Lt. Gov. John N. Dalton, the Republican candidate for governor, yesterday proposed that a nearly 20-mile pipeline be built in the median strip of I-66 in Fauquier and Warrenton counties to carry water from the Shenandoah River into Northern Virginia.

The plan, designed by former State Water Control Board chairman Noman M. Cole Jr., a Dalton adviser is aimed at solving the problem of water shortages in Northern Virginia, Dalton said.

As Dalton and Cole explained it at a press conference yesterday, the pipeline would eliminate the need for the $96 million Verona dam in Augusta County, would cost between $25 million and $35 million dollars, and would not take needed water away from the valley served by the Shenandoah River.

They said that 6 per cent or 100 million gallons a day of the Shenandoah's "average daily flow" could be si-phoned off a pumping station at Front Royal to start its journey to Northern Virginia. This 6 per cent, Cole said, is water that is now "lost to the ocean" and thus not necessary to the river area customers. Water would not be pumped from the Shenandoah when the river is low.

The water would travel by pipeline from Front Royal, over Manassas Gap and down the eastern slope of the Blue Ridge Mountains, and would then feed into Broad Run, Goose Creek and Cedar Run. The number of gallons dumped into each of these natural tributaries would be determined by negotiations between separate jurisdictions.

The transfer would increase the amount of water in five reservoirs - Accoquan. Goose Creek, Lake Manassas, Lake Jackson and Warrenton and would thus affect the countries of Fairfax. Price William Loudoun, Fauquier, and the cities of Alexandria, Manassas, Mannassas Park and Warrenton.

The on going water crisis, which has prompted the Fairfax County Board of Supervisors of impose mandatory water restrictions, beginning Monday, had affected over 600,000 Northern Virginians.

By building nearly all of the pipeline under the median strip of I-66 in Fauquier and Warren, which is the most direct route to the dumping-off points> the cost will be less because the land is already state-oened. Dalton said. He added that such construction would require federal approcal, and congressional approval if it were to be funded by federal money.

"Since this would cost a third of the $96 million Verona dam, which the federal government was going to fund, I see no reason why they wouldn't want to assist," Dalton said.

If they federal government refused to build the pipeline, it could be paid for with revenue bonds, Dalton said. This would require the creation of a water authority by the General Assembly but would not require a referendum, he said. A water authority would have to be created by the legislature in either case.

Although Dalton said that one advantage of the pipeline is that "it would take place entirely within one state," he also noted that it would require the permission of the Army Corps of Engineers. Cole said he thought the corps would be receptive to the idea because the Shenandoah water is "high-flow skim," or water that would not be used.

Dalton has previously opposed transferring water from one river basin in the state to another, in particular a proposal to send water from Southside Virginia to the populous Hampton Roads area. The proposal offered yesterday does not violate the no-transfer concept, Dalton campaign manager William A. Royall said, because the Shenandoah River water flows into the Potamac. "...It's all in the same watershed," he said.

Trying out the proposal before a group of Kiwanians in Alexandria before his press conference, Dalton found a receptive crowd. After a few respectful questions about the pipeline idea, however, the audience got restless and wanted to get down to something more interesting - politics.

"How are you going to beat that phony?" a man asked Dalton, referring to Dalton's opponent Henry E. Howell. After demurring that he had not come to make a "partisan political speech" Dalton asked the group if any one subject to his about the campaign.

The 50 or so Kiwanians chorused "no."

"What do you think we brought you up here for?" the man said.

Dalton went on to say that secret of Howell's victory in the primary was " banks in every one of the six cities in Tidewater. And they got out 35 per cent of the registered vote."

Although he has frequently castigated Howell's recent attempt to link Dalton woth a possible conflict of interest that Howell has not proved, Dalton closed his press conference by questioning Howell's relationship to labor union clients. Howell, like Dalton, is a lawyer.

"You know he put in 1968 a bill to take us away from being a right to work state and make us an agency shop state," Dalton said. "I'd be interested to find out if he was on any retainers or salaries from any unions (at the time)."

At his own press conference in Richmond, Howell said that he represented "six litle unions," of which three are still his clients. Those three are the carpenters unions, from which he gets a retainers of $25 a month, the United Auto Workers, $50 a month, and the pension fund of the International Organization of Masters, Mates and Pilots. The last group pays him between $1,200 and $1,500 a year.

Asked if he would consider it a conflict of interest if Howell did represent unions at the time he introduced 17 bills relating to either workmen's compensation or unions, Dalton said. "The people of Virginia will have to decide."