Minntac Tailings Basin - Proposed WQ Permit Compliance Points

Dark River @ CR 668GW014

Headwater of Dark River or Seep

GW013

GW012

Little Sandy Lake Inlet

Admiral Lake

Proposed Boundary MW

Timber Creek

Identified Parameters of Concern

Minntac Tailings BasinGroundwater & Drinking

Water (trout)Industrial

ConsumptionAgric. and Wildlife Observed Concentrations

Parameters of Concern Class 1Secondary Drinking

Water Standard

Class 3B (trout) Class 3C

Class 4A (irrig. And wild rice)

Class 4B (livestock

and wildlife)GW012 Dark River @

CR668

Sand River / Twin Lakes

(Twin 1-Sept 2013)

Bicarbonates (HCO3 as CaCO3) 250 mg/L N/A 505 314

Fluoride 4.0 mg/L 2.0 mg/L NM 8.67 (seep) N/A

Hardness (Ca+Mg as CaCO3) 250 mg/L 500 mg/L N/A 1430 NM

Specific Conductance 1000 uS N/A 2367 1890

Sulfate 250 mg/L 10 mg/L 1000 mg/L 435 900 650

TDS 500 mg/L 700 mg/L 840 1950 1390

Potential Analytes in GW and SW Classes

GW 2A 2B 3 4 GW 2A 2B 3 4Alkalinity (Bicarbonate as CaCO3) Aluminum TotalAmmonia Antimony TotalBicarbonates (HCO3) Arsenic TotalFluoride Barium TotalHardness (Ca+Mg as CaCO3) Beryllium TotalpH Boron TotalPhosphorous (N lakes & Forest) CadmiumSalinity ChlorideSpecific Conductance Chromium (total)Sulfate Chromium +6TDS Cobalt, TotalTemperature CopperTSS Iron TotalTurbidity Lead

Manganese TotalMercuryNickel (salts)SeleniumSilverSodiumThallium Zinc

Minntac Tailings BasinPresumed Water Quality Compliance Limits for Permit Reissuance as of 10/21/2013

West Surface Water East Surface Water Groundwater

Parameter Dark River Origin

Dark River CR668

Dark River (trout) Timber Creek Admiral Lake Sand River -

L. Sandy Lk. GW012 GW013 GW014 GW-Prop

Bicarbonate (HCO3 as CaCO3) 250 250 250 250 250 N/A N/A N/A N/A

Hardness (Mg + Ca as CaCO3) 500 500 250 500 500 500 N/A N/A N/A N/A

Specific Conductance (uS/cm) 1000 1000 1000 1000 1000 N/A N/A N/A N/A

Sulfate (mg/L) 1000 1000 250 1000 1000 10 250 250 250 250

TDS (mg/L) 700 700 700 700 700 500 500 500 500

Fluoride (mg/L) N/A N/A 2 N/A N/A N/A 2 2 2 2

Iron (mg/L) 2 2 2 2 2 0.3 0.3 0.3 0.3TSS (mg/L) 30 30 30 30 30 N/A N/A N/A N/AAmmonia unkown unkown unkown unkown unkown unkown N/A N/A N/A N/A

Phosphorus unkown unkown unkown unkown unkown unkown N/A N/A N/A N/AMetals unkown unkown unkown unkown unkown unkown unkown unkown unkown unkown

Surface water limits are the applicable usage class Water Quality Standards since the stream's headwaters are at the tailings basin and receive tailings-impacted baseflow as their main source

Sulfate limits for West Surface Water assume Dark River is not deemed "Wild Rice Production Water"Final permit limits will be established based on review by Effluents Limit Staff of monitoring data to be collected and submitted by permittee