Who gains from saving nature
Ledger 1 : 33 — For each dollar financing nature-based solutions in 2023, about $33 financed activities harmful to nature. (UNEP)
Cases / Water use · United States · 1985–2026

Gulf of Mexico dead zone (Mississippi nutrient runoff)

Nature's voice · report
No measurement of the harm done to me here is on record.
Did nature suffer? Not measured. Disputed
What the record lacks: 2 none on record · 1 not measured · 3 disputed · 1 unclear See the gaps
Accounts of the harm differ
Did the small 2026 dead zone show progress on nutrient reduction?
  • Government and regulators NOAA: The 2026 zone, 1,332 sq mi, was the second smallest in 40 years because Tropical Storm Bertha mixed the water just before the cruise; NOAA had forecast 7,027 sq mi. Marine Technology News
  • Researchers LSU/LUMCON: The near-goal size was the result of physical mixing, not progress; there have been no significant reductions in nitrate loading since 2001. LSU and LUMCON (gulfhypoxia.net)
Did the 2010 Deepwater Horizon oil spill change the size of the 2010 dead zone?
  • Researchers Nancy Rabalais (LSU/LUMCON), 2010: It would be difficult to link conditions seen that summer with oil from the BP spill in either a positive or negative way.
  • Researchers Rabalais, Smith and Turner (2018): Found no difference in oxygen concentrations for May, June or July 2010 with or without oil data; the analyses did not demonstrate that the spill affected, or did not affect, the size of the 2010 zone.
  • Researchers Kessler et al. (2011, Science): Found 3.0–3.9 × 10^10 moles of oxygen respired, primarily by methanotrophs, within about 120 days in a deep intrusion layer about 700–1,300 m down, not on the shelf. A published comment (Joye et al. 2011) disputed the paper.
  • Government and regulators Deepwater Horizon restoration plan (PDARP): Mentions concern about hypoxia due to bacterial consumption of dispersed oil but gives no finding.

Every summer a zone of low oxygen forms on the Louisiana and Texas shelf, linked to nutrient pollution carried down the Mississippi–Atchafalaya basin. The government size target set in 2001 has not been met, and farm fertilizer runoff sits outside the Clean Water Act permit system.

3,745 vs about 1,900 sq miFive-year average size of the dead zone vs the Hypoxia Task Force goal
Goal is 5,000 km² (about 1,900–1,931 sq mi) as a five-year running average; the current average is roughly twice the target (NOAA, August 2026).

Status As of October 2026: the 2026 measurement (1,332 sq mi) was under the 5,000 km² goal, but LSU attributed it to storm mixing; the five-year average of 3,745 sq mi remains about twice the goal, which now runs to 2035.

What?
Each summer a zone of oxygen-poor bottom water forms on the Louisiana and Texas shelf, linked to nutrient pollution from the Mississippi–Atchafalaya basin. NOAA
Where?
Louisiana and Texas coastal shelf, west of the Mississippi delta; the nutrient load comes from a basin of 31 states.
When?
Every summer; measured each late July since 1985. LSU researchers say low oxygen began to appear about 55 years before their statement, when Midwest agriculture intensified. LSU and LUMCON (gulfhypoxia.net)
Who?
Gained
None on record
Lost
None on record
Harmed
  • Fish and bottom-dwelling animals on the Louisiana and Texas shelf — Bottom oxygen falls to 2 mg/L or less; animals that can leave do, and those that cannot die.
  • Gulf shrimp market — Hypoxia cut the share of large brown shrimp and raised their relative price in 1990–2010 price data (Smith et al., PNAS 2017).
Why?
NOAA attributes it primarily to excess nutrient pollution from human activities in cities and farm areas; USGS SPARROW modelling attributes more than 70% of delivered nitrogen and phosphorus to agriculture. USGS
How?
Fertilizer not taken up by crops runs into streams and the river, mostly in spring; at the coast it drives algal overgrowth, and bottom oxygen falls. Farm runoff is outside the Clean Water Act permit system. Coppess, University of Illinois (policymatters.illinois.edu)
In proportion The five-year average (3,745 sq mi) is roughly twice the goal (about 1,900 sq mi). Marine Technology News
6 of 6 questions answered from the record

What happened

The record, in order.

The Mississippi and its distributary the Atchafalaya drain about 41% of the contiguous United States: 31 states and two Canadian provinces, including the Midwest corn and soybean belt. Nitrogen and phosphorus fertilizer that crops do not take up runs off into streams and then the river; city wastewater adds to the load. USGS SPARROW modelling (Alexander et al. 2008) attributes more than 70% of the nitrogen and phosphorus delivered to agriculture, with corn and soybeans alone supplying 52% of the nitrogen. NOAA describes the dead zone as “primarily a result of excess nutrient pollution from human activities in cities and farm areas.” The load travels mostly in spring, when rain and snowmelt peak.

The river discharges the nutrient load off the Louisiana coast, where it drives an overgrowth of microscopic algae at the surface. Oxygen in the water near the sea floor on the Louisiana and Texas shelf then falls to 2 mg/L or less, below the level at which fish and bottom-dwelling animals can live. Animals that can leave do; those that cannot die. Autumn storms and cooling layers of water break the zone up, and the load returns the next spring. A shelf-wide cruise in late July, led by LSU and LUMCON aboard the R/V Pelican with NOAA funding, has measured the zone every year since 1985. NOAA gives a 39-year average of 5,223 sq mi and a record of 8,776 sq mi in 2017. The measured size was 6,705 sq mi in 2024 and 4,402 sq mi in 2025.

Governments set a goal of reducing the zone to 5,000 km², measured as a five-year running average. The Hypoxia Task Force goal was set in 2001 for 2015 and extended in 2015 to 2035. The five-year average has never reached it; the current average is 3,745 sq mi. LSU said there have been “No significant reductions in the nitrate loading… since the Hypoxia Action Plan was adopted in 2001.” Under the Clean Water Act, the definition of a point source “does not include agricultural storm water discharges and return flows from irrigated agriculture,” and EPA's regulation 40 CFR 122.3(e) excludes nonpoint-source agricultural activities from discharge permits; nonpoint pollution is handled through grant programmes. Concentrated animal feeding operations are point sources and can need permits; row-crop fertilizer runoff does not.

The July 2026 cruise (24–30 July) measured 1,332 sq mi (3,449 km²), the second smallest in 40 years. Tropical Storm Bertha had mixed the water just before the cruise. NOAA had forecast 7,027 sq mi and LSU 7,532 sq mi. LSU called the 2026 size the result of “physical mixing,” not progress.

No comprehensive dollar figure for the economic harm exists. The often-cited $82 million a year comes from a 2011 NOAA coastal science office page and covers harmful algal blooms and hypoxia nationally, not the Gulf alone. A 2017 PNAS study (Smith et al.) found that hypoxia cut the share of large Gulf brown shrimp and raised their relative price in 1990–2010 price data. NOAA also reports the habitat area potentially unavailable to fish and bottom species: more than 4 million acres in 2024 and 2.8 million in 2025. The 2010 zone was 20,000 km² (7,722 sq mi), measured in the same year as the Deepwater Horizon spill; researchers have not shown whether the oil affected its size.

  1. 1985Annual late-July shelf-wide cruise begins (LSU and LUMCON, NOAA-funded)
  2. 2001Hypoxia Action Plan adopted; goal of 5,000 km² (five-year average) set for 2015
  3. 2010Zone measured at 7,722 sq mi (20,000 km²), one of the largest since 1985; Deepwater Horizon spill in the same year
  4. 2015Goal date extended to 2035
  5. 2017Record size: 8,776 sq mi
  6. 20246,705 sq mi (about 4 million acres of habitat potentially unavailable)
  7. 20254,402 sq mi (2.8 million acres)
  8. 20261,332 sq mi after Tropical Storm Bertha mixed the water; LSU: physical mixing, not progress

What was said

Claims, in the words of those who made them.

“primarily a result of excess nutrient pollution from human activities in cities and farm areas”

NOAA · 2026 · NOAA

“started to appear 55 years ago when agricultural practices intensified in the U.S. Midwest”

LSU researchers Turner and Rabalais (low oxygen in the Gulf) · n/d

“No significant reductions in the nitrate loading… since the Hypoxia Action Plan was adopted in 2001”

“physical mixing”

“does not include agricultural storm water discharges and return flows from irrigated agriculture”

“It would be difficult to link conditions seen this summer with oil from the BP spill … in either a positive or negative way.”

Nancy Rabalais (LSU/LUMCON), on the 2010 zone · August 2010

Where accounts differ

Each party's account, side by side, with its source. The record does not settle these points; it shows them.

Did the small 2026 dead zone show progress on nutrient reduction?
Government and regulators
NOAA

The 2026 zone, 1,332 sq mi, was the second smallest in 40 years because Tropical Storm Bertha mixed the water just before the cruise; NOAA had forecast 7,027 sq mi.

Marine Technology News
Researchers
LSU/LUMCON

The near-goal size was the result of physical mixing, not progress; there have been no significant reductions in nitrate loading since 2001.

LSU and LUMCON (gulfhypoxia.net)
Did the 2010 Deepwater Horizon oil spill change the size of the 2010 dead zone?
Researchers
Nancy Rabalais (LSU/LUMCON), 2010

It would be difficult to link conditions seen that summer with oil from the BP spill in either a positive or negative way.

Researchers
Rabalais, Smith and Turner (2018)

Found no difference in oxygen concentrations for May, June or July 2010 with or without oil data; the analyses did not demonstrate that the spill affected, or did not affect, the size of the 2010 zone.

Researchers
Kessler et al. (2011, Science)

Found 3.0–3.9 × 10^10 moles of oxygen respired, primarily by methanotrophs, within about 120 days in a deep intrusion layer about 700–1,300 m down, not on the shelf. A published comment (Joye et al. 2011) disputed the paper.

Government and regulators
Deepwater Horizon restoration plan (PDARP)

Mentions concern about hypoxia due to bacterial consumption of dispersed oil but gives no finding.

What does the dead zone cost?
Government and regulators
NOAA coastal science office (2011 page)

$82 million a year, covering harmful algal blooms and hypoxia nationally, not the Gulf zone alone.

Researchers
Smith et al., PNAS (2017)

Gulf brown shrimp prices for 1990–2010 show hypoxia cuts the share of large shrimp and raises their relative price; the study gives no headline dollar total.

How it looked

What was shown, beside what was recorded.

Shown

  • A goal of 5,000 km² for the zone, as a five-year average.
    Hypoxia Task Force
  • A 2026 measured size of 1,332 sq mi (3,449 km²), below the 5,000 km² goal.
    NOAA and LSU/LUMCON survey results · Marine Technology News

Recorded

  • The five-year average has never reached the goal and is roughly twice the target (3,745 sq mi against about 1,900 sq mi).
    Marine Technology News
  • LSU: the 2026 size was the result of physical mixing by a storm, not of lower nitrate loading.
    LSU and LUMCON (gulfhypoxia.net)
  • Row-crop fertilizer runoff is not covered by discharge permits under the Clean Water Act; concentrated animal feeding operations can be.
    Coppess, University of Illinois (policymatters.illinois.edu)
  • Researchers (Van Meter et al. 2016, 2018) estimated that releasing 99% of the nitrogen stored in Mississippi basin soils would take about 35 years, and that the dead zone would last at least 30 years even if inputs fell to zero.

Who gained

Money that reached nature, beside money that stayed elsewhere.

Reached nature or the ground

Not published
No figure published.

Gained elsewhere

Not totalled
Currency: · Window: . All figures cover the same period. * Estimate built from cited figures.

Responses on record

  • noaa (2026): The dead zone is primarily a result of excess nutrient pollution from human activities in cities and farm areas; the 2026 zone was smaller than forecast because Tropical Storm Bertha mixed the water just before the cruise. · Marine Technology News
  • lsu-lumcon (August 2026): No significant reductions in the nitrate loading since the Hypoxia Action Plan was adopted in 2001; the 2026 size was the result of physical mixing, not progress. · LSU and LUMCON (gulfhypoxia.net)

In court and with insurers

Every proceeding and every insurer decision on record.

Lawsuits and rulings

No court case on record. No court has ruled on this case.

Insurers

No insurer decision on record.

What nature saw

Outcomes measured on the ground, and nature's note.

Nature's report opens this page. Below: further outcomes measured on the ground.

Size in 2026
1,332 sq mi
Second smallest in 40 years; a storm mixed the water before the cruise; NOAA had forecast 7,027 sq mi
Five-year average vs goal
3,745 vs about 1,900 sq mi
Goal of 5,000 km² set in 2001 for 2015, extended to 2035
Record size
8,776 sq mi
2017
Habitat potentially unavailable to fish and bottom species
4M+ acres
2024 (NOAA); 2.8 million acres in 2025

What we don't know

Undisclosed, unproven, untried: recorded as data.

Nature

  • Not measured Harm to nature: The record holds no measurement of harm to nature.
  • Disputed Did the small 2026 dead zone show progress on nutrient reduction?
  • Disputed Did the 2010 Deepwater Horizon oil spill change the size of the 2010 dead zone?

Accounts

Record

  • None on record No good comprehensive figure exists for the economic harm of the dead zone; the often-cited $82 million a year covers algal blooms and hypoxia nationally and dates from a 2011 NOAA page.
  • Unclear Whether the 2010 Deepwater Horizon spill affected the size of the 2010 zone: the 2018 analysis “did not demonstrate that the oil spill affected, or did not affect” it.
  • None on record Single years below the goal have occurred only in drought or storm years; 2026 is confirmed, while 1988 and 2000 appear in the LUMCON record but their exact figures were not seen.

Did the harm stop?

The zone forms every summer. The 2026 measurement was the second smallest in 40 years, which LSU attributed to storm mixing and not to lower nitrate loading.

Who paid?

Sources

Voices on record: — Company or project✓ Government and regulators— Courts— Press and investigations— Communities and civil society✓ Researchers

Government and regulators

Researchers

  1. Dead zone size in 2026 (LSU/LUMCON release)
    LSU and LUMCON (gulfhypoxia.net) · 2026-08
  2. Shelfwide cruises
    LSU and LUMCON (gulfhypoxia.net) ·
  3. Environmental regulation of agriculture: the Des Moines Water Works issue
    Coppess, University of Illinois (policymatters.illinois.edu) · 2015

Connected cases

Related matters, and cases linked to this one through the same organisations, with the role each played in both.
Terms used on this page

Institutions

EPA
The US Environmental Protection Agency.
NOAA
The US National Oceanic and Atmospheric Administration, which leads damage assessment for coastal and marine spills.

Law and courts

Trustees (natural resource)
Government agencies that act on behalf of the public to recover and spend damages for harm to natural resources.

Science and environment

PFOA (C8) and PFAS
PFAS are a large family of human-made chemicals that persist in the environment and the body; PFOA, also called C8, is one of them and was used to make Teflon.
Similar cases
Insurance declined or withdrawn · Chemical pollution · Water use · United States · 2020–2026
PFAS insurance disputes (3M, Chemours, DuPont)
Same type: Water useSame countryHarm to nature disputed
Wind, hydro and other renewables · Water use · European Union / United States · 2002–2021
EU taxonomy hydropower exemption and California large hydro exclusion
Same type: Water useSame countryHarm to nature disputed
Liability shifting (spin-offs, bankruptcy, closure bonds) · Chemical pollution · Water use · United States · 2017–2021
Duke Energy coal ash cleanup cost recovery (North Carolina)
Same type: Water useSame countryHarm to nature not measured
Water use · United States · 2014–2025
Fondomonte groundwater pumping in Arizona
Same type: Water useSame countryHarm to nature not measured