being flushed to the storm system.  It is believed that chemical residue has settled on the leaves of trees and soil in the area, as well as on buildings and sidewalks. As downtown cleanup continues, Environmental Services will continue to have teams in the area to educate and enforce as appropriate to control those discharges.  
  • Monitoring. Environmental Services will follow the state Department of Environmental Quality’s direction and take additional samples from an outfall to the Willamette River when the next substantial rainfall occurs. The samples will be taken in the pipe system before discharge to the river. DEQ has directed Environmental Services to test for chromium, hexavalent chromium, lead, zinc, copper, barium, and perchlorate.

The public can play a role in protecting the Willamette River. Because of the federal Clean Water Act and the City and the public’s actions, the river is improving for salmon and fish habitat, and is clean enough for swimming and other water recreation. The public is asked to: 

  • Prevent pollution - only rain goes down storm drains. When cleaning pavement, commercial properties should put buffers around storm drains and use a wet/dry vacuum to collect wastewater. Don’t toss cigarette butts and other litter, and clean up pet waste, which is a source of E. Coli bacteria. 
  • Become a Green Street Steward - green street planters throughout the city are landscaped areas that collect and filter rainwater runoff, preventing pollution from reaching the river.  The City has more than 2,000 green street planters with more being constructed each year. www.portlandoregon.gov/BES/GreenStreetStewards
  • Enjoy your river - Environmental Services tests the Willamette River for bacteria weekly during the summer. All results this season are good. See results and COVID-19 safety tips for river recreation at www.portlandoregon.gov/BES/CheckTheRec.


Diane Dulken

Public Information Officer