Regional Drainage

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Phase 1     Phase 2     Phase 3     SMRID main canal

Horsefly Regional Emergency Spillway Project

Phase 1 in Construction

The expansion of an existing emergency spillway to divert overland floodwaters and stormwater runoff from the St. Mary River Irrigation District's main canal to the Oldman River. The project is located mainly on private lands near Taber, Alberta. The expansion would increase the diversion capacity of the existing spillway from approximately 7.6 m3/s to 47 m3/s.


Over a decade in the making.

From human development to farming, irrigation and land modifications, southern Alberta has seen a significant increase in agricultural production and several residential and industrial land development opportunities. From the City of Lethbridge to the City of Medicine Hat, this region produces an agricultural Gross Domestic Product contribution of $1.8 Billion supporting over 120 agri-food processing industries. These increases in development, however, have not come without consequence.

Increased development has altered the natural drainage of the landscape and reduced absorptive capacity creating stormwater management difficulties which threaten homes, businesses, public infrastructure, farmland, crops and vital drinking water. Compounded by a lack of natural drainage, much of the drainage corridors in many portions of the region are intercepted and conveyed by the existing irrigation canal system, a system not designed to adequately handle the excess volume caused by heavy rainfall and snowmelt runoff. With future weather events like those seen in 2010, 2011, 2013, 2014, and 2018 an emergency discharge corridor is critical to the economic stability and growth of the region.

In 2012, the Southern Regional Stormwater Drainage Committee (SRSDC) was formed to develop a long-term solution to the ongoing threat of these stormwater runoff events. Partners of the drainage committee include the Towns of Coaldale, Taber, and Bow Island, the Village of Barnwell, the City of Medicine Hat, the Counties of Lethbridge, 40 Mile, and Cypress, the newly amalgamated St. Mary River and Taber Irrigation Districts (SMRID), and the Municipal District of Taber as the managing partner.

From the SRSDC, the Southern Regional Stormwater Management Plan was developed identifying seven key flood mitigation projects from south Lethbridge to Medicine Hat and totalling over $170,000,000. Of these seven projects, the Horsefly Regional Emergency Spillway Project provided the biggest benefit to increasing the flood attenuation capacity of the entire regional system.

By strategically placing an emergency spillway near the midway point – a major capacity reduction point on the 312 km-long SMRID main canal – this project will help protect water/wastewater, transportation, and public infrastructure from repeated damage. The 15 km-long Regional Emergency Spillway will divert water from the main canal near Taber, Alberta and convey it using existing irrigation infrastructure to the Oldman River at a rate of 47 m3/s. 

Once operational, the regional emergency spillway will ensure the ongoing safety and security of residents across the region while creating up to 150 new construction jobs. The long-term economic impact of these infrastructure upgrades promotes long-term community resiliency and provides the necessary groundwork to attract further investment in the agri-food processing industry for a brighter future for all southern Albertans.



Location: From the Taber Lake Reservoir to the Oldman River 

Construction start date: December 6, 2022

Engineers: MPE Engineering Ltd, Stantec Engineering

Contractors: DeGraaf Excavating Ltd

Completion date: Summer 2024


Location: From the Horsefly Lake Reservoir to the Taber Lake Reservoir

Construction start date: 2024

Engineers: MPE Engineering Ltd, Stantec Engineering


Completion date:


Location: From the SMRID main canal to the Horsefly Lake Reservoir

Construction start date: 2024

Engineers: MPE Engineering Ltd, Stantec Engineering


Completion date:


Government of Canada

Phase 1


Investing in Canada Infrastructure Program (ICIP)

Phases 2 & 3


Disaster Mitigation and Adaptation Fund (DMAF)
Government of Alberta

Phases 1, 2 & 3


Alberta Community Resilience Program (ACRP)
Southern Regional Stormwater Drainage Committee Partners

Phases 1, 2 & 3


Partners are seeking further funding from the Provincial Government

St. Mary River Irrigation District

Phases 1, 2 & 3


+ Land and right-of-way acquisition contribution


Southern Regional Stormwater Drainage Committee Partners

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