Subdividing Land in Custer County, Idaho

The 20-acre Agriculture zone minimum, and how the pre-2003 exception actually works

Custer County's Zoning Ordinance No. 2007-09 sets a 20-acre minimum lot size in its Agriculture (A) zone. The documented exception: an original parcel that existed before November 10, 2003, and has not been divided since that date, may be eligible for up to three additional lot splits, with the specific number depending on the original parcel's size and its division history since that date. That's a meaningfully different question than simply asking "is this parcel over 20 acres" -- it requires tracing a specific parcel's ownership and division history back to a fixed date, which the county's own zoning certificate application process is set up to check. Before assuming a larger agricultural parcel can be split under this provision, request a review of the parcel's pre-2003 status and division history directly from Custer County Planning and Zoning rather than assuming eligibility from acreage alone.

A below-minimum split is possible in narrow cases -- but only through a Special Conditional Use Permit, and only if the parcel is small enough

The ordinance also documents a separate, narrower exception: when it is not possible to complete a lot split in the Agriculture zone while keeping every resulting parcel at 20 acres or more, a single lot split resulting in a parcel smaller than 20 acres may be allowed -- but only with an approved Special Conditional Use Permit, and only where the original "mother parcel" being split contains less than 40 acres. That 40-acre ceiling is a real, specific test: a mother parcel of 40 acres or more does not qualify for this particular exception, regardless of how the buyer might want to divide it, and would instead need to satisfy the standard 20-acre-per-parcel rule or the separate pre-2003 grandfather provision. For a buyer evaluating a smaller agricultural tract (under 40 acres) with a single-split subdivision in mind, this Special Conditional Use Permit route -- not the pre-2003 provision -- is the specific mechanism to ask Custer County Planning and Zoning about.

A formal plat goes through a separate Subdivision Ordinance -- and this page could not verify its current text

County ordinance indexes reference a distinct Subdivision Ordinance, cataloged separately from the Zoning Ordinance No. 2007-09 that governs the acreage rules above. A formal platted subdivision -- as opposed to a simple lot split under the zoning ordinance's provisions -- would be reviewed under that separate subdivision ordinance's own plat, road, and utility-access standards. This page was not able to independently verify the current text of that subdivision ordinance, including its specific road-standard, frontage, or utility requirements, during this research pass; rather than guess at those standards, this page reports the gap directly. Anyone planning a multi-lot platted subdivision (as opposed to a single lot split under the zoning ordinance) should request the current Subdivision Ordinance directly from Custer County Planning and Zoning before budgeting for road, utility, or survey costs.

Before you buy with a split or subdivision plan in mind

1. Ask Custer County Planning and Zoning ((208) 879-6894) to confirm the parcel's zoning district and, if it's Agriculture (A) zoned, whether the 20-acre standard, the pre-2003 grandfather provision, or the sub-40-acre Special Conditional Use Permit exception is the relevant path for your specific parcel.
2. If pursuing the pre-2003 grandfather provision, be ready to document the parcel's existence and division history prior to November 10, 2003 -- county records, not just a current deed, will likely be needed.
3. If pursuing the Special Conditional Use Permit route for a below-minimum split, confirm the current "mother parcel" acreage first; a parcel at or above 40 acres does not qualify for this specific exception.
4. If your plan involves a formal multi-lot plat rather than a single split, request the current Subdivision Ordinance text directly from the county, since this page could not independently verify its road, frontage, or utility standards.