Lake Diefenbaker Irrigation Canals are an essential part of the agriculture industry in Saskatchewan, Canada, as they provide irrigated water to the downstream farmers. However, filamentous algal blooms occur throughout canals every summer. These algae are not toxic but a nuisance. They block water intakes within the irrigation canals. At present, the approach for controlling algal blooms in Lake Diefenbaker’s M1 canal is manual cleaning of intake screens and periodic application of the algaecide Magnacide H, which is expensive (approximately one million dollars per year) and may be detrimental to the aquatic ecosystem and canal water quality if it is not handled properly. Therefore, there is a demonstrable need to develop cost-effective and environmentally friendly filamentous algal prevention and control technologies. Successful management of algal blooms in the M1 canal requires understanding nutrient dynamics in the canal, as nutrients are one of the critical factors that cause algal blooms. To date, there are no historical data on the characteristics of the M1 canal water and nutrient level in the periphyton. This study collected and analyzed water and periphyton samples from 18 Lake Diefenbaker M1 canal locations collected during nine field trips from June 2022 to October 2023. The results show that nutrient levels in the canal water were low, some below the detection limits. However, the nutrient levels in periphyton samples were much higher than that in the canal water. The results of the periphyton sample proved quantitatively that the internal source of nutrients is the main contributor to algal blooms in the M1 canal. In addition, site-specific nutrient prevention practices have also been developed to prevent the nutrients from outside the canals, such as from agricultural runoff. Keywords: Algal Blooms; Filamentous Algae; Internal Nutrient Loading; Lake Diefenbaker Irrigation Canals; Nutrient Dynamics; Nutrient Recycling