Welden was born in Boise, Idaho, and grew up in Twin Falls.
Throughout his childhood, he was engrossed in the emerging technology of the day, fabricating his own radios and a motorcycle. He graduated from Twin Falls High School in 1946 and then from the University of Idaho in 1951, earning a bachelor's degree in architecture.
He began his career working at the Hanford Site near Richland, Washington. There, he met and married Virginia Ann Leader, a mathematician from Michigan. The Clarks in 1953 moved east to Cambridge, Massachusetts, where both entered postgraduate studies. Welden earned his master's in architecture from MIT in 1955.
He then joined the engineering and architecture firm of Bolt, Beranek & Newman in Cambridge. In the late '50s, he transferred to its Los Angeles, California, office, when Virginia began her doctoral studies at University of California, Los Angeles
In 1962, Welden co-authored with J.C.R. Licklider a pioneering research paper, "On-Line Man Computer Communication," focused on a vision of the future of the Internet. He later became owner of a small architectural firm and also did consulting into the early 1980s.
The Clarks became airplane owners and pilots in the '60s and flew throughout the U.S. both for work and recreation. They thoroughly enjoyed the natural world and how it evolved. He had a passion for space exploration, geology and natural history.
When the Clarks retired to Sequim in the mid-1980s, they selected the site for their dream home on Sporseen Road. He designed a simple, open-space home with a wall of windows looking toward Sequim and the Strait of Juan de Fuca, and together, they built it.
As a team, they did everything: grading, setting foundations, plumbing and building their cabinets and bookshelves.
They welcomed friends and local organizations to their home, and many worthwhile projects advanced around their dining table, from design of the Dungeness River Audubon Center's wiring to SNOTEL gauge locations.
Welden did much of the initial research on the Dungeness River watershed and strongly supported the formation and early projects of the Dungeness River Management Team. He collaborated with the natural resources staff of the Jamestown S'Klallam tribe and the Clallam County water resources staff.
He and Virginia became founders of the Dungeness River Audubon Center. In addition to contributing funds, they helped fabricate the roof trusses and did extensive computer wiring and audio-visual installation. He designed, built and installed the office desks and shelving.
In the 1990s, Welden and Virginia organized and helped fund an extensive hawk migration research and count station on Bahokus Peak overlooking Neah Bay on the Makah Reservation. Coordinating with the Makah tribal staff and with Hawkwatch International, they recruited volunteers to document and count the numbers and species of raptors that moved north over the Strait during each March to May for 1994 through 1998.
Olympic Peninsula Audubon Society members elected Welden to many offices, and he served more than 20 years on its board. He developed its first website and its first computer-based membership and mailing system.
In 1991, the society presented the Clarks its highest award for achievement and service, the Harlequin Award.
In 2008, Welden and Virginia were honored with a Clallam County Community Service Award as local "heroes" for their many volunteer contributions.
Welden is survived by his wife, Virginia; nephews Dirk Yerrington of Everett, Washington, and Clark Yerrington of Anchorage, Alaska; and niece Jan Rogers of Troy, Illinois.
In lieu of flowers, his family requests that donations be made to the Dungeness River Audubon Center, P.O. Box 2450, Sequim, WA 98382.
There will be an informal gathering of friends at the Dungeness River Audubon Center at Railroad Bridge Park on Tuesday, November 19, 2013, from 2 p.m. to 4 p.m. to share happy memories of Welden.
Friends are invited to join the family in viewing photos and mementos of his life.