An Instream Minimum Flow Requirement (IMFR) is the minimum water flow that must be maintained in a river or stream to protect its aquatic ecosystem and overall health. Regional councils set IMFRs as part of surface water management and resource consent processes to provide an environmental baseline that balances water allocation for farms, orchards, and other users with the needs of the environment.
Setting an IMFR ensures enough water remains in a waterway to support fish, aquatic plants, invertebrates, and other instream life. It also helps maintain water quality, natural flow patterns, and the overall health and resilience of rivers and streams.
Waterways often face multiple pressures, especially in areas where farmers and growers rely on the same water source. An IMFR helps manage competing demands while protecting the ecological integrity of rivers and streams.
Instream minimum flows are essential for waterways of all sizes. Beyond ecological protection, they can safeguard Māori customary values, support recreational activities such as fishing and boating, and maintain the natural landscape values of the area. By establishing and enforcing IMFRs, communities can ensure sustainable water use for farms, orchards, and the wider environment while keeping rivers and aquatic ecosystems healthy.
Jessica Hunter
Environmental Consultant