NC0036269_Whole effluent toxicity test results_20180907

Division of Water Resources
August 31, 2018
To: Corey Basinger
Water Quality Program Re Tonal Supervisor, MRO
Through: Cindy A. Moore
Supervisor, Aquatic Toxicology Branch
From: Carol Hollenkamp
Quality Assurance Of icer, Aquatic Toxicology Branch
Subject: Whole effluent toxicity test results
Rocky River WWTP
NPDES Permit # NC0036269/001
Cabarrus County
The aquatic toxicity test using flow proportional composite samples of effluent discharged from the Rocky
River WWTP has been completed. Rocky River WWTP has a permitted discharge of 26.5 million gallons per
day (MGD) to Rocky River (summer 7Q10 of 25.2 CFS). Whole effluent samples were collected on August 7
and August 9 by Roberto Scheller for use in a chronic Ceriodaphnia dubia multi -concentration toxicity test.
The test using these samples resulted in a pass. Toxicity test information follows.
Test Type 3 -Brood Ceriodaphnia dubia chronic multi -concentration
Test Concentrations 0, 31, 46.5, 62, 81, 100%
Test Result ChV = >100% (Pass)
Control Survival 100%
Control Mean Reproduction 25.5 neonates
Test Treatment Survival
Treatment Mean Reproduction
First Sample pH
First Sample Conductivity
First Sample Total Residual Chlorine
Second Sample pH
Second Sample Conductivity
Second Sample Total Residual Chlorine
100% at 31, 46.5, 62, and 81%; 90% at 100%
24.3 neonates in 62% (62% is permit limit)
7.24 SU
545 micromhos/cm
<0.10 mg/L
7.24 SU
574 micromhos/cm
<0.10 mg/L
Test results for the above samples indicate that the effluent would not be predicted to have water quality
impacts on receiving water. These samples were split with Meritech. The test conducted by Meritech also
passed with a ChV>100%. Please contact us if you have any questions or if further effluent toxicity
monitoring is desired. We may be reached at [phone].
Basin: Yadkin
cc: Roberto Scheller (MRO)
Aquatic Toxicology Branch Water Sciences Section