Water
For a short video presentation on Thousand Oaks’ Water supply, click on the video below.
Our water comes a long way to reach us - from snowmelt in the northern Sierra Nevada Mountains north of Sacramento and over the Tehachapi Mountains to get to Thousand Oaks. Its delivery and treatment account for about 2% of our total greenhouse gas emissions.
Metropolitan Water District, or MWD, is responsible for bringing the water into Southern California through the State Water Project and treating it. Calleguas Water District buys it from MWD for distribution and sale to water agencies in Ventura County. Thousand Oaks relies almost 100% on this imported water. Further west, cities have access to some groundwater. At the far west, the cities of Ventura and Ojai rely exclusively on local water supply using Lake Casitas as their reservoir.
State Water Project map
Ventura County Water Resource Map
Water Use
The chart below shows the trends in water use from the City's water agency since 2017. You can see the effect of emergency measures taken in mid-2022 in response to the 2022 drought. Water use since the restrictions were lifted has remained below pre-drought levels due, at least partially, to permanent changes to landscaping such as turf removal, climate-appropriate landscaping and drip irrigation.
Water use by customers of City’s water agency since 2017.
Landscaping
More than half of the water used in the City is used for landscape irrigation. Transitioning thirsty ornamental landscaping to native and drought-tolerant plants saves water, energy, GHG emissions and provides co-benefits like support for birds, butterflies and native bees, improved soil, and helps to restore our natural ecosystem.
Water GHG Emissions
The majority of associated greenhouse gas emissions are due to water conveyance through the State Water Project, in particular, pumping over the Tehachapi Mountains. Treatment and delivery to the City make relatively small contributions to the overall footprint.
Water policy is complicated by the fact that the City is served by three retailers – California American Water (Cal-Am), California Water Service (CalWater), and the City’s own water agency. In total, about 40,000 acre-feet of water are used by the community each year. Energy use is directly correlated with the volume of water used. To reduce emissions, we need to conserve water, explore sources of local water, and transition suppliers to more renewable energy use.
GHG emissions from water consumed within Thousand Oaks
Cal-Am service area is shown in orange, the City’s water agency service area in blue, and CalWater service area in tan.
