Supplies Update

Water Supply


Bremerton's water sources are surface water from the Union River Reservoir and groundwater from production wells located in the Bremerton area. All sources are managed in accordance with Washington State Department of Health and federal EPA regulations and best management practices for water supply systems. Bremerton owns and protects the 3,000-acre watershed surrounding the Union River supply. Access to the watershed is secured and limited to water supply and forestry management. Each year the Washington State Department of Health inspects the surface supply. Groundwater wells are also safeguarded through efforts to protect critical areas around the wellheads. Water quality information can be found in the Annual Drinking Water Quality Report.

Water Use


The Bremerton water system serves about 55,000 people and the Bremerton Naval Complex. On average, the Bremerton Water Utility supplies about 7 million gallons each day. Each person uses about 100 gallons of water each day.

Water demand in Bremerton increases over 30% in the summer due to outdoor uses. On particularly hot days, water use can double. To use less water outside, it is recommended to water lawns in the morning or evening no more than 1 inch per week, wash cars at a commercial car wash that recycles, use a broom instead of a hose to clean sidewalks, and use native, drought-tolerant plants for landscaping.

Water Supply Measurement


Bremerton’s water sources rely entirely on precipitation and not snow pack. Water managers measure precipitation on a “water year” which is October through September. Water year 2016 started on October 1, 2015 and will end on September 30, 2016. Even though April and May were drier than average, Water Year 2016 to-date is much wetter than average and is currently 134% of the average precipitation, making it the fifth wettest water year so far in Bremerton’s 58-year record.

Bremerton currently has sufficient supplies in both surface water and groundwater sources to meet expected water demands. Customers would be informed should the situation change. Customers are advised to always use water wisely. The Bremerton Water Utility carefully monitors surface supplies and groundwater levels and alerts customers when increased conservation measures are needed.  

Water demand in Bremerton generally increases over 30% in the summer due to outdoor uses. On particularly hot days water use can double. To use less water outside, it is recommended to water lawns in the morning or evening no more than 1” per week, wash cars at a commercial car wash that recycles, use a broom instead of a hose to clean sidewalks, and use native, drought tolerant plants for landscaping. For conservation information, please visit Waterwise Guidelines.
Monthly Precipitation vs Average Precipitation
The Union River Reservoir forms behind Casad Dam. The dam is designed for water supply storage, not for flood control. McKenna Falls downstream of the dam is a natural barrier to migrating fish. When the reservoir fills to capacity, any further flows from precipitation to the reservoir pass downstream to the Union River, just as it would if the reservoir were not there. The chart below shows the level of the reservoir at the first of the month (blue) compared to the desired water level (green).
Union River Reservoir vs Firm Yield Curve
The water level in the Union River Reservoir as of September 1, 2016 is 36 feet below the overflow weir. Because of a construction project at the system intake this spring, the reservoir level will be held to a lower level than usual for this time of year. When the reservoir level is above the overflow, the lake is full to capacity and additional precipitation can increase flow downstream in the Union River. Information for residents living below the Union River Reservoir can be found in the Union River Flood Notification System brochure or visit Mason County's Emergency Management Division website.
Casad Dam
Last updated September 12, 2016.