Water Resources

Solving Sedimentation Woes in Hydro Leader

April 7, 2022 – Hydro Leader and Jaclyn Gnusti

When runoff carries sediment into lakes and reservoirs, it can build up and dramatically reduce water capacity—posing a threat to important sources of drinking water, recreation, wildlife habitat, and even flood control. Anchor QEA's Senior Managing Engineer Jaclyn Gnusti was featured in Hydro Leader in an exclusive interview, discussing how Anchor QEA tackles sedimentation problems through a variety of services that include aid with geotechnical and environmental evaluations, planning and permitting, engineering solutions, funding, construction implementation, and long-term maintenance.

In reservoirs or lakes, sediment accumulates over time, creating a multitude of problems. Sediment can reduce the capacity of a water body, affecting its ability to serve its flood control or irrigation and emergency water supply uses. It also creates water quality issues: The reduction in depth or the introduction of nutrients or contaminants affect the water quality and can cause nuisance vegetation, such as toxic algae, to grow. The toxins can then interfere with municipal, irrigation, or household uses or affect recreational opportunities, for example by causing swimming and fishing to be temporarily banned. 

Sedimentation can also affect existing dams, especially with aging infrastructure. Many of these dams weren’t built with sediment loads from upstream developments or even natural erosion in mind, and they weren’t built with a mechanism to remove the sediment. As sediment builds up on one side of the dam, it can create instability. Removing sediment may also create unanticipated structural problems, because the dam may have started to rely on the sediment for structural stability as it settles over time. And if a dam wasn’t designed with management in mind, there is often little space to get dredging or other equipment in to remove the sediment. As problems with sedimentation near dams grow, the need for creative solutions also grows.