seal  Purdue News

July 8, 2003

Floods may affect water and soil quality, Purdue experts advise

WEST LAFAYETTE, Ind. – Floodwater from recent heavy rains could affect water quality, however, overflows from livestock manure lagoons do not have to have significant impact, according to Purdue University experts.

flooded hog operation
Download photo - caption below

Many potential problems should be averted because rainfall dilutes contaminants, but plants likely will be damaged, said Ron Turco, agronomy professor and director of the Purdue Environmental Sciences and Engineering Institute.

"During floods, water often comes in contact with things it shouldn't, such as gasoline, oil, and pesticides in storage facilities, allowing a higher than normal potential for contamination," Turco said. "With a lot of rainfall the situation is still a problem, but the contaminants are diluted and pose less of an immediate risk.

"The floodwaters also can affect plants, from the grass on the golf course to corn and soybean crops."

Floodwater can harm plants in a couple of ways, including lessening the amount of oxygen and nitrogen in the soil, Turco said. Roots submerged for more than a short period of time can die because they aren't receiving enough oxygen. Nitrogen is lost to leaching or is converted to a gas and lost under the anaerobic conditions.

Drinking water also can be contaminated if floodwater gets into a water main or goes too near a wellhead, he said.

Don Jones, an agricultural and biological engineering professor who served on the state task force on confined feeding operations, said the storm over the weekend was "the storm of the century." Despite that, he doesn't believe significant water quality issues will arise due to flooding, but disposal of effluent, a water and manure mixture, will be a problem because of the rain-saturated soil.

"Most livestock manure storage tanks in Indiana are built for a 24-hour, 25-year storm, which is rainfall of about five and a half inches in a 24-hour period," Jones said. "For central Indiana – the areas affected by this storm – a 100-year storm is about six to seven inches. Most waste lagoons aren't built to withstand a storm like the one that went through Indiana in the past two or three days; Howard County had nine to 10 inches over a couple of days."

Jones said a recent change in Indiana's environmental rules allows for use of an emergency spillway from lagoons in order to safeguard the integrity of the structures' earthen sidewalls.

If a lagoon overflows its earthen sidewall, erosion could be severe enough to weaken the dam to the point of failure. Diverting effluent through a paved emergency spillway, while not desirable, is better than an earthen sidewall collapsing and emptying the entire lagoon contents, Jones said. However, state authorization is required to use a spilllway in any way other than that allowed by the farm's permit.

"It's a real dilemma because the ground is so wet there isn't a dry place or much higher ground to take the effluent," he said. "So farmers can't irrigate until the fields are dry enough to absorb the liquid."

Jones said when North Carolina and Georgia were faced with the same problems last year, they received exemptions from state environmental groups to irrigate some effluent on wet ground in order to relieve the pressure.

If a farm has a spill or overflow, or if it's impossible to maintain the amount of freeboard required by the farm's permit, the Indiana Department of Environmental Management (IDEM) must be contacted. Freeboard is the amount of open space between the water level and the top of the earthen wall. Jones said agency officials have told him that they will work with farmers on a case-by-case basis to alleviate problems.

"In talking with IDEM officials, they indicated that they are working on a policy for Indiana in response to the flooding emergency," Jones said.

Anyone who needs assistance to dispose of effluent should contact the IDEM inspector in the county were the farm is located, or call Angie Lee at the department's Indianapolis office at (317) 308-3045.

Max Michael, section chief of IDEM emergency response programs, said that as of today (Tuesday, 7/8) the state had no reports of drinking water problems.

"We expect the situation to worsen before it gets better," Michael said. "It's changing by the hour, and as the runoff seeps from the soil, rivers, lakes and ponds will continue to rise, even without more rain."

The State Emergency Management Agency (SEMA) is collecting information from county emergency management directors. Currently local states of emergency have been declared in Carroll, Cass, Wells, Adams and Howard counties. SEMA is working with the governor's office to determine if the state should declare a state of emergency in any counties.

Once local and state agencies have accessed the damage, information will be sent to the Federal Emergency Management Agency to determine if federal funds are available.

Pam Bright, SEMA spokesperson, recommended that citizens affected by the storms contact their county emergency office. She also urged people who have water rising around their homes to evacuate until the floodwater recedes.

Writer: Susan A. Steeves, (765) 496-7481,

Sources: Ron Turco, (765) 494-8077,

Don Jones, (765) 494-1178,

Max Michael, (800) 451-6027

Pam Bright, (800) 669-7362

Ag Communications: (765) 494-2722; Beth Forbes,;


Related Web sites:
Purdue Environmental Sciences and Engineering Institute
Purdue Department of Agronomy
Purdue Department of Agricultural and Biological Engineering
Indiana State Emergency Management Agency
Indiana Department of Environmental Management


Livestock manure storage at farms, such as the hog operation pictured, and water quality could be affected by the recent floods. However, Purdue University experts say that the large amount of rain dilutes contaminants, negating potential risks. (Agricultural Communication Service photo/Tom Campbell)

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