FlexiBaffle
FlexiBaffles are New Zealand-designed culvert baffles that assist with upstream fish passage and support natural fish migration by altering water flow through culverts and providing areas for fish to rest. The culvert baffles can be fitted before the installation of the culvert or retrofitted to existing structures.
Flexible baffles designed to suit round or box culverts
Perfect for round or box culverts, FlexiBaffles are culvert baffles available in standard heights of 100mm and 150mm but can be trimmed if required. Lengths go up to 1800mm, and units can be placed end-to-end to suit any width structure.
Not sure which baffle type and configuration you need?
Our Culvert Solution Tool takes the guesswork out. Just enter a few details about your culvert and we’ll recommend the right FlexiBaffle setup – complete with spacing, sizing, and a schematic drawing for installation.
FlexiBaffles placed inside culvert pipe can:
- Reduce velocity
- Increase depth
- Create nature-like complex flows
- Extend the range of flow characteristics including wetted margins for climbing species
- Retain stream bed material
- Create high and low flow passage
Made with sustainability in mind, FlexiBaffles – New Zealand’s trusted weir baffle – can be produced using recycled materials and are fully recyclable at the end of their service life. This supports both local environmental goals and circular economy principles.
ATS Environmental FlexiBaffles are made in New Zealand, Australia, Norway, the U.S.A, and the U.K. Our spoiler baffles are suitable for round or square culverts and can be modified on-site to fit any particular requirements in New Zealand and abroad.
Performance Under Pressure
The graph demonstrates the performance of the FlexiBaffle under varying levels of applied force. As force increases (measured in N/m²), the baffle height responds dynamically, gradually reducing to accommodate the pressure. This characteristic curve highlights the product’s ability to maintain a reliable seal while flexing to suit different operational conditions.
Overlayed on the graph is a cross-sectional illustration of the culvert baffle in multiple stages of deflection, visually representing how it adapts as force increases. Fish are unlikely to be migrating upstream during very high flow events when the FlexiBaffle is bent to its maximum extent, though fish migration is supported during normal conditions.
This flexibility supports a wide range of culvert flow conditions, making FlexiBaffle suitable for use in flood-prone zones, seasonal streams, and retrofitted culvert fish passage upgrades across diverse and challenging hydraulic environments in New Zealand.
Engineered for resilience and flexibility, the FlexiBaffle delivers optimum fish passage without compromising culvert baffle performance in New Zealand environments. It serves as a highly effective alternative to traditional fish ladders in culvert applications.
The FlexiBaffle’s flexible, high-strength design enhances fish migration by promoting recirculation zones and wetted margins, without impeding culvert flow or requiring major structural modification.
FlexiBaffle Installation Detail
Our performance testing demonstrates that FlexiBaffles maintain integrity and flexibility even under varying hydraulic loads. A typical performance curve shows how the baffle flexes to accommodate pressure changes (N/m²), maintaining a consistent seal while avoiding structural failure. Even under flood or high-flow events — when fish are unlikely to be migrating — FlexiBaffles bend safely without detaching or disrupting flow.
Installation Features:
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Typical Fixing Methods:
Culvert Material:
Concrete – M6 x 50mm or M6 x 60mm 316 stainless steel wedge anchors with cleats/washers.
Plastic – 14g (7mm) x 35mm hex screws with cleats/washers.
Steel – Self drilling self tapping hex drive tek screws with cleats/washers
Fiberglass – Pre-drill 6mm hole Self drilling self tapping hex drive tek screws with cleats/washers -
Typical Fixing Spacing: 100 mm
With modular spacing and straightforward installation, the FlexiBaffle provides a reliable culvert baffle solution for flow control, sediment retention, and improved fish migration in both new and retrofit scenarios across New Zealand. For many sites, FlexiBaffles provide a more adaptable and cost-effective solution than traditional fish ladders.