Richard Chamberlain is in love.

The chisel-chinned actor who has inspired heartthrobs for two decades--first as young Dr. Kildare and more recently as the steamily seductive priest in "The Thorn Birds"--publicly named the object of his affection yesterday morning at a public hearing on Capitol Hill.

It's a river.

"I fell in love with her," he said of California's Tuolumne River, after a white-water rafting trip last year. As gaggles of moon-eyed women waited outside a packed hearing room in the Dirksen Office Building, Chamberlain told the Senate subcommittee on public lands and reserved water about his aquatic love affair in passionate detail:

"Plunging down her rapids, camping in the evenings along the gentle tributaries and lush forests and fishing her abundant trout, I felt more whole and closer to the very source of nature than I'd ever felt in my life."

So naturally, when he heard the Tuolumne was in dam danger--"she's already pulling her own economic weight with five dams"--he did what any self-respecting hero would do.

"This is the first time I've ever testified before Congress," Chamberlain confessed with a shy smile over a cheese omelet and bacon breakfast in his hotel a few hours before the hearing. Previously he has shunned such publicity (during the filming of "Shogun" he told a reporter that "an actor should stay as distant as possible from public scrutiny") partly because "I never found anything I felt this strongly about before.

"But even though I've been around the world a bunch of times, I've never seen a more beautiful, dazzling river."

Looking beautiful and dazzling himself in a trim tan suit, blue shirt and navy silk tie, his graying moustache and sideburns meticulously trimmed and his skin a honey tan, the Monarch of the Mini-Series said he was "star struck" after spending Wednesday on the Hill visiting senators and representatives. "I was amazed," he said, "to see all those people I read about all the time--like Cranston and Kennedy and Percy--in the flesh."

The heartthrob admitted to some pulse poundings of his own at the prospect of testifying, where he would play one of his most difficult roles--himself.

"I've got stage fright," he confessed. "I don't have a character to hide behind this time. And I'll be talking about something I care about very, very much."

Until recently, Chamberlain said he wouldn't have dreamed of making this kind of public statement. "For one thing," he said, "I've had a phobia about reading in public ever since I was a little kid. I didn't read or do anything well in school. I remember being asked to read aloud in front of a formidable school administrator, Mrs. Abbey, and bungling it and getting very depressed."

He wrote his testimony on the plane in from California Tuesday night and had not had a chance to memorize it. "So I guess," he said, "I'll have to read it."

But a more significant reason for his decision "to finally speak out about something I feel strongly about" is "the personal growth and change" Chamberlain said he has experienced over the last few years.

"I grew up not liking myself very much," said Chamberlain, who despite published reports that he is 48 said adamantly, "I'm 46. That's all I'm going to say about it."

"Somehow as a child I got the idea that something was missing," he said earnestly, thrusting his square jaw forward onto his upturned palm. "I didn't like school and I didn't like sports and I didn't like anything everybody else liked. So I figured there must be something wrong with me, and I grew up with this sense of a certain unworthiness.

"I think that was one of the motivations I had for becoming successful, becoming known. I was very highly motivated, very hard-working. I thought if I was successful, I would be worthy."

But after achieving success, "I still had this core of discomfort. I was so busy pleasing people that I lost touch with myself. I didn't know when I was angry; I'd love.

The chisel-chinned actor who has inspired heartthrobs for two de get withdrawn. I inverted the anger and screwed myself up."

After several years of "psychological work," including sessions with a gestalt therapist and retreats with physician-turned-holistic-teacher Brugh Joy, he said, "That has all changed. I love what I do much more than I did. My reason for doing what I do now is very different."

While he used to work to please others, he said, "now I work to please myself."

As for becoming a public advocate, "I sort of feel I have a right now. I'm a human being, a citizen who cares about something and pays a stupendous fortune in taxes. We all sit around and think 'If only they do this' or 'If only they won't do that.' Well, I decided to stop sitting around."

This personal growth is one reason the man People magazine called "a confirmed bachelor" has never married. Asserting that "my private life is very private," he acknowledged, "I'm a bachelor, but 'confirmed' is too strong. Life is full of surprises."

Although he is dating several women, he said none of the relationships was very serious. "I've been serious before," he said. "I've been close to marriage. I'm not sure what happened; I probably got a job and went to Europe.

"The real reason I've been single so long is that I've been raising myself. The energy that some people put into children I've put into myself . . . and I've needed it."

Being an actor results in "a kind of schizophrenia," he said, "where I don't know who I am. I don't have that kind of constancy that I imagine other people have. My identity is more vague.

"And as far as children go, there are a few I like. But I'm not up to the day-to-day business of raising them, and I don't think it's fair to give someone else that full responsibility."

As for the future, Chamberlain said he'd like to do "a few more movies." He has just completed an upcoming CBS mini-saga, "Cook and Peary: Race to the Pole," in which he stars as "good guy" Frederick Cook to Rod Steiger's "bad guy" Robert E. Peary.

Recent reports that he almost died on location in Greenland, he said, "were greatly exaggerated. I was standing on this big ice island and it split in half all of a sudden. In my business you think everything's part of the show, and I thought, 'Hey what a great special effect.' Then everybody started screaming 'Jump, Jump.' "

Despite the example set by other leading men who have used acting as a springboard to political power, Chamberlain said he has no such aspirations.

"I think actors need to be real careful in getting politically involved. We have a little more attention-getting power than the average guy, and I think that should be used with great discretion."

Being a politician, he said, "is not my temperament at all. I get bored real fast, I like things to move fast and I don't have the patience or chess player's foresight to meticulously plan ahead.

"Also, in my one day in Washington, I've learned that compromise is all in politics. You can never have everything you want in politics, it seems. And I don't like to compromise. I like things the way I like them."