Newport’s Big Creek Dams were built decades ago. The lower dam was completed in 1951 and the larger, upper dam was added in 1968, then raised in 1976 to expand the city’s water supply capacity. Both dams are earthen, meaning they form an embankment that was constructed by compacting successive layers of earth, using impervious materials to form a core, and placing more permeable substances on the upstream and downstream sides. These dams were quite common at the time but were not constructed to withstand seismic events. Only within the last 20 years has Oregon been recognized as an area susceptible to sizeable seismic activity.
Research on the Big Creek Dams shows that they may be damaged or completely destroyed by earthquakes. Complete failure of the Big Creek Dams would cause a loss of water for an indefinite period of time and result in loss of life and financial losses quickly exceeding the cost of the proposed project to resolve the issue. Without water for business and industry, a significant number of jobs would be lost, resulting in many people leaving the region, perhaps permanently.
For the City of Newport, the research results yielded another unexpected outcome. The State of Oregon’s Dam Safety Engineer identified the Big Creek Dams as the second and third most seismically deficient dam structures in Oregon. If Newport cannot replace the dams, the state will require the city to lower the water level behind the dams to make the current dams safer. This would severely limit the amount of stored water available to residents and businesses during dry summer months, resulting in significant water curtailment and shortages.
The city has also learned that the Upper Big Creek Dam is seeping. Essentially this means that water is coming through the dam in places where there should not be any water leaking through. While an earthquake is obviously a major threat to the loss of these dams, we now know the structure of the upper dam itself is subject to potential catastrophic failure. We are monitoring this, of course, but it adds urgency to the situation. The state’s dam safety engineer has now labeled the dam “unsafe.” There is really no reasonably priced short-term solution to this other than lowering the water behind the dam, which will mean our community will not have enough water—this alone will exacerbate a challenging economic condition and put significant pressure on the industries in our community that rely on water—potentially threatening jobs.
If the Big Creek Dams Project does not come to be, and the dam were to fail, the economic impact of a water supply loss would continue to grow over time. Partial or complete disruption to the City’s water supply will negatively affect the operation of local industries such as tourism, fish processing, brewing & distilling, and oceanographic research and education, and businesses and residents would likely relocate to other communities.