MIRANDA - The history of California's damaged ecosystem can be traced back to the mid 19th century gold rush; then there was the forest rush, when the lumber industry arrived to plant and chop down countless trees.

And now, after decades of devastation from the mining and logging industries, some environmentalists are warning about the green rush. That would be the marijuana growers who are multiplying, and the natural resources they're using to nurture their crops are being depleted, says Scott Bauer, of the state's Department of Fish and Wildlife.

In Northern California, the three counties of Humboldt, Trinity and Mendocino comprise the “Emerald triangle,” considered to be the largest marijuana-growing region in the United States, he says.

In a dried river bed, Bauer points out coho salmon, a threatened species, and other fish that have perished because of the river's drought. They are the victims of intense — and illegal — irrigation to support marijuana fields and greenhouses, which prematurely dries up the rivers. “Because of this summer's severe dryness, California's water resources are highly compromised,” he says.

Near Salmon Creek, which flows into Miranda's Eel River, we count almost 500 marijuana farms irrigated by this stream and its affluents within a 40-square-mile area. It amounts to about 500,000 liters a day, as each seedling needs between five to 25 liters of water a day. On Google Earth, we can see some seedlings in the middle of fields along with trellises and plastic greenhouse roofs.

Environmental conservation agencies sometimes intervene against these kinds of breaches when they fall within their jurisdiction, but they have limited resources and are dealing with so much land that it calls to mind the Wild West. Medical marijuana use has been allowed in California since 2005, but its production and supply are still prohibited by federal authorities.

“We respond to complaints, conduct investigations, and if we find violations, we pursue the offenders,” says David Leland, who works at the California Water Board, the agency that controls permits and water quality. On July 8, for example, two Mendocino County farmers were fined $30,000 after building a reservoir without a permit.

But it's not possible to keep all the illegal practices under control. The Emerald triangle is the new El Dorado. Marijuana farmers from all around the world have flocked here to get in on an enormously profitable business.

A $14 billion California industry

There is no reliable data to quantify the magnitude of the black market, but one-third of American marijuana is believed to be grown in California. It is a $14 billion industry here, more than the market value of grapes, corn and animal feed combined. Marijuana farming is believed to consume one percent of the country's electricity. So it's not surprising that this drug made popular by 1960s counterculture has a poor image within the environmental community.

This intensive cultivation is causing a new wave of deforestation. Access roads and flood barriers are being built without authorization. The uncontrolled use of pesticides and chemicals kills animals and pollutes groundwater.

Even Mexican cartels use California forests “with very destructive farming methods,” says Brad Job of Arcata Land Management, an agency that works to preserve natural resources.

“I'm not armed,” he says. To avoid the cartels, “I stay away between April and December, when they are working, hidden by trees and vegetation to avoid detection by police helicopters.” Two of these fields were found in 2012, in the Sierra mountains and in the King Range National Conservation Area. For the first time, federal authorities charged these illegal farmers with crimes against environment on the public domain.

Of course, some cannabis growers praise responsible and “sustainable” farming. Kristin Nevedal, spokesperson for the Emerald Growers Association — a 415-member farming advocacy group — refuses to confirm whether she herself is a grower. “Nowadays, farmers don't feel like talking to journalists,” she says. Marijuana farmers “don't try to get permits because they fear they will be sued, especially in California, where there are federal raids on a daily basis,” she explains, adding that growing 100 seedlings carries a five-year jail sentence, or 10 years for 1,000 seedlings. She is lobbying in Sacramento for approval of farming regulation and medicinal cannabis distribution measures.

Eureka Sheriff Steve Knight says there's been an increase in criminal activities linked to marijuana farming. So while he generally disagrees with “weed farmers,” that's not the case on the question of legalizing the drug. “Without rules, the situation will not get better,” he says. “Maybe we should legalize it in the whole country, and deal with marijuana as we do with tobacco.”