Playing at the Oval on April 17 was “a real possibility,” Mr Willoughby said.
Council community assets and resources manager Laird Kennedy said the installation of automatic irrigation at all fields at The Oval was part of a wider sports park capital upgrade programme being undertaken around the district.
“The work at The Oval is scheduled for completion at the end of March.
“We've been engaging closely with sports codes and users to minimise disruption while this work is under way.
“The contractor is Recreational Services and they were selected through a competitive tendering process.”
Contractors were digging trenches and laying pipes at the Childers Road end of the Oval and between the two rugby grounds when the Herald visited.
Three water tanks to feed the irrigation system have been placed on the fenceline bordering the former St Marys School site.
The quality of the playing surface at the Oval has long been a concern and the surface was relaid as recently as 2010.
Mr Willoughby said the Lee Brothers Shield competition would not be compromised by the later start.
The premier competition still consisted of six teams and clubs had indicated they liked a 12-week competition with two full rounds and no disruptions before the play-offs.
A three-round competition with only six teams would be tiresome, said Mr Willoughby.
The union hoped, at some stage in the future, to return to an eight team premier competition.
The only disruptions to the 2021 club season would be the Town vs Country match and Poverty Bay's long traditional Queens Birthday encounter with East Coast.
Poverty Bay was due to host the Queen's Birthday Weekend fixture this year, but has agreed to play the match away as the East Coast union holds it centennial celebrations.