Significant Nexus

{
  "id": "MLC-T-ENV-025556",
  "term": "Significant Nexus",
  "field": "Environment",
  "definition": "1. That a water, including wetlands, either alone or in combination with other similarly situated waters in the region, significantly affects the chemical, physical, or biological integrity of a water identified in paragraphs (l)(1)(i) through (iii) of this section. The term “in the region” means the watershed that drains to the nearest water identified in paragraphs (l)(1)(i) through (iii) of this section. For an effect to be significant, it must be more than speculative or insubstantial. Waters are similarly situated when they function alike and are sufficiently close to function together in affecting downstream waters. For purposes of determining whether or not a water has a significant nexus, the water's effect on downstream (1)(i) through (iii) waters shall be assessed by evaluating the aquatic functions identified in paragraphs (l)(3)(v)(A) through (I) of this section. A water has a significant nexus when any single function or combination of functions performed by the water, alone or together with similarly situated waters in the region, contributes significantly to the chemical, physical, or biological integrity of the nearest water identified in paragraphs (l)(1)(i) through (iii) of this section. Functions relevant to the significant nexus evaluation are the following: (A) Sediment trapping, (B) Nutrient recycling, (C) Pollutant trapping, transformation, filtering, and transport, (D) Retention and attenuation of flood waters, (E) Runoff storage, (F) Contribution of flow, (G) Export of organic matter, (H) Export of food resources, and (I) Provision of life cycle dependent aquatic habitat (such as foraging, feeding, nesting, breeding, spawning, or use as a nursery area) for species located in a water identified in paragraphs (l)(1)(i) through (iii) of this section.\n\n2. A water, including wetlands, either alone or in combination with other similarly situated waters in the region, significantly affects the chemical, physical, or biological integrity of a water identified in paragraphs (o)(1)(i) through (iii) of this section. The term “in the region” means the watershed that drains to the nearest water identified in paragraphs (o)(1)(i) through (iii) of this section. For an effect to be significant, it must be more than speculative or insubstantial. Waters are similarly situated when they function alike and are sufficiently close to function together in affecting downstream waters. For purposes of determining whether or not a water has a significant nexus, the water's effect on downstream (o)(1)(i) through (iii) waters shall be assessed by evaluating the aquatic functions identified in paragraphs (o)(3)(v)(A) through (I) of this section. A water has a significant nexus when any single function or combination of functions performed by the water, alone or together with similarly situated waters in the region, contributes significantly to the chemical, physical, or biological integrity of the nearest water identified in paragraphs (o)(1)(i) through (iii) of this section. Functions relevant to the significant nexusevaluation are the following:(A) Sediment trapping,(B) Nutrient recycling, (C)Pollutant trapping, transformation, filtering, and transport, (D) Retention and attenuation of flood waters, (E)Runoff storage, (F) Contribution of flow, (G)Export of organic matter, (H)Export of food resources, and (I) Provision of life cycle dependent aquatic habitat (such as foraging, feeding, nesting, breeding, spawning, or use as a nursery area) for species located in a water identified in paragraphs (o)(1) through (3) of this section.\n\n3. A water, including wetlands, either alone or in combination with other similarly situated waters in the region, significantly affects the chemical, physical, or biological integrity of a water identified in paragraphs (1)(i) through (iii) of this definition. The term “in the region” means the watershed that drains to the nearest water identified in paragraphs (1)(i) through (iii) of this definition. For an effect to be significant, it must be more than speculative or insubstantial. Waters are similarly situated when they function alike and are sufficiently close to function together in affecting downstream waters. For purposes of determining whether or not a water has a significant nexus, the water's effect on downstream (1)(i) through (iii) waters shall be assessed by evaluating the aquatic functions identified in paragraphs (3)(v)(A) through (I) of this definition. A water has a significant nexus when any single function or combination of functions performed by the water, alone or together with similarly situated waters in the region, contributes significantly to the chemical, physical, or biological integrity of the nearest water identified in paragraphs (1)(i) through (iii) of this definition. Functions relevant to the significant nexus evaluation are the following: Sediment trapping, Nutrient recycling, Pollutant trapping, transformation, filtering, and transport, Retention and attenuation of food waters, Runoff storage, Contribution of flow, Export of organic matter, Export of food resources, and Provision of life cycle dependent aquatic habitat (such as foraging, feeding, nesting, breeding, spawning, or use as a nursery area) for species located in a water identified in paragraphs (1)(i) through (iii) of this definition.\n\n4. A water, including wetlands, either alone or in combination with other similarly situated waters in the region, significantly affects the chemical, physical, or biological integrity of a water identified in paragraphs (1)(i) through (iii) of this definition.",
  "references": [
    "40 CFR 401.11 (CFR 2017)",
    "40 CFR 230.3 (CFR 2016)",
    "40 CFR 232.2 (CFR 2016)",
    "40 CFR 300.5 (CFR 2013)"
  ],
  "url": "https://mlchart.com/terminology/environment/significant-nexus/"
}