OCEANSIDE -- From the banks of Loma Alta Creek, a meager trickle of water flowing from a 36-inch storm-drain pipe did not look like a pollution problem.

But to the small band of city workers tasked with cleaning up the city's urban water runoff, the trickle was the first in a string of clues leading to the source of chlorine, nitrates and phosphate detected in the creek bed.

New statewide water-quality rules require cities throughout California to be responsible for pollutants that enter local rivers, streams and creeks, ultimately washing onto public beaches.

If the city does not show tangible progress in cleaning up its waterways by 2005, it could face $10,000-a-day fines. To stem the flow of dirty runoff, Oceanside has decided to get tough by hiring full-time storm-water detectives to track runoff to its source and to write expensive tickets to the offenders if necessary.

A recent bit of detective work at Oceanside Boulevard and Crouch Street is a case study of how the stormwater detectives work their way back to the source of pollutants.

Periodic water testing conducted by the city first detected the chemicals entering Loma Alta Creek on Aug. 26. Stemming that flow continues today.

Where the drainage pipe enters Loma Alta Creek, chemical readings spiked beyond levels deemed acceptable by the federal Clean Water Act.

Just to make sure the readings were accurate, the workers tested a second set of water samples Sept. 11. The second set showed similar results where the pipe enters Loma Alta Creek.

"Some of (readings) were off the charts," said Mo Lasahie, the city's clean water coordinator.

Once the results were reconfirmed, the real detective work began.

Lasahie recently drove with city code enforcement officers Glenn Ericson and Robert Gremmels to the spot where the chemicals were detected, meeting public works employee Mark Sabelis there.

Ericson and Gremmels work full time enforcing new statewide stormwater runoff regulations in Oceanside.

Sabelis, the city's foremost gutter guru, has an encyclopedic knowledge of the Oceanside's extensive storm-drain network. After glancing at a map, Sabelis quickly determined that the drain pipe was connected to five storm drains along the north and south sides of Oceanside Boulevard.

Now that they knew where the storm drain went, the crew moved along the street methodically, with Sabelis using a short pry bar to lift manhole covers.

The job is not for neat freaks.

"It stinks in there," Ericson muttered after getting down on his hands and knees and sticking his face into the round opening.

At a manhole on the south side of Oceanside Boulevard, the crew spied a telltale trickle of water coming from a pipe that runs under the street. The pipe connected to a small collection of businesses nestled in the northeast corner of the intersection.

"That has to be where it's coming from," Lasahie said, pointing across the street.

When Sabelis pried up the corresponding manhole cover on the opposite side of the street, he discovered a pool of stagnant water.

"It's about this deep," he reported, holding his hands about 6 inches apart.

The four city employees let their eyes sweep over the collection of nearby businesses, which included auto repair and machine shops and a commercial landscaping business that stocks pesticides, herbicides and fertilizers.

After walking the fence line around the block of businesses, the party discovered a white plastic drain pipe, emptying directly into the storm drain. The pipe runs under the fence of the commercial landscaping business, so Ericson walked over and requested permission to enter.

A few minutes later, the crew was meticulously combing through the private business like they owned the place.

Ericson's eyes were quickly drawn to a rectangular opening cut in a concrete block wall.

"That's the storm drain that we saw hooked up to the white pipe on the outside," Ericson said.

Row after row of lawn mowers were stored near the drain, waiting to be repaired or to be picked up by their owners. Ericson and Lasahie noted that water running across the site washed over the lawn mowers before it entered the storm drain.

Ericson called the business's owner over and asked him to move the lawn mowers so storm water has a clear path to the storm drain without washing through the lawn mowers. He also asked the owner to install a special filter on the drain so pollutants would not eventually end up in Loma Alta Creek.

Just then Gremmels' voice drifted from deeper inside the storage yard.

"Hey Glenn, check this out," Ericson said.

Behind a large metal storage container, Gremmels had discovered a second smaller storm drain. Sitting on a bench next to the drain was an empty bottle of a herbicide called oxyfluorfen. Lasahie quickly found a safety manual for the chemical and turned to the page that highlights the chemical's effect on groundwater.

"You see, right here it says this product is harmful to aquatic plants and animals," Lasahie said.

"From what we're seeing here, this would definitely send our testing off the charts," Ericson added.

At that point, the crew had enough evidence to start writing tickets. Under city code, the first municipal citation is $100. The fine increases every day to a maximum of $1,000 per day after five days.

In this case, even though there were specific problems with the one business in question, there were also confounding factors. Gremmels explained that all of the urban runoff from the entire city block funnels into the storm drain on the landscaping business's property.

Instead of citing individual businesses, the crew decided that working with each business to control their runoff was a better solution.

"Simple fixes, that's all it is," Gremmels said.

Owners of the businesses at Oceanside Boulevard and Crouch Street were put in touch with urban run-off specialists to install filters and develop new ways of washing equipment and storing harmful chemicals that will keep nitrates, phosphates and other harmful materials out of the creek bed.

"We're going to ask them nicely to clean this stuff up. But, now that we know about this situation, we are going to be keeping a close eye," Ericson said.

Contact staff writer Paul Sisson at (760) 901-4087 or psisson@nctimes.com.