CAFO Wet Weather Event Management

Table of Contents

Permitted animal feeding operations in Missouri must meet design criteria that exceed national design standards for manure storage facilities. At times operators of these facilities are faced with precipitation events that exceed the design criteria for their operation. The objective of this web page is to help operators make the best possible decisions when faced with this situation.

Remarkably, 60 Missouri counties have encountered a rainfall event exceeding the 25-year 24-hour design storm criteria at some point in 2008.


Managing Wet Weather Events on your Farm

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Rule 1: Do not let your facility overflow or otherwise degrade the physical integrity of your manure storage facility.

CAFO and AFO owners/operators when faced with a lagoon or other manure storage facility that is likely to discharge should take action to ensure that the integrity of the lagoon berms are protected. Such actions can include pumping onto saturated ground or allowing manure to exit the spillway of the lagoon.

Such a discharge will likely result in a notice of violation (NOV). However, if it can be shown that the facility was operated properly and rainfall events affecting the storage facility exceeded the design capacity of the facility the penalties may be waived by MDNR.

Potential penalties for land application onto wet or frozen ground often are less than penalties for an over-flowing manure storage. In no case can any discharge from a facility result in degradation of the waters of the State of Missouri below water quality standards and penalties are likely if a spill results has measurable impacts on waters of the State.

See the publication "Emergency Lagoon Management Practices (.pdf format)" developed by Missouri Department of Agriculture, Missouri Department of Natural Resources, and University of Missouri Extension for guidance on managing full lagoons under wet conditions.

Always work with MDNR when faced with these types of difficult problems. If a spill is likely or imminent you must contact your MDNR Regional Office. They can provide more specific guidance for your situation.

For further information you can contact the Water Protection Program at 800-361-4827 or 573-751-1300.


June 2008 Wet Weather Event

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Above average rainfall coupled with record setting heavy rains throughout much of Missouri have posed challenges for managers of municipal and agricultural open waste storage facilities. In some parts of the state it is likely that some types of discharges will be covered as an authorized discharge under their permit if they meet the conditions. Emergency Lagoon Management Practices are likely to apply in many areas of the state.

Many counties in Missouri experienced rainfall that exceeded the 25-year 24-hour design storm during the precipitation event running from June 24-25. Dr. Pat Guinan, MU State Climatologist, developed a map delineating counties where some portion of the county was likely to have encountered such rainfall amounts.

Map of counties affected by rainfall exceeding the 25-year 24-hour design storm

On June 27, 2008 MDNR distributed the following press release:

Volume 36     392        Renee Bungart
(For immediate release)        573-751-4465

DEPARTMENT WAIVES CAFO REQUIREMENTS DUE TO
FLOODING IN NORTHERN MISSOURI

JEFFERSON CITY, MO, JUNE 27, 2008 - Following Executive Order 08-21 issued by Gov. Blunt on June 20, the Missouri Department of Natural Resources is allowing Concentrated Animal Feeding Operations, better known as CAFOs, in northern Missouri to discharge wastewater from their lagoons and land application process. The department is allowing such discharges to prevent lagoons from experiencing a catastrophic failure due to the record rainfall and flooding.

The department has determined that Gentry, Harrison, Daviess, Mercer, Grundy, Livingston, Carroll, Putnam, Sullivan, Linn, Chariton, Schuyler, Adair, Macon, Randolph, Knox, Shelby, Monroe, Lewis and Marion counties in Northern Missouri have exceeded the established catastrophic design storm event. Within these counties, a facility's water pollution permit allows discharges from lagoons or runoff from land application resulting from storm-related events.

Although a direct discharge may be allowed, the department strongly recommends that if a facility is faced with a lagoon that is likely to discharge, appropriate action should be taken to ensure that the integrity of the lagoon berm is protected so that complete failure does not occur. This must include land applying effluent on pasture or other vegetated ground that may be wet or saturated as opposed to allowing a lagoon to overtop.

Given the magnitude of the recent storm events and expectation of additional rain, the department has also waived the land application limits and restrictions within department CAFO permits until further notice for those counties listed above. CAFO operators are still required to keep detailed records of weather conditions, overflows and land application activities. As an alternative to the permit's land application restrictions, the department strongly recommends following the applicable portions of the department's wet weather guidance. This guidance can be found on the department's Web site at www.dnr.mo.gov/env/wpp/cafo/index.html.

In addition, the department should be notified if lagoon discharges are imminent or occurring. By contacting the department, staff can give specific guidance for on-farm situations.

"Communication between department staff and CAFO owners and operators is absolutely critical in these situations. Although our first concern is the safety of Missouri citizens, I want Missourians to know we are well equipped and ready to assist and guide operators, which can be key to ensuring that water quality is protected," said the department's Division of Environmental Quality's deputy director Earl Pabst. "I commend all those who have worked hard and sought guidance and solutions to protect both their operations and water quality and encourage everyone to maintain vigilance during what is expected to be the highest recorded rainfall in history in some portions of Missouri."

Northern Missouri has experienced an extended period of high rainfall and wet soil conditions this spring and summer. Analysis of 2008 rainfall has indicated that, beginning in December 2007, Missouri has experienced rainfall events significantly exceeding normal rainfall. Of greater concern is the frequency of the rain events over the last 30 to 60 days, as rain events have caused saturated soil conditions throughout the normal planting season over most of the state.

For more information, contact the department's Water Protection Program at 800-361-4827 or 573-751-1300. The department has additional flooding information and guidance available on the Web at www.dnr.mo.gov/disaster.htm.

For news releases on the Web, visit www.dnr.mo.gov/newsrel. For a complete listing of the department's upcoming meetings, hearings and events, visit the department's online calendar at www.dnr.mo.gov/calendar/search.do.


March 2008 Wet Weather Event

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Above average rainfall since December 2007 throughout much of Missouri coupled with record setting heavy rains throughout much of the state March 17 to 18 have posed challenges for managers of municipal and agricultural open waste storage facilities. In some parts of the state it is likely that some types of discharges will be covered as an authorized discharge under their permit if they meet the conditions. Emergency Lagoon Management Practices are likely to apply in many areas of the state. See maps below.

Many counties in Missouri experienced rainfall that exceeded the 25-year 24-hour design storm during the precipitation event running from March 17-18. Dr. Pat Guinan, MU State Climatologist, developed a map delineating counties where some portion of the county was likely to have encountered such rainfall amounts.

Map of counties affected by rainfall exceeding the 25-year 24-hour design storm

The high rainfall amounts that fell throughout Missouri on March 17-18 fell on land already saturated by above-average rainfall throughout the winter. According to Dr. Pat Guinan, MU State Climatologist, almost every county in the state has had rainfall amounts that meet the definition of a 90th-percentile chronic storm event for the period of December 2007 to March 2008.

Map of counties meeting 90th-percentile chronic storm criteria