The Science Behind The 2023 Supreme Court Ruling In Sackett v. Environmental Protection Agency

The U.S. Supreme Court’s exclusion of ephemeral streams from the Clean Water Act protections leaves over half of our waterways vulnerable to pollution, highlighting the urgent need for science-based policy decisions

I hear you. If you have an analytical mind, just like I do, you probably wished that important decisions that may affect hundreds of millions of people were made with empirical evidence in mind.

Do you want to rule on reproductive rights? Then, make sure you explore how certain regulations may affect our society. Read peer-reviewed research and consider every aspect, from medical terminology to cascading effects on the economy.

Do you want to rule on environmental issues? Well, the same applies.

Because I feel so strongly about the need to incorporate peer review research into policy-making and law interpretation, I am excited to report on this research, which explores how “right” a recent U.S. Supreme Court ruling was considering what the scientific evidence has to say.

Rivers and streams are vital to our environment, carrying water, nutrients, and life across landscapes. However, not all streams are created equal. Some flow continuously, while others, known as ephemeral streams, only flow in response to rainfall. Think of the surprise streams that overflow after unexpected heavy rainfall.

However, despite their temporary nature, these ephemeral streams play a significant role in our water systems. Recent research led by Dr. Craig Brinkerhoff and his team at the University of Massachusetts Amherst highlights the crucial contributions of these often-overlooked waterways. Beyond its importance from a scientific context, this study is a wake-up call to recognize its importance, especially in the context of environmental regulations and protections.

Ephemeral streams are unique in many ways. They don’t connect to groundwater and only flow after precipitation events. Because of this, they can be difficult to study and quantify.

However, Dr. Brinkerhoff and his colleagues developed a sophisticated model to address this challenge. They mapped out the contributions of ephemeral streams to the vast network of rivers, lakes, and reservoirs in the contiguous United States. The model they developed compares long-term monthly water table depths with predicted depths across more than 20 million water bodies in the US.

Thus, by identifying where the water table remains below the stream bed throughout the year, they distinguished ephemeral streams from intermittent ones, which connect to groundwater seasonally.

The researchers then routed this information through a comprehensive river-lake-reservoir network, ensuring their findings reflected true ephemeral contributions. They validated their model with field assessments from over 7,000 sites, providing a robust foundation for their conclusions. As a scientist myself, I need to recognize the hard work put into evaluating this large number of sites through fieldwork.

The findings of this study were truly eye-opening. As it turns out, on average, ephemeral streams contribute 55% of the annual discharge from the United States’ regional river systems. This means that over half of the water flowing in major rivers originates from these temporary streams!

Further, this contribution is particularly pronounced in the western United States, where the arid climate and low water table make ephemeral streams more common. For instance, in areas like the Black Rock Desert in Nevada and Humboldt County in California, up to 94% of river discharge comes from ephemeral streams. Imagine if we overlooked their contribution!

Even more, even in the wetter eastern regions, ephemeral streams still play a significant role. For example, 59% of the water entering Long Island Sound is sourced from ephemeral streams in the Connecticut River basin. Colin Gleason, an author of the study, illustrates this with a vivid image:

On a day in which every stream in the Connecticut River is flowing with its average annual condition, 59% of the water entering Long Island Sound was sourced from these ephemeral streams — a.k.a., dry gullies in the woods.

These findings have important implications for environmental policy and water quality regulation. For instance, the Clean Water Act (CWA), which governs water pollution in the United States, currently excludes ephemeral streams from its protections.

This exclusion stems from a 2023 Supreme Court ruling in Sackett v. Environmental Protection Agency, which narrowed the definition of protected waters to only those that are “relatively permanent, standing or continuously flowing bodies of water.” As you can imagine, not much scientific evidence was used in the ruling or, at least, it wasn’t considered.

However, according to this research, this ruling leaves a substantial portion (over 50%) of the nation’s waterways vulnerable to pollution. As Dr. Gleason points out, “If you now just go up into the hills and dump it in a dry gully… there’s every chance it ends up in the main stem of the Connecticut that you’ve worked so hard to protect once it rains.”

The study emphasizes that pollution in ephemeral streams can travel downstream, affecting water quality in major rivers and lakes. In other words, they should be considered protected waters for the negative effects they can have on populations and ecosystems.

Dr. Brinkerhoff and his team’s research also highlights the need for a broader understanding of water systems. Their model shows that even though ephemeral streams flow infrequently, their impact on the water system is significant. These streams act as conduits for pollutants and nutrients, particularly during storm events, when they can quickly transport accumulated substances downstream.

But more importantly, this study is a call for policymakers and environmental regulators to reconsider the scope of the Clean Water Act. Doug Kysar, a co-author of the study, argues that this research provides a clear constitutional basis for including ephemeral streams in federal water protections. He emphasizes that “water pollution is a transboundary issue that clearly implicates interstate commerce, such that Congress could regulate ephemeral streams even if they are not the kind of ‘navigable waters’ that Congress has historically exerted federal authority over.”

However, Kysar also acknowledges the challenges ahead that come with the implementation of new laws and regulations. Historically, state and local governments have struggled to protect waterways effectively, which was a key reason for the establishment of the federal Clean Water Act. He notes, “States don’t necessarily have incentives to adopt costly water protections when the benefits will be felt by ecosystems out of state.”

Protecting our waterways requires protecting all types of streams for their demonstrated contribution to the overall water system. Moving forward, and the most important take-home message here, it’s crucial for courts, especially the Supreme Court, to consider scientific research before making rulings that affect environmental protections and/or people’s lives. The failure to do so could leave vital parts of our water systems—and, by extension, our own societies—at risk.

Understanding and protecting ephemeral streams is not just about preserving the environment; it’s about protecting the very lifelines that sustain our communities.