Water Sources

  • Bull Run Lake
  • Bull Run Lake

Curious about where your water comes from and how it gets to your tap? Learn more about our region’s water.

Water is our number one natural resource. We rely on high quality water for drinking, protecting public health, recreation, sustaining our economy, fire protection, and fish and wildlife. The Portland, OR metropolitan area is fortunate to have multiple sources of water to serve the region. The region has four main surface water sources including the Bull Run Watershed, the Trask and Tualatin Rivers, the Clackamas River, and the Willamette River. There is also supply from groundwater wells and aquifer storage and recovery. Smaller surface water sources include Gales CreekAlder Creek and Brownell Springs.

This diverse portfolio of regional water sources improves the resilience of the region to drought and other potential water shortages. Each water system is unique and can be affected differently by drought and water shortages.

While some people living in rural areas have their own wells, urban areas rely on public water providers to plan and manage a complex network of facilities which treat and move water from its source to your home or business. This water supply infrastructure is comprised of water treatment plants, pump stations, reservoirs, in-town storage tanks, and thousands of miles of pipes. The various water systems are individually managed by cities, water districts, and public utility districts who are committed to protect and preserve this natural resource to ensure that people have safe and reliable drinking water around the clock.

Helping regional water providers manage their water supplies efficiently and safely are primary goals for the Regional Water Providers Consortium, a group of 24 water providers. The Consortium is a collaborative and coordinating organization that works to improve the planning and management of municipal water supplies in the greater Portland OR metropolitan region. Established in 1997, the Consortium with its members, work together in emergency preparedness, water conservation and regional coordination. To find out who your water provider is use the Consortium's Provider Lookup Tool or look at your water bill.


Regional Water Supplies Listed by Source:


Bull Run Watershed

Who it serves

The Bull Run Watershed is the City of Portland’s main water supply and serves over 950,000 residents in the region. It is a key source for the Water Bureau’s wholesale customers, which include City of Gresham, Rockwood Water People’s Utility District, Raleigh Water District, City of Sandy, City of Tualatin, Tualatin Valley Water District, and West Slope Water District.

About the Watershed

The Bull Run Watershed is located 26 miles east of downtown Portland, OR in the Sandy River Basin. The 102 square-mile protected watershed collects water from 135 inches of annual rainfall and some snowmelt that flows into the Bull Run River and its tributaries. Most of the land within the watershed is under federal ownership and the rest is owned by the City of Portland. The watershed is carefully managed to sustain and supply clean drinking water to a quarter of Oregon’s population.

The Water System

The Bull Run River drains into two reservoirs, where more than 9.9 billion gallons of water are stored during the summer. Bull Run River water is used for municipal and industrial uses and is also released to the lower river to improve habitat conditions for federal Endangered Species Act-listed fish.  The water sent to Portland is currently unfiltered but is treated before it enters three conduits that transport it by gravity to where it is stored in a series of in-town reservoirs.

How the Bull Run and its providers respond to drought

Because Bull Run is primarily a rain-fed system, there is less water entering the storage reservoirs in the summer when rainfall decreases. The 9.9 billion gallons of stored water supply in the reservoirs typically meets Portland and its wholesalers’ needs for the summer. The Columbia South Shore Well Field can also be used to supplement surface water or replace the Bull Run supply entirely due to turbidity or other issues. The Portland system is resilient to drought and other water shortage events due to its access to two water sources.



Tualatin and Trask Rivers

Who it serves

The Trask and Tualatin rivers provide high quality drinking water to 10 public water systems which serve 365,000 customers in Washington County. The Joint Water Commission (JWC) manages a water treatment plant on the Tualatin River and serves all or portions of the Cities of BeavertonForest GroveHillsboro, and the Tualatin Valley Water District. The City of Cornelius purchases water from the City of Hillsboro.

About the Watershed

The Tualatin River watershed is in a 220-square-mile portion of the upper Tualatin River Basin that supplies water into the JWC water treatment plant intake. The 8.2 square mile Trask River watershed feeds the Barney Reservoir in the upper Trask River Basin. Water released from Barney Reservoir is diverted to the upper reaches of the Tualatin River. Ownership in the watershed includes private landowners and public agencies. The western section is in the Oregon Coast Range and is characterized by steep terrain and forested land in timber production. The eastern section is dominated by flatter terrain and agricultural activities, including residential land and major transportation corridors.

The Water System

The Trask/Tualatin River Basin serves members of the Joint Water Commission (JWC) and a small municipal supply with stored water from the municipally-owned Barney Reservoir and the reservoir formed by the Bureau of Reclamation-owned Scoggins Dam (also known as Hagg Lake) along with natural stream flow. During the winter season the JWC receives water solely from the Tualatin River. During the summer or peak-season, water from the Tualatin River is supplemented with released water from the two reservoirs. Both reservoirs are designed to catch and store heavy rainfall in the winter months.

How the Trask and Tualatin Rivers and its providers respond to drought

The Trask/Tualatin system is highly managed to ensure water supplies are sufficient to meet peak summer demand. Reservoirs (Barney Reservoir and Hagg Lake) allow the JWC to store water for later release in the summer. Some of the JWC providers also have access to other sources, such as aquifer storage and recovery wells, Bull Run and the Columbia South Shore Well Field.



Clackamas River

Who it serves

The Clackamas River supplies high-quality drinking water to nearly 300,000 people in Clackamas and Washington Counties. Cities and water providers served by the Clackamas River include the cities of Estacada, GladstoneLake OswegoTigard, and South Fork Water Board (Oregon City and West Linn), Sunrise Water Authority (Happy Valley and Damascus), Oak Lodge Water Services (Oak Grove and parts of Jennings Lodge) and Clackamas River Water (parts of unincorporated Clackamas County).

About the Watershed

The Clackamas River begins on the western slopes of the Cascade Range in Mount Hood National Forest. Forty-seven miles of the river are federally protected as part of the National Wild and Scenic Rivers System. The Clackamas River Watershed drains nearly 940 miles of forests, mountain meadows, agricultural land, suburban neighborhoods, and light industrial areas before meeting with the Willamette River.  The Clackamas River is a highly-managed river with many uses including high quality drinking water, hydroelectric power, and outdoor recreation.

The Water System

There are five municipal surface water intakes on the Clackamas River - the City of Estacada, Clackamas River Water, South Fork Water Board, North Clackamas County Water Commission, and the Lake Oswego-Tigard Partnership. In addition, there are three hydroelectric dams on the main stem of the Clackamas River with fish passage facilities and two dams on the Oak Grove Fork, managed by Portland General Electric. These dams do not serve as municipal water storage facilities. The water used by municipalities therefore is considered “run of the river” meaning all the water used is captured as it flows down the river and is subject to natural fluctuations brought on by changing seasons or abnormally wet or dry weather.

How the Clackamas River and its providers respond to drought

Because there are no water storage facilities (reservoirs) on the Clackamas River, municipal water providers and other users rely on natural stream flows or “run of river” to meet water needs. Fortunately, some water in the watershed is stored as snow which melts over time, keeping water cool for fish and providing a gradual release of water into the river. The Clackamas is also fed by rain and groundwater. The Clackamas is carefully managed to meet all water needs.



Willamette River

Who it Serves

The Willamette River currently supplies water to Wilsonville and Sherwood. Several water providers have water rights on the Willamette and its use is being expanded. The Tualatin Valley Water District and the City of Hillsboro are partnering to develop the mid-Willamette River at Wilsonville as a future water supply source by 2026.

About the Watershed

The Willamette River Basin is the largest watershed in Oregon with 13 major tributaries along its near 190-mile stretch which starts near the City of Eugene and ends at the confluence with the Columbia River in North Portland. This basin drains over 11,000 square miles of forest, farmland, and urban areas. It's bound by the Coast Range to the west and the Cascade Mountains to the east, comprising nearly 12% of Oregon's land. Snowpack, rain, and groundwater all contribute to the Willamette River's flow throughout the year.

The Water System

The U.S. Army Corps of Engineers operates 13 dams along its 13 tributaries, resulting in a highly regulated flow for flood control, fish habitat, recreational opportunities, and a variety of other municipal, agricultural, and industrial needs.

For municipal use, a large water intake facility and water treatment plant located in Wilsonville currently provides water for the Cities of Wilsonville and Sherwood. Tualatin Valley Water District (TVWD) and the City of Hillsboro are partnering to further develop the mid-Willamette River at Wilsonville as a future water supply source. Planned for completion in 2026, the new water supply system will deliver water through more than 30 miles of water pipelines to TVWD and Hillsboro customers. The new system will also include an expanded river intake facility, a new treatment plant, and new storage reservoirs.

How the Willamette River and its providers respond to drought

The Willamette River is a reliable year-round water supply. The system is highly managed by a number of dams operated by the US Army Corps of Engineers to ensure water supplies are sufficient to meet peak summer demand flows for drinking water, agricultural, and environmental needs.

To provide additional reliability, Wilsonville's former water supply (a system of eight local wells) is available for use during dry periods or other emergencies. When the new water system is online, TVWD and the City of Hillsboro will be able to manage their various supply sources to respond to drought or other supply interruptions as well as recover more quickly from a large natural disaster.




Who it serves

Groundwater serves as the primary water source for the City of Milwaukie, the City of Troutdale, and the City of Newberg, and as a secondary source for the City of Portland and its wholesale customers. The City of Gresham and Rockwood Water People’s Utility District jointly own and manage their own wells.

About the Source

Portland Water Bureau’s Columbia South Shore Well Field (CSSWF) is the second-largest developed water source in the state and the largest developed groundwater source. The well field is comprised of 26 wells ranging in depth from 55 to 657 feet and can produce up to 102 million gallons per day. It is located south of the Columbia River, east of Portland International Airport and west of Fairview and is served by three regional aquifers. Wells serving Rockwood Water People’s Utility District and the City of Gresham are located in Gresham, OR and are part of the Cascade Well Field. Both well fields are covered by a wellhead protection program to prevent groundwater contamination. The City of Milwaukie taps the Troutdale Gravel Aquifer by means of seven wells that range from 250 to nearly 500 feet deep located around the City of Milwaukie.

There are also numerous aquifer storage and recovery (ASR) projects in the region. Aquifer storage and recovery is a way of storing drinking water underground, then pumping it out when it is needed. For example, during the winter and spring, the City of Beaverton and Tualatin Valley Water District inject treated drinking water from the Joint Water Commission (JWC) Water Treatment Plant into natural underground basalt formations (aquifers), displacing native groundwater. Stored water in the aquifer is pumped out of the ASR wells during the summer when customer demand increases for outdoor activities, such as irrigation for landscaping and gardens.

The Water System

Water pumped from groundwater wells is treated and pumped into the distribution system where it can then be delivered to customers.

How Groundwater and providers who rely on it respond to drought

Groundwater is less vulnerable to short-term water shortages and extreme weather events, but is still vulnerable to drought. Water providers who rely on groundwater depend on rain, stream flows and snowmelt to replenish aquifers. Depending on the geology, recharge can take weeks, years, decades or longer. Groundwater levels are monitored to track long-term aquifer conditions.


A case for conservation

We are fortunate to have plentiful water supplies capable of meeting our current and future needs for clean, safe drinking water. However, the amount of water available from each water source may vary from month to month, and the amount of water used by households in the summer months can be two to three times more than what is used in the winter months. It is also important to keep sufficient water in the rivers and streams to meet the needs of fish and aquatic life, as well as for other users.

What can you do?

Be smart with the water you use so that there is plenty to go around. Get more information about using water efficiently.

*Note: Boring, Fairview, Lake Grove, and Wood Village are not members of the Regional Water Providers Consortium. If you receive your water from these providers, contact them directly for more information about their source(s).