Pond Inspection and Repair

Transcription

1 Pond Inspection and Repair Handout 5.1a Ponds should be inspected periodically. Repairing damage immediately usually eliminates the need for costly repairs later. Damage may be small, but if neglected may increase until the entire structure must be replaced. Examine ponds after heavy rains. Fill rills on the side slopes of the dam and any washes in the spillway immediately. Use suitable material and compact thoroughly. Reseed or resod these areas and fertilize as needed. If the upstream face of the earth fill shows signs of serious washing or sloughing because of wave action, install protective devices such as booms or riprap. If there is evidence of seepage through or under the dam, consult an engineer. Keep trickle tubes, outlet structures, valves, and watering troughs free of trash at all times. Maintain protective plant cover on the dam and on the earth spillway by mowing it frequently and fertilizing as needed. Mowing prevents the growth of woody plants and aids the development of a cover and root system resistant to runoff. If the plant cover is protected by fencing, keep the fences in good repair. Burrowing animals such as badgers, gophers, and prairie dogs can cause severe damage to dams or spillways. A heavy layer of sand or gravel on the fill discourages burrowing. Poultry netting can be used, but will rust out and need to be replaced. Use fencing to prevent livestock, particularly hogs, from tramping. If fencing is not practical, pave the approaches to the pond with small rocks or gravel. Divert drainage from barn lots, feeding yards, bedding grounds, or any other source of contamination away from the pond. To control mosquitos, stock the pond with top-feeding fish such as Gambusia minnows. Algae and other forms of plant life may become objectionable. They can cause disagreeable tastes or odors in fish, encourage bacterial development, and produce an unsightly appearance. 119

2 Transparency 5.2a POND FENCING If livestock are grazed or fed in adjacent fields, complete fencing of embankment ponds is usually recommended. Fencing allows for the development and maintenance of plant cover on the dam, the earth spillway, and other areas. Fencing provides clean drinking water and eliminates damage or pollution by livestock. Fencing enables the establishment of an environment beneficial to wildlife. If the pond is used for watering livestock, install a gravity-fed watering trough just below the dam, thus allowing for fencing the pond area. If complete fencing is impractical, fence critical areas of the pond such as the earth fill and spillway. 123

3 Fertilizer Application Handout 5.3a Kind and Amount of Fertilizer To Use A mineral fertilizer is best for fishponds. A good fertilizer analysis is (an empirical ratio of 4:4:1) of available free nitrogen (N 2 ), phosphate (usually ammonium phosphate, NH 3, PO 4 ), and potassium (usually potash, P 2 O 5 ). This is also known as the N-P-K value. Growers may use lesser amounts of a strong fertilizer such as or It is important that the nitrogen and phosphate are equal in strength. Sample fertilizer application rates include 100 lbs. of lbs. of lbs. of Organic materials such as cottonseed meal, blood meal, offal, manure, and leaves encourage undesirable filamentous algae (sometimes called pond scum ). Nevertheless, some people believe natural fertilizers enhance soil texture at the bottom of the pond and provide other benefits. When To Fertilize Most ponds require about 12 applications of fertilizer each year. Ponds with little natural fertility or constant running water may need as many as 16 applications. To take full advantage of the growing season, ponds should be fertilized early in the spring. Test the water with a Secchi disk to determine fertility. Three to six applications, made at 10-day intervals, may be needed. Some fish, such as bluegills, achieve most of their growth in spring and fall. They grow little, if at all, during the summer spawning season. New ponds should be fertilized as soon as they fill with water. A pond needs to grow an adequate supply of aquatic animal food for the fish while the weather is warm. The start of water weeds must also be prevented. How To Fertilize Fertilizer is more effective if dispensed in water no deeper than 3 feet. The fertilizer can be applied by broadcasting it from the bank of the pond, and by dispersion from a platform suspended approximately 12 inches below the pond surface, near the pond edge. Wave action and water currents mix the fertilizer throughout the pond. 127

4 Transparency 5.3a WHY FERTILIZE A POND? Most natural waters have low or moderate fertility and therefore need additional fertilization. Fertilizer increases the growth of microscopic plants (phytoplankton). Fish do not eat the fertilizer, and most fish do not eat the phytoplankton. However, fish do eat the worms, insect larvae, and other aquatic animals that feed on these tiny plants. Fertile waters harbor millions of microscopic plants. These plants increase the turbidity and color of the water to a depth of 18 inches or more, thereby preventing sunlight from reaching the pond bottom. Lack of sunlight prevents the growth of submerged weeds. The lack of submerged weeds allows bass and sunfish to find and eat mosquito larvae. 129

5 Transparency 5.3b MAKE A SECCHI DISK To determine if a pond needs to be fertilized, test the water with a Secchi disk. A Secchi disk can be made as described below: Nail a white disk on the end of a stick. Mark the stick at 12 inches and 18 inches above the disk. 131

6 Transparency 5.3c TESTING POND FERTILITY Submerge the Secchi disk in the pond. If the disk disappears from view 12 inches below the surface, the pond is fertile enough to feed pounds of fish per surface acre. If the disk is visible at a depth of 18 inches or more, the water needs to be fertilized. 133