Los Angeles’ Invisible Reservoirs

The advent of the Surface Water Treatment Rule some 20 years or so ago posed some significant problems for water agencies throughout the United States. Arguably, no one was more impacted that the Los Angeles Department of Water and Power.

Surface water has been recognized for decades as far more prone to pathogen contamination than groundwater sources. And pathogens remain — by far — the most important water quality challenge, claiming over 4,000 lives every day worldwide. So it makes sense that a special set of requirements should apply to this far riskier source of drinking water. The result was the Surface Water Treatment Rule.

Regulations these days are hundreds or even thousands of pages long — too many lawyers, I suspect — and they are accompanied by “guidance manuals” that are often even longer — too many scientists and engineers, I suspect. So recognize that today’s topic addresses just one tiny little piece of an enormous regulation. And that piece pertains to the storage of treated drinking water.

Decades ago, the City of Los Angeles had taken advantage of its favorable geography to place drinking water reservoirs in the Hollywood Hills above the city. This wisely enabled gravity flow out of these huge reservoirs, and provided many days of emergency storage to the City’s residents. At the time, no one even considered building expensive covers for these reservoirs. They were high up in the pristine hills, so what could possibly cause a contamination threat there?

But the SWTR required that such reservoirs be covered, so as to minimize the pathogen contamination risk. And, if that means of protection could not be applied for some reason, the water would have to be treated when leaving the storage reservoir instead. It was left to the individual water agencies to determine the best course of action for themselves, so long as they dealt with the pathogen risk to the satisfaction of the USEPA.

That began a very long saga for LADWP, and one that is still a long, long way from being fully resolved.

LADWP tried to cover the reservoirs at first, but the folks that lived near these picturesque mountain lakes cried foul. These folks actually got new law written in California that essentially equated scenic beauty with water quality. After several years of battles, LADWP has all but given up on the idea of putting pathogen-thwarting covers on these treated water storage reservoirs.

What alternatives remained? Treating the treating water as it leaves the reservoir on the way to the customers is an accepted approach, and one which LADWP is using with at least one of their reservoirs, Stone Canyon. However, the same residents who fought covering the reservoirs also fought the construction of the treatment plants! In retrospect, LADWP may have been “lucky” to get even the Stone Canyon treatment plant built!

Another alternative is to abandon the reservoirs as drinking water infrastructure. There are several drawbacks to this alternative, including the fact that these reservoirs were designed to “drain” or “overflow” into the water distribution system. Where would storm flows into these lakes be directed — without flooding out the same residents that didn’t want covers or treatment plants?

But these reservoirs are an essential and incredibly valuable part of the LADWP system: they provide operational and emergency storage. In fact, they are so large that they also provide some seasonal storage as well. So just giving up these reservoirs would have constituted criminal negligence on the part of LADWP, in my estimation. Fortunately, they didn’t just give up.

Another alternative is the construction of replacement reservoirs. Building anything in LA — or anywhere in California, for that matter — is a multi-year effort just to get permission to do so. In a sad commentary on the state of the State, while some government agencies are threatening to punish LADWP for inaction, other government agencies continue to thwart efforts to resolve the problem.

In yesterday’s LA Times, a creative alternative is described. See:


LADWP will build “invisible” reservoirs, ones that are hidden underground. Above will be an open-space recreation area. Congratulations to LADWP for persevering through two decades of battles to develop viable alternatives to an almost impossible situation.

But this comes at a considerable cost. First, the project is now slated for completion in 2018 — and it’s a safe bet that it will encounter further delays beyond that date! Second, the cost of the reservoirs will be far more than one hundred million dollars more than a conventional alternative — we’re looking at a quarter of a billion dollars! And that is only a partial replacement of lost reservoir capacity!

Why is California going broke?

Perhaps we should form a new government agency to investigate?

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