The William Kaufman Organization and Principal Real Estate Investors will retake control of the office building at 77 Water St.

WKO's management and leasing operation, Sage Realty, will run the building starting April 1. The building is under a triple-net lease — an arrangement in which the tenant pays all expenses, including property taxes and insurance — with Goldman Sachs until then. Goldman Sachs's tenancy will revert to a gross lease, which runs for four more years.

Sage Realty has already arranged new deals with two other major tenants of the 26-story, 600K SF Financial District building. Law firm Lewis Brisbois Bisgaard & Smith and engineering firm Arup will sign leases with Sage when their subleases with Goldman Sachs expire March 31.

Lewis Brisbois will renew its 100K SF lease for the 18th through 21st floors for the long term, and Arup will expand from 125K SF on five full floors to add 25K SF on the full 25th floor on a new, three-year lease.

WKO has owned 77 Water St. since it was built in 1970, and has had a triple-net lease with Goldman Sachs for 17 years. Last year, Jonathan Iger took over as CEO after the death of his grandfather, Robert Kaufman.