Wisconsin's agriculture community and its dairy sector can credit a great share of their success to the availability of an abundance of ground and surface water.
How much of that water is being used per year is being tracked by the water use section in the Wisconsin Department of Natural Resources. One person who accumulates and reviews those state-wide statistics is Robert Smail, who gave a presentation on the topic in a breakout session at the 61st annual conference of the Wisconsin Land and Water Conservation Association.
Smail noted that there is approximately a 95 percent compliance rate on the part of users of large volumes of water in filing annual reports on their monthly use. These include about 12,000 that draw on groundwater and another 1,000, including municipalities and power plants that take in surface water, he said.
During 2012, those 13,000 entities used more than 292 billion gallons of water — an increase of 37 percent from 2011 because of the widespread drought during 2012, Smail noted. He said that volume of water is the equivalent of a quarter inch on Wisconsin's entire landscape or enough to fill Lambeau Field in Green Bay about 600 times.
Smail said the water use section estimates an additional use of 50 to 75 billion gallons by those who are not required to report. Those are mainly livestock farms and private residences.
Water use statistics for 2013 are not yet available, but requests for another 364 high-capacity wells for over 70 gallons per minute were approved during the year, Smail said. He added that more than 200 new requests are pending.
Of the high-capacity well owners, there are about 8,000 who have the capability of using more than 70 gallons per minute while another 4,000 operate at a capacity of up to 70 gallons per minute, he said. Smail also mentioned that cranberry bogs and golf courses are high-volume seasonal users.
Starting in 1977, there was a huge jump in water use for irrigation of agricultural land, Smail said. With maps dated every 10 years since 1960, he showed how the numbers and geographical location of high-capacity wells emerged across the state.
This happened through a combination of a population increase, growth in the economy and consolidations in agriculture and other sectors, he said. He identified the Central Sands and south central and west central parts of the state as the areas with the greatest increase during recent decades.
In one analysis, there has been a very strong correlation between corn prices and periods of drought with the volume of water used for irrigation, Smail added. He also cited an approximate 90 percent correlation between the location of high-capacity wells and a landscape geology with a minimum of either 50 feet of sand and gravel or bedrock.
Reports from 822 Wisconsin dairy farms for 2012 indicated a water use of about 5 billion gallons — an increase of 28 percent from 2011, Smail stated. He said this was right in line with other estimates of the daily use of 35 gallons per cow — as low as 20 gallons for a few Jersey herds to above 40 gallons for others.
For Wisconsin's dairy sector as a whole, Smail gave an estimate of 45 million gallons of water used per day or 16 billion for an entire year. In most cases, a high-capacity well is needed for a dairy herd of at least 2,500 cows.
Within the agriculture sector, irrigation of crops overshadows all other uses of water with daily totals running as much as 70 times the volume in the dairy sector, Smail said. The total use for irrigation in 2012 was 135 billion gallons, which was an increase of 83 percent from 2011 due to the year's drought.
That amount of water is enough to cover all of Dane County with 5.5 inches and is equal to how much water is in Lake Mendota or to the total annual flow of the Rock River in southern Wisconsin, he noted.
Among the more than 4,000 wells used for agricultural irrigation, most have a capacity of more than 1,000 gallons per minute, Smail said. He pointed out that 68 percent of the landscape in the Plainfield area of Waushara County is irrigated.
Of the water used for irrigation in Wisconsin during 2012, groundwater sources provided 46 percent. Across the United States, groundwater provides for 68 percent of the irrigation volume.
Whatever the volume of water use, there are probably opportunities to reduce the water use, Smail said. He suggested that irrigators can reduce their use in many cases by scheduling applications that match the plant phenology for making best use of the water and by targeting the placement instead of a broadcast application.
There's usually less opportunity for reducing use in the dairy sector, but this does not rule out the multiple use of water. Smail mentioned diverting cooling water to drinking water for cattle and using greywater for cleaning floors.
In a presentation at the same breakout session, Todd Boehne of the Wisconsin Department of Agriculture, Trade, and Consumer Protection described practices that make efficient use of water and the equipment. He mentioned system performance, uniformity of application and crop response as the items that affect efficiency.
System performance is affected by equipment sizing and by the amount of energy that is needed to run it, Boehne said. He suggested taking advantage of off-peak electric power rates.
Other variables are the effect of irrigation on nutrients, the settling of salts into the soil and erosion control, particularly in reducing the erosion of dry soil by the wind, he said. Boehne also cited the importance of maintaining the physical integrity of the irrigation system and showed the diversity of the equipment being used in Wisconsin.