Calypso water park has pleaded not guilty to 20 charges related to alleged safety violations at the park in 2011 and 2012, an Ottawa court heard Wednesday.

Fourteen of the charges relate to three separate incidents in 2011 involving the Steamer water slide and Calypso's alleged failure to report and respond to the incidents.

Three charges relate to an incident involving a serious injury on the ride Pirate's Aquaplay on June 27, 2012.

And the final three charges relate to an incident in which a man fractured his skull on the Orange Bobsleigh ride on June 19, 2012.

The trial of the Limoges, Ont., water park operator began Wednesday with Calypso's lawyer, Lawrence Greenspon, arguing there was no need to hear from eight of the 12 civilian witnesses in the trial who are expected to recount the events on the day of the Orange Bobsleigh crash.

Greenspon said Calypso's legal team would agree to several admissions if the witnesses were excused, arguing their testimony would "shed more heat than light" and force witnesses to recount and relive what happened.

But Crown lawyer Tom Ayres argued it was essential to hear testimony surrounding the "horrific and terrible results" alleged to have happened.

Witnesses are expected to testify that attendants at the top and bottom of the ride were inattentive and failed to respond after the crash, while others will testify they were thrown a considerable distance onto concrete and injured, Ayres said.

Justice Julie Lauzon is expected make a ruling Thursday on Calypso's request to waive eight of the Crown's witnesses.

Water park also facing lawsuits

The TSSA had already ordered two Calypso rides closed after some riders suffered serious injuries. Calypso made changes to the rides and reopened them.

Calypso has complained that the charges are an "abuse of power" by the TSSA and owner Guy Drouin has previously said any safety problems at the park have already been fixed.

The water park is also facing millions of dollars in lawsuits brought by individuals who say they suffered broken bones and other injuries on these rides.

Those allegations have not been proven in court.