The Panama Canal Authority (ACP) announced on Thursday it is lifting all the draft restrictions that have been in play for the past few months, but only for existing locks.
The new locks due to be inaugurated on June 26 as the centrepieces of the canal expansion project will not be covered by the lifting of these restrictions.
The restrictions had been imposed on Panamax vessels transiting the Canal since April. They were needed because of the effects of the El Nino weather phenomenon, which have included reduced rainfall in the Canal area for this time of year.
However, the start of the tropical rainy season has seen water levels restored to the point where the restrictions are no longer required, the ACP said.
The draft is the distance from the waterline to the bottom of the hull.
Whereas usually the maximum allowable draft for ships using the Canal is 39.5 feet (12.03m), it was initially reduced to 39 feet (11.89 m) with the first recent restriction, which was effective on April 18.
The second restriction, which cut the maximum draft to 38.5 feet (11.74 m), was effective from April 29. A third restriction should have brought the maximum draft down to 38 feet (11.59m) but it was deferred and never took effect.
Drafts for the new locks, which can accommodate the much larger new breed of vessels handling three times the cargo capacity of the existing biggest ships, will be 43 feet.