AS Washington--along with the rest of the country--flounders through another long hot summer, there is one thread that colors almost every conversation. That thread, of course, is the Watergate investigation.

It's a lot less tedious than those recent summers spent nervously following the riot potential in the black community. But it is, in many ways, quite similar to those summers. The hearings, like the riots, are a violent means of exposing criminal conditions which have been allowed to exist for too long.

The hearings, like the riots, are designed to move the government to action on a matter of the utmost importance.

The hearings are exposing a band of men who can be identified, charged and convicted for their criminal destruction of the Constitution. The face riots of the past were often much broader in their scope. They indicted the entire white population and plunged a portion of it into spasms of guilt, while another portion merely reacted, true to nature, with further violence and deeper prejudice.

A similar pattern emerges as the Watergate hearings proceed. Some, like Jeb Magruder and John Dean, seem swamped by feelings of guilt and self-recrimination. Others, like John Mitchell, gruffly deny any wrongdoing (as they see it), and seem quite willing to rape the Constitution again at their next convenience. Meanwhile, the White House, which once espoused "benign neglect" (guess who thought that one up) at the expense of our black population, now espouses benign neglect with regard to the Watergate hearings.

THE Nixon administration will only react to the proceedings (as to the blacks). It will never act to help move things closer to the truth, just as it has never acted to move blacks closer to citizenship.

And just in case you needed further proof that nothing really changes, Richard Nixon recently dredged up another of his notorious policies. In the past, the President has worked his way out of crises by slinging mud at some evil enemy who was oppressing poor, defenseless Richard M. Nixon. For example, he won election to the Senate by maliciously ripping into Helen G. Douglas.

And now, with his back to the wall, Mr. Nixon has once again seen fit to sling a mudball. This time it is aimed at a man who is barely cold in his grave, President Lyndon Johnson. In a memo from J. Fred Buzhardt, it was alleged that LBJ was the slimy creature who initiated the policy of presidential phone taps.

What Mr. Nixon failed to mention was the fact that LBJ always notified the other party that the conversation was being taped. Apparently, this distinction was an insignificant detail for Nixon and his associates. And LBJ did not tape indiscriminately--he used taping only during two series of sensitive negotiations.

All in all, Mr. Nixon's White House shows no sign of changing its practice of systematic lying (witness recent testimony dragged out by Harold Hughes that the mad bombing began in Cambodia in 1970). In that light, John Dean's revelation of the enemies list was hardly surprising to anyone around here. Senator Kennedy told a Boston reporter that he would like to thank his staff, the press and all those who had made it possible for him to be on the enemies list. In a more serious vein, Kennedy said he was not the least bit surprised by the list or his inclusion on it.

WHITE House non-cooperation has stifled the hearings to some degree, but there is plenty to go around without Mr. Nixon's cooperation. The hearings are indeed history in the making--and it is quite an experience to attend a session of the Senate Select Committee on Presidential Campaign Activities.

The committee convenes every morning at 10 a.m. in Room 318 of the Old Senate Office Building. Every morning by nine, there is a crowd in the public line on the second floor. The size of the line, of course, depends on the prestige or damage potential of the witness.

At about 9:30 a.m., members of the press start trickling into their seats at the tables in the front of the hearing room. At 9:45 a.m., the policemen admit as much of the public crowd as can fit standing around the back of the room. Then, right before 10 a.m., the senators and the witness of the day come into the room. As each enters, the crowd buzzes and shifts for a view of the VIP.

As it is, almost every office on the Hill has at least one television tuned to Watergate when the hearings are in session; and if a game show or two sneaks in during lunch recess, that's all right with the people in the office.

BUT the biggest game show for this summer is undeniably Watergate. Each of the "quiz kids" on the committee has developed an identity of his own. Sam Ervin and Howard Baker are almost universally liked and respected for their roles in the investigation--although many of the women are a little disappointed to find that Baker is only five feet six inches or so.

Ervin, of course, is the wise old sage of the hearings. Like a visiting uncle, he dispenses his pearls of wisdom with droll humor and biblical quotations. But it is when he gets angry that Ervin is at his best, Ervin, like none of the others, can bear down on a witness, cutting directly to the heart of the testimony and making clear the full implications of that testimony. His dogged emphasis on the Constitution and the ways in which it has been abused by a particular witness puts the matter in its proper, sweeping perspective.

Inouye, Weicker and Talmadge have all gained respect as tough, impartial questioners. Yet none commands the respect--perhaps because none is chairman or co-chairman--accorded to Ervin and Baker.

Weicker did some self-righteous dissociation of himself and the Republican party from the bugging, burglary and other illicit campaign activities conducted by a segment of that party. Yet he is afraid to set out on his own. He is still a captive, rather than a leader, in the Republican party.

Weicker continues to defend the moves of the President aimed only at maintaining secrecy and hiding the truth for a while longer. He continues to espouse the "few bad apples" theory rather than admitting that at least one whole barrelful seems to have gone rotten.

Gurney is either loved or hated--depending on whether you love or hate Richard M. Nixon. Weicker has said of Gurney that he is an honest and forceful man, that he is not being programmed by the White House.

Montoya, although he tries so hard, just cannot cut the mustard. As Art Buchwald says, the best time during the hearings to break for the bathroom is when Montoya is questioning the witness.

IN spite of some soft spots on the committee, the investigation attracts massive crowds dotted with some fairly unique specimens. For the first few weeks of the hearings, there was a raucously dressed woman named Fifi seen in the room every day. She would deck herself out in a weird hat, several layers of wild jackets and dresses and an extensive collection of bracelets and other jewelry. And from her perch in the press section, Fifi let those around her know exactly what she thought of each witness.

Other luminaries in the press section include Norman Mailer--who showed up for just a few days--perhaps he decided that the whole affair was not bookworthy.

And, of course, there is always the gaggle of network newsmen--Daniel Schorr, Sam Donaldson, Douglas Kiker, Mike Wallace, etc. Daniel Schorr has the best view in the whole room--on a television monitor placed in front of him on the press table.

But the poor view does not deter the crowds. For there is a magnetic attraction about the investigation that draws people back time and time again to witness the controlled violence of the Watergate hearings.