MANAGER TALKS OF FLOODING AND CONTROL
Lake Conway’s water level management has always been a topic of concern for fishermen and landowners living adjacent to the lake, and for good reason. Local residents are concerned about the possibility of flooding, fishermen don’t like fluctuating water levels and low water levels hinder access to piers and boathouses. Arkansas Game and Fish Commission (AGFC) personnel working in District 10 have recently been getting more calls from people concerned about these issues and why the AGFC manages the lake’s water level the way it does.
Matt Horton, Lake Manager Distrist 10, shed some light for those interested or concerned about the water levels.
Log Cabin Democrat: What is history behind Lake Conway?
Matt Horton: Lake Conway was the first lake created by the AGFC and is still the largest lake ever constructed by a state conservation agency in the U.S. Lake Conway is 6,700 acres and is encompassed by a 135 square mile watershed, wherein all the rain water drains into the lake. The purpose for building the lake was for it to function as a hunting and fishing lake, not as a flood control reservoir. However, since 1951, commercial and residential development has changed the watershed to the extent that flood control must be considered. The lake is contained by a 1,000-foot earthen dam and 100-foot spillway with 15 spillway gates that have to be manually operated to discharge water below the normal pool elevation.
LCD: What can happen during events such as rain storms?
MH: A multitude of factors influence runoff and discharge during rain events, such as ground saturation, amount of vegetative cover within the watershed, intensity and duration of rain events, and elevation of the Arkansas River. These factors make predicting rises in the lake’s water level and timing of gate operations difficult and require constant monitoring by AGFC personnel. In addition, the increase in commercial and residential development within the watershed has decreased the amount of permeable ground, causing rain runoff to enter the lake faster and increasing the probability of flood events.
LCD: So how is the water level managed?
MH: In January of 1976, the AGFC approved the first Water Level Management Plan for Lake Conway, which mandated how the lake’s water level was managed. The Plan restricted the operations of the spillway gates (no more than 3 spillway gates could be opened prior to the lake reaching 1.3 feet above normal pool) to minimize the duration of downstream flooding and damage to commercial crop land. It also called for a 1 foot winter draw down from Nov. 15-April 15 to allow for flood water storage during the historically wettest months of the year. In 2002, the Water Level Management Plan was revised to reduce the length of the winter draw down by a month to provide more water for the lake’s fishery during the critical spawning time of crappie and largemouth bass. In 2002, another hydrology study was conducted that confirmed that given downstream flooding liabilities (i.e. Grassy Lake Road) and the current spillway gate design, there still needed to be limited spillway gate operations and a 1 foot winter draw down to allow for flood water storage to adequately manage the lake to control flood events.
LCD: What has been done since then?
MH: Since 1976, the AGFC acquired most of the crop land that was a downstream flooding liability, which is now the Bell Slough WMA. Also, renovations were made to prevent the inundation Grassy Lake Road, which was the only legal ingress and egress to Rogers Country Estates Subdivision. Now that there is no longer a downstream flooding liability, the AGFC has contracted to conduct a new hydrology study to answer questions such as: 1) What is the most efficient method for operating the current spillway gates to control flood events? 2) With less restrictive spillway gate operations, can the lake he held at normal pool year round? 3) Is there an alternative spillway design that would control the lake’s water level more efficiently during flood events? 4) How much of an impact will the loss of water inflow from the Conway Waste Water Treatment Plant have on the lake’s water level, especially during dry summer months?
LCD: When will the study be completed?
MH: The results of this study should be presented to the AGFC sometime this year. The AGFC will look at revising the lake’s Water Level Management Plan if the FTN study recommends changes that will increase the efficiency of the lake’s management for flood events.
LCD: Are there times that landowners need to be aware of certain water levels?
MH: Since the lake must be maintained at specific elevations, water must be evacuated following rain events if there is a significant increase in the water level. Also, the AGFC understands that the lower water level during the winter makes it harder if not impossible for adjacent landowners to access their boathouses from the lake or catch fish from their piers. Unfortunately, given the need to manage the lake to prevent flooding of homes, the current spillway design, and environmental factors such as influences of the Arkansas River on the lake’s discharge require the water level to be managed in such a manner. We hope results of the FTN report will allow us to resolve some of these issues.
Sedimentation is also a contributor to worse shoreline access, especially near the mouths of the main tributaries. We know that several feet of silt has built up in the lake since its construction and continues to build up as it is brought into the lake by rain runoff. FTN is also conducting a study for the AGFC to determine how fast the lake is filling up with sediments. This information can be used to identify main sources of sediments and can be presented to local government and city officials to develop plans which could help reduce future sediment contributions to the lake.
If you have questions regarding the lake’s water level you can call the Lake Manager, Matt Horton at 877-470-3309 or if you call after 4:30 p.m., you can select to hear a recording of the lake’s most recent spillway gate operations and associated water level.