Salmon will join Kelda in mid-May as director of corporate affairs, replacing Richard Emmott, who left last month to join facilities management firm Jarvis (PRWeek, 24 January).
Salmon will report to Kelda CEO Kevin Whiteman, heading a 21-strong Yorkshire Water team covering PR, marketing, public affairs, publications and campaigns.
He will also handle comms for Kelda's customer relationship management business Loop, and the group's US water business, Aquarion.
From next month Kelda, which has around 3,000 staff, mostly in the UK, will be allowed to raise the price it charges for water to help offset rising costs resulting from increased requirements to monitor water quality.
Salmon, who will be based at the company's Bradford headquarters, said: 'As the company approaches key price reviews, its willingness to engage with those who shape opinions on the company will be critical.
'Having handled pan-European and global comms for Shell for five years, I am particularly interested in a strategic and not tactical approach to PR,' he added.
WS's Manchester office last week launched a search for a replacement for Salmon, who is likely to remain in his role until he starts at Kelda.
Meanwhile, WS's joint UK chief executive Colin Byrne last week became chairman of Weber Shandwick North - the agency's northern operations - and plans to divide his time between London and Manchester.
Salmon set up the then Shandwick International's Manchester office in 1997 and merged it with Jo Leah's McCann-Erickson PR in autumn 2000.
The office now employs 18 staff and has a turnover of more than £1.2m.