Water Conservation

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Photo of SMART Irrigation Controllers
Programming a Smart Irrigation Controller

Caltrans is replacing our legacy irrigation controllers with new controllers that dynamically adjust water applied to landscape plants based upon current weather conditions. This approach ensures healthy plant life and conserves precious water resources.


As a steward of California’s precious water resources, Caltrans actively manages, promotes and implements water conservation practices within the highway transportation system and associated facilities.  Cost effective and appropriate water conservation strategies are employed in the design, construction, operation and maintenance of transportation facilities including water conserving irrigation systems for highway planting and to the maximum extent practicable, the use of recycled water.

Other practices that landscape architects employ on highway planting projects to conserve the state’s limited water resources include:

  • Selecting regionally appropriate, drought tolerant or native plant material
  • Preserving established existing vegetation to the maximum extent possible.
  • Incorporating compost into the soil to reduce storm water runoff, and to hold water in the root zone.
  • Spreading wood mulch or inert ground covers such as gravel to conserve soil moisture.

For information on specific approaches taken by Caltrans to conserve water on highway planting and mitigation projects, please visit our planting guidance web page.

To meet the water conservation requirements of Executive Orders issued by Governor Brown, and to meet Caltrans' goal of a 50% reduction in water use based upon a 2013 baseline, the following mandatory actions have been identified. These requirements apply to all projects that include planting that will use potable water for irrigation, including planting by local partners, planting installed by encroachment permit, highway roadside and Safety Roadside Rest Area planting, and planting required for storm water quality and biological and visual mitigation.

  1. Evaluate and document all proposed irrigation using the Model Water Efficient Landscape Ordinance (MWELO) criteria.
  2. Include the Maximum Applied Water Allowance (MAWA) calculations for new and rehabilitated landscapes as project supplemental information.
  3. Prior to project advertisement, obtain written assurance from the local water purveyor stating that water is available for the construction and plant establishment phase of work, and include this documentation as supplemental project information.
  4. Evaluate all proposed planting work to ensure it meets the requirements described in Caltrans' Highway Design Manual, Topic 902.4, "Planting Procedures, Selection and Location."


Water Conservation Category Condition Required Actions
Caltrans Water Conservation Always in effect

1. 50% minimum statewide reduction in potable water use from 2013 baseline per Caltrans "Water Conservation for Highway Projects" Memo.

2. Comply with the Memo "Storm Water Management Plan Implementation and MWELO Compliance".

3. Comply with Deputy Directive 13 – "Water Conservation and the Model Water Efficiency Landscape Ordinance".

4. Limit planting to native and non-native plants appropriate for the project micro-climate so no water beyond natural rainfall is required for healthy plant survival after the plant establishment period.

5. Limit supplemental water provided by irrigation to non-potable, unless not practical.

Voluntary Water Conservation

At least one of the following actions occur:

1. Local water agency requires water conservation

2. State requires voluntary conservation statewide

1. Consider delaying the planting work until the voluntary conservation requirements are lifted.

2. Consider using non-potable water truck watering sources.

3. Submit written documentation of water availability with the submittal of the contract for advertisement.

Mandatory Water Conservation

At least one of the following actions occur:

1. Local water agency requires mandatory conservation

2. State requires mandatory conservation statewide

Do not advertise or award projects that include non-essential planting work irrigated with potable water.
Severe Public Drinking Water Emergency State Water Resources Control Board - Division of Drinking Water declares a local drinking water emergency due to an acute drinking water shortage Do not advertise or award projects that include any planting work irrigated with potable water.

Caltrans Recycled Water Goal

Caltrans is committed to conserving California's precious potable water resources. To demonstrate that commitment, Caltrans Director Dougherty has directed Caltrans to convert 100% of landscape irrigation to non-potable (recycled or other non-drinkable) water sources by 2036. Wherever fiscally feasible, designers should attempt to bring recycled water transmission lines to the highway right-of-way, and modify associated existing irrigation systems to operate properly with recycled rather than potable water.

A good summary of Recycled Water Law requirements for designers.

Maps listing existing recycled water transmission lines have been developed by local water agencies throughout the State. Please refer to the maps below (and those developed by your local water agency) to expand your use of recycled water use wherever possible.


Water Conservation Memos, Bulletins, and Guidance

2016-07-05 2016 Caltrans Drought Memo
2015-10-15 2015 Drought Response
2015-11-13 Governor Brown's Executive Order 08-36-15
2015-05-20 Caltrans Director - Memo on Caltrans Continuing Drought Effort
2014-06-26 Chief Engineer - Highway Construction Projects - Water Conservation Memorandum
2014-05-30 Division of Construction - Highway Construction Projects - Water Conservation Guidance
2014-05-30 Dust Palliative Design Guidance
2014-05-30 Estimated Water Usage for Water Availability Request Excel Spreadsheet
2014-03-11 Evaluation of "Essential" Planting Work for Water Conservation
2014-03-04 Division of Construction CPD 14-1 Water Conservation
2014- 02-07 Caltrans Drought Workshop Action Items
2014-02-06 Caltrans Director - Memo on Water Conservation
2014-01-01 Water Storage Status Sheet
2013-10-23 MWELO Compliance Mandatory
2013-09-11 Maintenance - Water Conservation Actions to Comply With Executive Order B-18-12
2010-08-19 Landscape Architecture Program - Water Conservation Memo
This memo provides an update on California water conditions, compliance with water rationing procedures, and clarification on the state's Model Water Efficient Landscape Ordinance. This document will help you understand and contribute to the Department's commitment to efficiently managing water use within the roadside.
2008-07-18 Landscape Architecture Program - Memo on Water Conservation
1993-09-01 Deputy Directive 13 - Water Conservation

Governor's Office Documents

01-17-2014 Governor Brown Declares Drought State of Emergency
05-20-2013 Governor Brown's Executive Order B-21-13
04-25-2012 Governor Brown's Executive Order B-18-12


Click here for a summary of the latest actions taken by Caltrans to address the drought.


Updated Nov 21, 2016