Source Water Supply

The City of Boulder is fortunate to have several high-quality sources of water both east and west of the Continental Divide, including the headwaters of Boulder Creek and diversions from the upper Colorado River on the west slope.

The city's ability to obtain water from both east and west slope sources (watersheds) provides a measure of water service reliability in response to moderate, localized droughts or other events. The city's Source Water Master Plan is the guidance document developed to help inform decision-making regarding our most valuable resource, water.


Water from the Barker Reservoir, Lakewood Reservoir and Silver Lake watersheds is either:

  • drawn directly from Middle Boulder Creek or North Boulder Creek; or
  • stored in Barker Reservoir, Lakewood Reservoir, Silver Lake Reservoir or another reservoir within the watersheds that are located on Middle and North Boulder creeks.

Water from the Boulder Reservoir and Colorado Big Thompson watersheds is either:

  • delivered to the Boulder Reservoir Water Treatment Plant from the Carter Lake Pipeline
  • stored in Boulder Reservoir.

The City of Boulder owns approximately 26,000 acre feet of reservoir storage capacity for its system. The city's ability to obtain water from both east and west slope sources provides a measure of water service reliability in response to moderate, localized droughts.

In addition to resevoir storage, the city owns and operates eight hydroelectric power plants.

Barker Reservoir

Barker Reservoir, located on Middle Boulder Creek, is owned by the City of Boulder. Water from Barker Reservoir is treated, along with the Silver Lake Watershed supply, at the Betasso Water Treatment Plant.

Each year, typically between mid-May and June, the Barker Reservoir spills over due to runoff from melting mountain snow. This is a normal and expected event that increases flows in Boulder Creek and residents are urged to take caution around the creek.

Boulder Reservoir

Boulder Reservoir, located northeast of Boulder, Boulder Reservoir was built by the city to provide another source of drinking water. Boulder Reservoir has also become a popular recreation site. Boulder Reservoir is owned by the City of Boulder, but is operated by Northern Water.

Northern Water also operates the Colorado-Big Thompson (CBT) Project and the Windy Gap Project. These two projects divert water from the upper Colorado River on the western slope and deliver it through a series of tunnels, canals and reservoirs to northeastern Colorado cities, farms and industries. Most of the water in Boulder Reservoir comes from the CBT and Windy Gap Projects via Carter Lake, although runoff from local drainage basins also adds to the water supply. Before the water in Boulder Reservoir is used for municipal purposes, the water is first treated at the Boulder Reservoir Water Treatment Plant.

Lakewood Reservoir

Lakewood Reservoir is primarily fed by water from the city-owned Silver Lake Watershed via the Lakewood Reservoir Pipeline, but may also receive water from North Boulder Creek and Como Creek.

Silver Lake Reservoir

Melting snowpack during the spring and summer months is captured in Silver Lake Reservoir. The amount of water that is available for community use varies from year-to-year and depends on the level of snowpack in the surrounding mountains.

Source Water Protection Program

Protecting drinking water at its source can help to prevent contamination and minimize treatment needs and costs. The city has long viewed source water protection as a proactive approach to preserving the water supply integrity, and worked with watershed stakeholders to develop a Source Water Protection Plan Source Water Protection Plan. Customers are encouraged to review the Source Water Protection Plan to learn more about the city’s watershed protection activities, and our routine source water monitoring and evaluation program, which allows for advance detection of a potential contamination event.

Water Conservation and Drought Planning

Hot and dry conditions make it increasingly important to conserve water! Visit the city’s Water Conservation webpage, which provides a variety of services to help customers manage water use in and around the City of Boulder.

The city’s Drought Plan provides guidance for recognizing droughts that will affect water supply availability and for responding appropriately to these droughts. Learn about drought conditions and responses to frequently asked drought-related questions on the city’s Drought Watch webpage.

Irrigation Ditches

The city is home to many irrigation ditches, or channels that deliver water from natural sources to homes, farms, businesses, industries and other uses. For further information about ditch companies, ditch maintenance, and information for homeowners and developers, please visit the city’s Irrigation Ditch Frequently Asked Questions.

Water Rights


To ensure that there will be an adequate supply of raw, untreated water available for future growth, the Utilities Division purchases water rights at market value, as they become available, from private individuals who own shares in local ditch companies.

Ditch Operations

The Utilities Division maintains a water portfolio that includes shares in numerous local irrigation ditch companies. As a shareholder, the city becomes a part owner of the ditch company.

City staff maintains close contact with the farming community through the ditch companies. The city can assist in ensuring adequate irrigation water supplies to select farming interests through its water leasing program.


Using city and contract legal services, the Utilities Division monitors all local water rights legal cases to ensure that the proposed changes have no detrimental impact to the city's water utility operations or to local ditch company interests.

Legal issues arising from city transfers are also litigated, with emphasis given to ensure that ditch company operations are not impacted by the transfers.

Past & Present

Within the projected build-out scenario, the City of Boulder will have sufficient water supplies to meet the city’s projected water needs to the level of reliability set by City Council. Several factors have contributed to this situation.

  • In 1989, City Council established standards for the city to assure a reliable water supply.
  • Prior to projected city growth, Boulder’s water facilities will have better delivery and storage capacities. Boulder has seen about 90% of its potential growth. Therefore, new homes and developments will have a limited additional impact on our water supply.
  • It has been determined that the city will have sufficient water supplies to meet Boulder’s future needs within projected city growth for the city water service area, as defined in the Boulder Valley Comprehensive Plan.

The story of Boulder’s waterworks is a long and integral part of the City’s history. Please see the Boulder Waterworks History PDF to learn more.