An unusual event occurred along the Osage River below Bagnell
Dam the first week of February 2014.
The winter of 2014 started bitterly cold and by the end of January 2014, the surface of the Lake of the Ozarks completely froze over, something not seen in many years in this age of climate change. Conditions along the Osage River were even more pronounced as ice, several inches thick, formed over the river along its entire length downstream of the dam. For a period of several days at the beginning of February, Ameren began discharging water from the Lake of the Ozarks to produce electricity as cold temperatures increased power demands in the St.Louis area (the primary customer of Bagnell power). This discharge, although not beyond normal operational parameters, was unprecedented for a winter month, and the impact more severe along the river due to the accumulated ice. Water released from Bagnell Dam is expelled from the turbines at the base of the dam, which means the discharge swelled from underneath the frozen river surface. As the Osage River rose and fell, sometimes several feet over the course of mere hours, the ice began to move atop a tsunami like wave of water. The ice would break apart, move downstream, then re-accumulate as water levels fell only to be again lifted and carried downstream at the next impulse. This process repeated several times over the course of six days and the impact on the river was devastating.
KRCG via Youtube
A
statement from Ameren soon after the event:
"Ameren is aware of the situation along the Osage River. As part of normal operations for generating electricity at the Osage Energy Center, Ameren Missouri continuously releases water into the river. Recent water releases have been consistent with operating procedures. Ameren Missouri has been contacted by property owners along the Osage River regarding property loss and is looking further into the matter."
Keeping any kind of structure near, or on, a river is challenging and can be costly. Riverside dwellers along the Mississippi often have their docks removed completely during the winter months in order to avoid inevitable damage. Property owners with docks on the Osage River are equally at risk and should understand Ameren is under no requirement to provide advance notice of when power will be generated and water discharged. Ameren’s position is not entirely tenable however, as there is an argument to be made that the February impulse of water did violate their responsibilities to the ecological condition of the river.
According to the U.S. Fish and Wildlife Service
“Article
412 of FERC's
license to AmerenUE for Bagnell Dam requires
establishment of the Lower Osage River Protection and Enhancement Program. The
purpose of the Protection and Enhancement Program is to continue adaptive
management actions to improve aquatic habitat, protect and improve aquatic
resources, and reduce damaging effects of dam operation on the federally
endangered pink mucket and scaleshell mussels in the lower Osage River. The
program is funded annually by Ameren Missouri and began in 2008.” -
US Fish and Wildlife
The actual relevant clause in the license states Ameren will take “measures to prevent/ reduce island and
bank erosion (e.g., vegetation buffer zones, hard points, etc.)”, as part of the
effort to protect wildlife habitat in the river basin. Clearly, the
release of so much water upon a river encrusted in thick ice is not conducive to
protecting bank or island erosion, nor improve aquatic resources. If the surge was capable of tearing and
twisting metal docks, it assuredly caused river bank destruction and river bed
scraping.
For the month of January 2014 precipitation was only .66
inches in the form of rain, and for the first week of February no precipitation
was measured at all. According to data
from the Missouri Climate Center, this was a historically dry period.
According to the U.S. Geological Survey, for the month of
February 2014 the Osage River basin streamflow was 10-25% below normal
levels.
Zooming in to Missouri specifically we can see that nearly every waterway south of the Missouri river was in low flow condition; the green region just west of the boot heel being the exception indicating normal flow rates on the Current, Jacks Fork, and Eleven Point rivers in the Oregon county region.
Zooming in to Missouri specifically we can see that nearly every waterway south of the Missouri river was in low flow condition; the green region just west of the boot heel being the exception indicating normal flow rates on the Current, Jacks Fork, and Eleven Point rivers in the Oregon county region.
These water conditions indicate there was no extenuating
circumstance to necessitate a high volume discharge other than the purpose
of generating electricity for an area in high demand during a particularly cold
period.
Charting the Impulse
The following charts incorporate a candlestick style data representation (barber poles), typically favored in stock market analysis, indicating the starting level, intraday high and low, and ending level. This model fits well for representing river and lake levels over time. Start time is midnight, end time is 11pm with data points every hour. The red and white indicate low start/high end, or high start/low end depending on direction(see figure1). Stripes starting from the left up to the right indicate a lower starting point with a higher ending level, while stripes starting from the left going down to the right indicate a higher start with a lower ending level. The center black line indicates the complete range of level for the day. The second set of data, represented by the date aligned light blue bar graph, represents the total daily discharge in billions of cubic feet, calculated as an accumulation of the hourly discharge rate over the entire day. The light blue horizontal dashed lines is a peak discharge level from April 2014 and placed as a reference. The thick light blue dashed line is a 2-day moving average of the total discharge and can be interpreted as the shape of the wave propagated along the river over time. |
Fig.1
River levels and discharge for the month of February
The candlestick chart makes it very easy to see the dramatic
level changes on the river over time.
For example, looking on February 6th starting at midnight, the
river level was at 559.5ft and ended the day (11pm) at 565.5ft. The thin black line running through the
center of each barber pole represents the total level ranged throughout the day,
in this example, the river first dropped as low as 555ft, a difference of four
feet from its start, and went as high as 566.5ft, for a maximum difference of 11
feet! Discharge during the same day was
nearly an astounding 1.5 billion cubic feet of water, well above even the
typical spring discharge when high discharge rates are common from seasonal
rains. The moving average trend line clearly shows the shape of the wave that propagated from below Bagnell Dam over the course of six days.
Data from the U.S. Geological Survey buoys for Jan 29th through Feb 6th confirms the discharge rate data.
Data from the U.S. Geological Survey buoys for Jan 29th through Feb 6th confirms the discharge rate data.
 |
| Jan 30th - Feb 6th |
The impulse arrives at St. Thomas, near Jefferson City 24 hours later.
 |
| Feb 3-Feb 9 highlighted |
For the Lake of the Ozarks, February is normally the time to draw the lake
down to its lowest levels of the year, and although the following chart shows
nothing unusual in terms of lake level, it does show a rapid drop of about one
foot over the same six day period, a rate of change that would be considered
dramatic in the summer.
From a property owners point of view on the river, with a peak discharge of over 42 million tons of water
surging into the ice choked Osage River it is unlikely any structure could withstand such a deluge. Although there is no solution for dock owners along the river, aside from simply removing their docks entirely in the fall, it is conceivable an alert system could be devised to notify property
owners of impending high level changes, but this would not solve the problem of damage to
habitat occurring in such circumstance. Ice will continue to form on the river,
and Ameren will continue to generate power, discharging water as the energy market
demands. In the future, one would hope
that Ameren would make an effort to be more considerate in notifying riverside property owners of potential surges such as these, and certainly more sensitive to the the ecological impacts and the requirements of their license.
