The Federal Energy Regulatory Commission today approved an application from Grand River Dam Authority to modify the rule curve requirements at Grand Lake.
GRDA made the request in July for the variance asking that the mandatory draw down of Grand Lake which begins August 16 be suspended this year for drought management purposes.
The order suspends the requirement to drop the lake level to 741' prior to the Labor Day holiday. The requirement was initially established to expose mud flats to seed millet for migratory waterfowl.
GRDA CEO Dan Sullivan presented a video at last week's GRDA meeting summarizing his plea to FERC to modify the rule curve this year.
It is no secret that a severe drought has been taking its toll on Northeast Oklahoma and really, the entire central section of the United States, Sullivan said.
As temperatures continued to hover above triple digits, moments of precipitation have been few and far between for several weeks.
All across the Grand River watershed – where the waters of the Neosho, Spring and Elk rivers and other tributaries usually provide steady inflows into Grand and Hudson Lakes – the Grand River Dam Authority, like all in Northeast Oklahoma, has watched the drought leave its mark.
“On hot, dry windy days, which have been the norm for much of July and into early August, more water evaporates from the lakes than actually flows in,” Sullivan said.
Those are key reasons why GRDA is dealing with conflicting Federal Energy Regulatory (FERC) licensing requirements for its Pensacola and Kerr dams and, as a result, petitioned FERC for suspension of the annual Grand Lake drawdown set to begin in mid August.
“First of all, there are the lake level issues,” said Sullivan. “Drought conditions have resulted in little or no inflow into Grand Lake to such an extent that we’ve not been able to meet the seasonal rule curve elevation of 744 feet on Grand Lake for quite some time. For much of July, Grand’s elevation was below that mark.”
According to GRDA Assistant General Manager of Ecosystems Management Dr. Darrell Townsend, GRDA’s licensing requirements for Kerr requires the Authority to implement a plan to mitigate for low dissolved oxygen (DO) levels.
“In order for us to meet this requirement and follow the dissolved oxygen testing schedule, we need some water flowing out of Grand and into Hudson.”
However, as that water is being released to meet Kerr licensing requirements, it continues to cause Grand Lake elevations to fall below Pensacola licensing requirements.
“In summary, the drought has put our licensing requirements for Pensacola and Kerr dams into conflict with each other,” said Sullivan.
Townsend said the DO testing in the tailrace below Kerr Dam is designed to prevent future fish kills. GRDA is very concerned about these days because low DO conditions have been present since mid-May.
“That is actually 2 to 4 weeks earlier than we would see them in a normal weather year,” said Townsend.
If GRDA were to hold water in Grand Lake and simply meet the requirements of the rule curve, the result may be an inadequate supply of water for DO mitigation at Kerr Dam through September.
So, in late July, GRDA presented a plan to FERC that would call for only releasing 0.03 feet of water per day from Grand into Hudson.
“We feel those releases will be enough to continue our testing and prevent future fish kills but that small amount would not equal a major drawdown of Grand Lake.”
Meanwhile, another issue related to the drought has been GRDA’s operations of the Salina Pumped Storage Project (SPSP), located on the Saline Creek arm of Lake Hudson. In order to utilize this generation facility the elevation of Lake Hudson must be at least 619 feet.
“We need that facility to be operational to meet other federal requirements related to electric reliability,” said Sullivan. “We need to have enough water to generate from SPSP if needed.”
GRDA addressed all these issues with FERC in late July, and laid out its plan for managing lake levels during the drought.
In a typical year, Grand Lake would be drawn down to an elevation of 741 feet by early September to expose mudflat areas around the lake and complete the annual millet seeding project. However, at a mid June meeting, the Pensacola Technical Committee (comprised of membership from GRDA and other resource agencies) recommended suspension of millet seeding in 2012. That suspension would eliminate the need to expose the mudflats and draw the lake down even further.
GRDA’s concern is that such a drawdown might limit the lake’s ability to recover to normal operating levels by October if this drought does persist.
“We also must consider the municipalities that draw their water supplies from GRDA lakes,” said Sullivan. “In such a drought – when large communities like Broken Arrow and Tulsa have already faced mandatory or voluntary water rationing -- we have indicated to FERC is that conserving the water level is prudent during this drought.”
Sullivan added that GRDA must address many issues associated with low lake levels including DO testing, electric reliability, adequate water supply.
“These are all needs that must be balanced in order for GRDA to continue to meet its electricity and lake management missions for the state of Oklahoma.”
See full story in Thursday's Miami News-Record print edition