2013-08-14_HYDROLOGY - C1981022

• Permit No: C1981022
• IBM Index Class Name: HYDROLOGY
• Doc Date: 8/14/2013
• Doc Name: Wet Study Results Reports
• From: Oxbow Mining, LLC
• To: DRMS
• Permit Index Doc Type: NPDES
• Email Name: BFB
• Email Name: SB1
• Media Type: D
• Archive: No

Enviro -Chem Analytical, Inc. Chronic Toxicity Testing
2493 Hwy 6850 Unit 7 OXBOW — July 2013
Grand Junction, CO 81505 2 Species
Table Of Contents
StudySummary ...................................................... ..............................1
Introduction.............................................................. ..............................2
Methods................................................................... ..............................3
Sample Collection ......................................... ..............................2
Sample Preparation and Usage . ............................... ................3
Test Performance .......................................... ..............................4
TestAcceptability ........................................... ..............................5
Statistical Analyses ........................................ ..............................5
Results...................................................................... ............................... 6
Effluent Chemistry Results .............................. ..............................6
Effluent Toxicity Results for Fathead Minnows . ..............................6
Effluent Toxicity Results for Ceriodaphnia ....... ..............................7
References .................................. ............................... ..........8
.....................
Table 1. Arrival Chemistry Values for Final Effluent Samples from Elk Creek
Mine, Somerset, Colorado
Table 2. Initial Chemistry Ranges for Fathead Minnow and Ceriodaphnia
dubia 7 -Day Toxicity Tests Conducted with Elk Creek Mine,
Test Dates July 23 -30, 2013
Table 3. Final Chemistry Ranges for Fathead Minnow and Ceriodaphnia
dubia Toxicity Tests Conducted with Elk Creek Mine
- Test Dates July 23 -30, 2013
Table 4. Percentage Survival and Growth as Mean Dry Weight (mg) for
Larval Fathead Minnows After 7 -Day Exposure to Elk Creek Mine
- Test Dates July 23 -30, 2013