Calgary Mayor Naheed Nenshi, left, and former Alberta premier Ralph Klein, centre, attend the opening of Ralph Klein Park. Meghan Grant/CBCCalgary Mayor Naheed Nenshi, left, and former Alberta premier Ralph Klein, centre, attend the opening of Ralph Klein Park. Meghan Grant/CBC

Former Alberta premier and Calgary mayor Ralph Klein made a surprise appearance at the opening of a park named after him in Calgary on Saturday.

It was Klein's first public appearance since it was revealed in April that the former premier has been diagnosed with a progressive form of dementia.

Even city officials were surprised by Klein's appearance, including Mayor Naheed Nenshi who was on hand for the opening.

"I have to tell you, I'm a little star struck here because I am so excited to be here with mayor Klein, and I'm going to call you mayor Klein because I believe once a mayor, always a mayor," Nenshi said.

"I'm so thrilled that you are here with us today. Thank you for coming today."

The $32-million Ralph Klein Park features a state-of-the-art environmental education centre, and uses natural vegetation to treat storm water before it is discharged into the Bow River.

"This is very exciting because we're taking education about the environment and putting it right into the environment," Nenshi said.

"We think that environmental education is an important aspect … of what we do here as a city."

The 30-hectare park, located off of 84th Street south of Glenmore Trail S.E., sits within 200 hectares of engineered wetlands.

Klein, whose language skills have been impaired by dementia, did not speak to the crowd or take questions from the media.