6  Regulatory Limits

We calculated regulatory limits based on freshwater quality standards listed from state and federal regulatory agencies…

6.1 Metals

6.1.1 Static Regulatory Threshold Values for Metals

Some regulatory threshold values for metals are static and do not depend on additional environmental parameters. The metals parameters in the downloadable table below have static thresholds assigned.

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6.1.2 Metals with Hardness-Dependent Regulatory Values

Some regulatory values for metals are not simple static values, and are instead hardness-dependent. Hardness varies by site, by season, and with hydrologic conditions. We calculated hardness according to the following formula:

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Hardness = 2.497(Total Calcium in mg/L) + 4.119(Total Magnesium in mg/L)


For sampling events with duplicate samples, we calculated average hardness.

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