City Addresses Low Level Of Lake Ponca
Ponca City Now - November 5, 2013 1:34 pm
In Monday’s City Commission work session, City Manager Craig Stephenson addressed the low level of water in Lake Ponca. Here are his comments from the minutes of the meeting.
City Manager Craig Stephenson noted that the water level of Lake Ponca is receiving a significant amount of attention from residents of Ponca City, as over the past several months the water level has not increased but rather decreased in spite of what might be perceived as significant rain events in and around Ponca City. State media has continued to discuss record rainfall in the state this year as well, with this being the third wettest year on record and just one and half inches shy of the second wettest year.
As of the end of October 2013, Lake Ponca was 63 inches below the spillway elevation. There have been many speculations as to the reason for Lake Ponca being 63 inches below the spillway, and staff has been gathering information to find out what the actual facts are on the reason for the low water level of Lake Ponca.
Some have speculated that Turkey Creek upstream has been dammed up by property owners to the north. Staff has recently driven the twenty-nine miles of the Lake Ponca watershed basin area, as well as studying the recent aerial photography taken this past winter to look for anomalies in the area that might indicate a portion of Turkey Creek being dammed and therefore diverting storm water runoff from Lake Ponca. There were no indications of anything out of the ordinary that would prevent storm water from being able to follow its normal path of migration and end up in Lake Ponca.
Others have speculated that oil/fracking operators are removing water from Lake Ponca in tanker trucks. It takes approximately 24 million gallons of water to lower Lake Ponca one inch based on its 700 plus surface acres. Staff does not believe the number of trucks and truck traffic necessary to carry out the removal of one inch of water would go unnoticed by the public. A large tanker can hold approximately 11,600 gallons, so it would take almost 2,100 trucks to lower the lake level by one inch.
And still others have speculated how Kaw Lake – a mere five miles to the east of Lake Ponca – can receive such significant amounts of water that it has had to release downstream to reduce its pool level and yet Lake Ponca is down. The Kaw Lake watershed is 1,500 times larger than Lake Ponca. The Kaw Lake watershed is 46,000 square miles and Lake Ponca’s watershed is 29 square miles. In July and August of this year, the National Oceanic and Atmospheric Administration ( NOAA) station at Mid Continent Airport, in Wichita, Kansas recorded over eighteen inches of rain in a 60 day period and Strother Field Airport Station, between Arkansas City and Winfield, Kansas recorded over fifteen inches of rain in a 60 day period. All of this rain fell not within Lake Ponca’s watershed, but with Kaw Lake’s watershed and draining into Kaw Lake.
The City of Ponca City uses Lake Ponca for two purposes other than recreation. Lake Ponca is used as a supplement to the community’s potable water supply during the summer and all year long for Wentz Golf Course irrigation. Wentz golf course uses approximately 32 million gallons a year or an estimated 87,500 gallons a day. Lake Ponca is used for potable water for the community during the summer months. The figures for the last four years have been: 2010 – 18 million gallons total; 2011 – 14 million gallons total; 2012 – 163 million gallons total; and 2013 – 91 million gallons total. During the highest demand year of 2012, the golf course and water plant used a total of 195 million gallons, which would have lowered the lake level only eight inches and in 2013, the golf course and water plant used 113 million gallons, which would have lowered the lake level only five inches.
Looking at rainfall events, the last time the Lake Ponca pool was full was in April of 2012, when it was overtopping the spillway. During a very intense and short duration rain event on April 29 and 30 of 2012, NOAA recorded over 11 inches of rain for the Lake Ponca watershed. So we know that Lake Ponca was full on that date and will use it for the base line coming forward to today when Lake Ponca is now five feet three inches lower. Since that time rainfall events in the Lake Ponca watershed have been in a deficit for the last eighteen months by 25.66 inches. The normal rainfall for this time period, eighteen months, is 58.03 inches yet only 32.37 inches of rain have been received, resulting in a deficient of 25.66 inches of rain in the Lake Ponca watershed – which is a significant amount. With the twenty-nine square mile watershed that feeds Lake Ponca being in a severe drought, it will take more significant rain events to saturate the area overtime or one very significant event that will fill the Lake Ponca pool.
So in summary the reason behind Lake Ponca’s water level being 63 inches below the spillway is that there have not been any significant rain events in its watershed. Even though rainfall stations show that there have been significant rainfall events near Ponca City, they have not fallen in Lake Ponca’s watershed.