Costs are low when seizing opportunities
From REFORM wiki
The benefits of mere river restoration often do not outweigh the costs in a cost-benefit analysis. Other projects on rivers and streams have much larger monetary benefits. Those projects, however, do offer opportunities of being combined with river restoration in a multi-purpose set-up. Seizing those opportunities is thus an important vehicle for the actual realization of river restoration. Practitioners are advised to be keen on integrating river restoration in projects for flooding risk mitigation, hydropower, navigability, urban renewal, real-estate development, etc.
