Existing water quality shall be determined using methods described in items A to D. The methods are listed in descending order of priority. Lower priority methods shall be used only if higher priority methods are not reasonably available. More than one method shall be used when a single method does not adequately describe existing water quality.
Using commissioner-approved monitoring data that exist at the time the determination of existing water quality is undertaken.
Monitoring surface waters, provided that samples are collected in a manner and place and of such type, number, and frequency as may be considered necessary by the commissioner to adequately reflect the condition of the surface waters. Samples must be collected, preserved, and analyzed following accepted quality control and quality assurance methods and according to the procedures in part 7050.0150, subpart 8.
Identifying reference surface waters that have similar physical, chemical, and biological characteristics and similar impacts from regulated and unregulated activities.
Use of a water quality model to characterize existing conditions in the surface water, provided that the model uses data from the same watershed as the surface water under review for existing conditions.
For surface waters impacted by activities that are regulated by existing control documents, existing water quality includes surface water conditions that are anticipated at loadings or other causes of degradation authorized in the applicable control document.
41 SR 545
December 9, 2016
Official Publication of the State of Minnesota
Revisor of Statutes