Water decides what the ground can become, and a domestic well is smaller than people think
Idaho defines domestic water use as use for homes, camps, campgrounds and livestock, including irrigation of up to half an acre, provided total use does not exceed 13,000 gallons a day. That is the ordinary domestic right.
The exclusions are the part that governs development. The definition expressly excludes mobile home and RV parks, apartments, condominiums and similar multiple-dwelling developments, subdivisions, and commercial or business uses. So a domestic well does not carry any of those — not because someone refused permission, but because the use falls outside the definition the right rests on.
And a subdivision arrives sooner than most sellers expect. For these statutes a subdivision is a tract divided into five or more lots, parcels or sites for sale or building development. Five. A parcel that supports one house comfortably may support no part of a development, and the difference is a water question before it is a planning one.
Irrigation is a separate system, with its own owners
Domestic water and irrigation water are different things carried by different infrastructure, and on Ada County ground the irrigation side is unusually crowded. The county's own irrigation districts map identifies twenty-seven separate entities operating in the county — irrigation districts, ditch companies, lateral associations and water users' associations.
Which one matters to a parcel depends entirely on where it sits. Settlers Irrigation District delivers to 13,187 acres across western Ada County — the West Boise, Meridian and South Eagle areas. The Boise Project Board of Control is the operating agent for five separate districts: Boise-Kuna, Big Bend, Nampa & Meridian, New York and Wilder.
One fact surprises nearly everyone. Title to the Boise Project's transferred works — Diversion Dam, the New York Canal, the Lake Lowell embankments and roughly 1,500 miles of canals, laterals and drains — remains with the United States. If a lateral crosses the parcel, the question of who you are dealing with is not rhetorical, and the answer is not always a local body.
You almost certainly do not control the road
Idaho permits only one countywide highway district to operate in a county whose electorate has voted to form one, and Ada County has one. The consequence is unusual and catches people who have owned property in other states.
A city inside that district may not maintain or supervise city highways, and may not levy taxes for their construction, repair or maintenance. The district is responsible for the design, construction, reconstruction and maintenance of city rights-of-way and their curbs, gutters, culverts and sidewalks. Ada County Development Services controls no roadway infrastructure within the county at all.
So an access question, an approach question or a frontage question is a highway district matter, not a city or county one — whichever city the parcel sits in or next to.
Septic, floodplain and boundaries are three more authorities again
Central District Health's Environmental Health Division permits septic systems, reviews land development applications and verifies the location of shallow injection wells across the county. That is a health authority, separate from both the city and the highway district.
Floodplain is separate again. Any development within the floodplain in Ada County requires a Floodplain Development Permit, and the county adopted new FEMA Flood Insurance Rate Maps in June 2020 — so a map a seller remembers may not be the map in force. Boise participates in the National Flood Insurance Program because of flood threats from the Boise River, the foothills gulches and several intermittent stream channels. In Star, development in certain flood zones requires a Flood Plain Development Permit under the city's own Flood Hazard Ordinance.
On boundaries, Kuna's guidance is the plainest statement of something true everywhere in the county: the best way to determine property lines is a professional survey. The Assessor maintains parcel ownership, land and improvement characteristics and parcel boundaries in its records, and those records are a mapping layer rather than a survey. On acreage, where a fence has stood for decades and a lateral runs somewhere near a line, that distinction is where disputes live.
Which authority governs the parcel is itself a question
Ada County uses Areas of City Impact — unincorporated land planned in conjunction with an adjacent city. That arrangement covers most unincorporated residents: 78.8 per cent of them, about 50,143 people, live inside one.
For a seller that means unincorporated ground is often being planned by a city it does not sit in, and the comprehensive plan that shapes what it can become may be that city's rather than the county's. Most of the residents living outside any Area of City Impact are in the planned communities — Avimor, Cartwright Ranch, Dry Creek Ranch and Hidden Springs — which run on their own frameworks again.
Ada County's engineering and surveying division reviews preliminary plats, drainage plans, private roads, hillside applications, floodplain permits and property boundary adjustments for unincorporated ground. Inside a city, the city's own planning department does the equivalent work under its own ordinances.
What this means if you are selling
The value of land in this county tracks what it can become, and what it can become is a stack of separate answers — water right, irrigation entity, highway district, health district, floodplain, and whichever authority actually governs the parcel. Nobody holds all of those in one place, which is why land takes longer to price than a house does.
We look at ground with complications: access issues, easements, floodplain, irrigation crossings, parcels without a clean boundary, and land where a previous plan fell over. We are the buyer rather than a party looking to assign a contract on.
We will not tell you what your land is worth. We will tell you what we would pay and show the reasoning, including which of these constraints we think binds hardest on your parcel.