Possible Sources of Nitrate in Ground Water at Swine Licensed-Managed Feeding Operations in Oklahoma, 2001

By Mark F. Becker, Kathy D. Peter, and Jason Masoner


Water-Resources Investigations Report 02–4257


Prepared in cooperation with the
Oklahoma Department of Agriculture, Food, and Forestry


The report is available in PDF format.


Samples collected and analyzed by the Oklahoma Department of Agriculture, Food, and Forestry from 1999 to 2001 determined that nitrate exceeded the U.S. Environmental Protection Agency maximum contaminant level for public drinking-water supplies of 10 milligrams per liter as nitrogen in 79 monitoring wells at 35 swine licensed-managed feeding operations (LMFO) in Oklahoma.

The LMFOs are located in rural agricultural settings where long-term agriculture has potentially affected the ground-water quality in some areas. Land use prior to the construction of the LMFOs was assessed to evaluate the types of agricultural land use within a 500-meter radius of the sampled wells.

Chemical and microbiological techniques were used to determine the possible sources of nitrate in water sampled from 10 wastewater lagoons and 79 wells. Samples were analyzed for dissolved major ions, dissolved trace elements, dissolved nutrients, nitrogen isotope ratios of nitrate and ammonia, wastewater organic compounds, and fecal coliform bacteria. Bacteria ribotyping analysis was done on selected samples to identify possible specific animal sources.

A decision process was developed to identify the possible sources of nitrate. First, nitrogen isotope ratios were used to define sources as animal, mixed animal and fertilizer, or fertilizer. Second, wastewater organic compound detections, nitrogen-isotope ratios, fecal coliform bacteria detections, and ribotyping were used to refine the identification of possible sources as LFMO waste, fertilizer, or unidentified animal or mixtures of these sources. Additional evidence provided by ribotyping and wastewater organic compound data can, in some cases, specifically indicate the animal source. Detections of three or more wastewater organic compounds that are indicators of animal sources and detections of fecal coliform bacteria pro-vided additional evidence of an animal source.

LMFO waste was designated as a possible source of nitrate in water from 10 wells. The source of waste in water from five of those wells was determined through ribotyping, and the source of waste in water from the remaining five wells was determined by detections of three or more animal-waste compounds in the well samples. LMFO waste in the water from wells with unidentified animal source of nitrate does not indicate that LMFO waste was not the source, but indicated that multiple animal sources, including LMFO waste, may be the source of the nitrate.




Purpose and Scope



Methods of Study

Site Selection and Sampling Methods

Analytical Methods

Quality Assurance and Quality Control

Identification of Possible Sources of Nitrate

Land Use

Water Quality and Chemical and Microbiological Techniques

Water Properties

Major Ions and Trace Elements


Nitrogen Isotopes

Wastewater Organic Compounds

Bacteria and Ribotyping

Possible Sources of Nitrate in Ground Water


Selected References


  1. Dissolved major ions analyzed in samples from 10 lagoons and 76 of 79 monitoring wells at swine licensed-managed feeding operations in Oklahoma, 2001

  2. Dissolved trace elements analyzed in samples from 10 lagoons and 76 of 79 monitoring wells at swine licensed-managed feeding operations in Oklahoma, 2001

  3. Wastewater organic compounds analyzed in samples from eight lagoons and 78 of 79 monitoring wells at swine licensed-managed feeding operations in Oklahoma, 2001

For additional information write to:


District Chief

U.S. Geological survey

202 NW 66 St., Bldg. 7

Oklahoma City, OK 73116


Copies of this report can be purchased from:


U.S. Geological Survey

Branch of Information Services

Box 25286

Denver, CO 80225-0286

Download the PDF version of the report for high-resolution, printable pages (6MB).

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