Tear gas residue is not significantly impacting Willamette River, Portland report concludes

By Monica Samayoa (OPB)
Sept. 11, 2020 4:29 p.m.

The study was based on samples from stormwater and sediment from downtown Portland storm drains.

Sediment and stormwater samples taken from downtown Portland show no significant amount of tear gas chemicals have impacted the Willamette River, but environmental groups say the report is an incomplete analysis.

The Bureau of Environmental Services released its Riot Control Agent Stormwater and Catch Basin Sampling Summary on Thursday and found there were higher concentrations of metals and other chemicals in their samples from stormwater and sediment that could be associated with tear gas and related chemicals. Results also indicated the elevated concentrations were not observed near the outlets of the storm basin, indicating little or low impacts to the Willamette River.


But the agency said this is only a small and limited portion of samples that were taken in August and the total contribution of tear gas metals or chemicals is unknown.

Green water from cleanup runs down a storm drain near Lownsdale Park across from the Mark O. Hatfield federal courthouse in Portland, Ore., July 30, 2020, the morning after law enforcement deployed tear gas to disperse protesters. Environmental specialists know little about the long-term effects of tear gas on plants, water and wildlife.

Green water from cleanup runs down a storm drain near Lownsdale Park across from the Mark O. Hatfield federal courthouse in Portland, Ore., July 30, 2020, the morning after law enforcement deployed tear gas to disperse protesters. Environmental specialists know little about the long-term effects of tear gas on plants, water and wildlife.

Monica Samayoa / OPB

More than 100 days have passed since the death of George Floyd prompted Black Lives Matters demonstrations and protesting against police brutality. These protests have occurred daily since the end of May and most of those days, demonstrators have experienced some sort of tear gas deployment by local police or federal agents.

BES Spokesperson Diane Dulken said samples are taken and tested year-round, but the city has never had large amounts of tear gas deployed over a long period of time. Therefore, the agency does not have any data to compare these results.

“We just have one snapshot in time at the epicenter of this,” Dulken said. “So we can say, it’s very important in our snapshot in time, we found higher levels at that location where there was discharge and we saw that those levels dropped as it mixed with other substances with stormwater before it reached the river.”

Related: Related: 60-plus days of tear gas leaves lingering questions about environmental impacts

Dulken said this was a very thorough sampling and data collection for this one-time testing and it was important to take samples from this area since it received so much tear gas chemicals over a period of two months at the time.

The release of the results come as Portland Mayor Ted Wheeler banned the city’s police force from using CS gas on protesters.

CS is a molecular compound associated with serious health effects, which have been well studied. It’s the primary component in tear gas.

“It’s good news tear gas and pepper spray residues were at normal levels where Portland’s storm drains reach the Willamette River,” Wheeler said in a press release statement. “That said, the risk tear gas and pepper spray create for our health, our environment and our ability to focus on ending systemic racism are too great.”

Related: Related: Portland Mayor Ted Wheeler bans use of CS tear gas in ongoing protests

The report focused on stormwater samples from three manholes and sediment samples from six storm drains gathered on Aug. 6 near the Mark O. Hatfield U.S. Courthouse and Lownsdale Square. This area is known as the epicenter of where large amounts of tear gas and other hazardous chemicals was deployed by police and federal agents during the many demonstrations held there since May.


BES sampled for 12 contaminants, those include metals such as zinc, copper, and lead that are found in crowd dispersal products but also are commonly found in stormwater from motor vehicle brake pads, roof runoff, and other urban sources.

Researchers also tested for barium, perchlorate and hexavalent chromium — substances found in tear gas but are far less commonly found in stormwater.

The stormwater sampling identified higher concentrations of metals and other chemicals not commonly found in stormwater. There were also higher concentrations of metals like zinc and chromium and chemicals in the sediment samples compared to other nearby sites.

“While pollutant levels that enter the Willamette River are thankfully low, the City is concerned about any and all additional pollution loads to the river that Portlanders love and continue to work hard to restore,” BES Director Mike Jordan said. “We will use this report to work with DEQ on additional steps for the downtown core and elsewhere in the city to address CS gas residue.”

Related: When Portland police use tear gas, protesters aren’t the only ones breathing it

The Oregon Department of Environmental Quality said in a press release statement that although some levels of metals and chemicals were detected in the stormwater, they are not high enough to cause immediate harm to human health. The agency will evaluate the report for several weeks.

But critics and environmentalists said the report is just from one location in Portland. It does not have samples from other areas like North Portland and Southeast Portland, where police have also deployed large amounts of tear gas chemicals.

Juniper Simonis is the Lead Scientist and an Aquatic Ecologist at DAPPER Stats, a Portland based ecological consultant company. Simonis also has a doctorate in Ecology and Evolutionary Biology from Cornell University.

They have been collecting chemical weapons, munitions, and residue samples from sites where tear gas was deployed and from the Willamette River. They have been testing for a wide range of chemicals to bring attention to what environmental impacts the public can see from these chemicals.

Simonis says the report is incomplete and there are some inconsistencies.

“There are multiple components that are inadequate with respect to sampling, sampling analysis and interpretation,” Simonis said.

They said the way the sampling collection was done should be called into question and they will continue to test their samples that they have collected along with Willamette River.

Environmental organization Willamette Riverkeeper Executive Director Travis Williams said BES' sampling is in no way representative of the problem of the riot control munitions and tear gas used in other places in Portland.

“BES focused on the stormwater system on the immediate area of the Hatfield Courthouse only, and does not appear to have examined the storm drains that lead to the Willamette River, and did not examine other areas such as the ICE building and nearby outfalls, where Riot Control Agents have been used,” Williams said. “We believe more should have been done.”

Williams said the BES report relied entirely on the information provided by Portland Police Bureau and its use of Riot Control Agents, because the federal agents did not provide RCA information. BES’s sampling is incomplete, and WR is concerned that risks to the aquatic environment and human health have already occurred and will remain without further action."

Federal officials have denied access to the BES to inspect and clean out a seventh storm drain, which is behind a fence constructed illegally around the perimeter of the courthouse.

The BES is taking enforcement action against the federal General Services Administration, which manages the courthouse. This includes an order for the agency to move the fence by Monday so the city can access the storm drain.