EBMUD: Moldy Water Problem




Video of Channel 2 Story on 5/24/10 - Rob Roth Reporting


Answers from EBMUD Representative Debra Skeaton

You asked several good questions. I will respond to them in the order that they appear in your letter.

I can appreciate your skepticism regarding the reported algae bloom in San Pablo Reservoir. Although algae can grow in San Pablo Reservoir or any other body of water at any time, an algae bloom represents a rapid growth or large concentration of algae. These blooms occur whenever ideal conditions exist to support them. There have been a few warm days in the East Bay within the past month; and the seasonal rainfall produced runoff with the right nutrients. These conditions supported aggressive growth of blue-green algae, a species known to cause taste/odor problems. Since San Pablo Reservoir is open to the public, you are welcome to visit so that you can verify this year’s occurrence. A similar bloom occurred in June 2009.

When it is in service, Sobrante WTP takes water from San Pablo Reservoir and supplies Crockett, Rodeo, Hercules, Pinole, El Sobrante, and portions of Richmond and San Pablo. This is why only certain communities are affected by the change in water quality. The Sobrante plant is used during high demand periods - usually in Summer. It was also the water supplier for a larger region when we seismically upgraded the Claremont tunnel several years ago.

EBMUD took two steps to correct the taste/odor problem:

EBMUD is using ozone, a form of oxygen, to correct the taste and odor issues that customers are experiencing. The ozone system was online and in operation when Sobrante went into service on Thursday, 5/20/10. When we became aware of a taste and odor issue, plant operators increased the ozone dosage.
We also changed the intake elevation in San Pablo Reservoir. In other words we started taking deeper water to move away form the influence of the algae blooms on the surface.

These two changes had a positive effect on water quality at the water treatment plant. Depending on consumption, customers could expect to notice a difference within the next few days as the improved water reaches different portions of our distribution system.

EBMUD places Sobrante in service every Spring to supply customers from San Pablo Reservoir during the high-demand spring and summer months. Normally it is removed from service in the fall because the Orinda Treatment Plant is large enough to handle winter use. This year we placed Sobrante in service later in the season since customer demand was low. Unfortunately, it happened to coincide with a bloom

The San Pablo Reservoir is used to store water that comes from the Sierra as well as local runoff.

Although I wanted to ensure that I responded to your questions, we have taken the Sobrante Treatment Plant out of service until we can resolve the problem. We can do this because the weather has reduced demand.

At 12:18 PM 5/24/2010, you wrote:

As discussed, EBMUD increased the ozone dosage at the water treatment
plant in response to the calls we received from customers. In addition,
we changed the intake point on the tower in San Pablo Reservoir so that
water comes in from a different elevation. Based on taste and odor
tests today at the plant, these changes resulted in improved taste and
odor in the water that you will receive. You should notice these
changes during the current week, depending on the time it takes that
water to reach your area. Please call or write if you require further

Debra Skeaton
Water Distribution Supervisor
East Bay Municipal Utility District
P. O. Box 24055
Oakland, CA 94623
(510) 287-1071 Office
(510) 715-9049 Cellular
(510) 287-1155 Fax