# Presentation: 524585

## Gulf of Mexico Hypoxia and Nutrient Management in the Mississippi River Basin

- Herb Buxton,
- U.S. Geological Survey

## What Causes Gulf Hypoxia?

- “Hypoxia in the Northern Gulf of Mexico is caused primarily by excess N delivered by the MR Basin in combination with stratification of Gulf Waters.” *– Integrated Assessment, 2000*

## Gulf 

- _Hypoxic Zone_
- Measured1985-2000
- Largest extent, 2001

- Gulf
- Hypoxia

## NITRATE LOAD, ANNUAL STREAMFLOW AND N CONCENTRATION

- 1955-70 Avg. = 350,000 t/yr      1980-99 Avg. = 950,000 t/y

**Notes:**
About a 3-fold increase in annual nitrate load between 1955-70 and 1980-96.

## MR/GM Watershed

- Nutrients Task Force

- Task Force Action Plan,
- January 2001

- CENR Science
- Assessment,
- May 2000

## A Science-based Action Plan 

- Adaptive management.
- Consider all sources and mitigating actions.
- Voluntary Basis.
- Watershed and Gulf goals.

## Reducing 

**Reducing **
**Nutrient **
**Loads**

**De****c****reasing **
**N losses**

-      Filter Strips

- Riparian Forest Buffers

- Fertilizer Management

-      Farm N Management

## Reducing 

**Nutrient **
**Loads**

**Reducing**
**Point Sources **
**and Urban Runoff**

**Restoring Wetlands **
** ****to Increase **
**Denitrification**

## Reducing 

**Nutrient **
**Loads**

**Lock & Dam**
**Management**

**Diversions to **
**Coastal Wetlands **

**Increasing Denitrification**

## Nitrogen 

**USGS Gaging Station**

- Nitrogen
- Loads,
- 1980-96

- 1500 Water-Quality Measurements
- on 9 large sub-basins.

***(2.9M km******2******)***

- Goolsby and others

**Notes:**
The Red and Arkansas, the Upper and Lower Missouri, and the Uper and Lower Ohio respectively are combined here, resulting in 6 6 large sub-basins

## Nitrogen Yield, 

- Yield on 42 small Sub-basins calculated from  >4000 additional water-quality measurements.

- Nitrogen Yield,
- 1980-96

- Goolsby and others

## SPARROW, a Large River Management Tool

- Extend measurements at representative sites across the basin.
- Define the magnitude and distribution of nutrient loads (losses).
- Comparatively evaluate causal factors.
- Provide a framework for design and evaluation of management actions.

## SPARROW: Distribution of Nitrogen Yield 

**SPARROW: Distribution of Nitrogen Yield **

- Alexander and others

## Fraction of In-Stream Nitrogen Delivered to Gulf

**Fraction of In-Stream Nitrogen Delivered to Gulf**

- Alexander et al. *Nature*, 2000

## SPARROW Model Estimation of Total Nitrogen Delivered to the Gulf of Mexico from:

**A - Municipal and Industrial Discharges**
**B - Atmospheric Deposition , and **
**C - Fertilizer and Livestock Wastes.**

**A**

- 6% +/- 3

- 64% +/-21

- 18% +/- 10

## Monitoring Stations used for SPARROW Model 

**Monitoring Stations used for SPARROW Model **

-  Water quality monitoring at approximately 20 % of stations.
-  New monitoring must include MNGT actions.

## For Info on USGS and other activities related to Gulf of Mexico Hypoxia

-  http://toxics.usgs.gov/
- Click on Investigations

## Total Nitrogen Yield Delivered to Gulf of Mexico

**Total Nitrogen Yield Delivered to Gulf of Mexico**

**Agriculture**

**Point Sources**

**Atmosphere**

*Alexander et al. Nature, 2000*

**Notes:**
In addition to predicting the amount of nitrogen delivered to the Gulf of Mexico from each part of the Mississippi River basin, the SPARROW model can predict which types of sources of nitrogen account for those delivered loads.  These maps show the predicted yields of total nitrogen delivered to the Gulf of Mexico from major sources in the various drainage basins of the Mississippi River basin.  Agriculture is the sum of fertilizer and livestock wastes.  Point sources is the sum of industrial and municipal point sources.  Atmospheric sources result mainly from combustion.

## USGS Info On the Internet

- Hypoxia in the Gulf of Mexico: _[http://](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)__[wwwrcolka](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)__[.cr.](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)__[usgs](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)__[.](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)__[gov](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)__[/](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)__[midconherb](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)__[/hypoxia.html](http://wwwrcolka.cr.usgs.gov/midconherb/hypoxia.html)_
- Flux and Sources of Nutrients in the MARB: _[http://www.nos.](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[noaa](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[.](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[gov](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[/](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[pdflibrary](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[/](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[hypox](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[_t3final.](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)__[pdf](http://www.nos.noaa.gov/pdflibrary/hypox_t3final.pdf)_
- Nitrogen in the Mississippi Basin – Estimating Sources and Predicting Flux to the Gulf of Mexico: _[http://](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)__[ks](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)__[.water.](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)__[usgs](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)__[.](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)__[gov](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)__[/Kansas/pubs/fact-sheets/](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)__[fs](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)__[.135-00.html](http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.135-00.html)_

## Other Info On the Internet

- EPA Mississippi Basin Home Page: _[http://www.](http://www.epa.gov/msbasin/)__[epa](http://www.epa.gov/msbasin/)__[.](http://www.epa.gov/msbasin/)__[gov](http://www.epa.gov/msbasin/)__[/](http://www.epa.gov/msbasin/)__[msbasin](http://www.epa.gov/msbasin/)__[/](http://www.epa.gov/msbasin/)_
- Gulf of Mexico Ecosystems and Hypoxia assessment: http://www.cop.noaa.gov/Fact_Sheets/NGOMEX.htm
- Integrated Assessment of Hypoxia in the Gulf of Mexico: http://www.nos.noaa.gov/products/pubs_hypox.html

## andSize of Hypoxic Zone

**Hypoxia**

**and****Size of Hypoxic Zone**

- NOAA

## Goals for the Gulf and the Basin

_*Coastal Goal:*_* By 2015, reduce the average zone to < 5,000 Km**2**.** *
_*Within Basin Goal:*_* To restore and protect the waters of the 31 States and 77 Tribes in the Basin.** *
_*Quality of Life Goal*_*: Improve the communities and economic conditions across the Mississippi Basin.*

## Extrapolated 

- Statistical  extrapolation from representative basins (from 42 measured Sub-basins to 133 Sub-basins of entire Mississippi Basin).**  **

- Extrapolated
- Nitrogen Yield,
- 1980-96

- INPUT

- YIELD

**Notes:**
Statistical models use water quality measurements on representative basins and information on N inputs to extrapolate throughout the MARB