North Somerset Council lost child protection notebooks
Notebooks containing confidential information about a child protection meeting are among private information lost by North Somerset Council.
The authority said six shorthand notebooks and four A4 pads had later been found by a council contractor who then handed them to police.
The data protection breach was one of 16 by the council in the past three years, according to a report.
A spokesman said a "significant" amount of training had been given to staff.
Other breaches include copies of a serious social care case review and a letter about child protection concerns being sent to the wrong people.
Minutes from a child protection case conference were also "accidentally disclosed" and a legal injunction had to be taken out to prevent the information being disclosed to other people.
Councillor Tony Lake, who is in charge of data protection at the authority, said it was an "appalling list".
"Where personal data has been involved we've taken immediate action to limit potential problems and contacted the families concerned.
"We do take data security very seriously and that is why we have reported incidents to the data commissioner."
Mr Lake added the authority was being fined for one of the breaches where information was sent to the wrong person but declined to reveal how big the fine was.
The disclosure came in a report by Big Brother Watch, which said private data has been lost by or stolen from UK local councils more than 1,000 times since 2008.
Big Brother Watch director Nick Pickles said the research - based on answers to freedom of information requests - showed a "shockingly lax attitude" to protection of confidential information by some councils.