Jefferson County to draft ADU ordinance, consider raising minimum lot size to two acres

The Jefferson County Board of Supervisors on June 20 directed staff to draft a local accessory dwelling unit ordinance and to prepare amendments to the county's subdivision ordinance after an extended discussion about sanitation, emergency response addressing and how to manage multiple dwellings on single parcels.

Speaker 4 opened the discussion by noting a new state law "that requires counties to allow 1 accessory dwelling unit" and proposed that the county "adopt our own ADU ordinance that complies with the new law of the state" while limiting ADUs to one per parcel. Board members debated how ADUs and movable 'mini homes' interact with county sanitation rules, whether units on foundations must be treated as real property and who is responsible for waste-disposal systems on leased lots.

Speakers pressed several operational details staff must resolve before an ordinance is finalized. Speaker 4 said permitting should be tied to the county sanitation permit so disposal systems are sized and approved before building permits are issued. Speaker 3 recommended visible unit numbering ("Unit A, Unit B") or separate 911 numbers so EMS can find the correct unit quickly. Speaker 4 repeated state code ADU limitations cited in the discussion: an ADU "shall not exceed 1,000 square feet or 50% of the size of that single family residence, whichever is larger."

Board members also discussed whether to use the terms "parcel" or "lot" in local code and whether the county should limit residential dwellings per parcel to force subdivision when additional legal lots are needed. Speaker 1 proposed increasing the minimum lot size in the subdivision ordinance from one acre to two acres to reduce the proliferation of small lots with independent disposal systems; Speaker 6 and others warned that a two-acre minimum would raise land costs for some residents.

The board asked staff to research the updated corn suitability rating (CSR) used to evaluate agricultural land and to check state definitions to align local language with Iowa law. Speaker 4 summarized the outcomes: staff will draft (1) an ADU ordinance using state language where appropriate; (2) amendments to the subdivision ordinance (including consideration of a 2-acre minimum); and (3) resolutions establishing fees for subdivision applications and ADU/building-permit review.

Fee and permitting examples discussed on the record included: suggested subdivision application fees from $0 for a simple split up to $1,000 for a major subdivision; an on-record suggestion of a $500 minimum fee; sanitation permit fees mentioned by staff (new construction $500, alteration $200); and a recommended $25 administrative check to confirm required sanitation and assessor letters before issuing ADU building permits. The board asked that fees be set by resolution so they can be revised later.

Speakers also raised infrastructure and homeowner association issues: Speaker 3 described cases where homeowners associations dissolved and left private storm-drain systems without maintenance funds; speakers noted the county's subdivision requirements call for covenants or legal instruments to ensure maintenance but that enforcing private maintenance obligations may be a civil matter.

Next steps: staff will draft the ADU ordinance and subdivision amendments, research CSR definitions, coordinate with sanitation and assessor offices on permit sequencing and addressing requirements, and prepare fee resolutions for board consideration. No final ordinance or fee was adopted at the meeting; the items were placed on the staff workplan for future meetings.