Can You Sever Your Farm? The Minimum Distance Separation (MDS) Formula Decides Before Planning Staff Do

Quick Answer

Confirm the land is rural lands or a prime agricultural area — MDS lives out here

Scan the surroundings: 750 m for a proposed Type A use, 1,500 m for a proposed Type B use

Compute Building Base Distance F = Factor A (odour) × B (nutrient units) × D (manure form) × E (1.1 or 2.2)

Read Storage Base Distance S off Table 6 by storage type — S is looked up, never calculated

F and S are separate setbacks; both must be met, and both round UP to the nearest metre

Dwelling location outside both lines → file it. Inside → find the reduction path before you spend

MDS I is your problem. MDS II is the farmer’s.

The names are nearly identical and the two formulas measure opposite directions.

MDS I governs proposed new development — new lots, new dwellings — approaching existing barns, manure storages and anaerobic digesters. That’s a severance. That’s you.

MDS II governs a proposed new or altered livestock facility approaching existing or approved development, dwellings, lot lines and road allowances. That’s the farmer expanding toward you.

Per OMAFRA (2017), they don’t even share factors: MDS I is F = A × B × D × E (Factor C is not used), MDS II is F = A × B × C × D (Factor E is not used). Worth knowing both if you’re the one selling to an operator who plans to build — you’d be handing them an MDS II problem, and that can change what your land is worth to them.

The formula is multiplication, not judgment

The MDS I Building Base Distance, called F, is four table lookups multiplied together:

F = Factor A × Factor B × Factor D × Factor E

A is odour potential by livestock type. B is a size factor derived from Nutrient Units. D is whether the manure is liquid or solid. E is how sensitive your proposed use is. Result rounds up to the nearest metre — per Implementation Guideline #32, a calculated 364.72 m becomes 365 m.

Sit with what’s missing from that equation: there is no term for merit, need, hardship, or how reasonable your proposal is. A planner’s job here is to run your inputs, not to soften the output. Municipal setbacks for livestock facilities cannot exceed what the MDS II formula produces, and a municipality going beyond MDS I distances has to justify it against provincial policy. The formula is the standard, in both directions.

Factors A and D: the barn’s odour, already priced

Per Table 1, Factor A ranges by species:
• Swine feeders (27–136 kg) = 1.2; weaners = 1.1; sows and boars = 1.0
• Dairy cattle, all age groups = 0.7; beef feeders and backgrounders = 0.8
• Chicken broilers = 0.7; layer hens = 1.0; milk-fed veal = 1.1
• Horses, sheep, goats = 0.7; mink and fox = 1.0

Factor D is binary: liquid manure (<18% dry matter) = 0.8, solid manure (≥18% dry matter) = 0.7.

Run the ratio and the field intuition falls out. Identical herd size, identical lot, identical everything else: a hog finisher (1.2) throws a setback roughly 70% farther than a dairy barn (0.7). Whether the barn across the road milks cows or finishes pigs isn’t a lifestyle detail. It’s hundreds of metres of your land.

Factor B: you’re measured against the barn your neighbour could build

This is the one that ends deals after the money is spent.

Factor B comes from Nutrient Units (NU) — more NU, bigger factor, longer setback. But per Implementation Guideline #26, when the barn sits on a lot larger than 5 hectares, MDS I doesn’t use the barn’s current size. It uses potential design capacity — what those existing facilities could reasonably grow into:

• Lot ≤5 ha → current design capacity, no multiplier
• Lot >5 to ≤25 ha → 2× design capacity above 5 NU; capped at 300 NU once above 125 NU
• Lot >25 to ≤50 ha → 3× above 25 NU; capped at 450 NU above 125 NU
• Lot >50 ha → 3× above 25 NU; capped at 600 NU above 125 NU

Read that again, because it reverses the normal logic of due diligence. Walking the property and counting animals gives you the wrong answer. The province is deliberately reserving room for that farm to expand, and it reserves that room out of your parcel. The neighbour has no obligation to actually expand — the setback exists regardless.

Factor E: one switch, and the whole distance doubles

Per Table 4, Factor E has exactly two values:

• Type A land use (less sensitive) = 1.1
• Type B land use (more sensitive) = 2.2

Exactly double, and Publication 853 says so in words: a new or expanding Type B use generates an MDS I setback twice that of a Type A use.

Where’s the line? Per Implementation Guidelines #33 and #34, the clause that matters for severances: creating lots outside a settlement area that would not result in four or more development lots in immediate proximity (sharing a boundary, across the road from each other) is Type A. Creating lots that do result in four or more in immediate proximity is Type B — and it counts whether or not any of those lots are vacant. New lots for agricultural uses stay Type A.

The trap is sequential severances. Lots one through three clear comfortably. Lot four tips the cluster over the threshold, Factor E jumps 1.1 to 2.2, and the distance doubles for the whole proposal.

Worked example: a 100-NU broiler barn, 30 hectares

Take a chicken broiler barn with 2,480 m² of floor area on a 30-hectare lot, solid manure on bedded floors. You’re severing one lot — no cluster of four.

Nutrient Units: per Table 1, broilers are measured by floor area at 24.8 m² (267 ft²) per NU → 2,480 ÷ 24.8 = 100 NU.
Factor B: lot is 30 ha (>25, ≤50) and capacity is 100 NU (>25, ≤125) → use 3 × 100 = 300 NU. Table 2: 300 NU → Factor B = 464.
Factor A (broilers) = 0.7　Factor D (solid) = 0.7　Factor E (Type A) = 1.1

F = 0.7 × 464 × 0.7 × 1.1 = 250.096 → rounded up, 251 m.

Now flip the one switch. Same barn, but your severance creates the fourth lot in a cluster → Factor E = 2.2 → 501 m. Nothing about the farm changed. Nothing about your parcel changed. The pattern of lots around you changed, and the setback doubled.

The manure storage is a second, separate line

F covers the barn. The manure storage generates its own setback, and per Implementation Guideline #24 the Storage Base Distance S is never calculated — it’s read off Table 6. Compute F first, then look up S by the storage’s odour class.

Table 5 sorts storages into four classes: Very low (V1–V6 — bedded pack inside the barn, liquid under slats, outdoor liquid with a permanent tight-fitting cover), Low (L1–L2), Medium (M1–M2 — uncovered straight-walled outdoor liquid), High (H1 — uncovered outdoor earthen liquid storage).

The spread is stark. From Table 6: at F = 500 m, a V1–V6 storage gives S = 500 m — identical, no penalty at all. At the same F = 500 m, an H1 earthen lagoon gives S = 600 m. At F = 600 m, H1 gives 680 m.

Two things follow. First, on a farm with an open lagoon, the storage — not the barn — is usually the binding constraint, so pricing the deal off the barn distance understates your problem. Second, a cover physically changes the class, and the class changes the number. It’s one of very few levers in this whole system that moves a real line on the ground rather than arguing about one.

Anaerobic digesters: no formula at all

If the neighbouring operation runs an anaerobic digester, stop multiplying. Per Implementation Guideline #22, MDS I setbacks from a digester are fixed, not calculated:

• 200 m to a proposed Type A land use
• 450 m to a proposed Type B land use
• 200 m to a proposed dwelling

Secondary elements — gas and water piping, generator buildings, wires — are not subject to MDS I setbacks, and the setback is measured from the closest associated component of the existing digester. Short section, but worth knowing: digesters are becoming more common on Ontario farms, and people reflexively assume something that industrial must carry the largest number in the system. It doesn’t. It carries a flat one.

Run the numbers before you spend a dollar

Use AgriSuite. OMAFRA publishes MDS calculation software inside Ontario’s Agricultural Planning Tools Suite. Per Table 2, operations above 5,000 NU require the software for Factor B. An afternoon with the tool beats a five-figure application that fails on arithmetic.

Scan wide enough. Per Implementation Guideline #6, municipalities investigate every existing livestock facility and digester within 750 m of a proposed Type A use and 1,500 m of a proposed Type B use — and large facilities (e.g. >1,200 NU) beyond that radius should be calculated too. Checking only the farm you can see from the road is checking the wrong sample.

Check the exemptions first. Per IG #8, no MDS I setback is required for several situations — including a severed or retained agricultural lot that already has a dwelling on it, easements and deed corrections that create no new lot, infrastructure, and lots for existing non-agricultural uses. Note the ceiling on that good news: lot creation policies still apply. Exempt from MDS is not the same as approvable.

Know the reduction path. Per IG #12, where four or more non-agricultural uses, residential uses or dwellings already sit closer to the barn than your proposal, within a 120° field of view between the two, on separate lots, and are at least as sensitive as what you’re proposing — the MDS I setback may be reduced so your proposal is no closer than the furthest of those four. That’s a technical argument built from the guideline, not a hardship plea.

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