Christian Heurich Jr., 77, a local real estate investor, philanthropist and former brewery owner, died Wednesday of cardiac arrest at Washington Hospital Cennter.

In 1976, Mr. Heurcih donated 10 Potomac River islands - approximately 150 acres of heavily wooded unspoiled land near Seneca - to the Nature Conservancy, a private, nonprofit group that acquires and preserves ecologically valuable land under the auspices of the American Land Trust.

In a Washington Post article that year, Mr. Heurich said he was donating the islands because "I had no use for (them) myself. At my age, I'm not going to be doing any boating or hunting (and) I want to give credit to my dad," an immigrant from Germany who loved this country.

The brewery, founded in 1873 by Mr. Heurich's father, was originally on 20th Street. In 1894, it was relocated to the site where the Kennedy Center now stands, and was a Washington landmark until its demolition in 1962.

The younger Mr. Heurich began working in the brewery in 1924 and assumed the company presidency when his father died in 1945, at the age of 102.

The brewery produced Senate, Old Georgetown, Maerzen and Heurich's Original Lager beers until it was closed in 1956.

In 1962, the brewery's castle-like building on the Potomac, one of the first fire-proof buildings in Washington, with 3-foot-thick walls, huge smokestack, turret and employes' gymnasium (an innovation of Mr. Heurich) was demolished to make way for the approaches to the Theodore Roosevelt Bridge.

In 1965. Mr. Heurich and two sisters donated a 3,750-square-foot tract of land on the site of the old brewery for the John F. Kennedy Center for the Performing Arts.

After selling the brewery equipment, Mr. Heurich devoted himself to managing his real estate investment business. Besides his Washington properties, he owned a farm in Potomac, which included the 10 islands donated to the Nature Conservancy.

He was born in Washington and grew up in the Heurich mansion at the corner of New Hampshire Avenue and Sunderland Place NW. The mansion now is owned by the Columbia Historical Society.

Mr. Heurich graduated from Western High School and earned a bachelor's degree in economics from the Wharton School of Finance and Commerce at the University of Pennyslvania.

He was a past director of the Metropolitan Washington Board of Trade, which named him "Man of the Year" in 1948. He was a director of the Real Estate Title Insurance Co. and served on the Interstate Commission on the Potomac River Basin. He also had been a member of the Columbia Historical Society since 1929 and served on its board of managers.

Mr. Heurich was a member of the U.S. Brewers Association, the Metropolitan Police Boys Club, Kiwanis International, the Columbia Country Club and the Corinthian Yacht Club.

He was a life member of the Gem Lapidary and Mineral Society of Washington.

Earlier marriages to Consuelo M. Young and Beverley B. Jones ended in divorce.

Survivors include his wife, Helen, of the home in Kenwood; two sons, Christian III, of Potomac, and Gary F., also of Kenwood; two daughters, Corinne Martin, of Bethesda, and Connie Hogan, of St. Petersburg, Fla.; two sisters, Anita Eckles, of Washington, and Karla Harrison, of Clearwater, Fla.; 11 grandchildren and two great-grandchildren. Another daughter, Carol Hoover, died in 1966.

The family suggests that expressions of sympathy be in the form of contributions to the Columbia Historical Society. CAPTION: Picture, CHRISTIAN HEURICH JR.