Columbia Gas Transmission Corp., the major supplier of natural gas to the Washington area, will get an emergency supply of 30 million cubic feet a day of gas from Texaco, Inc., the oil company announced yesterday.

This comes on top of an emergency authorization of Columbia from the Federal Power Commission to buy 250 million cubic feet of gas each day from Canada.

But the FPC said yesterday that it will hold a hearing Monday to see if it should divert some of that Canadian gas from Clumbia to other pipelines in greater need of the fuel.

Natural gas shortages have been appearing across the country as severe cold weather grips the eastern two-thirds of the nation.

A spokesman for the FPC, which regulates the natural gas which flows through pipelines across state lines, said that the City of Indianapolis has applied for 50 million cubic feet of the Canadian gas and that the Southern Natural Gas Co. has requested 125 million cubic feet.

In giving Columbia 60-day approval for emergency gas imports last Tuesday, the Federal Power Commission said it might decide Columbia had to give some of the gas to more severely hurt pipelines.

The 30 million cubic feet of gas it will get from Texaco on an emergency basis will come from gas reserves that Texaco requires in its own company operations. The oil giant said that most of its natural gas reserves are already committed under contract to existing customers but that it will dip into its internal sources for 60 days because of the gas shortage.

In another development, the FPC ruled yesterday that the higher costs of imported liquefied natural gas should be charged to all customers of three pipelines that will buy one billion cubic feet a day of the fuel from Algeria.

Columbia is one of the pipelines. It expects to start receiving 300 million cubic feet at its facilities at Cove Point, Md., by late summer or early fall. Consolidated Natural Gas Co. will take 350 million cubic feet at Cove Point while Southern Natural Gas Co. will get 350 million cubic feet at a facility in Savanmah, Ga.

Yesterday's FPC ruling reverses a 1972 order which would have required the pipelines to price the liquefied gas "incrementally," meaning that special purchasers should buy the gas and pay the higher price.

Since 1972, however, the price of natural gas risen dramatically and "the supply situation to these three pipelines has deteriorated drastically," the FPC said yesterday in a unanimous ruling.

While the Algerian gas - whcih must be converted back to a gas from a super-cooled liquid after being unloaded - still costs more than most other natural gas, the differential is not nearly what it was in 1972.

Furthermore, the FPC has rules which state that higher-priority customers such as homes and hospitals are the last to lose gas service. Selling liquefied gas at a higher price to special buyers (presumably industrial and commercial) could "allow lower-priority customers who have contracted for the supplemental supply to receive adequate service while higher-priority customers would be threatened by severe curtailment," the commission noted.

In 1972, the price of natural gas sold in a state other than the one in which it was produced was 30 cents per thousand cubic feet or less.

Today, all new gas delivered to the interstate market costs $1.44 a thousand cubic feet. In the current shortage, federally regulated pipelines have been permitted to buy gas from unregulated intrastate pipelines for as much as $2.50 a thousand cubic feet. The Canadian gas costs $1.94 a thousand cubic feet.

The commission said that Columbia estimates the gas will cost $1.23 when it is unloaded from tankers at Cove Point and it will cost another 43 cents to revaporize the gas and get it into its pipeline at Loudon, Va. The total cost is $1.66 a thousand cubic feet.

When that is rolled into the total gas supplied by Columbia, it will raise prices an average of 9.5 cents per thousand cubic feet. Consolidated's costs will go up 17.55 cents per thousand cubic feet and Southern by 13.3 cents a thousand cubic feet.

The liquefied gas will represent about 9.7 per cent of Columbia's total gas supply during the first full year of operation, presumably 1978, 18.3 per cent of Consolidated's supply and 16.9 per cent of Southern's, the FPC noted.

The commission said that while it realizes that this will result in a "significant increase in the cost of gas for each customer," the "supply is critical to the maintenance of adequate service."