Water catchment systems and water conservation or Saving

Water catchment systems and water conservation or, Saving Your Liquid Assets Joe Brown, Ph. D University of Alabama New College Southern Sustainable Agriculture Working Group January 16 -19 2008 | Louisville, KY

Rainfall: there ain’t any • Increasing climatic variability • More frequent and severe droughts in SE region – Alabama in particular • Farmers in the region must look at water as a scarce resource • Conservation is the name of the game

From the oracle (NOAA climate prediction center) • The forecast continues to indicate persisting drought across the Southeast through March 2008, with the odds favoring expansion into Florida and southeastern Georgia. • Precipitation totals for 2007 were around 15 inches below normal in many of the exceptional drought areas that stretched across portions of Alabama, Georgia, and the Carolinas. • Despite recent rainfall, the ongoing La Niña is expected to bring abnormally mild and dry weather to the region for most of the winter. • In contrast, at least some degree of improvement is expected from Tennessee and Kentucky northeastward through the middle Atlantic states, including some areas of exceptional drought in the central and western stretches of this region.

Outline • Designing a rainwater catchment system for domestic or garden use • Landscape and pond design • Irrigation: reducing losses • Managing crops to get the most out of your water • Other tips and tricks • Advantages: saving water, saving money • Advantages: protecting water quality • Advantages: marketing • Other advantages • Tools and resources to improve water efficiency on the farm

Rainwater catchment • But, I thought we were talking about not having any rain? • Well, we still have rain, but it comes in less frequent bursts – more variability – Still plenty more than out West, so stop complaining already – you’ve had it so good for so long! • Capturing it is the key • Basic rainwater catchment: roof improvements, foul flush system, and storage

A few calculations, first • • • Calculating potential supply Calculating demand Sizing the storage tank Sizing the foul flush system Costing the system

Potential supply • Use rainfall data to calculate total volume – One inch of rainfall X dripline area of roof = volume of water for a one inch rainfall event • Loss factor: multiply total volume by 0. 8 – Depends on the roof material and how well your gutter system is functioning • Look at monthly data to make calculations

For example: during an extreme, unprecedented drought (36 in/yr) • • • 4 inches of rainfall per month Roof dripline area is 1000 ft 2 0. 333 ft * 1000 ft 2 = 333 ft 3 1 ft 3 = 7. 48 gallons per ft 3 * 333 ft 3 = 2491 gallons per month • Times 0. 8 to account for losses = 1993 gallons

For example, during a “normal” to wet year (60 in/yr) • • • 5 inches of rainfall per month Roof dripline area is 1000 ft 2 0. 42 ft * 1000 ft 2 = 420 ft 3 1 ft 3 = 7. 48 gallons per ft 3 * 420 ft 3 = 3142 gallons per month • Times 0. 8 to account for losses = 2513 gallons

Sizing the tank • Say we split the difference and say 2200 gallons per month • That equals about 75 gallons per day • More than enough for domestic use for a conservation-minded family • Small garden plot use

Demand • How much water do you anticipate using? • 100 liters per day? 200?

Sizing the storage tank • Where supply meets demand • Major determinant of cost

Sizing the foul-flush system • Volume = 1% of maximum rainfall event

Roof materials • • The key to choosing building materials for all parts of a rainwater harvesting system is to select materials that are non toxic and inert (non leaching. ) This is particularly true of the roof that is subject to the oxidizing affects of sun and air borne pollutants. Avoid such contamination sources as lead flashings around sky lights or plumbing vents. Water quality from different roof catchments is a function of the type of roof material, climate conditions, and surrounding environment. When choosing a roofing material - the smoother the better. The quantity of rainwater that can be collected is also a function of roof texture. he most common type of roofing material used for rain catchment in British Columbia is galvanized metal that has been painted or enameled with a non -toxic material. Other materials include slate, terracotta tiles or concrete. Asphalt shingles are adequate but produce less water in summer and are harder to keep clean. Beware of the "modern" shingles that contain moss inhibitors if you plan to drink or bathe in the water. Water collected from cedar roofs is acidic for plants and is impractical for indoor use.

Gutters • Gutters should be made of inert materials. The most common gutters are continuous, baked aluminum gutters made and installed on site. Half-round vinyl is also excellent. • Bamboo can be a good choice for you DIYers if a bit difficult to work with for the uninitiated • When installing gutters make sure that there is a continuous slope towards the downspouts, and that there is no impediment to slow the flow of debris into the downspouts. Areas where the water can pool collect insects, organic materials and bacteria. Think of a gutter as a river - not a wetlands or swamp. • The decision to use gutter guard depends on the landscape and the number and type of shedding trees in the area. It keeps some debris out, but it also protects the debris that collects in the gutter, from the sanitizing and self cleaning of sun and wind.

Downspouts • Anything from chains to traditional aluminum downspouts can be used to get the water down from the gutters • Sealed PVC piping is often used close to the ground, and where the water needs to be transported horizontally. This piping must be sized for good flows, storm events, and easy cleaning.

Debris traps • The Rainwater Connection believes that a series of debris traps and filters and necessary to clean the water as much as possible before it enters storage. For agricultural water a small leaf trap and cleanable pipe systems to catch the larger heavier debris may be all that is required. • For potable water systems a series of leaf and debris traps are used as the first step - leaf traps to capture the leaves, needles and berries, and pipe "pigtails" collect the heavier black debris. • The Rainwater Collection has developed several types of debris traps that work well in local conditions.

First flush • • • The first flush diverter routes the first flow of water from the catchment surface away from the storage tank. It is designed to fill with contaminated water from a rain event and empty itself over a 24 hour period so that it is ready for the next time it rains This system is used in most parts of the world to improve water quality for potable water systems. First flush diverters ("FFD'S") have been shown to remove up to 80% of the pollutants that collect on the roof or in the gutters and become dissolved or suspended in the water. For example, it removes much of the discolouration and acidity from contact with cedar, arbutus and fir needle debris. The amount of water to reject depends on a variety of factors including: Roof and gutter slope Roof material smoothness Rain intensity Preceding dry period Airborne pollutants (dust, smoke, auto exhaust) Tree debris The rainwater Connection recommends rejecting at least the first 0. 02 inch (0. 5 mm) of rain. This amounts to 10. 4 imp gal per 1, 000 sq ft of catchment area or 50 litres per 100 m 2. In extreme cases this is increased to as much as the first 0. 04 or 1/25 th inch.

The barrels-in-series treatment system

Storage above ground

Clemson University system

Water storage • The key • Storage tanks/cisterns take many forms and vary greatly by cost, volume, and materials • The most common storage tanks in the US are the above ground molded polyethylene tanks (300 - 3, 000 gallons) • Ferrocement tanks are widely used elsewhere as well as historically in the US

Extras • Treatment for potable use (usually not recommended) • Use in ‘greywater’ system

Other considerations • Maintenance • Treatment for potable use

Water, water everywhere (but not on my farm) • Limiting the farming enterprise: land, energy, time, money, and WATER

Marketing opportunities • Touting drought resistant or low-water crops • Highlighting sustainable water use on the farm • Focus on farm impacts on water – Well-managed agricultural land provides for infiltration – Erosion controls and BMPs for reduction of runoff and therefore waterborne pollution • Watershed, riparian zone, or wetland protection

Drought resistance and cover crops • Sudan sudex is best – One sees sorghum and millet planted together in many dry places around the world – Sudan grass is not a legume, no nitrogen fixation • Hairy vetch is moderately drought resistant • Cowpeas (iron and clay peas) moderately drought resistant • Crimson clover is not drought resistant • I don’t recommend kudzu, although it is drought resistant!

• A good response to longer periods of dryness broken by more violent rainstorms is to make your soil droughtresistant. What you want is a way for your valuable plants to survive a temporary water deficit, without having to use a lot of water and perhaps pay a fine to your municipality. So, make sure that the water from a deluge doesn't run off. Make the water percolate down to plants' roots. Don't till the soil; bare plowed soil loses water to evaporation. Leave organic material lying on the soil surface or plant groundcover (a cover crop like clover or alfalfa in the case of farmers). Midwestern farmers are now leaving corn plants up after harvest to catch the snow and protect the soil. Encourage worms, whose tunnels, about the diameter of a pencil, direct water down to root level.

• • Plants are, in a sense, cannibals. They thrive when they have partially decomposed plant material—little bits of bark or crumbly leaves—to consume. (Though they'll also happily take up the minerals in decomposed animal material. ) Little bits of bark or crumbly leaves work like sponges, holding moisture in the soil. Humus, the name for that decomposing stuff, is sort of like exercise, which can make fat people thinner and thin people more rounded. It improves both sandy soils and clay soils, increasing the water-holding capacity of sand water penetration in clay. Some of the boosters of arid-region plants have insufficiently stressed that in a garden with heavy clay soil that doesn't drain well, or where water fails to percolate, drought-tolerant plants will suffer in times of average rain. The cheering news is that perennials on the whole are drought-resistant once their roots have developed well; they may flower less in dry conditions, but they're in it for the long haul. Annuals panic and go to seed, hoping their offspring will find moister conditions next year.

• Perennials, even the prairie and desert ones, do have to be watered thoroughly when they're planted. Last weekend I saw a woman filling the back of her station wagon with about a dozen achillea (aka yarrow, often first on the list of drought-tolerant plants) with lovely terra-cotta colored flowers. • "So, I don't have to water these at all, right? " she called in parting to the nurseryman, who kind of nodded as he moved on to another customer. I suppose it's a good thing that I restrained myself from running after her car, yelling that newly planted perennials don't have a big root system, that they need a lot of water at planting time and attentive watering through the first year until their roots have matured and spread out. It's a complex message to get across while appearing to be a deranged person running down the road.

• The achilleas at the home of the woman at the nursery may well be wilting right now, their nice ferny gray leaves sagging limply; she may be considering calling the nursery and asking for replacements. Roots have a hard time making contact with dry soil; watering at planting makes the soil stick to the roots and gets rid of air pockets where a root might dangle. Here is a gift to Scrabble players, a word likely to be mocked and challenged—turgor. To exhibit turgor means to be in a state of distension. From the Latin turgidus, swollen, inflated. (From which we have derived the idea of turgid prose—inflated and, thus, pompous. )

• When the roots encounter a dry place, a hormonal message travels to the leaves to close their pores to slow down water loss. The pores, called stomata, are usually on the underside of the leaf. Squash and cucumber plants, which have pores on both sides, are extremely sensitive to lack of water; veteran vegetable growers use them as the canaries in the coal mine. Plants owe their capacity to be erect to water pressure; with less water in the system, they grow limp.

• Which takes us to a much bigger picture. Scientists are working to make food crops that aren't adapted to arid places better at surviving drought by making their roots more efficient. A team of scientists headed by Roberto A. Gaxiola at the University of Connecticut has discovered a way to manipulate plant genes to increase root proliferation. Many naturally drought-resistant plants, especially the grasses of our great prairies, develop deep and dense root systems. It's a new idea; roots haven't previously been targeted in genetic engineering. Deeper, wider roots can spread out to more territory in search of water. The point, Gaxiola said, is to help agriculture in arid regions—Pakistan, Africa, China, and his native Mexico, not to mention Alabama. • In the past we've coddled our crop plants, giving them lots of fertilizer and water, things we used to think were unlimited. Gaxiola is aware that not everyone is on board with the manipulation of plant genes: "We are the witches of our time. People who don't understand the science would like to burn us. "

• Sprinkler evaporation loss can be reduced by changing sprinkler operating conditions to increase water droplet size or by operating the system under conditions of low climate demand. Climate demand is low at night and during early morning and early evening hours. • Evaporation loss can be increased by using small nozzles and operating sprinklers at high pressures to produce small water droplets, and by operating systems when climate demand is greatest. Climate demand will normally be greatest during the early afternoon, when relative humidity is lowest and air temperature and wind speed are highest. Sprinklers should not be operated outside the manufacturer's recommended pressure range because they may perform poorly under such conditions.

The tensiometer

El Nino: 2006 -2007

La Nina: current conditions

Trees • Mature trees in peak summer heat can use 250 gallons a day • Roots may go out horizontally as far as the height of the tree

Economics • The allocation of scarce resources • Creating a water balance for your farm (exercise)

Your own Walden Pond

Selecting a pond site • “Put it over yunder” has not been a successful philosophical viewpoint or modus operandi • Several factors to consider, including: – Safety – Soils – Geology – Topography – Irrigation access & proximity to crops

Factors to consider when siting your pond: safety • Visualize dam failure: it could happen • Locate and identify underground utilities • Think about recreational uses and potential for accidents – You may be liable in the case of injury or death resulting from use of your pond whether you authorized such use or not • Identify and reduce hazards: stumps, uncovered drains, debris, etc.

Factors to consider when siting your pond: soils • Good news for that cursed clayey soil of yours! • Soil should contain a layer that is impervious and thick enough (usually a 2 -foot minimum) to prevent excessive seepage – Clay and silt/clay are fine: sandy soils are not – Highly variable soils • May need to cover and compact a part of a proposed site with suitable material – More compaction can help less-than-perfect soils retain water – Liners are expensive but can be used for small ponds • Leaky ponds are difficult and expensive to fix – better to think ahead! • Soil under the dam is particularly critical

Factors to consider when siting your pond: geology • Can seriously limit the success of your pond • Limestone areas may have underground sinkholes or other formations that can drain your pond • Look around you: are there lots of other farm ponds in the vicinity – Google Earth may help you figure this one out

Factors to consider when siting your pond: topography • The “lay of the land” • Most important factor in cost – Locate your dam where you’ll need the least earthwork • Location location: locate your pond where the largest storage volume can be obtained with the least amount of earth moving • Look to create the pond where you’ll be able to establish a deep basin – E. g. , where a dam can be built between two ridges crossing a narrow section of a valley that is immediately downstream of a broad section of valley – Don’t want shallow areas • Excavated ponds are the most expensive to construct per volume of water stored – Aboveground water storage behind an earthen dam is always better for your money

Your watershed • For ponds in which surface runoff is the main source of water, the contributing drainage area, or watershed, must be large enough to fill and maintain adequate water in the pond during droughts. – However, the drainage area should not be so large that expensive overflow structures are needed to bypass excess runoff during storms

Watershed • • • For ponds in which surface runoff is the main source of water, the contributing drainage area, or watershed, must be large enough to fill and maintain adequate water in the pond during droughts. However, the drainage area should not be so large that expensive overflow structures are needed to bypass excess runoff during storms. Some characteristics of a watershed that directly affect the yield of water are the slope of the land, soil infiltration, and plant cover. These interrelated factors are variable and site-specific. There are no set rules for determining the exact size watershed needed to fill and maintain a given size pond. However, there are some rules of thumb that can be used. For example, some watersheds containing mostly pasture with heavy clay soils may need only 5 acres of land for each surface acre of water. At the opposite extreme, a sandy watershed in a wooded area may need 30 acres or more of land to contribute runoff for each surface acre of ponded water. If the drainage area is too small in relation to the pond size, the pond may not adequately fill, or the water level may drop too low during extended periods of hot, dry weather. Shallow water contributes to excessive aquatic weed problems and potentially to fish kills from low dissolved oxygen when average depth is less than 3 feet.

Watershed • • • Ponds with excessive drainage areas can be difficult to manage for fish production. They tend to be muddy, silt-in rapidly, and have erosion problems in the spillway area. Runoff from oversized drainage areas can flush out much of the microscopic plant and animal life that form the base of the food chain for fish, thus lowering pond productivity. Fish may also leave the pond during overflow from heavy rains. Contamination of ponds with wild fish from either upstream or downstream sources is more likely when watershed size is excessive. To avoid potential pollution of pond water, select a location where drainage from farmsteads, feedlots, sewage lines, dumps, industrial and urban sites, and other similar areas does not reach the pond. In order for the planned depth and capacity of a pond to be maintained, the inflow must be reasonably free of silt from an eroding watershed. The best protection is adequate erosion control on the contributing drainage area. Land under permanent cover of trees or grasses is the most desirable drainage area. If such land is not available, treat the watershed with proper conservation practices to control erosion before constructing the pond.

Pond sizing • • • The size of an embankment pond should be relative to the size of the watershed (drainage area) contributing runoff to the site. Ponds with too little watershed will have difficulty filling up and remaining full during drought conditions, and ponds with too much watershed require expensive water control structures and are difficult to manage (see Watershed/Drainage Area). To ensure a permanent water supply, the water in the pond must be deep enough to meet the intended use requirements and to offset probable seepage and evaporation losses. The minimum recommended depth of water for ponds in Alabama is 6 to 7 feet. Greater minimum depths are needed for ponds in which a permanent or yearround water supply is essential, such as for irrigation or fire fighting, or where seepage is more than normal. Most typical farm ponds in Alabama have 10 to 15 feet of water at the dam. The estimated capacity, or volume, of the pond can be determined by multiplying the surface area of the pond in acres by 0. 4 times the maximum water depth in feet measured at the dam. For example, a pond with a surface area of 3. 2 acres and a depth of 12. 5 feet at the dam has an approximate capacity of 16 acre-feet (0. 4 x 3. 2 x 12. 5 = 16 acre-feet); (1 acre-foot = 325, 851 gallons). An exact capacity of the pond can be obtained only through detailed surveys and calculations.

Calculate pond volume • Formula • Acre feet gallon conversion

Water quality issues • For irrigation, you’re mainly concerned with the solids content – Turbidity, Total Suspended Solids, Total Dissolved Solids • Consider a granular filtration unit – Rapid sand filter – Roughing filters, slow sand filters, others • Locating the intake to reduce solids content

Sources for your pond water: rain • The primary source of water for embankment ponds is rainfall runoff from the drainage or watershed area surrounding the pond. Rainfall runoff can be an excellent "free" source of water, depending on the physical and chemical characteristics of the watershed. The best runoff water source for ponds is a watershed containing undisturbed, well-vegetated cover such as timberland or grassland. Unvegetated watersheds should be avoided because of the potential for excessive muddiness and premature siltation of the pond. Watersheds containing concentrated livestock feeding areas or overfertilized pastures can result in problems due to excessive nutrients and other contaminants entering the pond. Watersheds with cropland receiving regular pesticide applications are of concern because of the potential for pond contamination from runoff or spray drift. Ponds receiving runoff from cropland should have a good buffer zone of grass or sod between the cropland the pond to serve as a filter for potential soil erosion and pesticide runoff.

Sources for your pond water: springs or other surface water • Surface water from nearby springs, streams, rivers, or reservoirs that have good water quality can be used as a pond water source • How reliable is it? What’s the flow rate? • Pumped groundwater: maybe not such a good source

Photo of our surface water sourced pond

Assistance… • For small ponds, the Natural Resources Conservation Service (NRCS) in Alabama may provide free planning, design, and construction assistance to private landowners in the state. The NRCS has been the recognized expert in this area for over 60 years. However, due to workload and workforce, the NRCS in some counties may only provide limited assistance on ponds. Private consultants (professional engineers) are available to provide this assistance for a fee. • “Sometimes government agencies will share the cost through watershed restoration and conservation projects ask about local programs. Just be aware of any strings attached, such as a requirement that your pond be kept open to the public. “

Purr-mitting: covering your liquid assets • Good pond sites will sometimes include land areas classified as wetlands. – Wetlands include marshes, swamps, and shallow areas that pool water seasonally and support wetland-type plants such as bulrush, cattails, cypress trees, etc. • • If wetlands are present on a pond site, they must be identified before construction of the pond. Federal wetland programs such as Section 404 of the Clean Water Act and Swampbuster provisions of the Food Security Act may apply to private landowners who construct ponds in areas considered to be wetlands. Always check with the U. S. Army Corps of Engineers or the USDA Natural Resources Conservation Service (NRCS) before construction to determine which specific law or regulation may apply to you. In some cases, it may be necessary to obtain a permit or additional planning assistance. If wetlands are present (depending on the type and amount), locating an alternative pond site without significant wetlands may be the best alternative. That way, paperwork and possible litigation can be avoided and, most importantly, the wetland its benefits to the environment will be preserved.

Permitting • Legal Issues. In the past, property owners could dig a pond anywhere on their land, and many people constructed ponds in wetland areas low-lying spots that already collected water. But more recently, the public has realized the value of wetlands for wildlife habitat and maintaining water quality, so there now are regulations that limit where you can put a farm pond. • If you construct a pond without acquiring the proper permits, you could find yourself in court, faced with heavy fines and huge wetland-restoration bills and worse yet, no pond. You can avoid this issue by choosing a pond site with care and following local regulations.

Permits • • The owner must obtain any required permits before hiring a contractor. If wetlands are involved, a permit may be required from the Corps of Engineers. Pond sites that involve a total of 5 or more acres of land disturbance during construction require a National Pollution Discharge Elimination System (NPDES) permit issued by the State environment department. – Will require that a Best Management Practices (BMP) plan be developed and implemented to control erosion during construction and also requires that the BMPs be monitored to ensure that they are working properly. • • Even if the site is smaller than 5 acres, the landowner and contractor should make a conscious effort to control erosion during construction. A simple way to do this is to perform no construction activities in the pool area until after the dam is near completion. This minimizes land disturbance and creates a basin to trap the sediment produced in the pool area. In all cases, vegetation should be established to control erosion as soon as possible after construction. Other state and local laws may apply as well.

Shaping your pond: form follows function • Look to maximize efficiency • Usually the shape will follow from the landscape • A pond constructed for the purpose of irrigation will be better the deeper it is, since you want to minimize surface losses due to evaporation • A circular pond will usually hold more water with less earthwork, all else (e. g. , average depth) being equal – “You have noticed that everything an Indian does is in a circle, and that is because the Power of the World always works in circles, and everything tries to be round. In the old days when we were a strong and happy people, all our power came to us from the sacred hoop of the nation, and so long as the hoop was unbroken, the people flourished. ” • From Black Elk Speaks

Hiring a contractor • • • Unless you have the necessary equipment, you will need to hire a contractor to build the pond. A list of pond contractors can be obtained at your local NRCS office. You may wish to receive bids from several contractors to be sure you are getting the best quality job done at the lowest possible cost. It is always best to talk with others who have had ponds built. Ask for references from your prospective contractor before finally contracting your construction project. Before contracting, have a set of plans and specifications prepared. The plans should show all elevations and dimensions of the dam and emergency spillway, the dimensions and extent of the cutoff trench and other areas requiring backfill, and the location, dimensions, and elevations of the principal spillway, bank contours, and other planned structures. The plan should also include a list of the quantity and kind of building materials required. The specifications should give all the information not shown on the plans that is necessary to define what is to be done, prescribe how the work is to be done if such direction is required, specify the quality of material and workmanship required, and define the method of measurement and the unit of payment for the various items of work that constitute the whole job. Construction work of the quality and standards desired will not result unless there is a clear understanding of all the requirements for the job between the owner and the contractor. For these reasons, good plans and specifications should be prepared for all ponds for which an owner awards a contract. The local Soil and Water Conservation District, the NRCS, and private consultants (professional engineers) can assist in preparing the plans and specifications. These people can also provide assistance during the construction phase; however, the primary responsibility to ensure that the job is constructed according to plans and specifications is the owner's.

Site survey and layout • Certain information for the potential pond site must be obtained through engineering surveys. At a minimum, information collected should include surveys for the proposed earthen dam location, emergency spillway location, and shoreline for the pond. Any soils investigation should be documented and referenced to the site survey. The information gathered from the field surveys will then be used by the designer to calculate the elevations and earthfill quantities associated with the construction of the dam. Just prior to construction, the site survey and design information is used to precisely lay out the earthen dam and emergency spillway for construction.

Pond types: embankment • • • The most common type of pond in Alabama is the embankment pond, also called watershed pond or hill pond (Figure 2). A watershed is the drainage area around the pond within which rainfall drains toward the pond. A dam or embankment is constructed in a depression between two hills and serves to impound water in a basin area on the upstream side of the dam. This type of pond is best suited for areas with slightly to moderately rolling topography. Embankment ponds usually depend on rainfall runoff to fill and then maintain water levels. Pond size, shape, and depth are limited by the topography of the site and the size of the watershed draining to the pond. Generally, the steeper the slope of the pond site, the smaller the pond that can be constructed. Well-sited embankment ponds generally require the least amount of earthmoving per acre of water impounded compared to other types of ponds. Because construction costs are based largely on the amount of earthmoving, an embankment pond is generally the least expensive type of pond per surface acre of water to construct. Building a dam across a large, permanent stream is not a recommended practice for constructing a pond. Following heavy rainfall, streams often carry large amounts of suspended sediments that will settle out in the pond and severely shorten its useful life. Ponds fed by large streams can be difficult to manage for fishing due to competition from wild fish, the introduction of fish diseases, and the inability to effectively fertilize the pond due to excessive outflow.

Embankment

Pond types: excavated • Excavated, or "dug, " ponds are constructed almost entirely below original ground level (Figure 3). This construction method is usually used only for construction of small ponds (generally less than 1/2 acre) because of the large amount of earthmoving required in relation to the size of the pond. Excavated ponds may require an external water source to fill and maintain the pond if springs, groundwater, or runoff are not sufficient. An excavated pond is usually the most expensive type of pond to construct on a per-acre basis.

Excavated

Pond types: levee • Suitable for flat or nearly flat land, levee ponds are only partially excavated. Earth from what is to be the basin area of the pond is removed and used to construct the sides, or levees, of the pond that impound the water (Figure 4). The water level in a levee pond is higher than the original ground level. Water depth is usually similar throughout the pond and is regulated by the height of the outlet pipes and constructed levees. An externally pumped water source, such as a well or creek, will be necessary to fill and maintain this type of pond due to the absence of a watershed. Per-acre construction costs of levee ponds generally fall between those of watershed and excavated ponds.

Levee

Pond types: combination watershed -levee • An example of a combination watershedlevee pond would be a two- or three-sided levee pond that connects to an existing hill to form its other side (Figure 5). Depending on the site, the hill side of the pond can provide a significant amount of watershed runoff to the pond, thus reducing and, in some cases, eliminating the need for pumping water to fill and maintain the pond.

Watershed-levee

Pond construction: costs • • • The cost of constructing a pond can be highly variable. On a per-acre basis, small ponds are generally more expensive than larger ponds. Small ponds can easily range from $10, 000 to $20, 000 per acre or more, while larger ponds (10 acres or more) can range from $1, 000 to $5, 000 per acre or possibly even less for ideal sites. The largest single factor controlling the cost of constructing a pond is the amount of earthmoving required. Other costs such as clearing, site preparation, pipe, concrete, and seeding and mulching are often only incidental compared to the earthmoving cost. The best way to contract the work of building the pond is to have individual unit prices and pre-agreed-upon costs for every item to be completed in the construction of the pond. Some pond owners elect to "lump sum" the job. That is, the contractor gives them one price for the entire completed job. This is fine unless changes in construction are required, in which case, modifications to the work are difficult to price. Some contractors may want to do all or portions of the work on an hourly basis. This could prove to be expensive since the pond owner has no control over the time required to do the work. The cost of installing a pond can sometimes be cost-shared through government programs if the pond actually reduces downstream water pollution or is used as a source of water for livestock. Check with the local Soil and Water Conservation District Office and the NRCS for potential cost-share money.

Reducing water losses in ponds • Surface plants

Leaky ponds • • • Excessive seepage is a common pond problem in many areas. Most severe seepage problems can be traced back to two fundamental causes: a poor site and/or improper pond construction practices. A poor site may be one in which either the soils are too permeable to hold water and/or the underlying geology is not conducive to holding water. Risky geological structure includes underlying cavernous limestone prone to develop sinkholes or exposed rock areas in the pond bottom around which water might channel beneath the pond. Seepage rates can vary considerably for ponds, depending on the dominant soil type. However, properly constructed ponds on good sites will have low seepage rates. Table 1 lists relative seepage rates plus average summertime evaporation in Alabama to show potential water level drop (assuming no added water from rainfall, runoff, groundwater, or other sources). Improper pond construction techniques are often the cause of excessive seepage. As discussed previously under Pond Construction, most embankment ponds require a cutoff and core trench compacted with a good-quality clayey material along the centerline of the dam and extending down into impervious material. Failure to properly install the core trench can result in excessive seepage through the base of the dam. This problem can sometimes be corrected through draining the pond and installing a new core trench in front of the dam. Proper soil moisture is very important for obtaining optimum compaction during the construction phase. Ponds constructed with soil either too dry or too wet can result in excess seepage due to poor compaction. Generally, the soil is too dry if it can't be molded in your hand too wet if it adheres to the construction equipment or is obviously saturated. There are several methods and materials that can be used to seal leaking ponds, including compaction, clay blankets, bentonite, chemical dispersing agents, and pond liners.

Is my pond leaking or evaporating? Seepage Rates Showing Potential Water Level Drop SUMMERTIME POND LEVEL DROP (inches per week) Low Medium High Seepage Rate + Evaporation* = Pond Water Level Drop** <1. 4 + 1. 0 = <2. 4 1. 4 to 2. 75 + 1. 0 = 2. 4 to 3. 75 >2. 75 + 1. 0 = >3. 75 *Evaporation averages about 1 inch per week (June-September) in full sun. **Assuming no water entering pond (and no irrigation either)

Pond maintenance

How much water do you have?

How much water is coming?

Drilling a well • Capitalizing on our stable past climate • Shallow groundwater • Deep wells: costs of drilling and operating

Build for the future • Given the increasing trend of severe weather, Matson says ponds need to be built better than ever. The construction of pond dams must take into consideration potential flood damage should the dam or overflow-spillway channel fail. It is even more important to build ponds with spillways that can handle what they used to call 50 - or 100 -year floods, Matson says. With continuing climate changes, you really want to make the dams sturdy and make spillways function properly with large water loads.

Maintenance • Keep your pond surrounded by large grassy areas to prevent soil from washing into the pond from nearby fields. Also keep in mind that the ponds own water can cause soil erosion. Windwhipped waves can eat away at a ponds banks, dam and spillway. Common solutions include breaking up waves with an obstacle such as a floating log boom, or building rock-lined banks called riprap which work well where the water level fluctuates widely. Keep livestock out of your pond as much as possible, both to prevent erosion and to maintain water quality.

New life for old ponds • • • Matson says the ideal pond is one that already exists and is maybe 20 to 30 years old and just needs to be cleaned out. If you have an old pond site on your property, its well worth taking the trouble to clean it up, rather than negotiating permits and incurring the expense for a new one. (See New Life for Old Ponds, above, for more on resurrecting an old pond. ) “Earth ponds flow naturally toward oblivion, ” says pond expert Tim Matson. “Vegetation decays, sediment accumulates and the basin erodes. Eventually, without help, the pond disappears. ” (Read Matson’s article “Maintaining Your Pond, ” at www. Mother. Earth. News. com. ) Nevertheless, it is possible to revitalize an old pond. Take, for example, the experience of Keith Crotz, a now proactive pond-keeper in central Illinois. The pond on his farm was 24 feet deep when his late grandfather, William, built it for fishing in 1962. Thirty-five years later, the one-acre pond was practically dead. “The pond had pretty much filled in because of poor farming practices, ” Keith says. “The silt came off of our land, which was plowed, disked and harrowed, regardless of the weather. In 1997, we dredged out about 20 feet of silt, rebuilt the dike and put in a new drain and overflow. ” Crotz still raises corn, soybeans and wheat on the farm that has been in his family since the 1860 s, but he no longer worries about soil erosion filling his pond. “Now that we’re no-till and organic, we don’t have those problems. ” A 100 -foot-wide grass buffer also encircles his pond. The U. S. Department of Agriculture picked up most of the cost for reviving the pond as part of a watershed-protection program; Crotz had to pay for only 20 percent of the project’s total cost. Now the reborn pond is full of bass, bluegill and bullfrogs, and attracts a variety of other wildlife. With an electric pump, the pond keeps a livestock water tank filled and provides plenty of irrigation water for a one-acre market garden.

Wells • Deep wells are effectively a non-renewable resource – Expensive to drill, uncertainty of where to drill – You pay by the foot, usually with a minimum charge (not including pumps, plumbing, electrical work, etc. • Shallow wells may experience water quality issues, but are generally suitable for irrigation uses – Not always available – Your land use will influence recharge • Both are subject to drawdown and depletion when you need it least! • Both can be expensive to operate and maintain • Yield can vary widely: estimate your needs – Both domestic AND agricultural?

Wells and water quality • Low solids: that’s good • Shallow wells may be subject to fecal contamination – 100% of septic systems fail at some point • Potential for pesticides: national survey in 1992 detected presence of pesticides in 4. 2% of all rural domestic wells (probably a low figure)

Water conservation on the small farm • Irrigation: reducing losses • Managing crops to get the most out of your water

Irrigation • “North Carolina is located in a humid region where irrigation must be planned in conjunction with prevailing rainfall conditions. In humid regions such as ours, applying routine amounts of irrigation water at regular intervals will almost always result in overirrigation and the needless waste of water and energy” – Evans, Sneed, and Cassell (1996) NCCES

Being stingy with your water by asking the tough questions

Checking soil moisture • The “feel method”

Moisture Deficiency Inches/ft Coarse Light (Loamy Sand) (Sandy Loam) Medium (Loam) Fine (Clay Loam) (Field Capacity) 0. 0 Leaves a wet outline on hand when squeezed; makes a short ribbon Leaves a wet outline on hand when squeezed; will ribbon out about 1 inch Leaves a wet outline on hand when squeezed; will ribbon out about 2 inches 0. 0 0. 2 Appears moist Makes a hard ball 0. 2 Forms a plastic ball, Slicks when rubbed Will slick and ribbon easily 0. 4 Makes a good ball. Makes a thick ribbon Slicks when rubbed 0. 6 Very dry; loose, flows through fingers Makes a weak ball Forms a hard ball 0. 8 Wilting point Sticks together Forms a good ball 0. 4 Makes a weak ball 0. 6 Sticks together slightly 0. 8 1. 0 Moisture Deficiency Inches/ft Makes a good ball Will ball but won’t flatten rather than crumble 1. 0

Irrigation scheduling • Delivering the correct amount of water at the correct time • Know your crops’ water sensitivity and needs at various stages of growth • Monitor soil moisture, even if it’s just through spot checking with the feel test

Weeds and trees • Compete with your plants for water

If you can, scale back • Reduce area planted: no use trying to stretch too little water over too little land – you run the risk of overstressing everything • Reduce production of water intensive crops if you can • Focus on giving adequate water to those most critical ($) crops and cut corners on the “extras” that may not be as marketable • Hard choices are sometimes needed

Crop selection • Certain crops and varieties are less sensitive to water stress – May not be as productive – May not have as high a market demand • Talk to your extension agent

Water and your soil • Soil type and structure is a major determinant of how much water is held and whether your crops can access it – E. g. , clay holds a great deal of water, but that water may not be easily accessible to plants • Soils that are too sandy may not hold water well at all • You can promote water infiltration, retention, and accessibility by developing proper soil structure and fertility – Organic matter, cover crops (promote infiltration and reduce evapotranspiration), etc – Advantage of reduced tillage, no-till systems: undisturbed soil holds water – Worms

The obvious • You know you’re doing something wrong when: – There are puddles of water hither and yon – You see jets of water coming up between rows, from valves, at couplings, etc – Tiny rivers appear out of nowhere

In a drought emergency… • Don’t prune or fertilize plants (creates more stress)