The Tualatin River
Progress and Challenges in a Warming World
A Polluted History
Roamer's Rest Park, courtesy Tualatin Life
The Tualatin River has always been central to the lives of the residents of Tualatin Valley. Native peoples used it for transportation and food. European settlers also used it for transportation, as a water source for agriculture, and for recreation. Swimming parks were created along its banks in the early 1900s.
As the population of Tualatin Valley grew, a combination of an excess of agricultural water diversion and dumping of inadequately treated wastewater by numerous unregulated treatment plants caused the Tualatin River to become dangerously polluted. By the late 1960's, the Tualatin could no longer be safely used, causing the State of Oregon's Department of Environmental Quality to step in.
Progress
1969
The state of Oregon issues a building moratorium in Washington County until sewage treatment is addressed.
1970
Voters approve the establishment of the United Sewage Agency to consolidate and improve wastewater treatment
1972
Federal Clean Water Act is established
1986
Northwest Environmental Defence Center sues EPA over adequate enforcement of the CWA
1988
EPA establishes Total Maximum Daily Loads (TMDL) for specific pollutants, to be met by 1993.
Courtesy OregonLive
The establishment of TMDLs for water quality aspects including temperature and levels of phosphorous, bacteria, and heavy metals forced the wastewater treatment facilities, now consolidated into Clean Water Services, Inc., to develop ways to keep the river clean. Thanks to the enforcement of the requirements of the Clean Water Act and dedicated state and local organizations such as Tualatin Riverkeepers, the condition of the river has improved signficantly. Residents can now recreate on the river and engage with its beauty.
Challenges remain
Despite the progress made in the quality of the River, recent analysis shows that challenges remain for the Tualatin River and the communities that rely on it.
Rising temperatures increase threats to salmon populations
The Tualatin and its tributary streams are habitat for several salmon species, including steelhead, cutthroat, and coho.
These fish rely on cold water to complete their lifecycle. Increased temperatures mean less oxygen for them as they spawn and emerge from streambeds as fry.
All three salmon species either spawn or emerge from their eggs in May. Although there has been improvements in temperature in a few parts of the watershed, the late spring and summer months are a challenge as instances of extreme temperatures increase.
The map shows many areas of the watershed have temperatures that are potentially harmful to salmonid species during the month of May.
All but one tested area show an increase in May temperatures and had at least one temperature reading of above 12.8 degrees Celcius in May 2019. 12.8 degrees C is the TMDL for temperature for spawning salmon. Temperatures higher than that increase the risk of reproductive failure and threaten the survival of the species.
Average May temperatures have been increasing in the Portland area. In 2019 the average May temperature was 2.1 degrees Celcius or 3.8 degrees Farenheit higher than the historical average
As the Portland area's average temperatures increase, so does the average temperature of parts of the Tualatin River. Average water temperatures in May and August at Scholls have been consistently above the TMDL limits for years. Similar conditions exist in many parts of the watershed.
Unless average temperatures of the Tualatin River can be reduced, salmon face an uncertain future in the watershed.
Steps residents can take to help keep temperatures down in the Tualatin:
+ Support efforts to plant shade trees along the rivers edge. These local organizations run volunteer tree planting events:
Tree for All https://www.jointreeforall.org/
Friends of Trees https://friendsoftrees.org/
+ Call your local representatives and let them know you support actions to keep the Tualatin River habitable for salmon
Image courtesy: Tualatin Soil and Water District
Phosphorous contributes to algal blooms
Phosphorous is a chemical that gets into the Tualatin River via erosion of phosphorous-rich soils and rocks and fertilizer run-off from agricultural fields.
Incidents of increased phosphorous tend to happen after large storms, when run-off into the river is high.
Phosphorous is a necessary nutrient for plant growth, but excess phosphorous in the Tualatin can lead to an overgrowth of algae. These algal blooms harm water quality, decrease oxygen levels for fish, and potentially sicken humans and pets.
Increased water temperatures increase the risk for algal blooms to form. The combination of high phosphorous and high temperatures can increase the risk that algal blooms will necessitate closure to recreation.
The map shows that there has been improvements in average phosphorous levels in some areas of the Tualatin watershed since TMDLs were established, but some areas still have challenges.
All but one tested site had at least one instance of phosphorous levels exceeding the 0.1 mg/L TMDL in 2019.
Steps residents can take to keep phosphorous out of the Tualatin:
+Limit the use of fertilizers in lawn and garden care. If you need a fertilizer consider Clean Water Grow, a slow-release fertilizer made by extracting excees phosphorous out of wastewater.
+Always stay on trails when recreating in the watershed. This helps limit erosion into the Tualatin
+ If you live on property adjacent to the Tualatin or one of its tributary streams take care to limit streamside erosion and run-off.
Tualatin Water and Soil Conservation District staff can help find solutions to private land management dilemnas.
E.coli bacteria can sicken people and pets
Another threat to human and animal health is e.coli bacteria. Ingestion of water contaminated with e.coli can sicken those that recreate on the river and their pets. Symptoms can include nausea, vomiting, diarrhea, and fever.
E.coli in the Tualatin occurs when animal feces is washed into the water. The feces can come from many animals, from household pets to populations of birds living on or near the water and tends to increase when storm run-off is high.
High amounts of e.coli in the Tualatin will result in closures to recreation.
Most areas of the Tualatin Watershed have seen signficiant decreases in the amount of e. coli bacteria present in the water. Unfortunately most areas still had at least one instance of e.coli higher than the TMDL of 400 cfu/100ml in 2019.
Steps residents can take to limit the amount of e.coli bacteria in the water:
+Pickup after your pets and encourage other to do so. Animal waste, especially waste left on trails adjacent to water, eventually ends up in the Tualatin through stormwater run-off.
Building on Success in an Uncertain World
The Tualatin River was once dangerously polluted and no longer fit to provide the citizens of the Tualatin Valley with clean water. Thanks to the Clean Water Act and organizations like Tualatin Riverkeepers, much of that pollution has been cleaned up. Tualatin Riverkeepers continues to safeguard the Tualatin River with ongoing projects, including trash clean-ups and tree plantings.
Challenges still remain to keep the water habitable for salmon and free of algal blooms and bacteria so that residents can continue to recreate on the Tualatin. Residents can take personal steps to help ensure the health of the River and encourage their legislators to protect this precious resource for the future.
Get Involved
Consider joining the mission of the Tualatin Riverkeepers to help protect the Tualatin both now and in the future. Become a member here:
Opportunities for volunteering with the Riverkeepers including tree plantings and habitat restoration, leading paddling trips on the Tualatin, and more can be found here:
Sign-up for Action Alerts to be made aware of simple actions you can take to support the protection of the Tualatin:
