Inadequate waste disposal practices from more than a century of oil and gas development — practices that are no longer permitted — are the chief source of salty brines in the waters of the Williston Basin, according to U.S. Geological Survey research.
The Williston Basin, one of the nation’s critical bird habitats and one of its top oil-producing regions, stretches across the northern Great Plains and into Canada. USGS researchers tested lakes and shallow groundwater at three sites in Montana and North Dakota.
Most of the water contamination is legacy pollution. Decades ago, energy companies let the salty water that flowed out of oil and gas wells evaporate in pits the size of Olympic swimming pools. The dried salts were then buried.
Salty plumes of water traveled at least 800 meters from the reserve pits, said Brian Tangen, a USGS ecologist and a study co-author. Under the right conditions, brine could move up to 1,600 meters.
The locations of the reserve pits, however, are not well marked.
“There are a lot of legacy pits out there, but there’s no census of where they are in relation to water resources,” Tangen told Circle of Blue.
The research team also identified some 30,000 oil and gas wells drilled in the basin between 1901 and 2011 and plotted them against the locations of wetlands and streams. Some 1,800 square kilometers of wetlands are within 1,600 meters of a known well.
Even though reserve pits are not allowed, spills of briny waters still occur at the well sites. North Dakota state officials counted nearly 1,700 spills between November 1, 2012 and November 11, 2013, according to the study.
Tangen said studies to assess the ecological effects of brine on wildlife and water will follow this spatial assessment.
More Salty Water
Concentrations of salts and other dissolved solids in rivers and stream are highest in the Midwest and Great Plains, according to a U.S. Geological Survey assessment of data from 2,560 water monitoring stations.
Concentrations are higher in these areas because it is a dry region where rivers carried comparatively little water.
Salt concentrations in rivers are increasing most quickly on the East Coast, where the substances spread on roads to melt winter ice are to blame. Nearly 14 percent of the salt load in the nation’s streams comes from deicers, compared to 71 percent from rock weathering and other natural processes. But in the Northeast, road deicers account for one-third of salts added to rivers.
The lowest salt concentrations are in the Pacific Northwest, New England, and Southeast.
Deflate a balloon, and it flattens. The same with the ground when too much water is pumped out of aquifers.
In California’s Coachella Valley the rate of land compaction, or subsidence as it is called, was fairly constant from the mid-1990s to 2010, according to the U.S. Geological Survey. Researchers used GPS and radar measurements to assess the changes.
Groundwater levels in some of the areas showing subsidence reached record lows in 2010. When the ground compacts, water storage capacity can be lost forever.
Regulations in Process
Federal agencies released their regulatory syllabi for the next six months.
The Department of the Interior highlighted six rules in various stages of development. One is the stream protection rule, which focuses on coal mining’s destruction of rivers and forests in Appalachia. The agency is working on a new environmental review for the rule.
West Virginia Chemical Spill
The federal agency that investigates chemical accidents will update the public on its assessment of the January 2014 chemical spill in the Elk River that left at least 300,000 West Virginia residents without municipal drinking water for days and suspicions that lingered for weeks.
The meeting will take place July 16 in Charleston, West Virginia.
Brett writes about agriculture, energy, infrastructure, and the politics and economics of water in the United States. He also writes the Federal Water Tap, Circle of Blue’s weekly digest of U.S. government water news. He is the winner of two Society of Environmental Journalists reporting awards, one of the top honors in American environmental journalism: first place for explanatory reporting for a series on septic system pollution in the United States(2016) and third place for beat reporting in a small market (2014). He received the Sierra Club’s Distinguished Service Award in 2018. Brett lives in Seattle, where he hikes the mountains and bakes pies. Contact Brett Walton