AlgaeNutrients 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.

Assessments of Practices to Reduce Nitrogen and Phosphorus Nonpoint Source Pollution of Iowa’s Surface Waters

Stream Nutrient Criteria to Protect Aquatic Life:
The DNR is utilizing a technical advisory committee (TAC) to assist with development of nutrient criteria for the protection of stream aquatic life. The TAC will examine important technical issues concerning nutrients and their effects in streams, and will develop criteria recommendations that represent the best-available scientific information.

Stream Aquatic Life Nutrient Criteria TAC Roster

TAC Meeting Agenda, November 25, 2013
TAC Meeting Slides, November 25, 2013
TAC Meeting Notes, November 25, 2013

Draft Report of Stream Nutrient Criteria Recommendations, August 23, 2013 
Draft Report Appendices, August 23, 2013
Draft Report TAC Comment Summary, August 23, 2013

TAC Meeting Agenda, May 24, 2011
TAC Meeting Slides, May 24, 2011
TAC Meeting Notes, May 24, 2011
TAC Meeting Agenda - September 29, 2010
TAC Meeting Notes - September 29, 2010
TAC Meeting Handouts - September 29, 2010
TAC Meeting Agenda - April 7, 2010
TAC Meeting Notes - April 7, 2010
TAC Meeting Handouts - April 7, 2010

Lake Nutrient Criteria to Protect Recreation:
Informal Regulatory Analysis
Notice of Intended Action
Fiscal Impact Statement
List of Lake Depths
How Many Lakes Will Meet New Criteria?
Literature Citations
Statistical Analysis of Lake and Watershed Characteristics
Nutrient Science Advisory Committee:
Nutrient Science Advisory Committee Roster
Final Report of NAC, February 14, 2008
Meeting Agenda - November 5, 2007
Meeting Minutes - November 5, 2007
Meeting Agenda - October 15, 2007
Meeting Minutes - October 15, 2007
Meeting Agenda - August 9, 2007
Meeting Minutes - August 9, 2007
Meeting Agenda - July 19, 2007
Meeting Minutes - July 19, 2007
Meeting Agenda - June 26, 2007
Meeting Minutes - June 26, 2007
Meeting Agenda - June 13, 2007
Meeting Minutes - June 13, 2007

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.

Nutrient Budget - Summary
Nutrient Budget - Full technical report

Nutrient Budget Maps
- Nitrogen Inputs and Nitrogen Stream Loads
- Phosphorus Inputs and Phosphorus Stream Loads

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