Rising in the Berkshire Mountains and descending gracefully over 115 miles of rolling New England countryside into Long Island Sound, Connecticut's Housatonic River has always been known more as an unspoiled haven for creative spirits than a waterway of commerce.

While the other great rivers of New England fostered the textile mills and fed on America's brash new industrial revolution, the Housatonic quietly gave itself to men of letters.

In this idyllic but unlikely setting, Herman Melville wrote "Moby Dick"; Nathaniel Hawthorne penned "The House of the Seven Gables" along the banks of the river, and Oliver Wendell Holmes and James Thurber derived their inspiration from the Housatonic.

The Housatonic has also always been known as a sports fishermen's paradise, abundant with trout and smallmouth bass. Old-timers say that at the turn of the century, the salmon ran so thick that farmers used to go down to the river with their pitchforks and ride away with wagonloads of fish.

For years, fishing and hunting magazines have listed the Housatonic as one of the East's top 10 trout rivers.

Now, Connecticut health officials have ruled that poisonous industrial chemicals have so saturated the bed of the Housatonic River that its fish are unfit to eat. And officials say it may be generations - if ever - before the contamination disappears.

The Housatonic joined a growing list of great rivers - including the Hudson - whose fish have been declared inedible because of the toxic chemical polychlorinated biphenyl (PCB), which for 40 years has been used in the manufacture of electrical capacitors, paint and cardboard.

PCBs have been linked to cancer in animals and to other illnesses in humans, and environmentalists claim that they have been leaked or purposely dumped into virtually every major watershed in the country.

About a year ago, sportsmen along the Housatonic began hearing rumors about PCBs, but it was not until a week ago that the state Department of Environmental Protection issued an advisory against human consumption of any fish taken from the river.

Charles Fredette, a sanitary engineer for the agency's water compliance division, said water and riverbed samples taken since July, 1974, showed increasing concentrations of PCBs, particularly in the northern reaches of the river near Pittsfield, Mass., where PCBs have been used since the 1940s.

Until recently, a General Electric plant was the only remaining source of PCBs, with about one pound of the chemical being dumped in the river daily. Last March the plant phased out all discharges of the toxin, officials said.

However, the chemical has permeated the plant and its grounds so much, health officials said, that it continues to leach into the river.

Moreover, the chemical is so resistant to breakdown that officials fear it may never disappear.

Apart from bringing fishing to a near standstill, the state's ruling on PCB-contaminated fish destroyed the dreams of one man along the Housatonic who thought he had carved out a new life for himself.

Four years ago, 42-year-old Joseph White of Gaylordsville, Conn., quit the factory job that he said was aggravating his asthma and opened a bait and tackle shop.

In his first year, White and his wife moved their bed into the living room, giving the bedroom over to their shop, and as business flourished they built an addition to their house.

"We were doing real good. We were selling 2,000 to 3,000 shiners [baitfish] a week. Then the roof fell in on us," White said in a telephone interview.

In the past weeks, White said, his entire stock of baitfish and worms died, and he has had to close his shop and return to his job in a welding equipment factory.His wife has gone back to work as a hairdresser.

White does not attempt to disquise his bitterness.

"If my septic tank was running into the river, the health department would be out here the next day. Here's an outfit doing more pollution in a year than I do in a lifetime, and they don't even slap their wrists," he said.

"I've been fishing on this river since I was a kid. I don't see how the state can do this.It's a river that belongs to the people, not General Electric."

No one knows the fate of the Housatonic. The discovery of PCBs in the scenic river is so recent that discussions of settlements or penalties have not even started.

However, another General Electric plant had previously been implicated in the fouling of the Hudson with about 500,000 pounds of the chemical.

The company, which had been dumping PCBs in the Hudson for more than 25 years, reached a negotiated settlement with the state in September in which the firm agreed to pay $3 million toward cleaning the sediment and $1 million for research on ending the problem.

New York State agreed to set aside another $3 million to help eliminate the chemical - primarily by dredging - in a 50-mile stretch of the Hudson from Fort Edward to Albany.

State officials noted at the time of the agreement that General Electric had obtained federal and state permits to dump PCBs into the Hudson, and that until 1975 nobody had ever claimed that the company's PCB discharges violated state or federal water quality standards.

A similar kind of tacit approval in Connecticut moved White to write President Carter recently, complaining that "your EPA [Environmental Protection Agency] gave permission to put PCBs in the river."

White said he received a reply containing an application for a Civil Service job.