Washington Gas Light Co. yesterday reported net income of $16.18 million before extraordinary items in 1977, compared with $15.84 million in 1976.

That works out to earnings per share of about $3.74 last year, compared with $3.70 in 1976. Washington Gas reports its earnings per common share after deducting dividends payable on preferred stock.

After preferred dividends net income was $13.15 million in 1977 ($3.04 per share) and $12.73 million ($2.97) in 1796.

Revenues were $320.6 million in 1977 and $370.5 million in 1976.

In 1976, settlement of a lawsuit added $1.39 million to Washington Gas's income, which totaled $17.23 million after extraordinary items in 1976. The company reported no non-recurring items last year.

Washington Gas said that most of the increase in revenues was due to higher rates. The company noted that although "temperatures for the heating seasons" of 1976 and 1977 were about the same, sales of gas were "lower in 1977 reflectings conservation efforts by the company's customers and the extended curtailments of interruptible customers during the very cold weather in the first quarter."

At the end of 1977 the company had 544.802 meters in services, 463 fewer than at the end of 1976.