Conservation Practices Help Control Flooding in Oklahoma

Recent historic flooding throughout Oklahoma has inspired us to talk about flood control structures, ponds and other methods used to prevent flooding in Oklahoma. Keep reading to learn more.

In the past two weeks, Tillman County has received almost 15 inches of rain (Tillman County has 13 flood control structures), and Pauls Valley has received over 10 inches (Garvin County has 146 flood control structures). These structures have been working as designed and have reduced the potential for flooding.

According to the Oklahoma Mesonet, April 2025 was the wettest since 1942! Oklahoma’s network of 2,107 flood control dams prevented an estimated $25.76 million in flood damage in April. Reports verified that 26 auxiliary spillways flowed on April 29^th and April 30^th.

Conservation District and NRCS staff have been in the field inspecting dam performance and identifying potential issues. Maintenance on the 2,107 dams performed by local conservation districts and the Oklahoma Conservation Commission is a key factor in the lack of damage reported. Dams, like highways and bridges, must be maintained regularly if we want to continue to benefit from them.

Oklahoma – $12.866M in damage prevented

Tillman County – $0.959M in damage prevented
– 10 dams in Jack Creek Watershed – $0.613M
– 2 dams in Deep Red Run Watershed – $0.311M
– 1 dam in Middle Deep Red Run Watershed – $0.035M

Wildhorse Creek Watershed – $2.278M in damage prevented
– 107 dams in Carter, Garvin, Murray & Stephens Counties

Rush Creek Watershed – $2.053M in damage prevented
– 54 dams in Garvin, Grady & Stephens Counties

Roaring Creek Watershed – $0.479M in damage prevented
– 40 dams in Grady County

April 2025 Benefits

Oklahoma – $25.764M in damage prevented

Tillman County – $1.413M in damage prevented, total rainfall = 15.47 inches
– 10 dams in Jack Creek Watershed – $0.669M
– 2 dams in Deep Red Run Watershed – $0.666M
– 1 dam in Middle Creek Red Run Watershed – $0.048M

Wildhorse Creek Watershed – $3.478M in damage prevented, total rainfall = 13.59 inches
– 107 dams in Carter, Garvin, Murray & Stephens Counties

Rush Creek Watershed – $2.813M in damage prevented, total rainfall = 12.57 inches
– 54 dams in Garvin, Grady & Stephens Counties

Roaring Creek Watershed – $0.873M in damage prevented, total rainfall = 10.21 inches
– 40 dams in Grady County

Upstream flood control dams provide essential protection from harmful flooding by allowing watersheds to temporarily confine and store water runoff after heavy storms. Oklahoma leads the nation in the construction of these essential dams, with 2,107 upstream flood control dams constructed with the assistance of the USDA NRCS Watershed and Flood Prevention Operations Program. This program assisted Oklahoma in developing watershed plans for 129 watersheds. By reducing potential flood damage, these dams save the state an estimated $96 million each year.

Several watershed dams are usually constructed on small tributaries in a watershed that drains to a large stream or river. These dams are designed to trap water from high rainfall events and slowly release it through a pipe in the dam over a period of several days or weeks. The dams not only reduce flooding immediately downstream from the dam, but also flooding from the stream or river where the water eventually flows.

The dams are designed with a permanent pool level and a flood level pool. During heavy rainfall events, water may back up into the flood pool level. Landowners should be aware of the elevation of the flood pool area, which may extend onto other landowners’ property. Structures such as houses, barns, etc,. should not be built in this area.

The concrete inlet in front of the dam is the principal spillway that controls the water level in the lake. When there is too much water for the principal spillway to handle, water will flow around the end of the dam through the earthen auxiliary spillway.

Keeping the concrete inlet free of debris and good vegetative cover on the earthen spillway is essential to the structure functioning as designed and for maintaining the safety of the dam. Landowners should not attempt to unplug a clogged inlet since it can be very dangerous.

Construction

Poor preparation or construction of a pond dam can lead to ponds that will never hold water correctly. Poor compaction and/or improper materials used in the construction of either the dam itself or its core trench can cause seeping to occur. Improper design of a principal spillway can cause flooding in your pond. This flooding can allow excess floodwater to flow over the dam, causing the dam to breach during high rainfall events. After construction, ensure that vegetation is established prior to introducing livestock.

Trees

Trees are a major cause of leaky ponds and dam failures. Tree roots bore through the soil of the pond dam and create many tunnels. A living tree will have a small potential to create a leak. When the tree dies, the root system begins to decay and no longer fills these voids. This is where water can flow through these tunnels, compromising the dam’s integrity. This can become evident by a seep or wet area on the backside of the dam.

Erosion

Pond dams are inherently at risk of damage brought on by erosion, especially in the early stages after construction. If a pond dam does not have adequate vegetation to protect the soil from surface runoff, gullies could form on both the front and back slope, that could reduce the structural integrity of the dam. These gullies could also cause the water to “breach” the dam and not flow through the spillway due to the eroded areas becoming lower than the spillway.

Livestock trails

Erosion on pond dams is also common on dams constructed for livestock water. Overgrazing of pond dams can lead to severe erosion issues due to the loss of soil cover and weakened grass roots holding the soil together. Animals will create “trails” across the pond dam where they travel to access water, thus the start of a gully and causing a failure. Keep livestock from grazing on the pond dam whenever possible. Installing an exclusion fence with a stabilized single point of entry for livestock to access the pond and not loiter in/near the water is a great way to ensure dam stability and better water quality.

Poor preparation or construction of a pond dam can lead to ponds that will never hold water correctly. A perennial wet area or the presence of vegetation that needs an abundance of water to survive are quick indicators of a leaky dam. Poor compaction or improper materials used in the construction of either the dam itself or its footing, the protective barrier between the pond floor and the dam, can cause seeping to occur.

Preventive maintenance/practices to minimize dam failures

As a minimum. Periodically inspect all structures, earthen embankments, spillways, etc., repair or replace damaged components, remove sediment when it reaches predetermined storage to allow for adequate impoundment, maintain vegetative protection and immediately seed bare areas, as needed, and prevent the establishment of woody vegetation on constructed embankments and around the spillway.