The Role of the Odor Footprint Tool in Livestock Nuisance Litigation

The Role of the Odor Footprint Tool in Livestock Nuisance Litigation

Steers in lot
Photo credit Troy Walz.

The following is a summary of the webinar “The Role of the Odor Footprint Tool in Livestock Nuisance Litigation” given on Jan. 21, 2021, as part of the University of Nebraska-Lincoln’s Department of Agricultural Economics Extension Farm and Ranch Management team’s weekly webinar series. The webinar and accompanying podcast can be accessed here.

Nebraska Supreme Court Case

In Nebraska livestock nuisance lawsuits, the major issue is how bad are the livestock odors. The worse they are, the more likely neighbors will win and the more money damages they will collect. The fewer the odors, the more likely the neighbors will lose their lawsuit. In Egan v. Lancaster County, the Nebraska Supreme Court ruled, in part, that the livestock odor footprint analysis indicating that neighbors would not experience significant livestock odors 94% of the time justified granting the county zoning permit for a proposed poultry facility. This analysis was based on the Nebraska Odor Footprint Tool (NOFT) developed at the University of Nebraska–Lincoln.

The NOFT is likely to become a key component of any future Nebraska livestock nuisance litigation. Up to now, testimony regarding the severity and frequency of livestock odors has been based on subjective evidence. If many witnesses testify that they experienced bad odors, the jury decides whether that testimony makes the livestock facility a nuisance or not. The NOFT provides more objective information regarding odor, which juries, judges, and zoning decision-makers may find more credible than subjective assertions about how bad odors will be or have been. 

Nebraska Odor Footprint Tool

The Nebraska Odor Footprint Tool provides objective, science-based information on odor risk from several common housing systems for livestock and poultry operations.  The output of the tool consists of separation distances in four primary directions that correspond with a range of odor risk levels.  A useful end product is a visual that shows one or more sets of these distances on a map, satellite image, or other graphic. This allows for siting an animal feeding operation in a strategic location that limits the likelihood of existing neighbors experiencing odors from the operation.

One of the goals for the NOFT is to encourage producers to give additional consideration to their rural neighbors and odor risk when siting new facilities.  A potential benefit of using the NOFT can be increased credibility of applications that are submitted for county approval of new or expanding animal feeding operations.  While the Egan v. Lancaster County ruling mentions a specific risk level, the ruling appears to prioritize the fact that county officials had done their due diligence in considering the well-being of residents. Utilizing objective information and evaluating the results of science-based tools, such as the Nebraska Odor Footprint Tool, was key to their process.

Frequently Asked Questions

Q: Was this a Nebraska Supreme Court decision or a US Supreme Court decision?

A: [Dave] The court case came out of the Nebraska Supreme Court. To our knowledge, this is the first court decision anywhere in the United States that was based on the outcomes from the Odor Footprint Tool or a similar quantitative method to project odor risk.

Q: What was the significance of this court case and how did this change legal precedent for livestock operations both in Nebraska and the United States?

A: [Dave]This case is a major development in Nebraska livestock nuisance law. This court case was the first to use a quantitative measure to assess odor risk. This will allow evidence and expert testimony to move away from subjective opinion to something that is quantifiable. Future Nebraska livestock nuisance litigation will likely rely on the Odor Footprint Tool or another tool to help quantify odor nuisance.

Q: What are the benefits and drawbacks of adding the Nebraska Odor Footprint Tool to the Livestock Siting Matrix?

A: [Rick]The footprint tool is currently an optional element of the matrix. One of the primary difficulties in creating the Livestock Siting Matrix was handling existing setback requirements. In Nebraska, there is a strong desire for counties to continue to control setback requirements for zoning. Consequently, the matrix still considers local setbacks as the primary determinant of the minimum separation distances needed. The footprint tool was used to develop representative separation distances to meet 94% odor-annoyance-free conditions. Counties are encouraged to consider information like this to gauge or calibrate their setbacks. 

Q: How was weather taken into consideration when developing the odor footprint tool?

A: [Rick]Ten to fifteen years of hourly historical weather data for six regions in the state were used in the odor dispersion modeling. Weather factors included wind speed, wind direction, temperature, humidity, and cloud cover.  Modeling results were projected odor concentrations for a mesh [fine grid] of locations around an odor source, showing the extent of the odor plume on an hour-by-hour basis. Using this information, frequencies of ‘odor-annoyance-free’ time were determined for all of the mesh points at various distances and directions from the source facility. No future changes in weather were incorporated into the models. While there are some assertions that the climate in Nebraska may be warming, this tool relies heavily on wind direction and wind speed, and I’m not aware of any robust research that indicates that wind patterns would change significantly with a changing climate. I’ve yet to hear suggestions that our prevailing wind directions are changing.

Q: Based on this decision, could neighbors sue existing operations if the operation was found to be non-compliant with “acceptable” odor footprint levels?

A: [Dave] Generally, the deadline for filing a lawsuit against an operation is within two years from when the nuisance first began. If there is an expansion or a remodel of an existing operation then this lawsuit deadline would restart from the time the expansion or remodel is completed. Expansion or remodeling of an operation is likely to be tied to the Nebraska Department of Energy and Environment (DEE) permits rather than seasonal or yearly fluctuations in livestock numbers since operations are permitted to operate within a certain capacity range. Expansion or remodeling beyond these capacity limits requires a new permit to be issued by DEE.

Q: How does the Odor Footprint Tool differentiate between total hours within the year that is classified as “odor-free” versus the number of hours within each day that is classified as“odor-free”?

A: [Rick] ‘Odor-annoyance-free’ levels were determined using 10 to 15 years of hourly data for the warm half of the year (April 15 to October 15). The tool does not report results on a seasonal, daily, or time-of-day basis. Many people like to communicate using ‘on-average’ numbers; for example, a 94% ‘odor-annoyance-free’ condition equates to 28 days out of a 30-day month, on average, during which potential for odor annoyance is not presented. However, caution and discretion need to be used when presenting results on smaller time scales or thinking of the footprint tool as an odor forecasting tool; one could expect similar lack of success as for predicting tomorrow’s or next week’s weather using monthly averages.

Q: How often is the science behind the Odor Footprint Tool updated to reflect new or current information, knowledge and/or research?

A: [Rick]There has been little updating since the tool was developed. There is little evidence that the science or modeling behind the Odor Footprint Tool was incorrect or invalid. Further, there’s little indication that the amount of odor – on a per-head or per-unit-area basis – generated by commercial livestock operations using conventional practices has changed dramatically since the tool was developed. One key strength of the tool is that modeled odor levels were verified using groups of people as the main sensors. This was important to developing credibility given there are currently no sensors that are reliable for quantifying livestock odor and many people would be reluctant to trust a device over the human nose.

Q: Are there sensors available that measure airborne “odor particles” that could be used to assess air quality?

A: [Rick] ‘Odor particles’ do not exist; although airborne particles, including dust, may contain odorants. Sensors for measuring dust levels are available and the concentration of particulate matter is a measure of air quality, but dust concentration is not a reliable measure of odor.  Livestock odor is challenging to measure due to the large variety of compounds that might be present, and the fact that some of the more odorous smells come from various volatile organic compounds that are hard to measure outside of the laboratory and break down quickly. There are reliable sensors to measure levels of common odorous gases, such as ammonia or hydrogen sulfide, but none of these sensors reliably translate measurements into human perceptions of farm odor levels. That is why the Odor Footprint Tool modeling was validated using people.

Q: Where can I find the Odor Footprint Tool and the Livestock Siting Matrix?

A: [Rick]The Nebraska Odor Footprint Tool can be found at and the Nebraska Livestock Siting Assessment Matrix can be found at Questions regarding either of these tools can be addressed to Rick Stowell at the University of Nebraska–Lincoln.