Protecting Public Health and the Environment.

Permit by Rule for Dairies

A permit by rule (PBR) is a process by which a facility that emits air pollutant(s) may register with DEQ in lieu of obtaining a site-specific air quality operating permit. A PBR is a simple and efficient alternative to an individual permit. In a PBR, requirements are spelled out in the rule and apply to all members of a particular industry.

In April 2005, in response to a request by the Independent Dairy Environmental Action League (IDEAL) and the Idaho Conservation League (ICL), a negotiated rulemaking was initiated to consider air quality permit rules to control ammonia from dairy farms. Participants in the negotiated rulemaking included representatives of the Idaho Dairymen's Association, Milk Producers of Idaho, ICL, Idaho State Department of Agriculture (ISDA), and DEQ. The negotiated rulemaking culminated in developing a PBR for dairy farms. The rule was approved by the Idaho Board of Environmental Quality in February 2006 and took effect July 1, 2006.

It requires dairy farms above specified threshold numbers of cows or animal units to register with DEQ and to implement industry best management practices (BMPs) to control ammonia emissions. A list of BMPs is contained in the rule. Each BMP is assigned a point value. Dairy farms must employ BMPs totaling 27 points.

Why control ammonia emissions?

Ammonia is a common by-product of animal waste. The volume of ammonia emissions depends on manure characteristics and how the manure is managed.

Ammonia emissions are an environmental concern because they can adversely impact water and air quality. Ammonia emissions can contribute to eutrophication of surface waters and nitrate contamination of ground water. In addition, when emitted ammonia is combined with acidic compounds in the upper atmosphere, fine dust particles (particulates) capable of being inhaled are formed. These particulates have been related to atmospheric haze, and also have been attributed to a variety of adverse human health effects, including premature mortality, chronic bronchitis, asthma, and other respiratory ailments.

Who does the PBR apply to?

The PBR applies to dairy farms with a capacity to produce 100 or more tons of ammonia emissions per year. (Dairy farms with fewer than the specified number of animal units or mature cows may opt into the PBR program as well.) The capacity to produce is based on the number of animal units or mature cows and the type of manure collection system. The tables below shows the applicable thresholds prescribed in the rule:

Animal Unit (AU) Basis Drylot Free Stall/Scrape Free Stall/Flush
  AU (100 t NH3) Threshold
No land app 7,089 3,893 2,293
27% volatilization1 6,842 3,827
80% volatilization2 6,397 3,700
Cow Basis (1,400 lb) Drylot Free Stall/Scrape Free Stall/Flush
  Total Cows AU (100 t NH3) Threshold
No land app 5,063 2,781 1,638
27% volatilization1 4,887 2,733
80% volatilization 4,589 2,643

1 Assumes expected level of N->NH3 volatilization for drop-hose or ground level liquid manure application.

2 Assumes expected level of N->NH3 volatilization for center pivot or other conventional sprinkler irrigation liquid manure application

What types of BMPs can dairies employ?

The rules prescribe various BMPs to control ammonia emissions, ranging from installing certain types of waste storage and treatment systems to implementing composting practices to exporting manure. A point value is assigned to each BMP. Dairy farms must employ BMPs totaling 27 points.

The use of Zeolite applications has been added to the list of Ammonia Control Practices. Refer to the following for supporting documentation:

How do dairy farms comply with the PBR?

To comply with the PBR, dairy farms subject to the rule must register with DEQ and ISDA by providing the following information:

  • Name, address, location of dairy farm, and telephone number
  • Information on the size and type of the dairy farm
  • Information on the type of BMPs that the dairy farm is employing to total 27 points

  • Permit by Rule Registration Form: Word  |  PDF

How does the state ensure compliance?

Within 30 days of receiving a dairy farm's registration information, ISDA conducts an inspection to ensure that the required number of BMPs are employed. ISDA also provides compliance assistance if needed. If ISDA finds that BMPs are lacking, it may issue a warning letter.

Enforcement of the rule is DEQ's responsibility. Enforcement methods include filing a notice of violation or referring the case to the Attorney General's office for civil enforcement. In the event of unforeseen equipment upsets and breakdowns, DEQ exercises enforcement discretion. So long as corrective action is taken within a reasonable time, which would depend on specific circumstances, the event does not reduce the BMP point value. In the event of an emergency, the farm may apply for and be granted an exemption for up to   1 year.

Staff Contacts

Air Quality Permitting Hotline
1-877-5PERMIT (1-877-573-7648)
Call to set up a meeting or ask air quality permitting questions.

Air Quality Permit Supervisor
Darrin Pampaian
DEQ State Office
Air Quality Division
1410 N. Hilton
Boise, ID 83706
(208) 373-0587

DEQ Resources

More Information

Rules for the Control of Ammonia from Dairy Farms (IDAPA

Dairy Air Emissions Analysis