There's a new product showing up in California supermarkets: Canadian Cheddar cheese embellished with red stickers, ''Fancy sharp - aged 15 months.'' Colored pale yellow, it doesn't look like US-made orange-hued Cheddar; but its special taste and its competitive price are making it a good seller.
While the amount of this new import is small enough to go almost unnoticed, California dairy producers are paying attention to its arrival - and others like it. The reason? California's dairy industry has a growing surplus of its own in cheese, butter, and milk powder, and it needs to take aggressive marketing steps to sell it.
Since 1970, over half of California's milk output has been processed into these types of ''Class 4'' products. In 1981, the figure swelled to 65.8 percent - broken down to fluid cream, 1.7 percent; butter, 30.6; cheese, 11.6; condensed milk products, 1.9; frozen dairy products, 11.1; and other manufactured products , 10.6 percent. And now the state's Milk Advisory Board is concentrating on an advertising campaign to help move at least one of the classifications: California-made cheese.
The expanding problem of more and more milk going into milk products has a simplistic origin for California: Per capita consumption of milk is declining - even despite the ''I drink milk for good'' slogan in a highly visible media campaign.
Nationally, industry researchers point out, annual milk consumption has dropped from about 150 quarts in 1950 to a little over 100 quarts in 1981.
California's decline - in a state where dairy products are the biggest sector of the agri-economy - has not been quite so severe. But available figures (taking into account the state's burgeoning population) indicate milk consumption dropped from 113 quarts per person in 1970 to 107 in 1981. This decline came in the face of a strong 11-year ad campaign by the state's Milk Advisory Board, which spent $15 million last year alone.
State industry analysts attribute the slump to these conditions in part:
* The influx of many Asians, whose diet has not traditionally included milk (because of cost and scarcity).
* Heavy competitive advertising and marketing of soft drinks - especially with convenient point-of-sale vending machines.
* An increase in older age groups, where milk is not heavily consumed.
* The trend away from animal fat products, which even 2 percent fat milk hasn't seemed to curtail (whole milk has a maximum of 3.5 percent).
In addition to facing less use of fluid milk by the consumer, California milk producers are looking at the problem of excess capacity. And with more and more of the excess being converted to butter, cheese, and milk powder (for which producers get less money), this surplus is an ongoing burden to the federal government.
Dairymen know the surplus has stemmed from generous government supports for 10 years and more. The Reagan administration is at present approaching Congress with plans to help reduce support prices and to make the industry more self-supporting through producer assessment quotas and other means.
Meanwhile, US cheese-eaters, especially in California, can look for lively competition to those import specials in the supermarket dairy cases. They can expect sharper domestic prices, upgraded quality, and probably some new look-alike home-processed products to vie with that French Brie, Danish blue, Dutch Edam - and the Canadian Cheddar.