Thanks to an alert Upvalley hiker, drug agents rooted out a large marijuana garden west of St. Helena.

Last week, a person hiking at the end of White Sulphur Springs Road noticed things were out of the ordinary. The hiker saw that about one acre of land near the creek had been cleared of brush, according to Napa Special Investigation Bureau Cmdr. Gary Pitkin.

The brush had been pushed into piles forming a fence around the pot garden.

The hiker found young marijuana plants in a makeshift nursery, and a tent nearby, Pitkin said. He told drug agents he saw three men hiding in the nearby woods. When he tried to approach them, they fled.

On Friday, NSIB agents combed the area and pulled up 1,490 pot plants growing in cups near the abandoned campsite, Pitkin said.

Pitkin said hundreds of branches had been cut down with a chain saw. Trash was scattered over the area and water was being diverted from a nearby creek. Tubing and marijuana growing supplies were also discovered.

Pitkin estimated that if the plants had been able to reach maturity, they could have yielded several hundreds pounds of high-grade marijuana with a street value of about $600,000.

No one has been arrested.

Pitkin pointed out signs of marijuana garden operations that could alert the public to the illegal activities. Watch for suspicious vehicles near creeks, springs or vineyards and people with food and camping supplies in areas where camping is not common. Other indications are people carrying plant materials, tubing, electric watering timers, drip lines, tubing or saws in unexpected locations.

Anyone with information related to a marijuana grow is asked to call NSIB agent Rick Greenberg at 253-4458.