Minnehaha County approves ordinance to allow accessory dwelling units

The Minnehaha County Commission on April 22 approved zoning text amendment 2,506 to the county's 1990 revised zoning ordinance to add regulations for accessory dwelling units, or ADUs. The amendment passed on second reading after a public hearing and a unanimous vote.

County planner Kevin Hookman told the commission the change grew out of the county's 2024 comprehensive-plan update and a task force that recommended adding ADU rules. "One of the things we'll be adding the definition to the accessory dwelling unit is a subordinate residential unit on the same property as a larger property, primary single family dwelling," Hookman said, describing the variety of ADU types the ordinance covers.

Supporters on the commission said ADUs can increase housing options and help families who need caregiver space. "Frankly, I'm very strongly supportive of this," said Commissioner Grenninger, citing both caregiving and rental uses. Commissioner Heisey said he had heard some constituent concerns but that the ordinance's requirements address them.

The ordinance sets distinct limits and requirements depending on whether an ADU is attached or detached. For attached ADUs the ordinance permits a maximum of 75% of the primary dwelling's main-floor area; detached ADUs are limited to 50% of the primary dwelling's main-floor area. Detached ADUs in rear yards will be allowed with 7-foot side and rear yard setbacks. The ordinance requires that ADUs be located on a single platted lot to prevent later separation from the primary dwelling and prohibits additional driveway access that could enable lot division.

The draft also requires a conditional-use permit (CUP) to approve an ADU. Hookman confirmed existing ADUs already present in the county would be required to pursue the CUP process to come into compliance. Commission discussion emphasized specific development controls: parking, construction standards and temporary structures. Heisey noted the ordinance provides an off-street parking requirement: "per item number 6, it does mention that 2 additional off street parking spaces must be provided for the ADU," and pointed to a construction requirement that ADUs be built on "permanent frost protective footings," which he said would prevent use of temporary structures such as campers.

The commission also clarified use limits: a short-term rental in an ADU would require a separate conditional-use permit in addition to the ADU CUP. When the chair asked whether short-term rentals would be allowed, Hookman said, "it would be a 2 part conditional use so you'd have to go through a conditional use permit to allow the ADU and then a second one to do a short term rental in the unit." The planning department said homeowners who believe they already have an ADU should contact county planning to begin the compliance process; Hookman added, "it would be best if they reached out to us and, if we do hear about something, we can reach out to them."

The commission voted unanimously to approve the amendment on second reading. Roll call recorded aye votes from Commissioners Weinberg, Ise, Bennegga and Kerski; the motion carried.

The new rules were presented as a regulatory framework designed to retain single-family residential character while creating legally permitted options for caregiver units and rental housing. The planning department will administer the CUP process for ADUs and answer homeowner questions about compliance and permitting.