Every working day for 40 years, Bob Rayhill has left his house in Warwick about half an hour before dawn so he can be out on the waters of Narragansett Bay by sunrise.
The water is smoother in the morning, and Mr. Rayhill usually skims his 18 -foot fiberglass boat toward the middle of the bay, where he will work his ''bullrake'' scoop over the bottom for clams.
Bullraking hasn't changed much over the years. But now Rayhill steers a boat with an 85 horsepower outboard engine in contrast to years of rowing a 13-foot wooden skiff. Today his clams bring about 80 cents a pound, as opposed to 5 cents a pound when he first started.
But the price increases have been offset by steadily rising costs. And, most important, the clams just aren't there in the same numbers they used be.
''We all came when it (clamming) was pretty good going, but a lot have ended up leaving. It has slowed up a lot,'' he says of friends who have quit or simply headed south to Florida.
The major problem for the industry here, Rayhill says, is the pollution that has claimed prime clam beds in the upper arm of the bay near Providence. Raw sewage, toxic chemicals, heavy metals, and other pollutants have closed nearly 10,000 acres of water, primarily in the upper bay, to all kinds of fishing for about four of the last five years.
''It (the bay) is in fair condition. The water has been getting better, but it's still pretty bad in the upper bay,'' Rayhill says.
Sewage bacteria ordinarily flush out of a clam's system within a week after the source of pollution stops. On the other hand, oils, metals, and chemicals may remain within such bottom-dwelling marine life for much longer periods, scientists say.
Although blatant dumping of toxic substances directly into bay tributaries and sewer systems has been standard industry practice for decades, that practice is under fire by environmentalists and may be changing.
Save the Bay - a citizens environmental watchdog group - has probably had the biggest impact on cleaning up the bay. The group has grown from a seven-member organization in 1970 to more than 10,000 dues-paying members and 475 active volunteers in 1984.
During the last 14 years, the group has developed considerable muscle. And federal, state, and municipal officials apparently are paying more attention to the bay's pollution issues. At a recent annual Save the Bay meeting, Al Alm, deputy director of the Environmental Protection Agency (EPA), promised members the agency would strictly enforce new federal restrictions to limit disposal of heavy metals (such as lead, cadmium, silver, mercury, zinc, and chromium used mostly by the jewelry industry here) into municipal sewers.
Though members liked Mr. Alm's message, they clearly are not willing to entrust the EPA with anything as important as cleaning up ''our bay.''
''If it hadn't been for them (Save the Bay), I don't know what we'd do. The EPA sure doesn't do much,'' says Loraine Tisdale of Cranston, who joined the organization two years ago.
''You don't know what kind of prosecution you're going to get from EPA,'' agrees Trudy Coxe, executive director of Save the Bay. ''If the agency isn't tough on this one (new heavy metal restrictions effective in April), it's going to be very tough to enforce later on.
'''We got going before EPA existed, and (we) got officials to say 'no' (to industry) a long time before saying 'no' was even heard of,'' she adds.
The Providence River has been closed to shellfishing for decades, and, since 1969, the upper bay has been closed much of the time due to high bacteria counts in the water.
After a 12-hour day of probing and scraping the bay's bottom, Rayhill returned home with about 87 pounds of clams - mostly littlenecks, cherrystones, and quahogs (pronounced CO-hogs). This winter the catches of less than 100 pounds have been ''very bad,'' he says. The clam beds are overworked and the industry in the Narragansett has steadily declined since 1977, Rayhill says.
Much of the pollution comes from the billions of gallons of untreated sewage that each year seep into the bay from bad septic tanks or gush in from poorly maintained, inadequate municipal treatment plants.
Last year 131 million gallons of sewage effluent daily entered the bay from 12 sewage treatment plants, says Eva Hoffman, a research scientist at the University of Rhode Island. An unknown percentage was untreated raw sewage.
How does this happen? On a rainy day in the Providence area, about 200 million gallons of storm runoff and raw sewage mix together to flow into the Fields Point treatment plant, Save the Bay's Ms. Coxe says.
Opened in 1900, the plant was built to treat 64 million gallons of sewage a day. Construction is under way to increase the capacity to 200 million gallons. But currently, more than 90 million gallons still flow untreated through the plant when it rains, Ms. Coxe says. That overflow increases the bacteria content of the water, making clams and other marine life unsuitable for eating.
Rayhill says he would like to see the upper bay reopened. It happened for several months in 1981 when there was little rainfall and the sewage plants worked fairly well.
''I don't think it'll ever open,'' he says. ''They talked about it for years, but it's been a long time now.''
In addition to sewage pollution, heavy metals and toxic chemicals are dumped by industry into the Providence sewage system. These substances are not removed by sewage-plant processing, but pass into the bay.
Rainwater runoff, carrying pollutants from the land, has also been found to wash an estimated 665 tons of oil annually into the bay, Dr. Hoffman says.
Other industrial toxins are dumped directly into the Providence River and a tributary, the Pawtuxet River. Pretreatment facilities costing millions of dollars would be necessary to remove those elements.
The federal and state governments have passed numerous and specific clean-water regulations for industry. Even so, Save the Bay has cast itself in the role of industry watchdog, spotlighting specific trouble spots to compel better enforcement of regulations.
Last year, the group spent almost $175,000 to publicize bay pollution, research its positions, seek out polluters, and lobby with state and local officials for stricter chemical-disposal laws.
Save the Bay's recent victories include:
* Unexpected passage in 1980 of a statewide referendum to wrest control of the Fields Point plant from the City of Providence. A new state commission was set up to operate the facility. The referendum also netted an $87.7 million bond issue to enlarge plant capacity, and set up a fee structure for users. The plant is responsible for half of all effluent entering the bay.
* Passage of new federal laws to require pretreatment of heavy-metal waste. Save the Bay spotlighted possible violations of federal water-pollution laws by the state's jewelry industry and pushed for the new laws, which begin to go into effect next month.
* Winning a two-year battle with Ciba-Geigy, a Swiss-based pharmaceutical manufacturer with an outlet in Cranston. The company used to deposit its chemical waste directly into the Pawtuxet River, but Save the Bay pointed out the violations to EPA officials, who forced compliance with federal regulations. Ciba-Geigy is now tied into the Cranston sewage plant.
Although other victories further illustrate the group's success, real progress will be achieved only if bay pollution can be reversed, Ms. Coxe says. Thus far, it has only been slowed, she says.
Environmentalists and research scientists in Rhode Island view Narragansett Bay as a microcosm of bays and estuaries along New England's entire coast. The political and ecological challenges of cleaning up and halting the flow of toxic chemicals and poorly treated sewage in the bay are not fundamentally different from elsewhere, they say.
Although heavy pollution in certain portions of the bay has spread to other areas, one expert on Narragansett marine ecology sees good reason for hope.
''Most of the bay is in pretty good shape. The severe impact is limited to the Providence River area. I see no reason why it couldn't be cleaned up,'' says Dr. Candice Oviatte, director of the Marine Eco System Research Laboratory at the University of Rhode Island.
More severe sewage problems are squarely confronting Boston Harbor, and residents who live near it. Boston Harbor has been adjudged by the EPA the No. 1 sewage-pollution problem on the New England coastline, ahead of the upper Narragansett Bay.
Despite Boston Harbor's dubious honor, popular support for groups such as the Conservation Law Foundation has not crystallized as it has around Save the Bay. Such backing, Ms. Coxe says, is essential to gain legislators' attention and win the fight for the harbor.