In Hillsboro, every drop of water that runs through your tap comes out of a river, or a dam and reservoir. Hillsboro Water recently received an award from the Oregon Health Authority acknowledging protection activities that substantially lower risks to the public water system’s source of drinking water. 

Hillsboro’s Drinking Water Sources

Hillsboro’s winter drinking water source is the upper-Tualatin River and its tributaries. In the summer, Hillsboro relies upon water stored in two reservoirs to meet demand. The Barney Reservoir in the Trask River Watershed holds 20,000 acre-feet of water at capacity, of which 14,886 acre-feet is available for drinking water. The Scoggins Reservoir — also known as Hagg Lake — is located near Gaston. The reservoir stores approximately 53,323 acre-feet of water when full, of which 13,500-acre feet is available for drinking water. 

An acre-foot is the amount that covers an acre with a foot of water and is equal to 325,851 gallons.

Sources of Water Pollution

Our water supply can become polluted when harmful substances enter rivers, reservoirs, groundwater, or springs. Common pollutants include:

• Gasoline and oil from leaking tanks
• Nitrates and pesticides from farms and lawns
• Pathogens from livestock and pet waste
• Chemicals from industrial sites
• Medications improperly flushed down toilets

Even small sources of pollution can have major impacts on water quality and treatment costs — which is why prevention is key.

5 Tips to Help Protect Hillsboro’s Drinking Water Sources

1. Prevent Wildfires to Protect Water Quality
   Wildfires pose serious risks to surface water sources. After a fire, rivers and reservoirs experience increased sediments, nutrients, and pollutants — all of which make water harder and more expensive to treat. Make sure all campfires are completely out and cold to the touch before leaving your campsite.
2. Only Dump Water Down the Drain
   Never pour household chemicals, fats, oils, grease (FOGs), paint, or medications down the drain. These pollutants can damage our water sources and increase treatment challenges. Participate in drug take-back events and freeze grease before disposal.
3. Volunteer to Help the Tualatin River
   Hillsboro’s drinking water starts in the Upper Tualatin River, and keeping the watershed healthy ensures cleaner water for all. Partner with organizations like the Tualatin Riverkeepers, Tualatin Soil & Water Conservation District, or the Tualatin River Watershed Council to volunteer or learn more.
4. Fertilize Properly in the Fall
   Fall is ideal for fertilizing, but overfertilizing can lead to harmful algal blooms in streams and lakes — threatening our water supply and recreation. Use slow-release, OMRI-labeled fertilizers or compost, and avoid overapplication.
5. Stop the Spread of Invasive Species
   Boating and water recreation may be slowing for the season but remember to clean all your gear once you leave the water. Invasive species can cause damage to our ecosystems and water quality. Wash, dry, and inspect all boats, motors, and gear after use.