West Coast leaders are worried about the cost of the government's new regional spatial plan requirements when ratepayers have just forked out $10 million for the region's new combined district plan.

Greymouth Mayor Tania Gibson says she fears the cost of the new regional spatial plan requirement passed down from the government will now directly fall onto ratepayers, after a suite of Resource Management Act reforms were passed into law last month. 

The Natural Environment Act and the Planning Act have replaced the old Resource Management Act (RMA).

The Planning Act now requires district councils to draw up regional spatial plans for the next 30 years, with draft plans expected to be publicly notified by mid-2028 and finalised by early 2029.

Last week, Mrs Gibson described the new spatial plan requirement as another "unfunded" mandate handed on to councils which in reality will have to be borne by ratepayers.

And it came just as councils were being told to brace for rates capping.

"I have my concerns of costs and these unfunded mandates again coming down to council," she said on Thursday.

"These planning processes, we have seen blowouts and they cost a fortune ... we keep getting these unfunded mandates from the Government that we have no money for.

"(Plus) we have a 4% rates cap. If we are paying for planning process, that is going to cost millions of dollars, they just cannot do it. We cannot do it.”

Councils were yet to see more information on the impact of the regional spatial planning system.

But Mrs Gibson said she was cost wary, based on her experience of the costs for the combined West Coast Te Tai o Poutini Plan (TTPP).

Westland Mayor Helen Lash. Photo: Vihan Dalal (LDR/Greymouth Star)

In a statement, Westland Mayor Helen Lash said the TTPP now risks becoming obsolete with the move to spatial plans.

"From my perspective, spatial planning sits ahead of the TTPP.

"The regulatory component (TTPP) should pull spatial planning together. Now, it has the potential for misalignment with the central government reforms and risks becoming obsolete."

The Local Government Commission in 2019 directed the West Coast councils to form a single district plan for the entire region.

The TTPP was widely seen as the West Coast being used as the blueprint for a government plan to institute widespread amalgamation of district plans across the country.

Mrs Lash said spatial plans will "create friction" with what is already outlined in the TTPP.

"That's not beneficial in any shape or form.

"For example, SNAs (Significant Natural Areas) require rigorous report-heavy proof from environmental experts. This can slow down localised development pathways rather than expediting them."

Buller Mayor Chris Russell also voiced concerns at the cost to the ratepayer by setting out on "another tranche of work".

"All of this work does cost the ratepayer money, and I am very conscious of that."

Meantime, how the regional spatial planning requirement will impact on the already ratified TTPP was not certain, Mr Russell said.

"There may be some overlap between them, but we are yet to establish what that might be."

In a statement to Local Democracy Reporting, the Ministry for Cities, Environment, Regions and Transport said the regional spatial plan requirement sets out "long term" direction to guide "where and when the region needs to change over time".

The plan would identify "the key drivers of growth and change", including population and climate impacts on land and infrastructure.

The plan would also set out broad patterns of land use, such as for housing, infrastructure, natural environment and natural hazards, the ministry said.

"It helps ensure important decisions about where development happens and where and when infrastructure is needed are well-informed and tested using robust evidence and analysis about the future of the region."

The TTPP to replace the individual Grey, Westland, and Buller districts plans remains in final mediation in the Environment Court, after six years of formulation.

• LDR is local body journalism co-funded by RNZ and NZ on Air