When can seed and mulch be used for permanent stabilization in a channel or swale?

Using seed and mulch for permanent stabilization in a channel or swale is most appropriate when the maximum runoff velocity is less than or equal to 2.5 feet per second (fps). At this velocity, the conditions are suitable for seed germination and establishment without being washed away by excessive water flow. Seed and mulch work well in these situations because they provide necessary coverage, reduce erosion, and promote vegetation growth that stabilizes the soil.

In contrast, at greater velocities, such as 4.0 fps or 6.0 fps, the forces exerted by moving water can displace both the seed and mulch, leading to a higher likelihood of erosion and less effective stabilization. Therefore, the choice to use seed and mulch in scenarios with a higher maximum velocity would not support successful long-term vegetation and stabilization efforts.