News Stories

Falls Lake Reallocation Feasibility Study to Aid City of Raleigh

Published Sept. 6, 2018

   In 2008, Raleigh, North Carolina was within weeks of having little or no water after Falls Lake Reservoir nearly dried up after a severe drought.  This spurred the city of Raleigh officials to look seriously at water conservation measures, and eventually developed into the U.S. Army Corps of Engineers (USACE), Wilmington District initiating the Falls Lake Reallocation Feasibility Study. 

   “The study was initiated because the city of Raleigh realized it was vulnerable to drought and that its population was growing,” said Chief of Planning Branch Elden Gatwood.  “They had not considered that there was potential for the Wilmington District to use Falls Lake as a reallocation source.  We received a waiver from Headquarters USACE, and we have almost completed the study which is now being processed and awaiting a final report in Washington, D.C.  If it’s approved, it will go to the Assistant Secretary of the Army for Civil Works for approval of a new water storage agreement which would increase the allotment of water that the city of Raleigh has within our Falls Lake project. This will give them approximately 5.5-billion gallons of storage which will help them in their drought contingency planning and to plan for future population growth.”

   Gatwood said the complex study looked at various levels of storage areas within Falls Lake to investigate whether it was possible to reallocate water.  Wilmington District planners found that there was excess storage space in the conservation pool. 

   “There are different pools within the Falls Lake Reservoir,” Gatwood said.  “The first one is on the bottom and is used for sediment storage.  The second one up is for water conservation storage and water supply, and it also has water quality storage.  The reservoir was originally designed to have more water quality storage than was probably needed after construction.  That pool has never been depleted.  We studied the effects of reallocating water from one side of the pool to the other.”

   Gatwood said that downstream stakeholders will not see any changes once the plan is in effect.  The study, he said, included a demand analysis and a flow analysis.

   “We determined that downstream flow would be insignificantly affected because we have enough storage within the existing conservation pool that we can meet downstream flow targets.  Therefore, people downstream shouldn’t be impacted.  And the city’s also planning and executing other means by which they can provide additional storage,” he explained. 

   Gatwood said the assumption in the Wilmington District’s modeling and in reality is that people will use less water in the future, and that people will learn to conserve water and become more knowledgeable.  In addition, there’s also an assumption that they re-use water in an expanded fashion in the future.

   “The city of Raleigh is already engaged in water conservation and re-use measures right now.  When there’s a drought situation everybody is going to have to do their fair share to contribute to using less water.  A critical part of the recommended plan is the assumption that they’re going to engage in further conservation and water use,” he said.

   Gatwood, who has experienced living in drought conditions in the west, said that water supplies are not infinite.  What helps conserve water at the grassroots level is how people think about using it more efficiently. 

   “In drastic areas that you see out west, they have planned for people to move into these areas. They cannot find additional water for them or water storage, particularly in the central areas of California that are very mountainous, or they don’t have a lot of opportunity for ground water storage.  The city of Raleigh is leaning very far forward  showing a great deal of foresight about what their water future is going to look like, so this makes their water future much more safe. They would have more storage available when they get to periods when they need it,” he said.  

   According to the North Carolina Office of Management and Budget, Wake County is predicted to have a population of 1.1-million people in July of 2020, and growing to 1.3-million by 2030.  And it’s expected to grow even larger in the future.

   “USACE is looking at water storage over an approximate 30-year period,” Gatwood said.  “The city of Raleigh will have to look beyond that.  At some point it’s going to become necessary to look at an even longer term.  And that being said, it’s unusual for communities in this part of the country to look at conservation at all.  There are people who are continuing to move to North Carolina.  The city of Raleigh is moving ahead and planning for its future.”