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.