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What is a lagoon?
On-site Wastewater Lagoons are a natural and effective way to break down and treat wastewater form residences. Lagoons are designed and sized based upon the number of bedrooms in the home. Waste and wastewater flow from the home into the properly constructed lagoon where heavy material sinks to the bottom of the lagoon and is digested by naturally occurring bacteria. A septic tank before the lagoon can improve the quality of the discharge from a lagoon, but is not mandatory unless the lagoon is constructed in a subdivision, on a property of 10 or less acres; or the residence has a garbage disposal. Wastewater in the lagoon is also treated by bacteria, algae, sunlight, and wind. The discharge pipe is allowed in a lagoon, but lagoons generally do not discharge if properly sized except when there are periods of heavy rain.
Lagoon maintenance is easy, if the following precautions are taken:
Septic Tanks ahead of Lagoons:
Screen your Lagoon with a Thuja Green Giant
The Thuja Green Giant is the fastest growing evergreen tree. It grows 3-5 feet per year, once it is established.They are widely grown as ornamental trees, and extensively used for hedges. A number of cultivars are grown and used in landscapes. Usually, homeowners will plant them as privacy trees between them and their neighbors. The cultivar 'Green Giant' is popular as a very vigorous hedging plant.
These evergreens grow in a uniform shape and height, without having to prune . In fact, you don’t have to do anything to them. They are drought tolerant and have no significant insect or disease problems. They are tough enough to resist ice and snow damage and grow well in almost any soil, even clay. They prefer direct sunlight, but also do well in partial shade.
These make an ideal shrub to screen off your lagoon from your home or your road. As long as they are not planted too close to the berm, their 20-30 foot height make a thick, compact privacy screen.
Common duckweed (Lemna minor) is a very small light green free-floating, seed bearing plant. Duckweed has 1 to 3 leaves, or fronds, of 1/16 to 1/8 inch in length. A single root (or root-hair) protrudes from each frond. Giant (Spirodela polyrhiza) or big duckweed is still relatively small (1/16 to 1/4 inch) with 1 to 4 leaves, or fronds, light green in color. Three or more roots (or root-hairs) protrude from each frond. Duckweeds tend to grow in dense colonies in quiet water, undisturbed by wave action. Often more than one species of duckweed will be associated together in these colonies and can be an aggressive invader of ponds and are often found mixed in with other duckweeds, mosquito fern, and/or watermeal. If colonies cover the surface of the water, then oxygen depletions and fish kills can occur. These plants should be controlled before they cover the entire surface of the pond.
Dense duckweed colonies provide habitat for micro invertebrates but if duckweed completelycovers the surface of a pond for an extended period it will cause oxygen depletions. These colonies will also eliminate submerged plants by blocking sunlight penetration. Many kinds of ducks consume duckweed and often transport it to other bodies of water.
Duckweed Control Options
Duckweeds can be removed by raking or seining it from the pond's surface.
Grass carp will seldom control aquatic vegetation the first year they are stocked. Young grass carp will consume duckweeds but are usually not effective control as large fish (over 10 pounds). Grass carp stocking rates to control duckweeds are usually in the range of 7 to 15 per surface acre or higher. In Texas, only triploid grass carp are legal and a permit from the Texas Parks and Wildlife Department is required before they can be purchased from a certified dealer.
Tilapia will consume watermeal but are a warm water species that cannot survive in temperatures below 55° F. Therefore, tilapia usually cannot be stocked before mid-April or May and will die in November or December. Recommended stocking rates are 15 to 20 pounds of mixed sex adult Mozambique tilapia (Oreochromis mossambicus) per surface area. Tilapias are often not effective for vegetation control if the pond has a robust bass population due to intense predation. In Texas, stocking of Mozambique tilapia does not require a permit from the Texas Parks and Wildlife Department. Any other species of tilapia would require a permit. Check with out County Extension Agent in other states for legality of stocking tilapia.
The active ingredients that have been successful in treating duckweeds include
Information and photos courtesy of:
For questions on lagoons, call the Randolph County Health Department at 660-263-6643 Ext. 3043.