An Ottawa co-operative has had its property assessment lowered, it says, after the Municipal Property Assessment Corporation told them it had made an error.

MPAC had sent representatives at the 83-unit Blue Heron co-op on March Road its 2012 assessment earlier this fall, telling the co-op the value of its apartments and townhouses had jumped from $7 million four years ago to nearly $20 million.

A representative of the co-op said the tax bill would not have been affordable, especially because they try to keep rent lower than market rates.

But Blue Heron's coordinator Michelle Bainbridge said Tuesday she received a call from MPAC Tuesday to let her know they would lower the assessed value to $11.7 million.

Error inputting data, MPAC tells co-op

Bainbridge said she was told the higher value was sent out after what an MPAC representative said was an error in inputting the data into a new software application.

"Somebody must have just made a key-stroke error," she said.

Bainbridge said the co-op could still request a re-consideration, even with the lower assessment.

Other co-ops and non-profit housing corporations in Ottawa reported a similar increase in their assessments.

The Centretown Citizens Ottawa Corporation, which owns 50 properties and sells units at affordable rates, has also seen its rates go up 120 to 130 per cent in the last four years.

It is not clear whether MPAC is reviewing all those evaluations. MPAC did not respond to requests for more information from CBC News on Tuesday.