Nutrients like nitrogen and phosphorus are necessary for healthy waters, but high levels of nutrients can cause a number of problems, ranging from nuisance algae blooms and cloudy water to threatening drinking water and harming aquatic life. Levels of nitrogen and phosphorus in Iowa's waters are generally two to 10 times the levels considered appropriate for Midwest streams.

For cleaner drinking water, for recreational opportunities -- substantially reducing the level of nutrients is a significant but necessary challenge for Iowa.

Iowa's nutrient budget, found below, investigates nutrient levels in Iowa and how excess nutrients end up in our water.

Nutrient Science Advisory Committee

Assessments of Practices to Reduce Nitrogen and Phosphorus Nonpoint Source Pollution of Iowa’s Surface Waters (*.pdf, 6.4MB)

Nutrient Budget

• Summary (*.pdf)
• Full technical report (*.pdf)

Nutrient Budget Maps (PDF files)

• Nitrogen inputs
• Nitrogen stream loads
• Phosphorus inputs
• Phosphorus stream loads

Iowa Code on the Nutrient Budget
According to Iowa Code 459.312(10)2b:

The department shall develop a state comprehensive nutrient management strategy. Prior to developing the state comprehensive nutrient management strategy, the department shall complete all of the following:

(i) The development of a comprehensive state nutrient budget for the maximum volume, frequency, and concentration of nutrients for each watershed that addresses all significant sources of nutrients in a water of this state on a watershed basis.

(ii) The assessment of the available nutrient control technologies required to identify and assess their effectiveness.

(iii) The development and adoption of administrative rules pursuant to chapter 17A required to establish a numeric water quality standard for phosphorus.

More nutrient information from the DNR:

• Nonpoint Source Pollution
• Animal Feeding Operations
• Water Monitoring
• TMDLs (Total Maximum Daily Load) and Water Quality Assessment
• Water Quality

For more information, contact:
Bob Libra
State Geologist
(319) 335-1585
blibra@igsb.uiowa.edu