MOHAWK NATION OF GRAND RIVER SECRETARIAT

Certificate of Determination

The six miles on each side of the Grand River

TDC001-261021-000002 · 21 October 2026

1. The determination

“…six miles deep from each side of the river beginning at Lake Erie and extending in that proportion to the head of the said river.” The line here determined lies six statute miles, measured on the ground, from the edge of the water of the Grand River, on each side, as the river is shown in the Grand River Conservation Authority’s river polygons. Its certainty is graded stretch by stretch, as set out in section 7. The riparian zone and the six-mile area are drawn from the same water and the same measure.

2. The measure

The choice of mile makes no difference that can be drawn.

3. The water

The river polygons of the Grand River Conservation Authority’s waterbody layer that touch the main channel, joined into one water surface (25.0 km²): two long stretches — the upper river to 44.13° N, and the lower river from the foot of Belwood Lake to Lake Erie — and ten small side channels, each within 560 m of the main channel.

Where the river is under 30 m wide, the Authority maps it as a line, not water; there, as far as its head at 44.146° N, the water is the Authority’s Watercourse main channel at its recorded half-width, which is its edge of water. Through Belwood Lake and other reservoirs, where the river’s banks lie under the water, the measure runs from the river’s own flow line through them. The Watercourse layer was updated by the Authority on 28 September 2026; its download’s fingerprint is dc71349c74a97a1be0b80d8ec99aae3cf456d5a6dad708528899d39cf4e16b9f. The river polygons were received as a converted file: 95.3% of the Authority’s own flow line for the Grand River lies inside them, and what lies outside lies in lakes and reservoirs; they are to be compared point by point with the Authority’s original download.

4. The drawing

Drawn in NAD83 / UTM zone 17N (EPSG:26917). The projection’s scale factor along the line runs 0.999611 to 0.999798 (mean 0.999664): a metre on the ground measures 0.99966 m on the grid. So that the line lies six miles on the ground, it is drawn on the grid at

9,656.064 m × 0.999664 = 9,652.818 m

from every point of the water’s edge. Its curves are drawn with 96 points to each quarter circle, so each straight piece is about 158 m long and cuts inside the true curve by at most 0.32 m; its straight runs carry a point at least every 60 m (9,025 points in all). Both are well within the verification below.

5. The verification

At 4,000 points evenly spaced round the line, the shortest distance to the water was measured on the ground (geodesic, on the GRS80 ellipsoid):

The spread that remains comes from the scale factor changing slightly along the river. For comparison, the first drawing — buffered 9,656.064 m on the grid, with points up to 739 m apart — lay 9,651.9 to 9,660.9 m from the water on the ground: its long straight segments cut inside the curve by up to 7.1 m.

6. The evidence of the surveys

Municipal limits laid out by survey are evidence of where the Crown’s surveyors placed the six miles on the ground. Every municipal boundary in the Authority’s layer was measured from the water every 100 m; those that stay between 5.5 and 6.5 miles from the water for 3 km or more are listed. A limit corroborates the line where its median lies within 500 m of six miles. The surveyors ran straight courses, so a limit swings either side of a line that follows today’s banks; the median, not each point, is the test. The Authority states its boundaries are cartographic, accurate to ±100 m.

7. The grades

8. What remains open

• Compare the river polygons point by point with the GRCA Waterbody original download
• Where dams have raised the water (Belwood, Dunnville, Caledonia), consider measuring from the river’s course before the dams
• Decide the reading of both ends: land only at Lake Erie? square or rounded ends?
• Confirm from the original survey plans and field notes which municipal limits were laid out as the tract’s edge

9. Sources, licence and position

Waterbody and municipal boundaries: Grand River Conservation Authority, GRCA Open Data Licence v2, built in part from the Province of Ontario’s data under the Open Government Licence – Ontario. Produced using information under licence with the Grand River Conservation Authority. © Grand River Conservation Authority, 2026. Contains information licensed under the Open Government Licence – Ontario. © King’s Printer for Ontario, 2026.

Survey lines are used here as evidence of where the Crown’s surveyors placed the six miles on the ground; relying on them does not accept the instruments behind them.

10. How it can be validated

1. Recompute it. Anyone with the data (its fingerprint in section 12) and the method in section 4 can draw the line again and measure it as in section 5.
2. Check the evidence against the original surveys. The plans and field notes of the townships and blocks along the river, held by the Archives of Ontario and the Office of the Surveyor General of Ontario, record the bearings and distances actually run. Where they place a limit at six miles from the river, its stretch rises from corroborated to confirmed.
3. Check it on the ground. An Ontario Land Surveyor can locate surviving monuments along the corroborating limits by GNSS, in NAD83(CSRS), and compare them with this line and with the original notes; and can measure the water’s edge where the banks are in question.
4. Have the method reviewed. The Surveyor General Branch of Natural Resources Canada sets the standards for surveys of Canada Lands; its comment on the method, and the standard it would apply, can be sought without submitting the Nation’s determination to any jurisdiction.

11. Another reading: the nautical mile

Six nautical miles are 11,112 m — 1,456 m beyond six statute miles. Municipal boundary running within a quarter-mile of each distance for 3 km or more, at every quarter-mile from 4 to 9 miles: 15–27 km at each distance up to 6¼ statute miles; under 4 km at every distance from 6½ to 9 miles; 1.8 km at six nautical miles (6.905 statute miles). Where the survey fabric follows the river, it ends at about six statute miles. The ground evidence does not support a nautical reading.