All three candidates for governor of Virginia today endorsed proposals to submit to voters next November a major bond issue to pay for college, prison, park and other projects.

Six bills proposing bond issues as large as $175 million have been introduced in the General Assembly this year and the agreement of the gubernatorial candidates to back a debt-financed construction program is considered important to legislative approval.

Gov. Mills E. Godwin has told Assembly leaders that he cannot support a bond issue uneless it has strong bipartisan support in both the House of Delegates and Senate and the cooperation of candidates for governor.

Any bod issue proposed by the Assembly will be on the Nov. 8 ballot with the candidates for governor, lieutenant governor, attorney general and House of Delegates.

The broadest bond proposal before the Assembly is a $175 million plan sponsored by Sen. Adelard L. Brault (D-Fairfax). It is a combination of two lists of building needs compiled by the Godwin administration and includes $12 million in construction at Northern Virginia Community College and George Mason University.

The proposal also includes a $5 million library building at the University of Virginia, where 40 per cent of the students are from the Washington suburbs, and $2.5 million in maintenance buildings at Western State Hospital, a mental health facility at Staunton that serves Northern Virginia residents.

Del. James M. Thomson (D-Alexandria) also has introduced a bond issue bill limited to Northern Virginia college project that total $29 million. All 19 Northern Virginia delegates have endorsed that bill.

Sen. Wiley F. Mitchell (R-Alexandria) introduced a bond issue bill that proposed construction of the $72 million in projects that Godwin sought unsuccessfully to include in the biennial budget adopted last year. That list includes $12 million in construction projects at George Mason and NVCC.

Of the $175 million in projects proposed by the Brault bill, $110 million is for buildings at the state's four-year colleges and two-year community colleges.

The proposal includes $35 million for prisons, $14 million for parks and other conservation projects, $12 million for pier construction at Hampton Roads, $3 million for mental health facilities and the balance for miscellaneous projects.

The Brault bill proposed submitting these projects grouped in six categories. Thiw would give voters the opportunity to reject one category of construction while approving another.

If approved by the Assembly, the bond proposal would be only the second of modern times in Virginia. In 1968, with Godwin's strong backing voters approved an $81 million college and mental hospital construction package by a two-to-one margin.

That was the maximum amount that could be borrowed by the state at that time for nonrevenue producing projects.The revised Constition of 1971 expanded borrowing authority to 28.75 per cent of sales and income tax revenues for the three years preceding approval of the issue. Under that formula, state tax officials estimate there currently is legal authority to borrow up to $294 million for construction projects.

The state now has only 46.4 million in debt remaining from the 1968 issue, less general obligation debt that the city of Alexandria has.

All witnesses testifying at a Senate finance subcommittee's hearing on the bond proposals yesterday endorsed the Brault bill except the fiscally conservative Virginia Taxpayers Association. Even the VTA witness endorsed borrowing for prison construction, however.

Endorsements by the gubernatorial candidates came in response to quiet inquires made by Brault last week. Former Attorney General Andrew P. Miller, a candidate for the Democratic homination, announced his support in a telegram calling on his Democratic opponent, former Lt. Gov. Henry E. Howell, and the likely Republican nominee, Lt. Gov. John N. Dalton, to do the same.

Howell and Dalton both endorsed a bond issue, but stressed that they had communicated their support to Brault before receiving Miller's telegram. Dalton said he backed the "concept" of a bond issue, but reserved a final judgment untill he sees the bond bill in its final form.

Because the Senate has only until Thursday to act on its own bills and the House only until Feb. 16 to act on its proposals, the final bond bill many be sent down by Godwin after those deadlines. CAPTION: Picture, SEN. ADELARD L. BRAULT . . . sponsors $175 million plan