Assaults by inmates in the Minnehaha County Jail rising with population

The daily average population of facility in downtown Sioux Falls was up 11% in 2022.

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The entrance to the Minnehaha County Jail in Sioux Falls.
Contributed / Minnehaha County

SIOUX FALLS – The inmate population and serious assaults were up last year at the Minnehaha County Jail.

The overall number of incidents at the jail – such as behavior violations, suicide attempts and medical emergencies – was down in 2022. However, the number of assaults increased, according to Mike Mattson, the jail’s warden.

Mattson delivered the data to the Minnehaha County Commission recently. The trend of offenders arguing with jail staff continues to go up which “requires a lot of attention,” he said.

Here are the numbers for 2022:

  • Jail population was up 11% to an average daily population of 516.
  • There were a total of 10,262 incidents reported, or about 28 per day. 
  • In 303 cases, staff had to use force, up from 230 in 2021. 
  • There were 114 inmate assaults.
  • Assaults by inmates on staff rose to 16 from 11 the year before.
  • Prosecutors opened 142 cases involving inmate incidents.

The increasing population also puts strain in the staff. Pay increases and bonuses have helped retain the jailers and correctional officers, yet the nature of the job will always make it a challenge to keep staff, Mattson said.


The $50 million facility will be built on the current site in southern Sioux Falls.

Staffing is also an issue in whether to expand the cells available.

The jail in downtown Sioux Falls was expanded in 2020 by adding two floors. One was opened at that time with another floor, with a capacity of 148 inmates, vacant and available for future use.

The current capacity of the jail is 603 inmates.

The growth in population last year was well ahead of the annual estimate of 2.5%.

Chief Deputy Jeff Grower said the sheriff’s department will begin planning to open the additional floor, including the budget, in 2024 if needed.

“The longer we can put it off the better,” Mattson said.

Gromer said it can take months to find the staff to open any new cells.

The county “saved a tremendous amount of money” by adding the unused extra floor when they did, Gromer said.


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