One of two men nominated to the suburban Maryland water and sewer agency by Prince George's County Executive Lawrence J. Hogan formerly was president of a bank that made loans that are being investigated by a federal grand jury in Washington.

The nominee is Dale L. Jernberg, who 15 months ago left his position as president of the National Bank of Washington after questions were raised about the involvement of the United Mine Workers union in the operation of the bank. The grand jury is investigating allegations about questionable loans made to leading businessmen by the bank.

Jernberg, named by Hogan to a seat on the Washington Suburban Sanitary Commission, described himself in a statement to the Prince George's County Council as an attorney with the Washington law firm of Lambert, Griffin and McGovern as well as president of Union Financial Services Inc., a corporation involved in mortgage banking business and union pension funds. The council approves or rejects Hogan's nominations to the agency.

Hogan's son and top aide, Lawrence J. Hogan Jr., said yesterday the executive had been aware of the controversy over the bank Jernberg once headed although he had not known an investigation of the bank was in progress. He said the executive "said there was no wrongdoing on his [Jernberg's] part and no suspicion of wrongdoing."