John Mink collapsed and died at his daughter's home in Northampton, family spokesman Calvin Tamura said. Gwendolyn Mink, the couple's only child, is a professor at Smith College.

John Mink's business partner of 20 years, George Yuen, said Mink hadn't been in ill health.

"In fact, before he left here, he told me that he had undergone a physical examination and everything was fine," Yuen said.

A native of Pennsylvania, Mink graduated from Penn State University and earned a master's degree in hydrology at the University of Chicago, where he met his future wife. They were married in 1951.

Patsy Mink died in 2002 at the age of 74. The veteran Democrat represented Hawai'i in the U.S. House for 24 years. She also served in the territorial and state legislatures.

"All of our Hawaii joins the Mink ohana (family) in mourning the passing of John Mink," Rep. Ed Case, D-Hawai'i, Patsy Mink's successor, said in a statement issued by his Washington office.

"John was best known to most as the rock on which his wife of 50 years, the late Congresswoman Patsy Mink, rested her legendary public career," Case said. "All who knew them could not help but admire their incredible marriage and partnership in love and life.

Case noted that John Mink was awarded the Distinguished Flying Cross for service in World War II, and "earned respect and renown in his own right as a world-class hydrologist whose expertise was sought throughout Hawaii and the world."

Sen. Daniel Inouye, D-Hawai'i, said in a statement that John Mink played a key role in Patsy Mink's rise to prominence.

"Just as the water he studied is essential to sustaining life, he was the water in Patsy's life that helped to give her the strength to serve as a champion for peace, equal opportunity, education and women's rights," Inouye said.

John Mink's company, Mink & Yuen Inc., specializes in water resource studies, planning, development and management. It has done work throughout the Pacific.

Before going into private business, Mink worked for the Honolulu Board of Water Supply and the U.S. Geological Survey.

Funeral arrangement were pending.