Working towards establishing performance standards and assessment criteria for instream flow needs in agricultural watersheds of Canada

Land- and water-use practices impact streamflow generation within agricultural watersheds, with adverse effects on sediment transport, water quality, and physical habitat of aquatic ecosystems. The Instream Flow Needs (IFN) project of the Canadian National Agri-Environmental Standards Initiative focused on the development of standards and assessment criteria for IFN in agricultural watersheds of Canada to ensure riverine ecosystem conservation and protection. A national flow regime analysis revealed the challenge of producing a broadly applicable “IFN standard” within Canada because of climatic variability and insufficient long-term hydrometric data. A Level 1 Assessment was developed, based on Indicators of Hydrological Alteration (IHA) and the Range of Variability Approach (RVA).  Key steps in this Level 1 Assessment are: 1) Identify study streams; 2) Analyze observed and/or modelled flow data for IHA parameters; 3) Quantify deviation from reference (Naturalized) flow using RVA; 4) Calculate Canadian Environmental Flow Index (CEFI) using biomonitoring data to assess eco-hydrological alteration.  Impaired ecological status detected by IHA/RVA results and supported by CEFI invokes a Level 2 Assessment.  The latter would be determined by stakeholder-defined protection goals (e.g., fish habitat protection) and could require detailed eco-hydrological studies. Fieldwork is currently ongoing to validate the Level 1 assessment approach.