It was like the slow unraveling of a television mystery.

First, Anne Arundel County health inspectors this fall discovered an unapproved septic system that was contaminating ground water in a waterfront community north of here.

Health department records showed that the system was built without a permit after the ground failed required percolation tests.

Next, further investigation revealed that the attached house was also illegally built, and had been occupied without having been first inspected for safety, county officials allege.

But then, instead of "negotiating" a settlement, a frequent route taken with permit infractions here in the past, county officials quickly filed a civil lawsuit against the house's owners, Robert G. Rodriguez and Yvonne Brown.

The county is seeking a court order to evict them from the house and to prevent them from using the failing septic system.

This new "get-tough" stand has been repeated time after time in the last few months as County Executive James Lighthizer, spurred on by citizen complaints, has ordered a crackdown on building violations he says threaten the quality of housing.

"My philosophy is, you help quality builders and developers, but you have to insist upon rigid enforcement of the rules," Lighthizer said in a recent interview. "It's imperative we have enforcement of the rules. It's also imperative we have the confidence of the citizens.

"We want to maintain the features of this county so it continues to be a desirable place to live," he said.

"The demand for housing in this county is largely predicated on its environment," said Thomas L. Osborne, recently appointed director of inspections and permits. Osborne administers the day-to-day enforcement of county building codes and decides when to shut down construction sites for code violations.

Anne Arundel, with more than 430 miles of shoreline along the Chesapeake and various rivers and creeks, has become increasingly popular in the last decade and has undergone a building boom in the last few as the economy has brightened.

But it is also an environmentally delicate area that has been hurt by poor development practices and lackadaisical enforcement, residents and officials agree.

Citizens, who previously criticized the county government for inaction and turned to the state for help, say they are surprised and delighted with the new tack.

"There is definitely a movement in the right direction," said Lena Valavanios, a civic activist. "Before, everything was very, very good on paper, but nothing was being implemented. Sediment was running into our streams. I was screaming and screaming, and kept being told everything is okay."

"Inspectors were turning aside. The bottom line was a lack of consistent support and management," said Valavanios. "Now, there is clear direction from the top."

Even developers such as Stuart Greenebaum, whose 1,150-home Shipley's Choice subdivision on the Severn River has been repeatedly shut down for sediment control violations, said the county's tougher enforcement is "long overdue."

"Most good developers will be supportive of the county's efforts, as long as it's evenly applied," Greenebaum said.

Greenebaum has established his own inspection team at Shipley's Choice. He gives homebuilders 24 hours to correct sediment control violations before he sends in his own crew to do the work and then charges the responsible builder.

One criticism by developers is that Lighthizer is perhaps too responsive to citizen complaints. "Some developers feel that he is turning sediment control over to citizen groups, that he has played to the crowd," said one, who asked not to be named.

Lighthizer's crackdown began earlier this year after state inspectors responded to citizen complaints

and found sediment violations at a construction site on the Severn River which was previously approved by county inspectors. Barriers were substandard or nonexistent and sediment was flowing into the state-designated scenic river.

"It became apparent to me our system of enforcement wasn't working," Lighthizer said. He started listening more closely to citizens and taking tours of construction sites himself.

In the last eight or nine months, the county has repeatedly shut down residential and commercial development sites, sometimes for days, at substantial cost to developers. Most of the cases involve sediment control violations, but Osborne is also increasing building and electrical inspections.

An example is M & W Real Estate Co. Inc. which, in an unusual move, was barred from obtaining new building permits in the county in August after it didn't correct building code violations in a Glen Burnie subdivision. Criminal charges have also been filed against the company and its president, Howard E. Webb, in connection with problems in the subdivision.

And, as in the case of Rodriguez and Brown, the county is also going to court for civil injunctions against developers and individual builders.

While injunctions are a common tool used by county governments to stop violations, assistant county solicitor David Plymyer said, "In the last 1 1/2 years, we've increased their use dramatically. We've just taken a much more aggressive stance to protect the permitting process."

The crackdown is reflected in violations cited for the first four months of the current fiscal year, when compared with 1983, before Lighthizer took office.

Building code violations rose from 564 in the 1983 period, to 1,619 this year. Grading (sediment control) violations rose from 69 to 259.

The county issued 30,000 building permits between July 1983 and July 1984. "The caveat is: If you build in our county, you're going to follow our regulations," Osborne said.

As for Rodriguez and Brown's house in Pasadena, the couple's attorney has yet to answer the petition for an injunction, but county attorney Plymyer said he will continue to push for the house to be vacated.

"This case comes to the essence of why we require people to get a permit," he said. "So we can guarantee people do things right. The permitting process is essential to our ability to protect the environment."