Be sure to plan pond’s building
Pond construction takes planning and preparation, according to Scott Jones, small impoundment specialist in the Department of Aquaculture and Fisheries at the University of Arkansas at Pine Bluff.
Sites that discharge runoff into “waters of the state” require permits from the Arkansas Department of Energy and Environment, Division of Environmental Quality (DEQ), he said.
This should be completed before excavation and/ or construction of a new pond begins. Producers with permitting questions should contact DEQ at 501682-0640.
Dams that are 25 or more feet tall or impound 50 acrefeet or more of water must obtain construction and operation permits from the Arkansas Department of Agriculture Natural Resources Commission (ANRC), Jones said.
The application is reviewed to ensure the dam’s design is sufficient to handle the anticipated water volume, and the site will be inspected for compliance. Permitting fees are based on the size of the project. Contact ANRC at 501-6283969 for questions relating to dam permits.
The Natural Resources Conservation Service (NRCS) offers site visits, guidance and cost-share programs for certain pond construction projects, he said. When possible, producers should speak with county NRCS conservationists about design, construction and repair of ponds especially if they are used for agricultural or livestock purposes.
The NRCS publication, “Ponds - Planning, Design, Construction” (found at https://nrcspad.sc.egov.usda.gov/distributioncenter/pdf.aspx?productID=115) is a comprehensive guide to the construction of ponds, dams and drainage structures, Jones said. While a great deal of emphasis is focused on the dam and drainage structures during construction, the often-overlooked step of clearing trees and topsoil from the pond basin can doom the project.
“Removing topsoil can
expose hidden rock veins, limestone and permeable sand or gravel layers,” he said. “These potentially permeable substrates can cause rapid water loss preventing the pond from fully filling or staying full.”
Sometimes small areas of permeable substrate can be excavated until a clay-based soil remains. In situations where the questionable substrate cannot be removed, such as bedrock formations or permeable substrates covering most of the basin, installing a clay blanket over the suspect area or the entire basin is the next step.
“Clay blankets are made of well-graded soil with at least 20% clay,” Jones said. “Sourcing the soil from another point on the property or a nearby supplier will reduce hauling costs.”
The minimum recommended compacted thickness of the blanket is 12 inches, with a 2-inch increase in blanket thickness for every one foot of water over 10 feet deep to be impounded, he said. As with dams, the blanket should be laid in lifts of 6-8 inches and compacted by a loaded dirtpan or, ideally, a sheepsfoot roller before laying the next layer. An 8-inch lift will compact to about 6 inches after about six passes from proper compaction equipment under proper soil moisture (moist, but not dripping wet).
“There are parts of the state where soil permeability is naturally low and pond basin preparation and compaction are not necessary for successful completion,” Jones said. “However, it is wise to at least remove topsoil and compact the basin properly to ensure leaks will not occur as they are potentially costly and time-consuming to repair.”
Pond basin preparation also includes grading proper slopes to the shoreline, he said. A 3:1 slope (1 foot deep for every 3 feet from shore) is recommended for most situations. Steeper slopes will likely require some form of reinforcement or excessive erosion will occur. Minimizing water shallower than 3-4 feet will help prevent excessive aquatic weed growth.
Test the basin’s soil chemistry during construction so that, if needed, agricultural lime can be more easily spread before the pond fills, Jones said. Install fish habitat covering 2030% of the total area of the pond for better fish growth and survival. It’s also much easier to build docks/piers before the pond fills.
“Finally, spread grass seed along what will be the shoreline and above, and cover with straw to reduce wash-out. Some seed manufacturers offer ‘tank dam mixes’ that include blends of fescue, rye, Bermuda and several other pasture species that do well on sloped clay banks,” he said. “Liming the pond banks when treating the pond basin will help grass establish and thrive. Water the seed daily until it is growing well, then water as needed until the pond is full.”