Partial answer to narrow down the potentially relevant politicians:
The Metropolitan Water District of Southern California is a cooperative of fourteen cities, eleven municipal water districts, and one county water authority. Specifically:
- City of Anaheim
- City of Beverly Hills
- City of Burbank
- City of Compton
- City of Fullerton
- City of Glendale
- City of Long Beach
- City of Los Angeles
- City of Pasadena
- City of San Fernando
- City of San Marino
- City of Santa Ana
- City of Santa Monica
- City of Torrance
- Calleguas Municipal Water District
- Central Basin Municipal Water District
- Eastern Municipal Water District
- Foothill Municipal Water District
- Inland Empire Utilities Agency (IEUA)
- Las Virgenes Municipal Water District
- Municipal Water District of Orange County
- San Diego County Water Authority
- Three Valleys Municipal Water District
- Upper San Gabriel Valley Municipal Water District
- West Basin Municipal Water District
- Western Municipal Water District of Riverside County
Metropolitan is governed by a 38-member board of directors
representing the 26 member agencies consisting of 14 cities, 11
municipal water districts and one county water authority. The member
agencies or their sub-agencies serve the residents and businesses of
more than 300 cities and numerous unincorporated communities.
(Source)
The officers and members of the Board of Directors of the district were as follows (from the same source, there may be a more recent list, but I didn't find one and I suspect that it hasn't changed that much from this time to when the decision was made):
BOARD OF DIRECTORS
July 1, 2019 to June 30, 2020
OFFICERS OF THE BOARD
- Chairwoman...................................Gloria D. Gray
- Vice Chair...................................Jerry Butkiewicz
- Vice Chair.................................. Cynthia Kurtz
- Vice Chair...................................Lorraine Paskett
- Vice Chair.................................Heather Repenning
- Secretary ....................................... Judy Abdo
MEMBERS OF THE BOARD
- Anaheim........................Stephen J. Faessel
- Beverly Hills............................................Barry D. Pressman
- Burbank............................................Marsha Ramos
- Calleguas Municipal Water District ..........Steve Blois
- Central Basin Municipal Water District .....................Robert Apodaca
- Central Basin Municipal Water District ............... Frank M. Heldman
- Central Basin Municipal Water District ........ Phillip D. Hawkins
- Compton ........................................Janna Zurita
- Compton ...........................................Tana L. McCoy
- Eastern Municipal Water District ........................Randy A. Record
- Foothill Municipal Water District..................... Richard W. Atwater
- Fullerton................................................. Adán Ortega
- Glendale............................................ Vartan Gharpetian
- Glendale..................................................Ardy Kassakhian
- Inland Empire Utilities Agency ..........Michael Camacho
- Inland Empire Utilities Agency .........Jasmin A. Hall
- Las Virgenes Municipal Water District..........Glen D. Peterson
- Long Beach..............................................Gloria Cordero
- Los Angeles........................................... Glen C. Dake
- Los Angeles..........................................John W. Murray Jr.
- Los Angeles.................................. Jesús E. Quiñonez
- Los Angeles..............................Lorraine Paskett
- Los Angeles......................................... Mark Gold
- Los Angeles.............................................Tracy Quinn
- Los Angeles................. Heather M. Repenning
- Municipal Water District of Orange County ...........Linda Ackerman
- Municipal Water District of Orange County ............ Brett R. Barbre
- Municipal Water District of Orange County ................. Larry D. Dick
- Municipal Water District of Orange County .............. Larry McKenney
- Pasadena .................................. Cynthia Kurtz
- San Diego County Water Authority..................... Michael Hogan
- San Diego County Water Authority..................Jerry Butkiewicz
- San Diego County Water Authority........................ Tim M. Smith
- San Diego County Water Authority...................S. Gail Goldberg
- San Fernando .............................Sylvia Ballin
- San Marino.........................................John T. Morris
- Santa Ana.................................... Jose Solorio
- Santa Monica ..................................... Judy Abdo
- Three Valleys Municipal Water District....... David D. De Jesus
- Torrance................................Russell Lefevre
- Upper San Gabriel Valley Municipal Water District ......Charles M. Treviño
- West Basin Municipal Water District.............Gloria D. Gray
- West Basin Municipal Water District.............. Harold C. Williams
- Western Municipal Water District of Riverside County...Donald Galleano
Determining among these individuals "Which politicians (if any) are driving the residential bans?" is challenging.
Probably, the board directed staff to review cuts that needed to be made and suggest options and somebody on staff presented options including a residential ban.
Then, a committee probably reviewed this option and perhaps some others and greenlighted it for further development, perhaps on staff recommendation or perhaps on their own accord.
Then it probably went to the full board where it probably received majority support to float the idea, probably with the tacit approval of the Chair and possibly all or most of the officers.
But, pinning it down to particular individuals as the "driving force" is challenging and there may be no one spotlighted individual since the process isn't like the process in a state legislature or Congress where a particular elect official introduces a bill and it goes through the process with the introducing sponsor's guidance and support.
The debates and votes are at least partially listed in meeting minutes and reports from meetings, but that is a bigger task that I don't have time to track down at this time. It should be available at the district website as a matter of public record. Most or all of this seems to be available here. The committee in question is probably the "One Water (Conservation and Local Resources) Committee" whose documentation if found here. The buzz word appears to be "non functional turf". Video of the meetings is available if you have the time to watch it.
A presentation on the alternatives can be found here. It begins as follows:
Subject
Information on policy alternatives Metropolitan may consider for
reducing non-functional turf in its service area
Executive Summary
As a result of the record drought in the Southwest and in response to
adopted board policy, staff seeks feedback on policy alternatives to
reduce the use of potable water for irrigating non-functional turf in
the service area.
Non-functional turf is defined by the State Water Resources Control
Board (SWRCB) as mowed grass that does not provide a recreational or
community gathering purpose. Commonly this refers to commercial,
industrial, and institutional properties (including multi-family
housing and Homeowners Association-managed property.)
Staff seeks Board input and direction on the following policy
alternatives to address non-functional turf:
Use existing or expanded financial incentives to encourage the replacement of non-functional turf.
Promote a model ordinance for voluntary adoption by local governments or agencies that bans watering of non-functional turf with
potable water.
Establish a water allocation method that preferentially curtails imported water supply use on nonfunctional turf during a declared
emergency.
Seek state legislation to permanently ban irrigation of non-functional turf with potable water (either statewide or within
Metropolitan’s service area) modeled after the SWRCB emergency
regulation. Staff believes that a combination of these actions would
improve long-term water supply reliability for the region.
Staff will return to the Board with preferred alternatives for further
action in September 2022.
The whole memo signed by two managers on the staff runs to four pages and fits the first step of the process that I discussed above, a staff presentation of options.
The article appears to refer to an earlier action, however, reported on June 2022 and presumably considered before then.
dispassionately describe the arguments that they are making.
While this is a supposition to some extent, no doubt the driving concern is to reduce demand for water given shrinking supplies. It would take considerable research to pin down further, but the links above have the relevant information.
