Many Oklahomans think of state lakes as recreational pleasure points. We camp, fish, hike, swim and otherwise enjoy these outdoor spots without much thought as to why they exist and how they got there.

To the men and women who are part of the Water Resources Hydrology and Hydraulics Branch of Tulsa District Corps of Engineers, those aren’t lakes – they’re reservoirs – and they were built to protect the public from flooding.

All of Oklahoma’s large lakes are man-made.

David Urban, chief of forecasting, and Greg Estep, chief of water management, said their branch of the Corps must operate groups of reservoirs as interrelated systems rather than single reservoirs.

“What happens at one (lake) impacts the others,” said Urban.

In managing the reservoir systems, Corps experts must consider land owners who live downstream, concessionaires who earn their living on the water, and recreational users such as campers and fishermen with public safety as a primary concern.

Reservoirs do pretty much what the word implies, reserve or retain water that would otherwise fill rivers downstream. By retaining water behind dams, the Corps can reduce flooding and erosion.

It’s a complex system that requires monitoring and coordination of effort.

“We get data every hour,” said Estep.

Forecasting and Water Management come under the Hydrology and Hydraulics Branch of the Corps. These are the men and women who take on the responsibility for making judgments about amounts and timing of water releases and other factors. They also coordinate with Emergency Services to provide early warning so that endangered residents can evacuate when necessary.

Part of the forecast system includes 400 stream gauges monitored by the Corps. One hundred of those are Corps gauges and the other 300 belong to the U.S. Geological Survey.

Data from those gauges feeds into Corps computers, are interpreted and analyzed by a mix of software programs, and combined with radar and other input to produce the most accurate information ever generated in the history of Oklahoma’s reservoirs.

Hydraulic Engineer John Daylor works with four computer monitors. He said the combination of in-house, commercial and Corps designed programs offer a high level of accuracy.

“Probably the biggest challenge of what we do here is to provide the earliest possible lake forecast with the greatest degree of confidence that is possible,” said Daylor.

Though the Corps can’t prevent all floods –the lakes aren’t big enough– it does reduce the numbers, amount of damage done, and the risks that come from flooding.