The head of the Regional Transportation District, Dave Genova, announced Friday that he is retiring after 26 years of service with the agency, as RTD faces severe challenges with employee retention and declining ridership. No date was announced for his departure; Genova told the agency he would remain in the post “to assure a seamless and smooth transition.” In a press release issued late Friday afternoon, RTD said Genova informed Doug Tisdale, the chair of the board of directors, of his decision Thursday night. “It has been a privilege to serve the Board, our incredible team of employees and our community,” Genova said in a statement.