"It's true, but necessary," is the response generally offered by local members of Congress to former President Ford's criticism of greatly expanded congressional staffs in his State of the Union address last month.

The departing chief executive complained that employment by "the legislative branch has increases substantially although the membership of the Congress remains at 525." Ford said "Congress now costs the taxpayers more than a million dollars a year per member."

Congressional staff have, indeed, grown. As of last June there were 18,019 persons working for Congress and all its committees, 3,156 more than three years before.

Seventeen or 18 employees work for each of the six local members of the Fauntroy (D) and Reps. Joseph L. Fisher (D-Va.), Herbert E. Harris II (D-Va.), Majorie S. Holt (R-Md.), Gladys N. Spellman (D-Md.) and Newton I. Steers, Jr. (R-Md.).

Most Senators are entitled to hire far more employees than are the Representatives, who are limited to 18. Sen. Charles Mc. Mathias Jr. (R-Md.) has 42 persons working for him, including some assigned to his congressional committees. Newly elected Sen. Paul S. Sarbanes (D-Md.) already has 29 employees and expects eventually to have 35 to 40.

Virginia's Senator have comparatively small staffs. Sen. William L. Scott (R) has only 14 full-timers in his own offices, while Sen. Harry F. Byrd Jr. has 18. Despite the size of Congressional staffs, one Capitol Hill aide spoke for many when he contended, "People here work damn hard."

The staffs for local members of Congress, though no larger than those of their colleagues, have much heavier work loads because in most instances they are only a local telephone call away from constituents.

Local members of Congress get called about broken traffic lights, rat problems and snakes being discovered in basements.

"Lately we've had a lot of calls from people whose streets have not been snow-plowed. A Congressman from Colorado wouldn't be bothered with that," said a Spellman aide.

Some examples of the Congressional workload:

The offices of Fauntroy and Spellman receive and average of more than 300 telephone calls a day.

Sarbanes gets more than 200 letters daily.

Fisher's office last year opened files on 8,190 cases in which it was seeking to assist constituents with government-related problems.

There is someone in Harris' office as early as 7 a.m. because a few constituents apparently call as soon as they are out of bed. "They look upon their Congressman as an ombudsman. They don't hesitate to call about anything," said a Harris aide.

Every local member of Congress has at least four or five employees who are employed full-time as case-workers trying to help a grived constituent solve problems with the government.

Despite the workload, there is a great demand for Hill jobs, especially with the convening of a new Congress, a spot in a local Congressional office are bleak.

Each of the six local House members has been approached by 250 to 350 job applicants since the November general election. Holt hired two, Fauntroy and Spellman one each, and Fisher and Harris, none.

Steers, of course, had to hire an entire Congressional staff, but only one of the 17 employed by him had not either worked for former Rep. Gibert Gude (R-Md.), his predecessor, or in Steers' campaign.

On the Senate side, Sarbenes has been flooded by hopeful persons with resumes, receiving 2,000 job applications since his election. The Maryland Senator has hired 11 persons who had not worked for him previously in the House.

House members have $255, 144 that they can divide up on staff salaries as they see fit. The total funds alloted Senators depends on the population of their state.

Each Senator can pay his top aide up to $41,750 a year and a House member can pay his administrative assistant up to $39,600. Most Congressional employees make far less, some only $7500.

The top assistants for Sarbanes earn $39,000; for Byrd and Mathias, $38,500; for Scott, about $35,000.

The top assistants for Fisher earn $34,500; for Steers, $32,000; Holt, $29,000; Fauntroy, about $28,000; and Spellman, $24,500.

There are more women than men employees in all but one of the ten local Congressional offices. Steers, the exception, has 10 men and seven women staffers, only three of the 17 being over 30 years old.

Many of the women employees in the local offices have more than secretarial responsibilities, working as caseworkerw, legislative assistants or press aides. Mrs. Spellman has a woman as her executive assistant.

Byrd and Scott have no black employees. Asked about majority employment a Byrd aide said that a Chinese-American had worked in the office until recently. An assistant said that Scott only discriminates in insisting that all members of his staff by Virginians.

The number of black employees working for other local members of Congress who are white, are: Mathias, seven; Spellman, four; Sarbanes, Steer, Fisher and Harris, two each; and Holt, one.

Fauntroy, the only black among local Congressmen, has three whites on his 17-member staff.

The local members of Congress vary in maintaining from as many as three to no offices their home district for the convenience of constitutents.

Harris has auxiliary offices in Alexandia, Manassas and Springfield. Fisher has them in Falls Church and Leesburg, Holt in Oxon Hill and Glenn Burnie, Steers, in Wheaton and Bethesda, Spellman, in Hyattsville and Fauntroy, here in the General Accounting Office building at 441 G. St. NW.

Byrd, however, doesn't maintain a branch office in Virginia, while Scott has one at the state capitol in Richmond. Mathias has offices in Lanham, Baltimore and Cumberland. Sarbanes has two offices in Baltimore and is planning to open other elsewhere in Maryland.