Beneficial Use Impairment Delisting in the St. Louis River Estuary

What is a Beneficial Use Impairment?

Restoration Science has its own lingo. One term that is used frequently and important to understand is Beneficial Use Impairment, this is often shortened to its acronym BUI. A BUI is way of referring to the negative factors that are influencing the estuary, such as the presence of tumors on fish, the closing of beaches, or the loss of fish or wildlife populations.

When the St. Louis River Estuary was declared an Area of Concern, the Remedial Action Plan (RAP) team identified nine specific BUIs – these are listed below, and following the links will take you to documents that provide great detail on the rationale for listing a particular BUI, the data behind the decisions, and the timeline for removing the BUI. The removal of a BUI is referred to as Delisting, and the end goal of all the restpration efforts described on this site is to have all nine BUIs delisted from the estuary. At that point the designation of the estuary as an Area of Concern will be removed.

August 2014 was a milestone in the estuary, with the removal of the one of the nine BUIs. The “Degradation of Aesthetics” BUI was placed because of oil, chemical, and tar residue on the surface of Strkyer Bay, noxious smells at Newton Creek, and grain and grain dust blowing into the waters of St. Louis and Superior Bays. Remediation and Restoration efforts have cleaned up these impacts, and we have achieved the final delisting target of “ verified persistent occurrences of objectionable properties in surface waters of the St. Louis River Estuary during the previous five year period”.

The BUIs

BUI 1 Restrictions on Fish Consumption: When contaminant levels in fish or wildlife populations exceed current standards, objectives, guidelines,or public health advisories are in effect for human consumption of fish or wildlife. Contaminant levels in fish and wildlife must be due to contaminant input from the watershed.

BUI 2 Degraded Fish and Wildlife Poplulations: When fish and wildlife management programs have identified degraded fish or wildlife populations due to a cause within the watershed. In addition, this use will be considered impaired when relevant, field validated, fish or wildlife bioassays with appropriate quality assurance/quality controls confirm significant toxicity from water column or sediment contaminants.

BUI 3 Fish Tumors and other Deformities: When the incidence rates of fish tumors or other deformities exceed rates at unimpacted control sites or when survey data confirm the presence of neoplastic or preneoplastic liver tumors in bullheads or suckers.

BUI 4 Degradation of Benthos: When the benthic macroinvertebrate community structure significantly diverges from unimpacted control sites of comparable physical and chemical characteristics. In addition, this use will be considered impaired when toxicity (as defined by relevant, field validated, bioassays with appropriate quality assurance/quality controls) of sediment associated contaminants at a site is significantly higher than controls.

BUI 5 Restrictions on Dredging: When contaminants in sediments exceed standards, criteria, or guidelines such that there are restrictions on dredging or disposal activities.

BUI 6 Excessive Loading of Sediment and Nutrients: When there is a high load of sediments or nutrients coming from within the AOC designated area.

BUI 7 Beach Closings and Body Contact Restrictions: When waters, which are commonly used for total body contact recreation, exceed standards, objectives, or guidelines for such use.

BUI 8 Degradation of Aesthetics: When any substance in water produces a persistent objectionable deposit, unnatural color or turbidity, or unnatural odor (e.g., oil slick, surface scum).

BUI 9 Loss of Fish and Wildlife Habitat: When fish and wildlife management goals have not been met as a result of loss of fish and wildlife habitat due to a perturbation in the physical, chemical, or biological integrity of the Boundary Waters, including wetlands.

The timeline for removing the remaining eight BUIs is listed below:

Figure 1. Interactive timeline of Benefical Use Impairment Removal in the St. Louis River AOC

Click these links to go deeper on BUIs: