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Spillways are structures built into dams to provide a controlled release of flows from a dam into the downstream area. Designed to accommodate major surge events from water that need to be able to withstand very high water velocities.

Cement and concrete can be used in many different ways in spillways. Conventional concrete can be employed to build specifically shaped and sized ramps down dam faces or in other directions. Spillway tunnels can be constructed as a spillway.

Subcon has a large expertise in the application of in-situ and precast concrete product for newbuilt spillways as well as spillway repairs.


We typically recommend our precast coast matt for spillway revetments.

It incorporates a geotextile filterlayer bonded to the base of the mattress. This releases pore pressure but retains the bed material preventing erosion beneath the mattress.

Block matts are approximately 50% more stable than rock revetments. Our stainless steel anchor pin options can be used to provide further stability.

Block heights can be adjusted row by row to increase roughness and help mitigate against hydraulic jump.

We believe fish passages are one of the most important aspects of a spillway.

Our habitat solutions and engineered fish passage solutions have been used to provide fish passage across the full range of flow conditions.

We can incorporate resting pools and channels with shelter against predation and high currents for any height weir or dam.

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