Photograph of Marsi Steirer
Marsi Steirer, Deputy Director,
Long-Range Planning and Water
Resources, City of San Diego
Public Utilities Department

Marsi Steirer, Deputy Director, Long-Range Planning and Water Resources at the City of San Diego Public Utilities Department, recently visited with WRF to discuss her role in implementing potable reuse in San Diego and the challenges the utility is facing in activating its new programs.

Water Research Foundation: What are the biggest challenges San Diego Public Utilities faces in implementing potable reuse?

Marsi Steirer: How we are pursuing this is different than other utilities. For example, Orange County, California, has had a facility that has been operational for about five years and their purified water goes into a groundwater basin. We do not have large groundwater basins in our service area, so our water goes into a reservoir. Currently, there are no regulations for reservoir augmentation. Part of moving forward is trying to ensure that what we propose to do will fit into the future reservoir augmentation regulations, which are supposed to be completed at the end of 2016. California is also supposed to determine if direct potable reuse is feasible at that same point in time. There is an advisory committee associated with this effort, of which I am a member, of people from throughout the state.

How has public acceptance of potable reuse evolved in San Diego?

We started doing telephone surveys of our customers in 2004 and have been asking the same questions every time we do them. The continuity facilitates the tracking of responses from year to year. In 2004, public acceptance of potable reuse was 26% and in 2012, it was 73%. We had a comprehensive outreach effort going on during that time which included an active tour program. In 2011 we began offering tours of the demonstration project, where people could come and actually see the treatment process and the water. The tours continue to be very popular and aid the public in overcoming the “yuck factor” by seeing the science of potable reuse first hand. We have also made a lot of informational materials and a virtual tour video available on our Website,

For the last year or so, we have been working on a program geared towards younger audiences between the ages of 6 and 18. We think it is really important for them to understand the water situation, as they are the future.

What are some research issues that will help expand the implementation of potable reuse?

There are a couple of areas which will be helpful: research on public outreach as well as public acceptance, research that is associated with the feasibility of direct potable reuse, and research about regulatory acceptance.

How is San Diego Public Utilities distinguishing between indirect and direct potable reuse?

For indirect, the purified water is treated and then goes to a very large reservoir where it mixes with runoff from rain as well as imported water. It then goes to a water treatment plant before going to our customers’ homes and businesses. Direct basically skips the reservoir step and takes the water directly to a water treatment plant.

We actually have some research underway presently in San Diego on two additional treatment steps that could replace the environmental buffer, which is the reservoir, so we are doing some direct potable reuse testing.

How do you balance potable reuse with other supply alternatives?

In terms of pursuing potable reuse, what we would really like to do is reduce the total amount of water that we import, which is about 85%, and be a little bit more water independent. That really resonates with local officials as well as the general population. Right now, it is a bit of a precarious situation in California with all of the cutbacks. We have no control over that, so the idea of creating your own local water supply is very appealing.

How our system works, and the commitment that we have made in the past, is that the majority of the water we buy is untreated, or raw, water because we have three water treatment plants. There are a lot of other water agencies in the region that buy treated water. We also have a desalinization plant that is coming on line. We have a small portion of our service territory that is not connected with our treated water system, so the desalinated water basically will be the treated water for that area. We are estimating that this represents about 3% of our total water supply; the rest of our service territory is served by our three water treatment plants. So it is kind of an easy decision to make, we just buy enough of the desalinated water to equal our treated water needs.

How do you balance developing new supplies with demand management activities?

We are at the end of an imported water pipeline so we have been pretty aggressive at pursuing demand management over the course of the last 20 years. For example, our water sales are the same amount as they were 30 years ago. We attribute that to water conservation. We have had population growth of about 400,000 people and we are selling the same amount of water. What we are pursuing is working.

If the current drought subsides in the next year or two, how will that impact your planning?

It wouldn’t. We would still be pursuing exactly what we are currently pursuing. We do long-range water resource supply planning; we update our planning document every five to 10 years and most recently completed it in December of last year. Since we import 85% of our water, we are very keen on water conservation. At the end, in 2035, we could be creating enough water supply to equal about 30%. We recognize, because of the situation where we are in Southern California, and because we are at the end of an imported water pipeline, that there is no one magic solution; we need all of it.