Sustainability & Water


Water conservation  infographicAdditional water resources will be needed to meet the growing population and economy of the SCAG region. Sufficient water supplies are needed to meet these future water demands. In addition water quality and watershed management needs to be addressed.

Water supplies in the SCAG region come from a blend of local and imported sources. Water conservation, or efficiency, involves technological and behavioral changes that lower the demand for water.

Past Events

Southern California Stormwater Meeting
Friday, June 13, 2014

In the midst of a historic drought and challenging regulatory orders that Southern California reduce the effects of stormwater pollution from the built environment, leaders agree that now is the time to act. That means designing, approving, and finding ways to pay for the stormwater capture projects we need that will also infiltrate water into our local groundwater basins and increase our water supply reliability in future years. A meeting was held on Friday, June 13, 2014, to discuss and develop practical strategies for overcoming the biggest challenges to stormwater capture. There were three panels that discussed various topics pertaining to stormwater. Watch the videos:


The Water Planning Program was concerned with the comprehensive management of water resources in the urban watersheds of the SCAG region. These resources include the use and reuse of imported and local water, the discharge of highly-treated wastewater, the conservation of water supplies, the reclamation of water supplies and the management of stormwater and urban runoff. Of special importance in this urban setting is the collaboration of local agencies to jointly plan and implement pollution control measures that protect the environment, are cost-effective and sustainable.

The Program recognizes a connection between water supplies and water quality and between land use, water quality and water supplies:

  • As water quality impairments lead to more extensive pollution controls in the region’s watersheds, higher levels of water treatment will result in new, purer water for reuse.
  • With the increasing use of more compact land development designs, more extensive natural areas will create new opportunities for pollutant removal from storm flows and also encourage the conservation of stormwater by providing areas for infiltration.

The Program developed a series of reports for the Caltrans Environmental Analysis Section that relate stormwater management issues to the planning and implementation of the proposed major projects in the 2004 Regional Transportation Plan.

In addition, SCAG’s Regional Comprehensive Plan (RCP) was updated in 2008. The Water Chapter of the RCP focused on themes such as meeting the region’s water supply needs, the relationship between land uses and water quality, the important relationship between regional water reliability and water storage facilities, the continuing need for more water conservation, and the connection between agency collaboration, best management practices and cost-effective pollution control measures.

2008 SCAG Regional Comprehensive Plan Water Chapter​ 


Groundwater accounts for most of the region’s local supply of fresh water. Growing water demand has led to over-pumping of these natural groundwater basins.


Surface storage involves the use of reservoirs to collect water for later release and use. It has historically played an important role because it can store water in wet times and release it during dry times. However, it is very difficult to build new storage capacity because of environmental concerns, stream flow and loss of habitat.


Recycling involves the collection of wastewater followed by treatment to make the effluent suitable for non-potable uses. Reuse can include irrigation, commercial and industrial processes and groundwater recharge. While many potential uses exist for recycled water, a number of health and cost barriers limit the use of recycling.

Case Study: Orange County Water District’s Groundwater Replenishment Program


Conservation is intended to lower the demand for water through technological or behavioral changes. One mechanism is through groundwater banking, where one water agency “holds” water conserved by a different agency for future use, such as during a period of drought. Other techniques include water saving devices (e.g. low flow toilets) and practices (e.g. restrictions on yard watering).


Most of the SCAG region is serviced by a number of large publicly owned wastewater treatment facilities, such as the City of Los Angeles’ Hyperion Facility.  Future population and economic growth will require new or expanded wastewater facilities.

Case Study:  Hyperion Wastewater Treatment Plant 


The general quality of surface water and groundwater in the SCAG region tends to be degraded as a result of land uses and water management practices. Agricultural lands use fertilizers and pesticides that degrade water quality. Septic systems degrade groundwater. The urbanization of the region has led to increased use of impervious surfaces and the concentration of pollutants that infiltrate the ground or are carried out to the ocean.


The SCAG region has historically depended on imported water to supplement local water supplies. Water is conveyed to the SCAG region by three major water projects:

The water from these projects is fully allocated and cannot accommodate future growth projections in the SCAG region.


Water demand in the SCAG region can generally be divided between water used for urban and agricultural uses and water necessary for maintaining existing ecosystems. In the SCAG region approximately three-quarters of the potable water is provided from imported sources. Through advances in water conservation, recycling and infrastructure improvements, an additional 3.5 million people have been accommodated with the same amount of imported water.


California Department of Water Resources 
California State Water Resources Control Board  
US EPA Watershed Approach Framework 
US Army Corps of Engineers 
US Bureau of Reclamation 
Santa Ana Watershed Project Authority 
Metropolitan Water District of Southern California 
Association of Groundwater Agencies 
California Stormwater Quality Association