The Nelson and Tasman regions will move out of a state of emergency and into the official recovery phase this afternoon.
The state of emergency was put in place two weeks ago, after severe weather caused the Maitai River to breach its banks and triggered more than 350 landslides.
Civil Defence is also asking people to stay away from an operation to remove trees caught in a slip in the hills behind Nelson.
There have been onlookers drawn by the use of a Sikorsky UH60 helicopter - best known as the Black Hawk in its military role.
Nelson Tasman Civil Defence controller Alec Louverdis said the Black Hawk's arrival had piqued the interest of many, but it was important people stayed away from the work site.
There were four trees in a slip near Atmore Terrace that were placing downstream properties at risk, he said.
"We've been absolutely bombarded with heavy rainfall and the entire area is very wet and our geotechnical engineers have identified four trees in particular that have to be removed."
The helicopter had the ability to lift heavy items of up to 3.2 tonnes and was being operated by Black Hawk helicopter heavy lift services, Kahu NZ.
"It's ideal for the operation, we can't use conventional machinery, the area is just too wet and it is too dangerous and unsafe so the logical thing to turn to was a helicopter and it will be working today and tomorrow to remove those trees."
Louverdis said the operation was complex and needed to be done without interruption in order to get the trees cleared in a timely manner.
"It's a very delicate operation ... everything has to go right to protect the safety of the helicopter crew, those on the ground, the residents in the fly zone and where we are depositing the trees."
Cordons will be in place around Nile St East and the Atmore and Cleveland Terrace junction between 9.30am and 5.30pm today, and possibly on Thursday.
As the Nelson Tasman area regroups from the damage, a recovery manager will be appointed to lead an operations team through the next stage.
The response will continue to provide support to affected people - particularly those whose properties have red or yellow stickers.
So far, more than half a million dollars has been donated to the Nelson Tasman mayoral relief fund for those affected.
Fund coordinator Jim Frater said there have been 25 applications so far, for a total of $122,000.
The sums sought range from $75 to $30,000.
Frater said there could be at least another hundred applications to come as people pieced their lives back together.
People can apply or donate to the fund on the Nelson City Council website.
Detectives flew to Victoria, NSW and Queensland as part of the investigation.