Update (6:30 a.m. May 31): The Keystone Dam output has been reduced to 200,000 cubic feet per second as of 6 a.m., with an inflow estimate of 182,000 cfs. The inflow has dropped about 13.5% since midnight, according to the Army Corps of Engineers' website.
10 A.M. UPDATE: The output from the Keystone Dam rose to 275,000 cubic feet per second at 7 a.m. Monday, with that additional outflow already reaching western Tulsa County, according to the City of Tulsa.
That flow is expected to be felt around noon in central Tulsa and later this afternoon in south Tulsa County. The U.S. Army Corps of Engineers expects to continue discharging 275,000 cfs through Thursday.
"Currently, the Keystone Dam and the Tulsa County levees are working as they should and there have been no levee breaches at this time," according to a statement from the city. "With the additional volume of water being discharged through the levee system, officials continue to monitor this situation."
Tulsa finds itself in an uncertain and unusual situation Monday morning.
Memorial Day weekend typically signals the start of pool season, with families and friends also flocking to bodies of water much larger than a pool to enjoy the holiday. For many people adversely affected by flooding, they've already seen enough water.
But the Arkansas River in Tulsa continues to rise, and severe storms are forecast for the area on Tuesday.
The Arkansas River level in Tulsa has crept up to 22.37 feet as of 8:30 a.m., with the latest floodwater projected to reach a height of 23 feet on Monday, according to the National Weather Service's Advanced Hydrologic Prediction Service.
The weather forecast isn't helping assuage concerns, either. Any significant additional rainfall in the Keystone basin is a potential prompt for another increase in its floodwater output.
NWS meteorologists predict "scattered to numerous showers and thunderstorms" Tuesday across eastern Oklahoma and northwest Arkansas as a strong upper level system moves into the central plains.
The "enhanced risk" for storms is to the north and west of Interstate 44. There is considered to be a "slight risk" below I-44.
"All modes of severe weather will be possible, and heavy rainfall will likely result in additional flooding concerns," the NWS stated in an early Monday weather update.
Below the version of this story published in Monday's newspaper.
Another long night of storms and rain drove home the realization Sunday that Tulsa is in for a long battle with water levels that won’t recede for days and still might rise.
Floodwater releases at Keystone Dam increased to 265,000 cubic feet per second at 7 p.m. Sunday and were set to rise to 275,000 by 7 a.m. Monday, according to the Tulsa District U.S. Army Corps of Engineers.
The Arkansas River level at Tulsa was forecast to inch ever closer to the high water mark of 25 feet set in 1984, with a crest of 23.7 feet forecast for late Monday afternoon.
Keystone Lake is at 110% of its available flood pool and well into a 3-foot “surcharge” allowance. If allowed to rise higher, the water could spill over the dam’s gates and create an even more hazardous situation, according to David Williams, Tulsa District chief of hydrology and hydraulics engineering section.
“Whenever the gates become inoperable, then you lose the ability to control those releases,” Williams said. “Then all of a sudden, instead of 250,000 coming through town, what if we have 450,000 coming through town. That you don’t want.”
The Corps had planned to keep levels at 255,000 cfs through Thursday, but rainfall of 1 to 2.5 inches across the region with a storm that brought straight-line winds and a possible tornado through Tulsa ultimately dashed that plan.
More rain is in the forecast, as well. While the National Weather Service called for a sunny Memorial Day holiday, it posted warnings for more storms and widespread rain Tuesday.
The 275,000 cfs rate will continue through Thursday, barring any significant change, Williams said at a Sunday news conference. The decision to increase flow doesn’t take into account any rain in the forecast, only the rain that has already fallen and run off, he said.
The current release could mean another foot of water in the homes west of Tulsa that are already flooded, County Commissioner Karen Keith said.
“If you’re behind that levee, please heed all warnings and prepare to evacuate,” Keith said. “Because you have very little time if we do have a major issue over there.”
The expected duration of the high water and new increased flow raised concerns among local officials.
Tulsa Mayor G.T. Bynum said erosion and sinkholes continued to worsen in Tulsa River Parks on the east bank of the river, and the park was closed between 11th and 96th streets Sunday.
“Trees in River Parks have also started to fall due to erosion of the soil under them. It is not a safe place for people to be during this event,” Bynum noted.
He also urged concerned residents to evacuate, saying they should be prepared for “the flood of record” but hope for the best.
The amount of time water has been on the levees and the potential for higher water levels are concerns for Todd Kilpatrick, Levee District 12 commissioner for Tulsa County.
“We are holding at the status quo, and with help from the National Guard, we’ve got more monitoring and it’s running as smooth as we can expect,” he said Sunday. “We’re just hoping we don’t see an increase in the volume of water in the river. ... The longer the duration of the water on the levees, the more your failure rate goes up, as well, so that can get you as well as the higher water can.”
Flooding is even more severe at Muskogee, where the Verdigris and Grand rivers flow into the Arkansas. The river is forecast now to crest at 46.5 feet, just 1.7 feet shy of the 48.2-foot record.
“Unregulated runoff” entering the lake from local tributaries and the Cimarron River pushed up the need for a release, Williams said.
The Corps’ gauge in the Cimarron at Ripley showed an increase from 25,000 cfs Saturday to 75,000 cfs Sunday.
Williams said hydrologists are looking ahead to a change to a “summertime weather pattern” by mid-week. “It’s all based on timing, and it’s a delicate balance,” he said. “We need to get through the next two or three days.”
Six northeast Oklahoma reservoirs now are at or above the top of their flood pool level, and three more are at 95% or higher. Several Tulsa District U.S. Army Corps of Engineers lakes in Oklahoma and Kansas have topped “pool of record” heights, said district spokesman Preston Chasteen. It will take time to drain those reservoirs, especially if rain events refill them time and again.
“Right now, on our current path, we expect the river to be back within its banks at Muskogee around June 8, barring any additional significant weather,” he said.
The record lake levels follow record-setting rainfall, said Gary McManus, state climatologist with the Oklahoma State Climatological Survey. North central and northeast Oklahoma are in their wettest 30-day period on record, he said.
To further illustrate the point, he broke it down for the calendar month. The north-central region is posting its wettest May on record through the first 26 days, while the northeast is in its second-wettest May, but those records were set decades apart — not in both regions at the same time.
“Across southern Kansas, they had even more rain in places than we’ve had,” he said.
In the northern Oklahoma regions, some localized areas have seen 15 to 25 inches this month, while in Kansas, some areas have had 20 to 30 inches, he said.
“All of that has to flow through the state to get to the Gulf of Mexico,” he said. “It’s not just what falls on us, it’s what falls north of us.”
Record rainfall and reservoir levels have the Arkansas River experiencing bank-side erosion, and concerns are growing for the levee system that protects Sand Springs and west Tulsa neighborhoods.
“Mother Nature has not been kind here across the Tulsa District in Oklahoma and Kansas,” Chasteen said, noting the sheer volume of rainfall. “From a historical perspective, we have hit pool of record, which is the highest water has risen, at several lakes.”
Record setters the past week include Oologah and three Kansas lakes upstream in the Verdigris Basin, including the Toronto, Fall River and Elk City lakes. Skiatook and Birch lakes, which drain to Bird Creek and the Verdigris, also hit new record heights. Keystone hit its all-time high, as did Kaw and the Kansas lakes of Chaney and Eldorado upstream in that basin, he said.
The Corps follows a playbook that governs decision-making and takes into account the increased risk to dam structures that reach capacity, he said.
“There are trigger points on the water levels that put us into daily surveillance and others that go into 24-hour surveillance — that is literally engineers and maintenance and rangers watching at all times,” he said. “Currently, we have 15 structures in 24-hour surveillance and five on daily surveillance.”
Crews monitor the dams for any seepage, constantly check gauges and are in contact with engineers and hydrologists who use modeling to determine how best to bring the system back to normal levels, he said.
“People can sometimes get focused on that one lake, but we want people to remember that this all works as a system with multiple lakes and reservoirs with the No. 1 goal being public safety and doing all we can to mitigate flooding and try to lessen the impacts,” he said.
The goal now is to “get the system back in balance,” he said. “Especially the ones that are above the flood pool, to get them below that 100% (filled), but to bring them down as a system without increasing the flow in the channels. It may mean lessening the releases at one so it can be increased for another, but it all has to work as a system and it’s going to take a while.”
Chief Photographer Tom Gilbert went up in a helicopter to show what the flooding looked like on Friday.