Tile drainage in the Portage la Prairie area

Tile drainage in the Portage la Prairie area. The soils here range from deep clay to delta sand, and each needs its own drainage design.

Two very different soils

The RM of Portage la Prairie covers about 21.5 townships, and most of it falls in two landscape regions described in its federal-provincial soils bulletin:[1]

  • Red River Valley: level lacustrine loams and clays. The bulletin says the clay soils have slow to very slow permeability and are subject to surface ponding and slow runoff without adequate drainage.
  • Lower Assiniboine Delta (southwest corner): sands over finer material, with high water tables and a saturated zone above the clay subsoil, particularly in spring or after heavy rain.

Smaller areas in the northeast belong to the Interlake Plain and Woodlands Plain, and the land along Lake Manitoba to the north is mostly poorly drained marsh.[1] The clay under the Portage area is deep: provincial geology notes describe up to 50 m of Lake Agassiz clay in the Portage la Prairie area.[2]

What the soil survey says about drainage

Soil drainage class (RM of Portage la Prairie)Share of RM
Imperfect62.2%
Poor11.9%
Very poor6.4%

Figures from the RM soils bulletin.[1] The earlier Portage la Prairie soil survey (1972) describes the area as having some of the most productive soils in the province, with ponding and salinity among the main issues on the clay soils.[3]

On heavy clay, water moves slowly, so laterals need to be closer together than on sandier ground. On the delta sands, the water table and the clay layer underneath matter most. We take this into account at the design stage.

Watershed districts

The RM of Portage la Prairie belongs to four watershed districts: Whitemud, Central Assiniboine, Redboine and West Interlake, depending on the ward.[4] Which one applies depends on where your field drains. If your outlet runs into a district drain, the district’s approval is needed, and municipal sign-off may also be required.[5]

Working with Innovative Agri Tiling

  • The whole job, start to finish: field survey, design, drainage permits and licensing, installation and the outlet. You deal with one point of contact throughout.
  • An owner-operated company, founded in 2010. Every job runs under the management of the business owner.
  • A small, steady crew: our main employee has been with the company since it started.
  • A field survey and a written estimate before you commit.
  • Drainage design for each field: outlet, pipe sizing and lateral spacing, matched to the soil and the crop.
  • Lift stations and outlet control structures when the design calls for them. See lift stations and control structures.
  • GPS-controlled installation machinery.
  • We take care of the drainage permits and licensing for you: the provincial registration or licence application. See drainage licensing in Manitoba.
  • Irrigation line installation as well. See irrigation line installation.

Related pages

Sources

  1. Land Resource Unit, Soils and Terrain: An Introduction to the Land Resource. Rural Municipality of Portage la Prairie, Information Bulletin 97-22, Agriculture and Agri-Food Canada
  2. Manitoba Science, Technology, Energy and Mines, Geological Resources of the La Salle River Watershed (La Salle River IWMP documentation)
  3. Michalyna, W. & Smith, R.E. (1972), Soils of the Portage la Prairie Area, Manitoba Soil Survey Report No. 17
  4. Rural Municipality of Portage la Prairie, Watershed Districts
  5. Province of Manitoba, Environment and Climate Change, Drainage & Water Control

Last checked against the sources above: November 2026.

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