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North Dakota

Securing Freshwater for People and Nature in the Sheyenne Delta

Story Highlights
  • We are developing water "budgets," like household budgets, but with a finite amount to "spend" on drinking water and irrigation for people and sustained moisture for water-loving plants and animals throughout the growing season.
  • The Nature Conservancy and the US Forest Service are developing an approach for identifying limits to groundwater withdrawals based on ecological thresholds.

TNC Botanist Rhett Johnson surveys for wetland indicator plant species on the Sheyenne National Grasslands of North Dakota.

Groundwater. We all depend on it, but sometimes we take it for granted. We drink it. We water our crops with it. And many wetlands owe their very existence to this unseen resource. Known as groundwater-dependent ecosystems, these wetlands often lose out as humans withdraw groundwater for our own uses. But it doesn’t have to be that way. The Nature Conservancy and the US Forest Service (USFS) are developing an approach for identifying limits to groundwater withdrawals based on ecological thresholds, termed Environmental Flows and Levels. We are looking at several areas across the country where both people and wetlands count on clean, reliable sources of groundwater. Through the use of field studies and hydrological modeling, we are developing water “budgets,” like a household budget to pay for utilities, the mortgage, and groceries. A finite amount of water is available, and can be “spent” on different things. But we want to be sure that we can cover the basics, such as municipal drinking water and irrigation for people, and sustained moisture for water-loving plants and animals throughout the growing season. Phil Gerla, Hydrologist with the Conservancy’s Minnesota, North Dakota and South Dakota Chapter, is applying the Environmental Flows and Levels framework to the Sheyenne Delta of North Dakota. Working with Allison Aldous and Leslie Bach of the Oregon Chapter, and numerous USFS partners, Phil is working out thresholds that can accommodate agriculture’s need for ditching and drainage as well as wetlands’ needs for sustained water levels and flows. Using a series of groundwater wells and indicator plant species, he determined that ditches can impact water availability to wetlands at a distance of nearly half a mile on either side of the ditch. Information gathered over two seasons of sampling will be put to use to recommend ditch placement, setbacks, depth, and engineering with the goal of balancing wetland groundwater needs with requirements for agricultural drainage.

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