Tribal Police Chief Chad Johnson first noticed a change on the wind-swept prairies of the reservation around six years ago.
Small-time methamphetamine dealers known to the police officers for the Mandan, Hidatsa and Arikara tribes — known as the MHA Nation — were ceding territory to dealers from California, Colorado, Utah and even Latin America. Many were heavily armed and dealing in pounds of meth.
Local and federal officials estimate 90% of the drugs on the reservation now come from other states or countries. And it's not just meth. In 2012, Justice Department officials spotted heroin on the reservation for the first time.
"Instead of finding an 8-ball of meth, now you're finding pounds," said Tim Purdon, U.S. attorney for North Dakota. "When we serve search warrants now, we don't just find drugs; we find firearms. Everyone is heavily armed. There are more and more guns."
Driven by the new wealth of the Bakken oil fields, drug dealing has spread across the reservation, tearing apart families and destroying the fabric of this once-isolated community.
Local tribal law enforcement officials have been overwhelmed. The reservation has about 20 officers and a handful of criminal investigators to police about 1,500 square miles — roughly three times the size of Los Angeles.
For drug dealers, the reservation is a unique haven — the meeting point of money, a vast and isolated terrain and a rat's nest of federal and local law that makes it difficult to arrest and prosecute outsiders.
"We're easy pickings," said MHA Nation Chief Judge Diane Johnson.
Johnson said that before the oil bonanza, about 30% of the cases that came to her court were drug-related. She said that number is now closer to 90%, and she struggles to keep up.
Drug-related arrests of tribal members on the reservation have grown from 47 in 2008 to over 800 last year, according to tribal public safety statistics.
MHA Nation Children and Family Services Department officials said they never had to take custody of children born addicted to opiates until 2010, when child services officials saw their first drug-addicted baby born on the reservation. There have been at least 15 such cases since.
"It's a tidal wave," Judge Johnson said. "This is beyond the capability of our tribes."
The new criminal scene came into the open in 2012, when Michael J. Smith, a Colorado man armed with rifles and a pistol, barricaded himself in a house on the Three Affiliate Tribes reservation. After a two-day standoff, tribal police used a front-loader to demolish the home and get him out.
Smith was indicted with dozens of others in "Operation Winter's End," a major FBI effort to quell drug dealing on the reservation. Local and federal officials believe the sellers had ties to Mexican gangs.
The problem continued to grow and became so urgent that the three tribes flew Guatemalan gang experts to the area in October 2013 to teach local law enforcement officials how to detect members of the notorious Central American gang Mara Salvatrucha.
Known as MS-13, the Los Angeles-bred gang began proliferating outside the U.S. after many of its members were deported to Central America.
One of the experts, Francisco Foppa, said he noticed MS-13 tattoos on people in a Wal-Mart in Minot and the 4 Bears Casino and Lodge at the MHA Nation's capital in New Town. "It was alarming to see people with those tattoos on the reservation," he said.
Authorities have not arrested any MS-13 kingpins, but the gang's presence is palpable and many speak about it in whispers.
"MS-13 is strong enough and scary enough that I question whether I should speak out at all," said a former tribal leader who requested anonymity out of fear of reprisal. "They're vicious. Just like any ripe feeding ground, they have competition, but obviously they are the big bad wolf. They are the ones that are the most terrifying."
With the wealth generated by the Bakken oil fields, crime has increased so much in the region that voters just across the state line in Roosevelt County, Mont., recently passed a bond to increase jail space. The FBI plans to open an office in the region.
The reservation has about 4,000 tribal members, and more than double that number in nonmembers who live and work in the area.
During the day, big rigs and other oil vehicles barrel down state Highway 23, a two-lane road that was never meant to handle so much traffic. The road slices through the heart of New Town, a collection of old and frayed one-story buildings that makes up the biggest town on the reservation.
The Missouri River, which cuts the reservation in half, can be seen to the west. To the east, oil rigs pockmark the landscape to the horizon.
When night sets, flames from the oil burning off lick the night sky.
Mary Eleanor Fox, a 66-year-old silver-haired matriarch of a large family, said she never thought she'd see the day most of her grandchildren would be addicted to the sort of drugs she'd once only heard about "in the big cities."
"Now everyone is on meth and heroin," Fox said. "It just makes me sick to my stomach."
Her daughter, Jackie Powell, a robust 47-year-old with a quick smile, was forced to quit her job and become a full-time mom to her two grandsons — ages 1 and 2 — who were born addicted to methamphetamine.
Their father, Powell's son Mason Fox, struggles with his meth addiction. Their mothers grapple with the same. Amelia Reed, mother to the youngest, first tried meth nearly five years ago and says she's addicted to "the devil's drug."
"Now my first son was born with it," Reed said. "I was pregnant and selfish and wouldn't stop doing it."
Reed receives oil royalty money from land she inherited on the reservation, and says the monthly checks made it easy for her to drop at least $400 a month for her habit.
Many tribal members receive royalty money — from a few hundred dollars to tens of thousands of dollars a month. Reed says she once cashed out $147,000 and blew most of it on meth.
"This used to be home," she said. "Because of the drugs and the oil boom, it's not the same as when I was growing up.… Everyone is scared here."
For Police Chief Johnson, it's a tragically familiar story of drugs.
"I don't think there is a family on this reservation that hasn't been affected in one way or another," he said.
Purdon, the U.S. attorney, says that authorities are making headway in dismantling some of the drug rings, and that Operation Winter's End has led to the indictment of more than 60 people for dealing meth or heroin.
But the arrests only scratch the surface of a web of drug dealing and use that has become woven into some families on the reservation.
Two of Mary Fox's grandchildren — Akaka Katrina Aulaumea, 25, and Kealoha Asaga Aulaumea, 22 — were picked up in Operation Winter's End, accused of possessing and conspiring to distribute meth.
Another granddaughter, Amanda Yazzie, became addicted to heroin about three years ago.
Unable to afford full-fledged treatment, Yazzie tried to wean herself from drugs last spring while staying at her mother's house. She cried, scratched her hands, stroked her auburn hair. Her legs shook uncontrollably.
Yazzie, a pretty 21-year-old, doesn't get oil royalties. But friends who do fed her habit.
"I get high for free," she said. "So I keep going and going."