DNA water runoff tests questioned

Alex Coolman

NEWPORT BEACH -- City officials may learn the origin of bacteria flowing

into the harbor by conducting DNA tests, but the results could be of

limited use if they don’t spell out how much contamination comes from

each source, water quality experts said Tuesday.

“That’s what we need to know: the percentage of human waste versus the

percentage of animal waste,” said Ken Theisen, a Santa Ana Regional Water

Quality Control Board sanitary engineer. “Quantifying it is really what

we need.”

The tests are scheduled to begin in late June or early July.

Representatives from the county Health Care Agency, county Sanitation

District and other offices gathered Tuesday at City Hall in a meeting

intended to give officials a better picture of the DNA program, Deputy

City Manager Dave Kiff said.

Some who attended said they were concerned by what they heard.

Charles McGee, a laboratory supervisor for the sanitation district, said

he was skeptical that Mansour Samadpour of the University of Washington

in Seattle -- who will probably head up the study -- can provide a

breakdown of the contaminants to be found in Newport Beach water samples.

Others, including Southern California Coastal Water Research Project

statistician Molly Leecaster, said they worried about whether the

sampling of local waters was sufficiently broad to give an accurate

picture of which contaminants might be lurking offshore.

She said the samples will not be as useful if they are a small group from

a limited area.

The study -- a state-funded, $175,000 effort to pinpoint the specific

types of pollution that end up in Newport waters -- would use DNA testing

to match strains of E. coli bacteria from water samples against a

database of bacteria strains from sewage, animals and other sources.

In theory, the program would provide a picture of what kinds of

contamination are found in the water, allowing officials to use their

pollution-fighting dollars in the most effective way.

But the individual DNA tests don’t indicate how much of a given kind of

bacteria is in the water; they merely indicate that certain bacteria are

present. Drawing broad conclusions from this data, some officials worry,

could lead to an inaccurate picture of the contamination.

“It will still be a mystery after this [study] unless we can work out a

way to quantify [the relative levels of contaminants],” McGee said.

Kiff said he found the program criticisms to be fair but argued that the

study would still be useful.

“There’s really no better process out there” for identifying pollution

sources, he said. “If there was something better, we’d be doing it.”

For his part, Samadpour said criticisms about the study’s accuracy could

be addressed by tinkering with the way the water samples are taken.

“It’s all in the sampling plan,” he said.