What could make a riverbed a better place for a power line than solid ground?
This article explores three reasons engineering professionals are rerouting power lines underwater and looks at what these reveal about choosing more practical and cost-effective transmission solutions.
Building overhead power lines is not always straightforward because rivers, developed land, and existing infrastructure can limit the available routes between power sources and consumers. This is why engineering professionals are considering in running cables underwater, as it provides another way to cross these obstacles and connect areas that are difficult to reach by land.
The proposed Columbia River transmission project illustrates how this approach can help establish a connection across a major geographical barrier. According to the Washington State Standard, the $1.5 billion project would connect power generation east of the Cascade Mountains with consumers along the Interstate 5 corridor by installing a high-voltage cable beneath the Columbia River, linking Dalles, Oregon, with Portland.
The proposed installation method uses a specialized machine called a hydroplow, which directs high-pressure water jets at the riverbed to create a trench for the cable before laying it beneath the sediment.
While underwater routes provide a way to cross geographical barriers, engineering professionals also consider construction costs, environmental impacts such as disturbance to aquatic habitats, reliability under operating conditions, and the difficulty of accessing cables for maintenance when deciding whether this approach is suitable for a project.
A 2025 study titled “Generating Alternative Transmission Line Routes: A Balanced Approach to Technical and Socio-Environmental Criteria” highlights how comparing these factors help in assessing possible trade-offs and in identifying an option that balances technical feasibility and overall costs.
Electricity generation alone cannot meet demand if transmission infrastructure cannot carry available power to consumers. This makes transmission route planning important because electricity must be able to move from generation sites to the areas that need it. When geographical barriers complicate this connection, an underwater cable may provide an alternative to an overhead route.
The proposed Columbia River transmission project illustrates how route planning can help address limitations in electricity delivery. By creating an additional transmission pathway, the project could give the wider network another way to move available power toward areas of demand.
The Australian Energy Market Operator’s (AEMO) 2026 Integrated System Plan outlines the generation, storage, and network investments needed to meet consumer needs at the lowest overall cost through to 2050.
This highlights an important principle in transmission infrastructure planning: decisions should be based on the needs of the wider electricity system, such as connecting remote wind farms to growing cities or expanding capacity to supply power-hungry industries. Aligning new routes with these needs can help ease transmission bottlenecks and would make better use of existing generation resources.
An underwater transmission route may cost more to build, but its long-term benefits could justify the initial investment. The proposed Columbia River project is estimated to cost $1.5 billion, but it is also designed to carry up to 1,100 MW of renewable electricity from east of the Cascade Mountains to the Portland area. If built and operated as intended, this could help meet rising electricity demand and bring more renewable power to consumers over time.
A 2023 study published in Energies, titled “Whole Life Cycle Cost Analysis of Transmission Lines Using the Economic Life Interval Method,” highlights the importance of considering costs throughout a transmission line’s service life, including construction, operation, and maintenance.
A transmission line that is cheaper to build may incur higher maintenance and repair costs over time. By assessing these expenses together, engineering professionals can compare options more effectively and determine whether a higher initial investment could offer better value in the long run.
Underwater transmission projects highlight why engineering education must go beyond technical design to teach professionals how to make decisions under competing constraints. By learning to balance feasibility, network needs, and life-cycle costs, aspiring engineering professionals can better judge not only whether a solution works, but whether it is the right investment for the system it serves.
The Engineering Institute of Technology’s (EIT’s) engineering courses help students develop the technical knowledge and critical thinking needed to assess whether a solution is not only technically feasible but also a worthwhile long-term investment.
References
Army Corps to look at 1.9B underwater Columbia River power line project
Whole Life Cycle Cost Analysis of Transmission Lines Using the Economic Life Interval Method
This article was published November 4th, 2026 and the content is current as at the date of publication.
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