Actually no one ever said they would kill the bears.

But federal regulations were looming over officials at the Baltimore Zoo where an aging but unnamed trio of polar bears have splashed about for the last quarter of a century. And so when it seemed that the bears might have to be destroyed in order to satisfy the cruel bureaucracy, a sentimental uproar was touched off across the nation, and even politicians like House Speaker Thomas P. (Tip) O'Neill got involved.

The upshot of all the controversy: the three polar bears of the Baltimore Zoo are no longer on the endangered species list.

The bears first made national headlines last month when the director of the 104-year-old zoo said the zoo couldn't afford to buy a filtering system that would bring the bacteria in the bear's bathwater into compliance with federal standards. And he added that as a very last resort, the bears might have to be "euthanized."

"I did not think we would ever come to that," said Steve Graham, zoo director. "It's never gonna get to that point. But if you carry the what-ifs out to infinity, that's where it ends."

In the weeks since, the specter of such grisly recourse, especially recourse prompted by heartless federal regulation, has aroused emotions rivaled in recent years only the death of Bubbles, the "freedom-loving hippopotamus," who accidentally suffocated two years ago in California after she was tranquilized by zoo police trying to recapture her.

The Baltimore Zoo has been inundated with phone calls, money and letters, including the note from one Andylee Anderson of Cedar Lake, Ind., who wrote, "Here's $2 to save the polar bears. I wish I could send more but it's been a bad year." "Good Morning America" television show told of the plight of the three bears, along with numerous radio stations and newspapers from as far as Sacramento.

Where opprobrium is being heaped, it is on Richard Crawford, chief veternarian for zoo and exhibition, of the Department of Agriculture.

"This has really been blown out of proportion," Crawford groaned. "I've gotten calls from two congressman, and hate mail calling me a typical pinheaded bureaucrat from the West, the Midwest, the South and the East."

In a droll bit of doggerel, Baltimore's comptroller and perennial publicity hound Hyman Pressman, asked, "Why should we kill a polar bear/ Who for 25 years is no worse for wear?/ I'd rather get rid of that awful vulture/ Who works for the Department of Agriculture."

But under the Animal Welfare Act, the Department of Agriculture sets health standards for 1,200 animal exhibitors, requiring them to keep coliform bacteria counts below a 1,000 parts per 100 milliliters of water. (The standard for drinking water is 1 part per 100 mills.) In 1979, the Baltimore Zoo was granted a three-year variance to comply with the bacteria level standard, which the city estimates would cost $125,000.

"Our main concern is for the humane care and well being of the animals," Crawford said. "Destruction would be the last thing. If it came to that, I'm sure we would not demand that the bears be destroyed."

The bears, unperturbed by all of the hubbub among the two-legs, are in fine fettle, despite occasionally high levels of bacteria in their 155,000 gallon pool, and despite their advance age, according to director Graham.Feral bears average 8 to 12 year life spans.

"If they were laying out prostrate we'd do something, but they're healthy," Graham said, adding that but for some inflexibility in the law, the Animal Welfare Act was a good piece of legislation. "I don't want to see it gutted. The reasonable thing would be to get a variance."