Water sources for small scale irrigation
The water supply for small irrigation or greenhouse system is the heart of system. Success is often the result of good forward planning before you ever need to start moving water.
Irrigation water capacity requirements for greenhouse production and summer field production are about the same. In Michigan and Indiana evaporation and plant water use from the soil are between 0.25 inches and 0.30 inches for several days each summer or at peak growth in greenhouses. Systems that can provide five gal/acre irrigated will meet the 0.25 inches/day. Seven gal/acre irrigated is needed to provide 0.30 inches water requirements. This capacity will be require 24 hours per day seven days per week continued pumping in time of drought or double the capacity for 12 hour per day use.
Ground water is the best choice for most situations. Nearby large volume irrigation, municipal or industrial wells are an excellent source of information water availability. Well drillers familiar with drilling wells in your area are also excellent resources. Michigan has available groundwater mapping tools that can help evaluate potential water withdrawal sites. Indiana also has information on groundwater available.
A typical well system for 70 gallon per minute of continuous water would often be five or six inch plastic pipe well with 15 feet of screen and a seven and a half horse pump. They could be controlled with a variable frequency drive unit to allow changes in output or a pressure regulator and a pair of large pressure tanks (40-60 gallon). Large tank increase the cycle time to prolong the life of the pump. Pressure regulator will cycle the pump on and off while the pressure tanks maintain the flow and pressure much like our common house systems. Cost for the well under a 100 feet deep, screen, pump and pressure tank will be in the $10,000 area and more if a variable frequency drive unit is used.
Try to avoid using the home water supply for irrigation. Conventional home wells are not designed for continuous use. Adding irrigation of just three to four acres can be costly on pump and controller repairs. Home well screens and pump intake placement is often not designed for the volume needed to irrigate. The necessary back flow equipment needed to protect the potable water supply is very expensive and can be a challenge to maintain.
Surface water may be available at some sites in dependable usable volumes for small scale irrigation. These quantities need to available at the time of maximum irrigation, often late July early August- field production and late spring early summer for green house production. Late summer is the season the surface waters are near their lowest. Make sure to evaluate available flow the summer before you start irrigating. In most areas you may not deplete stream flow to the extent that it negatively impacts neighbors or the environment. If not, consider part of water of the states drainage ditches flow maybe depleted. Remember there can be major challenges in using surface water for vegetable irrigation and cooling and meet food safety requirements and filtration issue for trickle irrigation uses.
Make sure you understand your rights and obligation to use water in your State. For example Michigan operates as a riparian state for surface water use allowing only the property with legal description adjacent to the surface water to receive the water, but well water maybe transfer between properties. For information on Michigan water rights be sure to look at the Michigan State University Extension page. There is also information on Indiana water rights.
State water registration is often required. Even small scale irrigation water use is often a large volume water use (capacity to pump > 70 gal. / min.). Seventy gallons per minute is enough capacity to meet the average summer time removal for 14 acres of irrigated crops if ran 24 hours/day seven days a week. In both Indiana and Michigan new installations require a registration. In Indiana this is handled by Indiana DNR.
In Michigan you will need to work through the Michigan Water withdrawal assement tool to determine if your purposed water use is likely to cause a negative environmental impact. At the end of the process you will either be able to register online or may be required to request a site specific review for MDEQ. MDEQ site specific review may result in allocation of the water resulting in registration or the opportunity to bring together all large volume water users in the water shed to negotiate reduce use by existing water users to allow allocation for a new water use. Check out Michigan’s water use registration process to find out more information and for Indiana’s water use registration processes.
Identify available power sources; three phase power line near the potential water source is the cheapest and least restrictive. For small scale irrigation wells, single phase power is often feasible. Variable frequency drive unit can be used to run three phase pumps from a single phase power source in many situations. Liquid fuel storages near wells and surface water have potential risks along with higher equipment maintenance and fuel cost leave internal combustion engine as a last resort for irrigation power.
Good irrigation planning can set your direction for a profitable and effient irrigation future. For more irrigation design and management information visit the Michigan State University Extension irrigation page.