This month has been a tale of many lawsuits.

On Friday, Attorney General Aaron Ford joined a lawsuit challenging the Trump administration’s decision to revoke a waiver allowing California to set its own vehicle emission standards. 

The Clean Air Act permits California to set higher emission standards, but it requires the state to receive authority from the EPA and the National Highway Traffic Highway Safety Administration. And last week, President Trump tweeted that his government would revoke California’s waiver. 

The move comes as the administration plans to freeze vehicle mileage standards that were set to increase under President Obama. Although carmakers have wanted more flexibility with the rules, much of the pushback has come from the oil industry, The New York Times reported.

In a statement, Ford said he joined the lawsuit to address air quality and climate change.

“My commitment to protect our families includes protecting our health and safety whenever possible,” Ford said last week. “California's heightened vehicle emissions standards have measurable benefits to our air quality and environment, and by revoking these emissions protections, the Trump Administration is not only harming Nevada, but our nation as a whole.”

Andy Maggi, who directs the Nevada Conservation League, applauded the move, noting the American Lung Association consistently ranks Las Vegas and Reno with poor air quality. 

“President Trump's attack on our ability to set strong emissions standards puts the health and safety of millions of Nevadans at risk, especially communities who already disproportionately suffer from asthma and other respiratory and heart diseases,” Maggi said in a statement. 

And on Monday, Ford joined a lawsuit challenging the Trump administration’s efforts to weaken the Endangered Species Act. The complaint reads like a full defense of what is considered to be one of the toughest environmental laws.

But to the frustration of some environmental groups, the state has not pushed back on Trump when it comes to the Clean Water Act.

Earlier this month, the Trump administration finalized a rule to strike an Obama-era regulation broadening the scope of the Clean Water Act. Obama’s rule, approved in 2015, said the federal act applied to wetlands and seasonal streams. That definition of Waters of the United States (WOTUS) under Obama came in response to a vague Supreme Court opinion in 2006 that left uncertainty about the extent to which the EPA could regulate water.

Gov. Brian Sandoval and Attorney General Adam Laxalt sued over the 2015 definition. In a statement earlier this month, Ford’s office effectively said that the state’s position is unchanged — that Nevada still supports the rules as they were before Obama expanded the EPA’s regulatory scope.

Developers, agricultural interests and mining companies had pushed back on the Obama-era rules. They cited it as an example of federal overreach that would lead to more regulatory uncertainty. In 2014, the state said it was concerned Obama's definition would apply to streams that run infrequently, arguing that "insignificant streams cannot have significant impacts."

Now that the Trump administration has repealed the 2015 rule, it is working on a replacement that conservation groups argue would dilute the Clean Water Act. Former Supreme Court Justice Anthony Kennedy said that the Clean Water Act encompassed waterways with a “significant nexus” to navigable waters. For its new rule, the Trump administration is using a narrower definition from late-Supreme Court Justice Antonin Scalia, a conservative stalwart. As a result, the new rule could exempt at least 85 percent of the mapped streams in Nevada, according to USGS data. That is because most of the state's streams are "ephemeral streams," flowing after precipitation.

In comments submitted to the EPA in April, a letter from three state agencies described Trump’s proposal as “a considerable improvement over the 2015 rule,” despite some new jurisdictional issues. The letter, led by the Department of Conservation and Natural Resources, was also signed by Gov. Steve Sisolak’s Department of Agriculture and Department of Transportation. 

Maggi said he doesn’t think the state's current position is its “final word” once state officials have more time to review what is a complex issue. 

Patrick Donnelly, Nevada director of the Center for Biological Diversity, said in  a statement that his group was disappointed in “Ford and the Nevada Division of Environmental Protection for siding with the Trump administration and giving cover to polluters who threaten our water supply.”

Since the 2018 election, New Mexico and Colorado withdrew from litigation challenging the Obama-era rules. Both states are now led by Democratic governors and attorney generals. Nevada remains a party to the lawsuit.

In the arid West, the flow of water is often intermittent and interconnected in subtle ways. That fact makes any legal interpretation of the Clean Water Act difficult, and it almost guarantees that this issue will end up back in court.

Here’s what else I’m watching:

‘Our house is on fire:’ My colleagues Shannon Miller, Mark Hernandez and Jackie Valley produced a great story on last week’s climate strike in Reno and Las Vegas. They shared with me quotes from participants they interviewed, and one common theme that struck me was the importance of showing up.

Several people talked about how important it was to actually stand and strike somewhere, rather than simply liking a Facebook post. As one sign said during a walkout at A-Tech in Las Vegas: “Raise your voice, not the sea level.”  

RELATED: Commissioners want Clark County to fight climate change (Review-Journal)

A USGS report: The U.S. Geological Survey recently published a report on the potential effect of groundwater pumping at more than 40 sites on the Nevada-Utah border in Snake Valley. The study, first reported by the Circle of Blue, found pumping would lead to a significant drawdown, affecting springs and wetlands. It builds on a paper last year that shows pumping could affect habitat for a threatened fish. The valley has been targeted by the Southern Nevada Water Authority for a possible project to augment Colorado River supplies. The water authority told Circle of Blue that the valley, where it has groundwater applications, is “not a high priority for us at this time.” The study found the available water is at a lower elevation than the water authority's are expected to reach, which could mean a reduction its planned withdrawals.

Diamond Valley order: The closely-watched plan to create a water market in Diamond Valley appears to be moving forward. For decades, water users in the central Nevada basin have pumped more water than is sustainable. It has lead to a declining water table and put agricultural producers at risk. Earlier this year, Nevada’s top water regulator approved a novel management plan that aims to restore the aquifer by gradually limiting groundwater pumping through a market-based approach. The goal is that such a plan would avoid the harsh impact of a curtailment, a legal tool whereby the state engineer can cut off water rights, based on historical use, without regard to immediate economic consequences. Many farmers worry such a move would be devastating.

With a new order, the state is implementing the groundwater plan. Under the plan, water rights would effectively become shares that could be bought and sold, allowing water users to reallocate water rights in a manner that is more flexible than curtailment. Each year, the value of the shares — or the amount of water they represented — would decrease until pumping within the aquifer returned to a sustainable level. The order facilitates this process. It’s mostly a procedural order but it marks a significant step. Many view the "water market" as a model, including some people in other parts of the Southwest (I was at a water conference in Phoenix in March, and three speakers asked me about it).

Yet its fate could left to the courts. The plan is being appealed by several farmers and ranchers, and a judge could strike down a major part of the plan. The plaintiffs argue that the plan deviates from Western water law, whereby those with the earliest claims to water — senior rights users — get to use water before those with later claims — junior rights users. The plan gradually cuts the amount of water available to  both classes, albeit at different rates. The state has argued the plan will withstand a legal challenge because senior rights holders receive more shares than users with junior rights. 

The first briefs from the challengers were filed last week. I still need to finish reading them, though I did see that one begins with this colorful quote: “Democracy has been described as four wolves and a lamb voting on what to have for lunch.” Rhetoric aside, this is an important legal case to watch.

The news from our Anaconda series: This past week, we published a series on the past, present and future of the Anaconda Copper Mine outside of Yerington. What turned into a project started out as one feature story on where things stood with cleaning up the mine, which predated many mining regulations and contaminated a local aquifer with arsenic and uranium. 

At the suggestion of my editors, it morphed into a three-part series to explain all of the moving parts at the 3,600-acre site. Since the stories are lengthy and often technical, I wanted to share some of the main findings here:

• Gov. Sisolak said that he supports the deferral agreement, signed by Gov. Sandoval and then-EPA administrator Scott Pruitt, after talking to tribal leaders and stakeholders. He said in a statement that his administration “will continue to closely monitor the cleanup efforts to ensure that the NDEP continues holding the Atlantic Richfield Company accountable to the high standards and costs necessary for cleaning up the site.”

• State regulators said that they need to rebuild trust after a history of downplaying the extent of contamination at the site. Yet there still remains concern that the state does not have enough leverage to hold Atlantic Richfield, a subsidiary of BP, accountable for the task of cleaning up a groundwater plume that has snaked toward the Yerington Paiute Tribe.

• To that end, Atlantic Richfield recently argued that the former copper mine, for which it is responsible, has contributed substantially less groundwater contamination than was previously modeled. This finding, if upheld, could have huge implications for how the groundwater — with pockets of uranium contamination — is cleaned up and who ends up paying for it. 

• More than a year since the deferral agreement, the state is still negotiating memoranda of understanding with the Yerington Paiute Tribe and the Walker River Paiute Tribe. There are several issues that need to be worked out around funding for technical assistance to comment on reports. The tribes stand to get far less funding than they received when the EPA was leading the cleanup effort, what some point to as an effort to sideline the tribes’ involvement.

• Meanwhile, the state is considering allowing Atlantic Richfield to cease water bottle deliveries for about 120 residents, including tribal members, if they live beyond the plume or are connected to a municipal system. It raises questions about property rights, the state’s responsibility to deal with contamination and who will ensure that residents can have access to safe water.  

• A common theme from most people I interviewed was that Anaconda served as a “lesson learned.” State officials argue that new regulations would prevent Anaconda from happening again. But mining watchdogs want the state to consider adopting rules that prevent pollution in perpetuity, especially with more demand for copper due to decarbonization and electrification. 

Wild horses are at a “devastating level”: “Nevada is ground zero for the West’s increasingly disastrous problem of growing herds of wild horses and burros,” E+E News recently reported after a visit to Eureka County. There are no simple answers to the wild horse issues — here’s a great book that explores the history. But Nevada continues to hold more than half of the 88,000 horses that roam federal public land in the West, and it’s a huge issue for habitat.

Clips from the news:

• The U.S. Bureau of Reclamation, Fish and Wildlife Service and the Pyramid Lake Paiute are starting a project to help Lahontan cutthroat trout swim upstream to spawn (AP)

• Las Vegas water use has dropped, but not for the uber-rich. (Las Vegas Sun)

• “We’re going to be fragmented in different states.” A look at what it means for the Bureau of Land Management to send staff out West, including to Nevada. (ProPublica)

• Supreme Court restores water rights priority dates for ranch (Nevada Appeal)

• A wilderness group is suing a Lake Tahoe ski resort over its attempt to construct a Gondola, approved by Placer County, that will go through a national forest. (AP)

• Cry while you're moving,' says rider who pedaled Pony Express route (RGJ)