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Wesr E!k Mine • Table 55 Representative TDS Standards/Criteria TDS Standazds or Criteria TDS (mg/L) Secondary Drinking Water Standard 500 <450: None Restrictions for Irrigation 450 - 2,000: Slight to Moderate >2,000: Severe Restrictions for Livestock <1,000: None 1,000 - 3,000: None for Acclimated Livestock Restrictions for Recreation No restrictions High TDS can cause deposits in heat Restrictions for Industrial Use exchangers and boilers. (Ambient North Fork water would require treatment). Aquatic Life No TDS standards (SAR) is an indicator of the risk that soils may have low permeability. Thus, waters high in sodium and low in calcium and magnesium (the constituents used to calculate SAR) may impose a risk to soils that are used for agriculture. If the SAR is less than 3, there is little to • no risk of soil "swell". Water with SAR values ranging from 3 to 6 slightly increase the risk for detrimental impacts to soils, and those with values greater than 6 are cause for concern. WWE calculated the values of sodium, calcium, and magnesium for the combined flow of the North Fork and the fault inflow effluent and found the new SAR to be 3.6 during low flow conditions. These results are shown in Table 56, below. Table 56 SAR Values at Various Locations • Location Flow (cfs) Sodium (mg/L) Calcittm (mg/L) Magnesium (mg/L) SAR N. Fork upstream 69 6.6 20.1 3.4 0.36 Fault water discharge 5 87.2 3.1 1.6 99.6 Mixed downstream 74 65.1 19.0 3.3 3.6 It is important to note that the increase in SAR will be temporary, due to sodium exchange with calcium and magnesium on sediments and additional downstream inflows. Also, the analysis assumes that the pond discharges consist solely of fault water. Other water reaching the ponds, such as runoff, will have a lower SAR, thereby reducing the SAR of the pond discharges. 2.05-202 Ravisedlun. 1995 PRO6: Revised Nov. 1998 TR80: l/98 PR08