Livestock feedlot operations are polluting both surface waters and groundwater. The risk of water pollution is especially high in the “karst” geology which makes southeast Minnesota’s Driftless area such a phenomenal trout mecca. This karst region has porous bedrock close to the surface which creates the large, cold springs which in turn produce the amazing spring creeks concentrated here. Unfortunately, the porous bedrock also allows contaminants on the surface to easily reach this groundwater and our beloved trout streams.

A livestock feedlot is a type of animal feeding operation used in intensive animal farming for finishing livestock, including beef cattle, swine, sheep, turkeys, and chickens prior to slaughter. Large feedlots are called “concentrated animal feeding operations” or “CAFOs”. Feedlots are used to increase the amount of meat each animal produces as quickly as possible. Animals confined in feedlots put on weight more quickly than pastured animals and allow a farm to raise more animals.

The Minnesota Pollution Control Agency (MPCA) regulates the collection, transportation, storage, processing and disposal of animal manure. It has developed feedlot rules which apply to most aspects of livestock management including the location, design, construction, operation and management of feedlots and manure handling facilities. Only CAFOs with 1,000 or more “animal units” need a permit.

Manure contains a variety of nutrients, including Nitrogen which is converted to other forms such as nitrates and ammonium, when it interacts with soil micro-organisms. When manure is applied and there is sudden rain-fall event, the manure washes directly into streams leading to oxygen depletion and fish kills. There are two primary pathways by which feedlot operations can pollute groundwater and trout streams:

  • Runoff of manure (primarily liquid) from the feedlot itself or manure storage area
  • Runoff from the manure which is applied to cropland, typically over a wide area

Rising surface and groundwater nitrate levels and fish kills indicate that current feedlot rules are not adequate to protect our waters.

The MPCA’s monitoring of surface waters has shown elevated nitrate levels, particularly in Minnesota’s Southeastern corner. Very high nitrate levels in groundwater and trout streams harm both humans and aquatic ecosystems.

  • Nitrates reduce the size and potentially survival of trout populations.
  • Nitrates act as a fertilizer in water, just like on land, and this can lead to algal blooms, oxygen depletion, and a general deterioration of trout habitat.
  • Increased nitrates in streams can lead to decreased suitability of habitat, especially for spawning and nursery areas, and stress adult fish which can make them more susceptible to disease and impact their reproductive success.
  • Increased nitrates have been shown to decrease the number of aquatic insects available as a trout food.

What’s next?

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Read more about Agricultural Runoff, Fishkills, Nitrates, Neonics, and Groundwater.

See the MNTU blog for recent news concerning various feedlot proposals.