The reservoir site is temporarily closed
We’re still working to complete some elements of the reflecting pools, promenade, and surrounding areas on top of the reservoir. Because the site is an active construction area, it is not yet ready for permanent public access. Sign up for project emails for updates on the reopening.
Find the latest project updates for Washington Park Reservoir
Walking tour overview
The Washington Park Reservoir is in Washington Park, just east of the International Rose Test Garden. In the 1890s, the City built two drinking water reservoirs in Washington Park. Since then, the park has continued to play a key role in Portland’s water system.
The original drinking water reservoirs are no longer in service. In 2021, the Portland Water Bureau completed a new 12.4-million-gallon underground reservoir. We built the new reservoir to withstand future earthquakes and movement from an ancient landslide. Gravity brings water to the Washington Park Reservoir. From there, the water flows to 360,000 people throughout Portland’s west side.
This walking tour will guide you through the reservoir site and its educational displays. Follow along to learn about the history, construction, and engineering of the reservoir.
One: Grand staircase
Location and background
This site was previously home to two open reservoirs (the upper Reservoir 3 and the lower Reservoir 4). The reservoirs were supported by
- Two gatehouses
- A weir building
- Three pump houses
- A generator house
- Lots of underground piping
The open reservoirs served Portland’s west side for more than a hundred years before being replaced. They were part of a gravity-fed water system that still delivers Portland’s water today!
Historic urban planning
Washington Park Reservoirs 3 and 4 were constructed between 1893 and 1894. At this time, the City was also building the original system to deliver Bull Run water to Portland.
The reservoir basins, buildings, and dams were constructed during the City Beautiful movement. This wide-ranging movement was a response to the industrialization of cities. It aimed to promote health and civic virtue through beautiful and inspiring architecture and planning. This movement influenced the design of the site.
The reservoirs and their accompanying structures were built in the Romanesque Revival style. In addition, they were nestled into the natural ravines of the landscape. These choices embodied the values of the City Beautiful movement and its commitments to enhancing the natural beauty of the area.
Bull Run pipeline (on-site educational display)
Thanks to the ingenuity of Portland’s early engineers, water from the Bull Run River—a clear forest stream 30 miles away—travels to the underground reservoir by the force of gravity.
From forest to faucet (on-site educational display)
In 1895, two uncovered reservoirs on this hillside served as the end point of the city’s new pipeline from the Bull Run River.
The city now uses an underground reservoir beneath this reflecting pool to store drinking water from both the Bull Run River and the groundwater wells.
Two: Cascading water feature
The cascading water feature consists of two high-powered pumps that use recycled water, not drinking water. From this view, enjoy the beautiful reflecting pool, water feature, and promenades. Explore the interpretive elements to learn about the marvel of modern engineering below your feet.
Historic timeline wall (on-site educational display)
Early history
These hills have been important to people for thousands of years: as places to live and travel and as a route to the streams below. Since 1894, they’ve also been part of Portland’s drinking water system.
For ages, Tualatin Kalapuya and Clackamas Chinook peoples have lived and traded along these slopes. Early city history includes accounts of native women selling berries, baskets, and kindling from camps just downhill of this spot.
Tanner Creek carved the canyon at the base of these hills. Early settlers built a road alongside the creek and later, when the creek flooded and damaged the road, routed the creek into a sewer. Tanner Creek now flows through pipes below the land it carved.
1870s
Chinese farmers terraced these hillsides. Race-based laws meant they could not buy the land they worked, and eventually development drove them out.
Portland was growing. City officials recognized a need for more city parks, as well as a need for a protected, clean water source that could serve the whole city. They laid plans for a park on these slopes, with this corner of the park eventually dedicated to drinking water reservoirs.
1880s
This very spot featured the city’s early zoo: a seal, a bear, and four deer. The zoo moved in the 1890s and again in the 1920s before settling at its current location in 1959.
In 1885, the city’s Water Committee chose a drinking water source for Portland: the Bull Run River, a clear forest stream 30 miles away.
Within 10 years, workers would build two reservoirs at Washington Park, plus a pipeline to reach them.
1890s
In 1893, engineers chose a ravine on these slopes, then deepened and broadened it to build reservoirs that nestled into the hillside like pools in a river. They inadvertently built the reservoirs on the top of an ancient landslide, which caused problems for years to come.
In 1894, three weeks before the new water system opened, a landslide cracked one of the reservoir basins. Landslides continued to damage both reservoirs until the city replaced them in 2020.
Building these reservoirs meant hundreds of new jobs during an economic depression. City contracts didn’t benefit everyone, though: Only white men could apply.
In 1895, Water from the Bull Run River flowed to Portlanders’ taps for the first time. Pipes bypassed the damaged Washington Park reservoirs to serve water to Portland’s west side.
1905
Engineers devised a system of drainage tunnels and workers dug them into the hillside. This slowed the landslide, allowing for reservoir repairs. Ten years after Portland’s water system was built, water finally filled the reservoirs in 1905.
1950s
By the middle of the 20th century, the Water Bureau supplied water to more than half a million people. The water system included one major dam on the Bull Run River, almost 700 miles of pipe, four reservoirs at Mount Tabor, and two reservoirs at Washington Park.
The ancient landslide continued to push against the reservoirs, and the city continued to repair them. By 1958, officials began to acknowledge the need to rebuild the reservoirs using modern methods.
1980s
In keeping with national trends in drinking water storage, in 1981 the city built its first major underground reservoir at Powell Butte in outer southeast Portland. Portland’s modern drinking water storage facilities—such as the reservoir underneath this reflecting pool—are underground.
In 1984, the Water Bureau developed a groundwater system, with wells up to 650 feet deep, to complement the Bull Run River source. Both Bull Run River water and city groundwater can flow through the reservoir at Washington Park.
2020
After more than 100 years of repairing the original reservoirs here, the city replaced them with an underground reservoir and a reflecting pool on top. As well as being vulnerable to landslides, the original reservoirs weren’t up to modern earthquake or public health standards. The new reservoir continues this site’s tradition of serving drinking water to people on Portland’s west side.
Three: Dam 3
Marking the edge (on-site educational display)
In 2020, the city built an underground reservoir to replace the two uncovered drinking water reservoirs on this site. The amber posts along the hillside mark the edge of one of the original 1890s reservoirs.
Fun facts
Washington Park’s 12.4-million-gallon reservoir supplies water to Portland’s west side, including:
- 360,000 people
- 20 schools
- 5 hospital complexes
- 60 parks
- All downtown businesses and residences
During construction of the new underground reservoir:
- We used 3,000 truckloads of concrete, amounting to 120 million pounds.
- We received 35,000 truckloads of soil.
- We installed 7.4 million pounds of rebar.
- We put in 100,000 plants.
- More than 40 full-time construction workers and tradespeople worked to bring this project to life for the community.
Hear neighbors’ perspectives on the construction project from Kathy Goeddel and Brooks Haxton.
Four: Gatehouse 3
Letting in light (on-site educational display)
During the second half of the 19th century, architects all over the world incorporated glass pieces into flooring to allow natural light into dark spaces below.
In the 1890s, when city workers built this gatehouse to access water system infrastructure deep underground, they use engineer Ernest Ransome’s patented technique for embedding glass cylinders into concrete floors.
The natural light allowed water system operators to better navigate the deep, dark building.
Five: Reservoir 3 Plaza
We are always working to build more water infrastructure that can withstand earthquakes. The new reservoir site keeps the historic look and feel of the original reservoir. But we built the new reservoir using modern technology and building standards so it can withstand an earthquake.
This site is on an ancient landslide that extends from the International Rose Test Garden down the hill to the reservoir area. We used innovative construction methods to address landslide and earthquake risks, including:
- Heavy, four-foot-thick concrete floors and walls, and 7.4 million pounds of rebar for seismic reinforcement
- 176 pilings embedded in stable bedrock to support the bottom of the reservoir
- State-of-the-art compressible material that absorbs shock from earthquakes and landslide movement
Six: Lowland habitat (formerly Reservoir 4)
Reservoir 4 was decommissioned during the reservoir improvement project. In addition to building new walkways and a reflecting pool around the upper Reservoir 3, we wanted to create a vibrant space at the former Reservoir 4 site. As part of that work, we developed a lowland habitat for all creatures to enjoy.
We planted a wildflower meadow along the hill of the landslide, as well as a variety of flowers and grasses inside the footprint of the original Reservoir 4 to make a better habitat for wildlife. We put in over 100,000 plants as part of the reservoir construction.
Marking the edge (on-site educational display)
In 2020, the city built an underground reservoir to replace the two uncovered drinking water reservoirs on this site. The amber posts along the hillside mark the edge of one of the original 1890s reservoirs.
Seven: Pump Station 1
Building on tradition (on-site educational display)
All around the world—from ancient Rome to the pre-contact American Southwest—people have used gravity to bring drinking water to cities. Portland’s drinking water system follows this ancient tradition.
An elegant and enduring design (on-site educational display)
Portland’s early engineers determined that gravity alone could deliver water from the Cascades foothills to reservoirs on this spot.
Though science and engineers have advanced since the 1890s, the drinking water system still relies on the simple principle of using gravity to move water across long distances.
Water as power and Thumpers (on-site educational displays)
From here, water must be pumped to reach houses in the hills above. Pumps require power.
Electricity was not widely available in the 1890s, so engineers harnessed the power of water falling from the high reservoir to the lower reservoir to drive the pumps that raised water into the hills.
For over 100 years, hydraulic pumps inside this building sent water up Portland’s west hills.
In these pumps, pipes shot water to spin a paddlewheel, which drove a piston. The back-and-forth movement of the piston drove water up the hill. Engineers nicknamed the pumps Thumpers for the thumping racket they made.
The Thumpers are retired. An original Thumper still sits inside Pump Station 1 at Washington Park Reservoir.
Eight: Reservoir 4 plaza
Form and function (on-site educational display)
When city engineers built drinking water reservoirs here in the 1890s, they had both function and beauty in mind. Instead of building rectangular pools, they designed graceful, curving reservoirs that nestled into the landscape. Instead of building drainage ditches, they designed walkways that could both drain rainwater and, as an Oregonian article suggested, become “the most popular promenades in the city.”
In 2020, the city retired the original reservoir on this spot and built a reflecting pool to honor its legacy.
Transportation (on-site educational display)
In the 1890s, streetcar and cable car companies developed an extensive network serving the city. One cable car route led to this spot, which, before the reservoir was built, housed the park zoo.
Marking the edge (on-site educational display)
In 2020, the city built an underground reservoir to replace the two uncovered drinking water reservoirs on this site. The amber posts along the hillside mark the edge of one of the original 1890s reservoirs.
Nine: Lower Dam and Gatehouse 4
We decommissioned the original dam of Reservoir 4 and turned it into a lowland habitat, but we preserved many historical elements like Gatehouse 4. As you walk to the southern part of the lowland habitat, you will find much of the historic fencing and concrete still in use today.
Ten: Olmsted view
In 1903, landscape architect John C. Olmsted saw this view of Portland and Mount Hood beyond and knew it was a view worth keeping. In official parks recommendations to the city, he suggested buying the land at the base of this hillside, which now forms the eastern edge of Washington Park.
