Seqwater chief executive Jim Pruss resigned after it was discovered he had accessed "inappropriate websites" at work.

Another staff member has resigned and a "handful" of Seqwater employees were being counselled after an information technology audit detected the breaches.

The Queensland government bans the access of such websites at work and Seqwater is a government statutory authority overseen by Water Supply Minister Mark Bailey.

Seqwater manages the dams in south-east Queensland, including the large Wivenhoe, Somerset and Hinze dams and the $10 billon water grid that connects them.

Mr Pruss tendered his resignation on Wednesday and Seqwater's staff were informed after lunch of the reasons he resigned.

Mr Pruss's resignation was confirmed on Wednesday afternoon by Seqwater chairman Dan Hunt.

"Mr Pruss used Seqwater work resources to access prohibited websites," Mr Hunt said.

"While investigations have determined the breach was not illegal, we cannot condone or accept those actions.

"Nobody is exempt from the high standards we set for ourselves."

Workers were reportedly shocked and upset after being told.

Mr Pruss had 30 years' experience in Queensland's water supply industry before becoming Seqwater's chief executive in January 2017. He had worked at Seqwater for 10 years.

He is one of Queensland's most experienced water engineers, working in executive roles in Queensland water supply and sustainable water policy areas before being appointed chief executive.

Before Seqwater, Mr Pruss worked at Redland Shire Council for 15 years and at Sydney Water.

Seqwater general manager Dan Spiller has been appointed acting CEO.