Current Source

Thanks to the visionary planning of early City leaders, Hillsboro has owned a dependable, high-quality water supply for 70 years. An active conservation program should keep Hillsboro well-situated for another 10 years, but because development of new water sources can take decades, it is important that today’s leaders plan now for future supply.

Current Source Graphic

Current Source

Hillsboro Water (HW) has used the Tualatin Basin for its water source since 1913. The Tualatin River itself is the exclusive water source for Hillsboro in the winter and spring months and has been a water source for Hillsboro since 1940.  (To find out which Tualatin Basin water source was used prior to 1940, click here.)  However, in the summer months the river is supplemented with water from two reservoirs in which Hillsboro has ownership – Scoggins Reservoir (also known as Hagg Lake) and Barney Reservoir.

Currently, HW gets its water from the following two water treatment plants on the Tualatin River:

  • Joint Water Commission (JWC) Water Treatment Plant (WTP): This is the largest conventional treatment plant in Oregon and is owned jointly by Hillsboro, Forest Grove, Beaverton, and the Tualatin Valley Water District (TVWD). The Tualatin River intake is located on a channel just off the Tualatin River and is shared with the Tualatin River Irrigation District. The JWC WTP was built in 1976 by Hillsboro and Forest Grove. The original plant could treat up to 21.3 million gallons per day (MGD). It has been expanded through the years to accommodate the addition of Beaverton and TVWD, as well as population growth. The Plant is now capable of treating up to 75 MGD.
  • Cherry Grove Slow Sand Filter Plant (CGSSFP): This is a small WTP that is owned entirely by HW. It is located on the site of the original intake built in 1940 to serve Hillsboro customers. The CGSSFP is capable of treating up to three million gallons of water a day. This plant serves Hillsboro’s upper system customers. The upper system consists of customers who live in the county along the original 18-inch transmission line that was built in the 1940s. When the line was built, customers who lived along it were allowed to hook up and buy water from Hillsboro, even though they were not Hillsboro residents. County residents are no longer allowed to hook up to the 18-inch line, except in very limited circumstances.
Water Quality

JWC and CGSSFP both produce drinking water of exceptionally high quality. The drinking water from both Plants exceeds all minimum compliance standards set by the Environmental Protection Agency’s (EPA) Safe Drinking Water Act. The latest consumer confidence report can be viewed by visiting Hillsboro's Water Quality Report page, or review detailed water analysis data at .

  • The cost to construct the original Barney Dam (completed in 1970) was $1.8 million. 
  • The cost to construct the original diversion pipeline (completed in 1970) was $330,000. 
  • The cost to construct Scoggins Dam and Hagg Lake (completed in 1974) was $27 million.
  • The cost to construct the original Joint Water Commission Water Treatment Plant (completed in 1976) was $4.5 million.
  • The cost to construct the Slow Sand Filter Plant (completed in 1992) was $1.8 million.
  • The cost to construct the Barney Dam expansion (completed in 1999) was $28.5 million. 

Rate Scenarios


The JWC WTP is a conventional treatment plant that cleans the water through a filtration and disinfection process. Under normal operations, the turbidity of treated water leaving the plant is .03 NTU, which is 100 times better than what the State requires of a conventional plant.


Hillsboro has three in-town storage reservoirs and has acquired the land to build one more. The 24th Street Reservoir, Hillsboro's oldest reservoir (built in the 1960's), holds six million gallons (MG), Evergreen Reservoir, built in mid-2000, holds 15 MG, and Hillsboro's newest addition, Crandall Reservoir, was completed in 2013 and holds 10 MG.   Hillsboro has an agreement with its partners to store a three-day supply of water for emergency use.

Regulatory Issues

Hillsboro meets all regulations for its current supply and uses water rights owned by Hillsboro to meet its water demands.