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Water Resources Mitigation Measures

Mitigation measures to avoid or reduce water resource impacts from low-head hydropower development.

The following are examples of mitigation measures that could be applied to reduce water resource impacts of a project depending upon site- and project-specific conditions. Impacts to water resources are related to the project activities (e.g., land disturbance, erosion, changes in runoff patterns, and hydrological alterations), project emissions (e.g., sediment runoff and water releases), and resource use (e.g., water use). Many impacts can be reduced or avoided when taken into account during the siting and design phase.

Develop a final set of mitigation measures for any project in consultation with the appropriate federal resource management agencies and with stakeholders. Conduct these consultations as part of the project development process and preferably prior to final project siting and design.

Siting and Design Mitigation Measures

Siting and design considerations that mitigate impacts include:

  • Contact local stakeholders early in the process to identify sensitive water use issues, including downstream water users.
  • Identify and avoid unstable slopes.
  • Develop a contingency plan to prevent potential groundwater and surface water contamination.
  • Develop a stormwater management plan to ensure compliance with regulations and prevent off-site migration of contaminated stormwater or increased soil erosion.
  • Minimize the amount of land to be disturbed as much as possible by using existing roads, borrow pits, and quarries.
  • Locate access roads to minimize stream crossings and to minimize impacts where crossings cannot be avoided.
  • Use special construction techniques in areas of steep slopes, erodible soils, and stream crossings.
  • Construct drainage ditches only where necessary. Use appropriate structures at culvert outlets to prevent erosion.

General Mitigation Measures

General mitigation practices and principles that could apply to any or all phases of a low-head hydropower project include:

  • Apply erosion controls relative to possible soil erosion from vehicular traffic.
  • Monitoring rights-of-way (ROWs), access roads, and other project areas for indications of erosion.
  • Clean and maintain catch basins, drainage ditches, culverts, and trash racks regularly.
  • Refuel in a designated fueling area that includes a temporary berm to limit the spread of any spill.
  • Use drip pans during refueling to contain accidental releases and under fuel pump and valve mechanisms of any bulk fueling vehicles parked at the project site.
  • Limit herbicide/pesticide use to nonpersistent, immobile herbicides/pesticides.

Project Phase-Specific Mitigation Measures

Mitigation measures specific to a particular phase of a low-head hydropower project include:


  • Save topsoil removed during construction and use to reclaim disturbed areas upon completion of construction activities whenever possible.
  • Avoid creating excessive slopes during excavation and blasting operations.
  • Monitor construction near aquifer recharge areas to reduce potential contamination of the aquifer.
  • Dispose of excess excavation materials in approved areas to control erosion and minimize leaching of hazardous materials.

Decommissioning/Site Reclamation

  • Develop and implement a decommissioning plan that includes the removal of all aboveground facilities, including intake and tailrace structures, and dams.
  • Reestablish the original streamflow to the extent practicable.
  • Reestablish the original grade and drainage pattern to the extent practicable.
  • Restore the banks of water bodies to their natural condition.
  • Backfill any foundations and trenches, preferably with excess excavation material generated during construction.