Before You Grade a Homesite in Cochise County: What a Topo Map Shows

A good share of the houses going up in Cochise County are being built by the people who will live in them, on four to forty acres, often under the county's owner-builder opt-out. The excavator is usually the first big cheque, and it is where the hard-to-reverse decisions get made — where the pad sits, which way the drive comes in, where the water goes when it rains — usually by walking the ground and pointing.

A topographic map lets you make those decisions against numbers instead of a hunch, before the dirt moves. This is what one costs here, what it tells you, and what it does not.

What $750 buys

The minimum mapping call-out on our rate card is $750 and covers up to 10 acres. That gets you an orthomosaic — a flat, scaled aerial of the parcel at a few centimetres per pixel that you can measure on — and a surface model, the same parcel as a grid of elevations. Above 10 acres it is $15 an acre to 100, so a 40-acre parcel is $1,350. There is no travel charge in the Sulphur Springs Valley; Benson is $50 and Sierra Vista $125, both waived on jobs over $600.

Here is the part that matters. Without ground control, that surface model is shape, not elevation. The aircraft is a non-RTK DJI Mavic 4 Pro; its own GNSS puts the model within metres horizontally and potentially tens of feet vertically, with a slow warp across the block. Relative statements — this corner is lower than that one — hold up reasonably well. Absolute heights do not, and we will not deliver contours or cut-and-fill from an uncontrolled flight. The numbers are in our accuracy article.

When you need the add-ons, and when you do not

The typical owner-builder package on 4 to 10 acres is call-out plus ground control plus contours: $1,650, delivered as orthomosaic, surface model, 1 ft contour drawing and the point data if your engineer wants it. We quote 1 ft contours and not half-foot, because at 5–8 cm vertical error a half-foot contour is a promise the data cannot keep.

The questions a map answers before the excavator arrives

Which way does the parcel actually fall? Valley-floor ground that looks flat on foot almost always has a fall on it, and not always the direction you assume from the mountains. The model gives slope and aspect across the whole parcel, not at the three spots you happened to stand.

Where does water enter, cross and leave? A flow-path analysis shows where runoff concentrates, where it ponds and where it exits onto the neighbour. If the proposed pad sits across a flow line, you find out now for the cost of a map rather than in August for the cost of a French drain.

How much dirt does the pad need? Set a finished pad elevation and the software returns cut and fill. On a controlled flight that is good to a few percent — adequate for ordering material and keeping the excavator honest, not a pay quantity.

Can the drive make grade? A 400 ft drive that climbs 30 ft is 7.5 percent. The map says so before the first load of base arrives.

Where are the washes, really? Small washes under the mesquite are invisible from the county road and obvious in an orthomosaic flown after monsoon. Their position relative to the pad bears directly on the county's rules.

What the county requires

Permit requirements are set by Cochise County Development Services and the Flood Control District, and the authoritative version is on the county's permit portal, linked at the foot of this article. What follows is what the county's published documents say as of this writing.

Building permits. The county's 2020 staff presentation on the opt-out states that a building permit is required for all new structures or improvements valued at $1,000 or more. The Owner-Builder Opt-Out, adopted in 2006 and the reason October is proclaimed "Opt-Out Month," is available on parcels of four acres or more in RU, SM or SR zoning in unincorporated areas; it limits plan review and the associated inspections and requires a disclosure recorded against the deed. It exempts nobody from zoning, health or floodplain requirements — the 2025 proclamation says opt-out homes must still comply with the county's Building Safety Code, Zoning Regulations and Floodplain Regulations.

Floodplain and drainage. The county's Floodplain Regulations (adopted December 2015, revision proposed October 2023) require a Floodplain Use Permit before any construction or land disturbance in a regulatory floodplain or FEMA special flood hazard area. Where more than one acre is disturbed, or imperviousness rises more than fifty percent, they call for a drainage analysis certified by an Arizona Registered Professional Civil Engineer. They set erosion-hazard setbacks from watercourses — 20 ft minimum from top of bank, 50 ft on washes carrying 500 to 2,000 cubic feet per second in the base flood, 300 ft on the San Pedro and Babocomari — and give the Floodplain Administrator, the County Engineer, authority to require a landowner to establish floodplain limits by study where none are mapped.

We could not find a published county grading ordinance for individual lots outside the floodplain regulations, so we are not going to describe one. Whether any of this applies to your parcel is a question for the Floodplain Administrator and the permit desk. A drone map does not change the answer; it means you arrive at the counter knowing where the wash is.

When to fly

Vegetation is lowest in late winter and spring, so a bare-earth model is cheapest and best then. Evidence of where water actually went — scour, debris lines, fresh sediment — is clearest in September and October, right after the monsoon. If drainage is the worry, fly after the rains and accept more grass in the model. If you need clean contours on open ground, any dry month works, and here that is most of them.

Ground control takes an hour or two on site, the flight on ten acres well under an hour, processing a few working days. Most of Cochise County is Class G airspace, so there is no authorisation wait. Phone call to a map in your engineer's inbox is typically inside two weeks.

The topographic mapping page has the full deliverable list. If you have a parcel number and a rough idea where you want the house, send them through the contact form and we will tell you which add-ons you need and which you can leave off.