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Tuesday, August 16, 2022

To reduce harmful algae blooms and dead zones, the US needs a national strategy for controlling agricultural pollution

Midsummer is the time to forecast the size of this year’s “dead zones” and algal blooms in major lakes and bays. Will the Gulf of Mexico dead zone be the size of New Jersey, or just as big as Connecticut? Will the Lake Erie bloom turn into a human health crisis, or just ravage the coastal economy?

We are scientists who have spent nearly 50 years figuring out what causes dead zones and what it will take to revive them and reduce the risk of toxic blooms of algae. Researchers can predict these events fairly well and have calculated the reductions in nitrogen and phosphorus pollution needed to reduce them.

These goals are now spelled out in formal government commitments to clean up Lake Erie, the Bay and the Chesapeake Bay. From 2005 to 2015, farmers and landowners nationwide received US$30 billion to support conservation, including practices designed to reduce water pollution, and $60 billion more between 2019 and 2028. are determined to do.

But these efforts have fallen short, mainly because controls on nutrient pollution from agriculture are weak and ineffective. In our view, there is no dearth of solutions to this problem. What is needed is technological innovation and strong political will.

The Gulf of Mexico hypoxic (dead) zone in 2021, which measured 6,334 square miles (16,400 square kilometers). Lower values ​​represent less dissolved oxygen in the water.
University of Louisiana Maritime Association, CC BY-ND

Problems return to Lake Erie

State and federal agencies have known since the 1970s that overloading lakes and bays with nutrients produces huge blooms of algae. When algae die and decompose, they deplete the oxygen in the water, creating dead zones that cannot support aquatic life. But in each of these “big three” water bodies, efforts to curb nutrient pollution have been slow and stalled.

The US, Canada, and cities around Lake Erie began working in 1972 to reduce phosphorus pollution in the lake from household and industrial waste. Water quality rapidly improved, dead zones shrunk and harmful algal blooms decreased.

But in the mid-1990s crises of low-oxygen waters and sometimes toxic algae reappeared. This time, the source was mostly runoff from farm soil saturated with phosphorus from repeated use of fertilizer and manure. Climate change made matters worse: Warmer water holds less oxygen and causes the rapid growth of algae.

Bar Chart Showing Phosphorus Entering Lake Erie 1967-2001.
Phosphorus load in Lake Erie, 1967–2001. Non-point sources are wide areas without a separate discharge point, such as farm fields.
Scavia et al., 2014, CC BY-ND

Slow progress in the Chesapeake Bay

Nitrogen and phosphorus reach the Chesapeake Bay from sources including wastewater treatment plants; air pollution emitters, such as factories and cars; and runoff from urban, suburban and agricultural land. In 1987 the federal government and the states surrounding the Gulf agreed to reduce these flows by 40% by the year 2000 to restore water quality. But this effort relied on voluntary action and failed to make much progress.

In 2010 states and the US Environmental Protection Agency entered into a legally binding commitment to reduce pollutant loads below the set maximum levels needed to restore water quality. If states make insufficient progress, the EPA may limit or revoke their permitting authority, and states may lose federal funding.

Nitrogen and phosphorus pollution has mainly been reduced by tightening permit requirements and upgrading wastewater treatment plants. Air pollution controls for power plants and vehicles have also reduced nitrogen reaching the Gulf. Water quality has improved, and the annual dead zone has shrunk marginally.

But with the commitment’s 2025 deadline approaching, the nitrogen load has been reduced to less than 50% of the target amount, phosphorus to 64%. Much of the remaining pollution comes from farm runoff and urban storm water. Intensive agriculture in rural areas and sprawl in urban areas counteract other cleanup efforts.

Several states and thousands of pollution sources are involved in cleaning up water bodies with large watersheds such as the Chesapeake Bay (64,000 sq mi/165,000 sq km).

failure in the gulf of mexico

Dead zones form in the Gulf of Mexico each year during the summer, fueled by nutrients washing up the Mississippi River from Midwest farms. It generally covers at least 6,000 square miles, sometimes extending up to 9,000 square miles (23,000 square kilometres), and affects an area very rich in fisheries.

In 2001, the EPA and the 12 Mississippi River Basin states agreed to take action to reduce the Gulf’s dead zone by two-thirds by 2015. The researchers estimated that this would require reducing the nitrogen load reaching the Gulf by about 45%, mostly from the Corn Belt. ,

Now that deadline has been extended to 2035. Nitrogen and phosphorus loads at the mouth of the Mississippi River have not increased in 30 years, so actions taken so far have failed to reduce the Gulf’s dead zone.

Bar Chart Showing The Measurement Of The Gulf Of Mexico Dead Zone Since 1985.
The Gulf of Mexico dead zone has covered an average of 5,380 square miles (14,000 square kilometers) since 2017, which is 2.8 times larger than the 2035 target set by a federal task force.

fascinated by agriculture

In 2020, the EPA and Ohio adopted an agreement similar to the Chesapeake to reduce phosphorus pollution below a set maximum load from the Maumee River watershed at the western end of Lake Erie, where algae blooms often occur. To date, Mississippi River basin states and even the EPA have resisted mandating maximum pollution loads to reduce the Gulf of Mexico dead zone.

Despite substantial government subsidies to implement various agricultural management practices, nitrogen and phosphorus pollution in streams in Iowa and Illinois has actually increased above the 1980–1996 baseline of the Gulf Agreement.

With increased crop yields and more efficient use of fertilizer, the expansion and intensification of agriculture in the Midwest has outweighed any benefits of water quality. One driver is ethanol production, which has increased forty-fold since the adoption of the Gulf Action Plan in 2001. Today, more than 40% of the corn grown in America is used for ethanol, mostly in the Midwest, while the rest is used for food. animals.

In all three regions, the growth of large-scale livestock farms – hogs in the Midwest, poultry around the Chesapeake Bay – is also contributing to nutrient pollution. Improper management of animal waste increases the nitrogen and phosphorus load in soil and local waters.

Studies suggest that agriculture contributes 85% of Lake Erie’s Maumee River phosphorus load, 65% of the Chesapeake Bay’s nitrogen load, and 73.2% of the nitrogen load, and 56% of the phosphorus load in the Gulf of Mexico.

incentives not working

We believe the evidence is clear that the largely voluntary approach taken to date with technical support and adequate public funding is not working.

Economists have called for a fundamental change in policies that control agricultural pollution. These experts argue that instead of subsidizing polluters to clean up their operations, the strategy should be to pay farmers for performance, which is measured or measured at an appropriate scale and at specific locations, based on environmental consequences. can be predicted.

Under this approach, the government would set limits on the amount of nutrients that can be lost to the environment, and farmers would choose which type of action works best for their specific soil and climate. How to meet them For example, restoring wetlands within watersheds can help capture nutrients that essentially wash away farmland.

The ongoing shift to electric vehicles offers much less grain to grow for ethanol, which also doesn’t help the climate. And in the long run, developing efficient, plant-based food systems will reduce nutrient pollution and limit climate change.

In June 2022, the Government Accountability Office concluded that federal agencies charged with preventing and controlling harmful algal blooms and dead zones under a 1998 law had failed to establish a national program to address these issues. have been. Fifty years after the federal Clean Water Act came into force, we believe such a program is long overdue.

World Nation News Desk
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