The Trump administration's stated goal for a rule defining which wetlands and waterways get Clean Water Act protection: Write a simple regulation that landowners can understand.
"I believe that any property owner should be able to stand on his or her property and be able to tell whether or not they have a 'water of the U.S.' on their property without having to hire an outside consultant or attorney," acting EPA Administrator Andrew Wheeler told the Senate Environment and Public Works Committee in mid-January.
But scientists who specialize in the study of wetlands and waterways say it's not that simple.
"In a lot of cases, I still don't think landowners could stand there and figure it out on their own," said Siobhan Fennessy, a biology professor at Kenyon College. "You're still going to need the industry of consultants we have to come out and offer assistance. I don't think they're going away."
The new "waters of the U.S.," or WOTUS, proposal would erase federal protections for the more than 51 percent of wetlands and 18 percent of streams without relatively permanent surface water connections to nearby waterways, according to data from the U.S. Geological Survey. Wetlands — marshes, bogs, swamps and other soggy areas — are protected by law as stormwater buffers, pollution filters and wildlife habitat.
Jennifer Tank, a professor who teaches the ecology of streams and rivers at the University of Notre Dame, said the proposal would be the most significant rollback of Clean Water Act protections since the Reagan administration, but that doesn't make it easy to understand.
"If you want to throw a ton of money at it, sure, but not just by looking at a stream," she said.
The proposal would eliminate federal protections for "ephemeral" streams that are fed by rain or snowmelt and are otherwise dry. It would keep protections for intermittent streams fed by groundwater or snowpack that flow seasonally.
"It's impossible to tell just from looking at a stream where it gets its water from," said Mark Rains, who runs the University of South Florida's Ecohydrology Research Group.
The best way to determine whether a stream flows ephemerally or intermittently is to monitor its flow over a long time.
"If we find one that flashes only in the hours or days after a rainfall, we call that ephemeral," Rains said. "If we find one that goes for weeks independent of rain, we call that intermittent."
Such monitoring requires the installation of equipment in a streambed for weeks or months at a time. Using that approach, he said, different consultants or experts might still disagree on how many days a stream has to flow after rainfall to prove it is also being fed by groundwater.
"This will shift where we fight the battles, but we'll still have the battles," he said.
The Trump administration's proposal might seem simpler to follow on wetlands because it wouldn't protect those that are dry most of the time and don't connect to larger downstream waters.
But navigating the definition could be confusing when it comes to wetlands that do connect to streams that are dry during parts of the year.
Knowing whether those wetlands are jurisdictional would first require determining whether they get wet when the stream flows and then figuring out whether the stream is ephemeral or intermittent.
"I don't see how you can claim this rule clears up uncertainty the way it was written," Fennessy said.
The Trump administration's emphasis on clarity in its WOTUS proposal is rooted in criticisms the farming, housing and energy industries lobbed at the Obama administration's Clean Water Rule.
Industry groups argued that the Obama rule expanded federal jurisdiction and was too complicated for average people to understand.
By contrast, American Farm Bureau Federation President Zippy Duvall has praised the Trump administration's proposal for "giving us what we want."
"Farmers should be able to sit in their pickup trucks and drive across their land and say, 'Yes, this is a water of the U.S.' and 'No, I know that's not,'" he said as the administration rolled out the rule proposal at EPA headquarters in December.
But Notre Dame's Tank argued that the administration's attempt at simplicity is complicated by the "political goal" of restricting Clean Water Act protections.
She noted that the Obama administration's Clean Water Rule would have protected any waterway if it had a streambed, banks or ordinary highwater mark. Those "landscape signatures," she said, indicate that a stream had a significant impact on downstream waters, regardless of how often it flowed or where its water originated.
Tank acknowledged that most people might not initially know those "signatures," but if they learn, it's easier to figure out whether a stream has those features, which are visible to the naked eye, than whether it is fed by groundwater.
"Understanding the water table is complex. Understanding the water cycle is complex. These physical marks, the signatures on the landscape, are a lot easier to understand," she said. "The problem is, you can't use those physical visual features if you don't want to protect ephemeral streams, because many have them."
Robert Brooks, a professor emeritus of geography and ecology at Pennsylvania State University, agreed.
The Trump administration, he said, has used a "false premise" in saying the Clean Water Rule was complicated in order to justify rolling back protections.
"There's a lot of misunderstanding and ignorance in the sense that people don't bother to inform themselves, and the industry groups that could help educate them fought for rollbacks instead," he said.
Brooks, Rains, Fennessy and Tank all sat on the EPA Science Advisory Board panel that reviewed a 300-page "connectivity report" published by the Obama administration describing how different wetlands and waterways affect larger waters downstream.
Obama's EPA and Army Corps of Engineers based their Clean Water Rule on the scientific report, while the Trump administration has argued that the question of Clean Water Act jurisdiction is a legal — not scientific — one.
How to draw the line?
In their proposal, President Trump's EPA and Army Corps ask for public comment on whether the final rule should only protect streams where it has been proved they are fed by groundwater.
That would make it even more complicated for landowners themselves to know whether a stream on their property is regulated by the federal government, as the proposed WOTUS rule itself acknowledges.
It says that identifying whether groundwater is the source of a stream could involve installing monitoring wells or gauges to identify the presence of water or estimate base flow, and that installing such equipment could be difficult, as groundwater tables in many areas rise and fall depending on the season, and some are under rocky substrates that would be difficult to access.
"The agencies note that identifying whether the channel bed intersects with the groundwater table may be challenging to accomplish in the field, that gathering the relevant data could be time consuming, and could require new tools and training of field staff and the regulated public," the proposal says.
Tank said she fears that predicating Clean Water Act protections on proving that a stream is fed by groundwater would, in effect, deregulate intermittent streams because landowners wouldn't want to spend the time or money to drill down to the groundwater table.
"It would be adding an unnecessary burden of proof when we have easier ways to show it," she said.
Drilling to find a groundwater connection also isn't as simple as it sounds.
In the Sacramento Valley, for example, water tables are hundreds of feet below the surface, while layers of semipermeable soil near the surface can trap water.
"You could find three layers of aquifers in one place," the University of South Florida's Rains said. "Is it groundwater even if it's not part of the water table? I would say it is. But someone else could say something differently."
Another complication is the role soil plays in streams that flow only after rain.
Soil beneath many headwater ephemeral streams will absorb and capture water. Then, the next time it rains, the soil will release water. What flows downstream is a "cocktail" of the newly released water, which could be a few years old, and the ongoing rain.
"I'm a geologist, so I say anything underground is groundwater, and this counts," Rains said. "Someone else might say it's not part of an aquifer, so it doesn't."