At least 40 people were arrested Monday morning in two frac sand mining protests in Winona, Minn.
About 20 people that were part of a larger group of 100 stood in the path of sand trucks for more than an hour, preventing the frac sand from being loaded onto barges at the city's harbor. A second protest was being held at a sand washing facility on Highway 14 in Winona.
Winona Police Chief Paul Bostrack said the protesters were cited for trespassing on private property.
Silica sand is used in hydraulic fracturing -- commonly known as fracking -- to get natural gas and oil out of the ground. In Winona, seven companies are either mining, washing or transporting the sand.
Minnesota's fast-growing frac sand industry, fueled by the oil boom in neighboring North Dakota, has divided some communities. While some landowners and local governments benefit from the investment in sand mining, others are concerned with air quality, the impact on the landscape and increased traffic from sand-hauling trucks.