The Future of Water in the U.S. West is Uncertain, so Planning and Preparedness are Critical

Water authorities in the Western U.S. don’t know what the future will bring, but they are working collaboratively and with scientific rigor to make sure they’re prepared for anything.

By Sharon Udasin, Ensia (CC BY-ND 3.0).

Editor’s note: This story is part of a four-part series — “Hotter, Drier, Smarter: Managing Western Water in a Changing Climate” — about innovative approaches to water management in the U.S. West and Western tribal nations. The series is supported by The Water Desk , an independent journalism initiative based at the University of Colorado Boulder’s Center for Environmental Journalism. You can read the other stories in the series, along with more drinking water reporting, here.

In a thirsty Western United States that has become increasingly vulnerable to extreme weather events, rampant wildfires and years of unprecedented drought, those at the helm of the region’s water agencies are accelerating their plans to grapple with climate change.

“The Western United States — especially the 40 million people who use the Colorado River — we’re in the bullseye of climate change,” says Cynthia Campbell, water resource management advisor for the City of Phoenix. “This is not a conceptual conversation anymore. We’re in full-on adaptation.”

With that reality comes the need to plan around the future of water for the people and wildlife who call the Colorado River Basin home.

“You can’t just plan for one future.”

–Carly Jerla

But, says Carly Jerla, an operations research analyst for the United States Bureau of Reclamation’s Lower Colorado Region, “you can’t just plan for one future.”

As climate change casts its shadow over water resources in the Western U.S., water authorities must navigate uncertainty in the form of the many possible futures in front of them. Those futures almost certainly hold more of what climate change has already brought — rising temperatures, changes in precipitation, shifts in snowpack, longer and more severe droughts, more frequent flooding — plus people’s responses to those changes. Taken together, these fateful forecasts go into climate projections: models that explore an array of possible future climate conditions or scenarios.

Today, planning agencies are working together to diversify the technology they’re using and integrate scientific research into local and regional adaptation strategies in an effort to be rigorous in their analysis of the uncertainty.

Adapting to climate change “shouldn’t be scatter-shot,” Campbell says. “It can actually be more scientific.”

Mix of Solutions

Although local regulations vary among Western water agencies, the inclusion of climate projections into authorities’ planning processes has become all but universal. Grappling with uncertainty requires water managers to account for supply and demand challenges that are (and will be) driven by climate change, says Jerla, who is currently stationed at the University of Colorado Boulder. On the supply side, she explains, are factors such as higher temperatures, precipitation and snowpack changes, and droughts and flooding. Shifts in demand, meanwhile, are from things like rising evapotranspiration rates in agriculture and impacts to residential irrigation.

A longtime expert on modeling applications and planning operations for the Lower Colorado Region, Jerla was the study manager for the Bureau of Reclamation’s Colorado River Basin Water Supply and Demand Study. The assessment was completed in 2012, and its technical foundations helped guide climate adaptation policies. The research, which occurred under the umbrella of the agency’s larger Basin Study Program, quantified water imbalances through 2060 and suggested potential strategies for mitigation and adaptation.

For water authorities in the Colorado River Basin states, climate change means uncertainty in the form of the many possible futures in front of them. Photo courtesy of the U.S. Geological Survey (public domain).
For water authorities in the Colorado River Basin states, climate change means uncertainty in the form of the many possible futures in front of them. Photo courtesy of the U.S. Geological Survey (public domain).

The study identified shortfalls between projected supplies and projected demand in the Colorado River Basin by looking at a range of possible future climatic scenarios and analyzing many possible outcomes, according to Jerla. One particular scenario, called a downscaled general circulation model (GCM), forecasted that as the climate continues to warm, the mean natural flow of the Colorado River at Lees Ferry, Arizona — significant because it’s the point that separates the river’s Upper and Lower Basin, and from which water allocations for the Basin states are determined depending on river measurements — would decrease by about 9% over the next 50 years, alongside longer, more frequent droughts. 

“One of the things that this opened our eyes to is the importance of communicating the uncertainty with respect to future outcomes, especially when you’re looking 50 years in the future,” Jerla says.

In addition to examining these scenarios, she and her colleagues evaluated adaptation and mitigation strategies that might reduce supply and demand imbalance. One important conclusion, according to Jerla, was the notion that water agencies would need to diversify their portfolios to include a variety of mechanisms like water reuse, desalination and increased water transfers to urban areas.

“There was no one solution that was going to be a fix-it,” Jerla says. “It has to be a mix of stakeholders involved.”

A Critical Period

The next few years will be a critical policy planning period for Western water agencies, culminating in the particularly pivotal year of 2026. The drought contingency plans for the Upper and Lower Basins of the Colorado River, which have helped further the understanding that the status quo is no longer sustainable, will expire that year and likely undergo significant changes. In the plans, first approved by Congress in 2019, the seven Colorado River Basin states committed to protect the water levels of Lake Powell and Lake Mead — the human-made reservoirs that store Colorado River water and serve the basin states — through various conservation mechanisms.

Not only will the Colorado River Drought Contingency Plan expire in 2026, so too will the 2007 Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead, as well as the terms of the International Boundary and Water Commission’s Minute 323 — an updated “implementing agreement” of the Mexican Water Treaty of 1944 that established U.S.-Mexico protocols for collaborative management of the Colorado River. Experts agree that new negotiations on the interim guidelines, as well as between the U.S. and Mexico on a new Minute, will be instrumental in shaping collaborative water management for the future, which will no doubt involve serious consideration of climate change projections.

Persistent drought has contributed to the ongoing drawdown of Lake Mead—a large reservoir straddling the Nevada and Arizona border. The decline is visible in these images, acquired 15 years apart with instruments on Landsat satellites. The top image was acquired July 24, 2015 with the Operational Land Imager (OLI) on the Landsat 8 satellite. The middle image was acquired July 6, 2000, with the Enhanced Thematic Mapper Plus on Landsat 7. During this period, the lake’s elevation (measured near the Hoover Dam), dropped by about 37 meters (120 feet). Turn on the image comparison tool to see how the drop in water level has changed the lake’s perimeter.
Persistent drought has contributed to the ongoing drawdown of Lake Mead—a large reservoir straddling the Nevada and Arizona border. The decline is visible in these images, acquired 15 years apart with instruments on Landsat satellites.

The initial image was acquired July 24, 2015 with the Operational Land Imager (OLI) on the Landsat 8 satellite. The second image was acquired July 6, 2000, with the Enhanced Thematic Mapper Plus on Landsat 7. During this period, the lake’s elevation (measured near the Hoover Dam), dropped by about 37 meters (120 feet). Turn on the image comparison tool to see how the drop in water level has changed the lake’s perimeter. NASA Earth Observatory images by Joshua Stevens (public domain).

“In the Colorado River Basin, we’ve been at work really since the Interim Guidelines for Powell and Mead Operations, since 2007, slowly building and adding to our operational decisions, planning efforts, policies — all with a mind toward more flexibility, enhanced resiliency, preparing for the challenges ahead, building science into the activities,” Jerla says.

For the Colorado River, Jerla and her colleagues have been making projections about relevant reservoir elevations through 2025, as they know what the operational guidelines will be until 2026. Generating such projections and sharing them with their local and regional partners remains crucial in order to help stakeholders understand what water reductions they might need to make.

Jerla says she is confident in the “robust set of policies” in place through 2026, which specify the water reductions that both U.S. states and Mexico will need to implement when the basins reach specified levels. Although she acknowledges the “dismal hydrology” that the region will likely encounter for the next five years, Jerla expresses hope that through “the spirit of cooperation the basin will come together.”

A Collaborative Approach

Beyond 2026, once new guidelines are in place, Jerla says she envisions more collaborative decision-making, more incorporation of science and more involvement from area tribes and Mexico as the region embraces new action plans for coping with a drier future.

While the Bureau of Reclamation has taken responsibility for many of the climate modeling efforts and continues to work collaboratively with local programs, it is the states that “have the most primary responsibility for allocating and receiving the water in their own state,” with their own sets of water laws and systems, Jerla explains. Down another level, she adds, local government authorities, urban municipalities, water councils and water associations employ the state regulations to manage water supplies on a local level. As a federal body, the Bureau’s role is to facilitate agreements across state boundaries — a process that has largely gone smoothly through mutual consensus.

“All the states have interests and priorities. The Colorado River ties us together.”

–Amy Ostdiek

“All the states have interests and priorities,” says Amy Ostdiek, deputy section chief at the Colorado Water Conservation Board, a cohort appointed by the governor to represent each major Colorado basin and relevant state agencies. “The Colorado River ties us together.”

As demands have continued to shift, the Colorado River Basin states have been “negotiating and renegotiating,” with a keen interest in furthering collaborative solutions, Ostdiek says. The Bureau of Reclamation, she explains, has always played a key role in this process, but planning occurs at the state level.

Individual states are now implementing the commitments made in the 2019 Drought Contingency Plan. Upper Basin states, which sit upriver from the Lower Basin states and are therefore responsible for not depleting the flow of the Colorado River, are focused on planning for a future with less water. Colorado itself sits at the headwaters of the river and is exploring options such as temporary compensated reduction of use, in which water users could get paid for using less water, Ostdiek explains.

U.S. Drought Monitor, September 28, 2021. Author: Brian Fuchs, National Drought Mitigation Center.
U.S. Drought Monitor, September 28, 2021. Author: Brian Fuchs, National Drought Mitigation Center.

Internally, state water agencies also have individual programs that focus on a sustainable future, such as the 2015 Colorado Water Plan. The Water Plan was Colorado’s first such program and in its first five years funded more than 241 water projects, such as infrastructure improvementsirrigation efficiency measures and engagement projects like taking science teachers on a five-day trip of the Rio Grande to show them various water issues facing Colorado. Set to be updated in 2022, the Water Plan builds upon previous supply planning and projects how much water the state will need in the future, according to Megan Holcomb, climate change risk management specialist at the Colorado Water Conservation Board.

A recent pilot initiative of the Water Conservation Board, the Future Avoided Cost Explorer (FACE:Hazards), aims to anticipate Colorado’s economic impacts from flood, drought and wildfires in 2050. The study, funded predominantly by the Federal Emergency Management Agency, according to Holcomb, paired four population scenarios (ranging from current population to high growth) with three climate scenarios (current, moderate and more severe change). The authors then discussed actions that Coloradans could take to reduce economic impacts from these hazards, as well as the relative cost associated with each action.

“If we can quantify what impacts from climate change will be without any action, then we have a baseline to say why resilience investments are worthwhile now,” Holcomb says.

Another internal Coloradan water program that takes climate change into account is the Drought Task Force, which is able to recommend mitigation measures as necessary statewide. While the governor makes the ultimate decision regarding these measures, the Task Force involves representatives from departments of natural resources, public safety and agriculture, among others.

Moving forward, both Ostdiek and Holcomb say that operational flexibility and a willingness to adopt creative solutions will be key to coping with climate change in water planning. Due to Colorado’s unique headwater position — which already limits how much Colorado River water the state is entitled to each year — Holcomb argues that Colorado needs to be particularly creative about water rights by furthering innovative tools like water leasing, which allows water rights holders to lease their water to other users.  

“We can all acknowledge that we need to be able to share within the state as well,” she says.

At the other end of the Colorado River Basin, water officials in Phoenix, Arizona, are recognizing that some 40% of the city’s water supply may be in jeopardy due to climate change, according to Campbell from Phoenix Water.

That’s one reason, Campbell explains, planners in Arizona are observing shifts in the flow pattern of the Colorado River that are the direct result of climate change. She and her colleagues are strategizing how they might replace the supplies that are in jeopardy — looking at exact times and places where reductions can be made through “targeted demand management.”

For example, Campbell suggests, a project could work to reduce the amount of water used by cooling towers at a power plant by studying the precise impact of changing the water used by certain towers. Such adaptation tactics, according to Campbell, would have a much more significant impact than, for example, shutting off the water while brushing teeth — a practice that, while good for conservation, is “not going to yield the type of water we’re talking about.”

And because the amounts of water experts are talking about are not set in stone, dealing with that uncertainty will continue to be a critical responsibility of water agencies going forward. Collaboration and scientific rigor are key, all these experts agree, to making sure the region is as prepared as possible for any future that may present itself.

Will Climate Change Increase the Presence of Pathogens in Drinking Water?

As storms grow more severe and temperatures climb, contamination of groundwater by animal and human waste could be on the rise as well.

Water poured into a clear glass.
Water poured into a clear glass.

By Kari Lydersen (@karilydersen1), writer, ensia (CC BY-ND 3.0).

Editor’s note: This story is part of a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from the Park Foundation and Water Foundation. View related stories here.

Many people assume that the water that flows from our taps is free of harmful microorganisms. But each year thousands of Americans in rural areas, small towns and even some cities are sickened by living pathogens that can flourish in untreated or inadequately treated water from private wells and municipal systems.

An increase in heavy precipitation with climate change means the risk of drinking water contamination by bacteria, viruses and other microbes could also increase, especially in places where reliance on groundwater, proximity to agricultural operations and certain types of geology increase vulnerability.

Bacteria like E. coli, Salmonella and Campylobacter, and viruses like hepatitis, norovirus and rotavirus, are all found in drinking water contaminated with human and animal fecal waste. These can cause gastrointestinal and other ailments. For some that’s a matter of discomfort, but for children, the elderly and those with compromised immune systems, this can be dangerous, debilitating and even deadly.

“We’ve known for years that extreme [weather] events can cause risk for waterborne outbreaks — in developing countries, but also in developed countries,” says epidemiologist Elsio Wunder Jr., an expert in water sanitation at the Yale School of Public Health.

Pathogens in U.S. public drinking water systems cause upwards of 4 million digestive tract illnesses each year. A 2017 study by Florida State University assistant professor of geography Christopher Uejio and colleagues predicted an increase in such illnesses in children under age 5 in relation to climate change, noting the impact on “small rural” municipalities that distribute untreated groundwater in their systems.

Multiple studies have documented the risk of precipitation-driven drinking water contamination in Wisconsin, a state especially susceptible because of its livestock operations and geology. A 2010 report by Medical College of Wisconsin, Milwaukee, associate professor of pediatrics Patrick Drayna and colleagues found that visits to a Wisconsin pediatric hospital for gastrointestinal symptoms increased an estimated 11% four days after rainfall.

Rainwater courses through lagoons of manure or manure spread on fields as fertilizer, picking up pathogens and carrying them into groundwater as it seeps down into the soil. The porous dolomite that underlies parts of Wisconsin and surrounding states allows pathogen-laden rainwater to make its way into the aquifers that feed wells and municipal water systems. Human fecal pathogens can also make their way from septic systems into drinking water supplies as rainwater permeates.

“Groundwater was rainfall, it just takes a while to get there,” explains Mark Borchardt, a microbiologist for the U.S. Department of Agriculture (USDA), who reported in 2019 that 60% of wells in northeastern Wisconsin’s Kewaunee County were contaminated with microbes found in fecal waste. “Rainfall has chemistries that detach microorganisms. When it touches a pathogen attached to a soil particle, the pathogen can be released and move on.”

In northern climates, frozen ground makes it less likely that pathogens can get into groundwater in winter. But warmer winters expected with climate change likely mean that ground will be frozen less of the time and that precipitation will fall as rain instead of snow, increasing the chances for pathogens to move.

Meanwhile drought — also expected to increase with climate change — can increase the risk of pathogen contamination as well.

“At the most basic level, drought can leave people without easy access to water, and they have to get water from a less-safe source,” says Jeni Miller, executive director of the Global Climate and Health Alliance. “And with less water in the aquifers, [pathogens] become more concentrated,” meaning someone could get a higher dose of pathogens from drinking water from aquifer-fed wells, and the pathogens may be more likely to cause illness when ingested.

Source Matters

Private wells often pose the greatest risk of sickness from pathogen contamination, since there are typically no requirements for testing or treating wells, and it is usually up to an individual homeowner to discover or deal with contamination. More than 13 million households nationwide get their drinking water from such wells.

Well contamination has been a problem in not only the Midwest but in Appalachia and other regions as well, often in areas where residents lack the funds for testing or comprehensive maintenance. The organization Appalachian Voices in 2009 cited a USDA study, saying it found “over 50 percent of the private drinking water wells in the Appalachian area of Kentucky are contaminated with disease-carrying pathogens” because of poorly managed “straight” sewage pipes that contaminate surface water. A 2017 report by University of Tennessee registered nurse and then–doctoral student Erin Arcipowski and colleagues reported that pathogenic contamination of drinking water is a serious issue in low-income rural areas of Appalachia. The researchers noted that some residents lack funds for maintaining wells and might rely on “expensive bottled water from a remote convenience store” if they don’t have drinkable water at home. The study found E. coli or fecal coliform bacteria in 15 of 16 sites where water was used for drinking or recreation.

Municipal water systems that tap groundwater can also be at risk, since there are no federal mandates that groundwater be treated before distribution, according to Borchardt. About 95,000 such systems nationwide do not disinfect their water, and about 85,000 people in Wisconsin are served by systems that do not disinfect.

Federal law does require disinfection of drinking water drawn from surface sources, so there is seemingly less risk people will get sick from these systems. But treatment systems can malfunction when heavy rain makes the water more turbid (cloudy).

Parasite illustration.
Parasite illustration.

In 1993 the city of Milwaukee suffered an outbreak of Cryptosporidium, a tiny parasite, that sickened more than 400,000 people with diarrhea and killed 69. A water treatment plant had inadequately treated turbid water that may have been contaminated with the parasite by agricultural or human waste carried into Lake Michigan by rain and snow melt. Between 2009 and 2017, contaminated drinking water caused 339 cases of Cryptosporidium nationwide, according to the U.S. Centers for Disease Control and Prevention.

Pipes can be a problem, too. If the distribution systems that deliver drinking water contain cracks, pathogen-laden rainwater or groundwater can infiltrate them. If pipes carrying sewage are nearby and are also leaking, rainwater can help move pathogens from sewage into drinking water.

“When pipes leak, they don’t just leak out, they also leak in,” Borchardt notes.

Groundwater was a suspected source of contamination by the “brain-eating” amoeba Naegleria fowleri in Louisiana in recent years, which is typically deadly if it enters the nose. If groundwater tapped for drinking water is not disinfected or if disinfection systems fail, Naegleria may be present in tap water. Naegleria-contaminated groundwater can also enter water systems when pipes break.  There was also an outbreak in Texas this fall, and because Naegleria thrives in warm temperatures, it may become an increasing problem with climate change.

Reducing Risk

Governments and individuals can take a number of measures to reduce the risk of pathogens in drinking water. State or local governments can impose stricter controls on manure storage and spreading, including buffers and setbacks from residences.

“We currently have industrial-scale ranching and raising animals for meat and eggs, producing industrial-size pools of animal waste,” says Miller. “We need to reduce all those things that threaten our water supply as much as possible.”

Widespread testing can help identify contamination before people get sick. And municipalities that aren’t disinfecting their water can do so with UV light or other systems. Individuals can also install treatment systems for their own well water.

“More people are installing treatment systems in their homes, but systems are quite expensive, it could be several thousand dollars and requires regular maintenance which we people are not always very good at,” says Scott Laeser, water program director of the advocacy group Clean Wisconsin. “Ultimately we need to be focused on preventing pollution from contaminating our groundwater.”

Karen Levy, an associate professor of environmental and occupational health sciences at the University of Washington, has long studied waterborne disease. She said that while increased rains could mean more contamination risk in the U.S., it’s important people have faith in public drinking water systems, building the will to maintain and protect those systems, rather than turning to expensive and environmentally destructive bottled water.

“It’s really important to not scare people away from drinking water,” Levy said.

Meanwhile the risk of drinking water contamination is just one more reason, scientists agree, that people and governments must do all they can to curb climate change.

“All of the climate models show an increase in the frequency of extreme events, this means at both ends, more droughts and more floods,” says Jonathan Patz, director of the Global Health Institute at the University of Wisconsin-Madison. “The bottom line is it should be a multi-pronged, multi-level approach where not only do we have to anticipate heavy rainfall events that are expected with climate change, but instead of building systems for what we’re used to now, our water systems need to be much stronger.”

Explainer: Who regulates U.S. drinking water, and how?

Federal, state and local governments all have a hand in protecting public water systems and private wells from contamination.

Drinking Water
Photo by LuAnn Hunt on Unsplash

By Brett Walton, writer, ensia (CC BY-ND 3.0)

Troubled Waters: This piece is part of Troubled Waters, a collection of stories around safe drinking water.

Originally published on September 29, 2020 — Editor’s note: This story is part of a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from the Park Foundation and Water Foundation. Read the launch story, “Thirsting for Solutions,” here.

Who’s responsible for making sure the water you drink is safe? Ultimately, you are. But if you live in the U.S., a variety of federal, state and local entities are involved as well.

The Safe Drinking Water Act (SDWA) forms the foundation of federal oversight of public water systems — those that provide water to multiple homes or customers. Congress passed the landmark law in 1974 during a decade marked by accumulating evidence of cancer and other health damage caused by industrial chemicals that found their way into drinking water. The act authorized the U.S. Environmental Protection Agency for the first time to set national standards for contaminants in drinking water. The EPA has since developed standards for 91 contaminants, a medley of undesirable intruders that range from arsenic and nitrate to lead, copper and volatile organic chemicals like benzene.

In 1996, amendments to the SDWA revised the process for developing drinking water standards, which limit the levels of specific contaminants. Nearly a quarter century after those amendments, an increasing number of policymakers and public health advocates today argue that the act is failing its mission to protect public health and is once again in need of major revision.

EPA Regulated Drinking Water Contaminants
EPA Regulated Drinking Water Contaminants

Setting Limits

The process for setting federal drinking water contaminant limits, which is overseen by the EPA, was not designed to be speedy.

First, the EPA identifies a list of several dozen unregulated chemical and microbial contaminants that might be harmful. Then water utilities, which are in charge of water quality monitoring, test their treated water to see what shows up. The identification and testing is done on a five-year cycle. The EPA examines those results and, for at least five contaminants, as required by the SDWA, it determines whether a regulation is needed.

Three factors go into the decision: Is the contaminant harmful? Is it widespread at high levels? Will a regulation meaningfully reduce health risks? If the answer is “Yes” to all three, then a national standard will be forthcoming. Altogether, the process can take a decade or more from start to finish.

Usually, however, one of the three answers is “No.” Since the 1996 amendments were passed, the EPA has not regulated any new contaminants through this process, though it has strengthened existing rules for arsenic, microbes and the chemical byproducts of drinking water disinfection. The agency did decide in 2011 that it should regulate perchlorate — which is used in explosives and rocket fuel and damages the thyroid — but reversed that decision in June 2020, claiming that the chemical is not widespread enough to warrant a national regulation.

Two other chemicals have recently advanced to the standard-writing stage. In February, EPA administrator Andrew Wheeler announced that the agency would regulate PFOA and PFOS, both members of the class of non-stick, flame-retarding chemicals known as PFAS. For those two chemicals, the EPA currently has issued a health advisory, which is a non-enforceable guideline.

The act of writing a national standard introduces more calculations: health risks, cost of treatment to remove the contaminant from water and availability of treatment technology. Considering these, the EPA establishes what is known as a maximum contaminant level goal (MCLG), which is the level at which no one is expected to become ill from the contaminant over a lifetime. The agency then sets a standard as close to the goal as possible, taking treatment cost into account.

Standards, in the end, are not purely based on health protection and sometimes are higher than the MCLG. These standards, except for lead, apply to water as it leaves the treatment plant or moves throughout the distribution system. They do not apply to water from a home faucet, which could be compromised by old plumbing.

The EPA also has 15 “secondary” standards that relate to how water tastes and smells. Unless mandated by a state, utilities are not required to meet these standards.

Once the EPA sets a drinking water standard, the nation’s roughly 50,000 community water systems — plus tens of thousands of schools, office buildings, gas stations and campgrounds that operate their own water systems — are obligated to test for the contaminant. If a regulated substance is found, system operators must treat the water so that contaminant concentrations fall below the standard.

Omissions and Nuances

That is the regulatory process at the federal level. But there are omissions and nuances.

One big omission is private wells. Water in wells that supply individual homes is not regulated by federal statute. Rather, private well owners are responsible for testing and treating their own well water. The U.S. Geological Survey estimates that about 15% of U.S. residents use a private well. Some states, such as New Jersey, require that private wells be tested for contaminants before a home is sold. County health departments might also have similar point-of-sale requirements.

Primary Water Source for U.S. Households
Primary Water Source for U.S. Households. Source: 2017 U.S. Census Bureau American Housing Survey.

The nuance comes at the state level. States generally carry out the day-to-day grunt work of gathering water quality data from utilities and enforcing action against violations. To gain this authority, they must set drinking water standards that are at least as protective as the federal ones. If they want, they can set stricter limits or regulate contaminants that the EPA has not touched.

State authority had long been uncontroversial because only a few states — California and some northeastern states — were setting their own standards. That has changed in the last few years as states, responding to public pressure in the absence of an EPA standard, began regulating PFAS compounds.

“There was always a little bit of state standards-setting,” says Alan Roberson, executive director of the Association of State Drinking Water Administrators, an umbrella group for state regulators. “But it’s gone from a little bit to a lot.”

Six states — Massachusetts, Michigan, New Hampshire, New Jersey, New York and Vermont — adopted drinking water standards for certain PFAS compounds, while four others, including North Carolina and Minnesota, have issued health advisories or guidelines for groundwater cleanup.

States are also putting limits on other chemicals that the EPA has ignored. In July, New York adopted the nation’s first drinking water standard for 1,4-dioxane, a synthetic chemical that was used before the 1990s as an additive to industrial solvents. The EPA deems it likely to cause cancer, but the agency has not regulated it in drinking water. In 2017, California approved a limit for 1,2,3-TCP, another manufactured industrial solvent that the EPA considers likely to be carcinogenic.

The burst of state standards, especially for PFAS chemicals, has raised eyebrows. Some lawmakers worry that mismatched standards are confusing to residents. New York and New Jersey, for instance, set different limits on PFOA and PFOS in drinking water.

“This can create poor risk communication and a crisis of confidence by the public who have diminished trust in their state’s standard when it fails to align with a neighboring state,” Rep. Paul Tonko of New York said during a House Energy and Commerce subcommittee hearing in July.

Other representatives countered with the view that the EPA should concentrate on a select number of the most concerning contaminants so as not to overwhelm utilities and states with too many rules that are too hastily put together. Rep. John Shimkus from Illinois, echoing statements made by other committee members, said he does not want a system in which “quantity makes quality.”

Tonko, however, argued that the federal process “has not worked,” pointing to the two-plus decades since a new contaminant was regulated.

This debate, and other considerations like regional drinking water standards, is likely to carry over into the next Congress.

Federal, state and local governments all have a hand in protecting public water systems and private wells from contamination.