"It's a big number, but it's a number that we expected," acting Chief Minister Nicole Manison said.
Of those cases, 14 are from households in Katherine following a testing blitz in the town.
These include eight children under 12, five people in their 20s, 30s, and 40s, and one 70-year-old woman.
"We are finding the cases that we thought were there and we can expect more cases," Ms Manison said.
All of Katherine has been declared an exposure site, and a new testing mandate has been put in place.
People from outside Katherine who have spent any time in Katherine, Binjari or Rockhole since Monday, November 29, are mandated to get a COVID-19 test in the next 72 hours.
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Those residents are not required to isolate.
"Obviously Katherine has been the ground zero for COVID-19 in the Territory," Ms Manison said.
She added the issue is the high likelihood of the virus spreading from Katherine to other communities.
"I have to say that this is really serious," Chief Health Officer Dr Hugh Heggie said.
Ms Manison said there is a strong chance some communities outside Katherine will have active wastewater COVID-19 test results.
"It is likely that we are going to have to escalate our responses to some of these communities to a lockout in the next day or two," Ms Manison said.
"That means locking down people who are not fully vaccinated."
Ms Manison said a positive wastewater result has already been recorded in Tennant Creek, and health authorities are awaiting further results from additional testing.
"About the number of COVID tests that we had in Tennant Creek was very disappointing. There were only five COVID tests done in Tennant Creek and frankly that is not good enough," Ms Manison said.