SUMMARY OF EFFLUENT TOXICITY TESTING - NORTHEAST TREATMENT PLANT
        Percent Mortality Percent Effluent         Residual   Hardness Alkalinity Ave. Plant Upstr. Salt Effluent Instream
Sampling Agency/   Test Acute Acute Chronic 24-Hour 48-Hour 96-Hour   NOEC     LOEC     Cond.   Temp. D.O. Cl2 NH3-N as CaCO3 as CaCO3 Flow Crk. Flow Toxicity Toxicity
Period Lab Comments Organism 24-Hour 48-Hour 7-Day LC50 LC50 LC50 Survival Growth Reprod. Survival Growth Reprod. IC25 µmhos/cm pH °C mg/l mg/l mg/l mg/l mg/l cfs cfs TUc [1] TUc [2]
09/26/1988 A&L 24 Hr. Effluent Composite C. dubia 100.0%                         1,305 7.3 19.5 8.3 <0.1 9.57     8.23 #N/A    
to Midwest   P. promelus 0.0%                                                
09/27/1988   Grab Sample at W. Prop. Line C. dubia 100.0%                                                
    Above Treatment Plant P. promelus 0.0%                                                
5/17/89 to EPA No mortality at <= 50% eff. C. dubia 15.0% 100.0%   None 70.7%                 1,482 8.35-8.61 25.6-25.8 4.9-7.3 <0.02 #N/A 240 271 7.79 #N/A    
5/19/89 Region 7 23% 48-Hr. Mortality @ 50% Effl. P. promelus 23.3% 100.0%   71.7% 60.2%                                        
07/09/1990 A&L Original Effluent Sample C. dubia 80.0%                         1,469 7.44-7.69 20-20 8.4-8.4 <0.5 9.67-8.55     8.51      
to Midwest   P. promelus 0.0%                                                
07/10/1990   Ammonia Stripped Sample C. dubia 5.0%                         1,469 8.49-8.45 20-20 8.40-8.40 <0.5 1.61-1.29            
      P. promelus 0.0%                                                
04/15/1991 A&L Original Effluent Sample C. dubia 100.0%                         1,280 7.68-7.88 20-20 10.35-NA 0.3 15.19-15.05     8.78 #N/A    
to Midwest   P. promelus 80.0%                                                
04/16/1991   Ammonia Stripped Sample C. dubia 0.0%                         1,348 8.63-8.45 20-20 8.80-7.81 <0.5 2.10-1.50            
      P. promelus 95.0%                                                
    Chlorine Stripped Sample C. dubia 50.0%                         1,281 7.73-7.86 20-20 10.20-NA <0.5 15.38-14.42            
      P. promelus 35.0%                                                
    Both Cl2 & NH3 Stripped C. dubia 0.0%                         1,352 8.63-8.47 20-20 8.90-7.85 <0.5 1.49-2.03            
      P. promelus 95.0%                                                
3/30/92 to EPA No Mortality at <= 50% Effl. P. promelus 76.7% 100.0%     70.7%                 1224 8.50-8.77 24-25 6.7 <0.02 16.5 240 294 8.22 #N/A    
3/31/92   No Mortality at <= 50% Effl. C. dubia 30.0% 100.0%     70.7%                                        
06/15/1992 A&L Original Effluent Sample C. dubia 0.0%                         1254 7.60-8.12 20-20 7.62-7.00 0.24 8.61-13.0     9.10 #N/A    
to Midwest   P. promelus 45.0%                                                
06/16/1992   Ammonia Stripped Sample C. dubia 10.0%                           7.14-7.60 20-20 7.71-4.10 0.27 5.81-4.06            
      P. promelus 0.0%                                                
    Chlorine Stripped Sample C. dubia 0.0%                           7.74-8.13 20-20 7.74-6.70 ND 12.5-11.8            
      P. promelus 35.0%                                                
    Both Cl2 & NH3 Stripped C. dubia 85.0%                           7.24-7.73 20-20 7.70-4.35 ND 4.90-4.76            
      P. promelus 0.0%                                                
06/28/1993 A&L Original Effluent Sample C. dubia 100.0%                           8.06-8.30 24.5-22 9.80-8.45 0.55 13.5-11.76     11.00 #N/A    
to Midwest   P. promelus 100.0%                                                
06/29/1993   Ammonia Stripped Sample C. dubia 100.0%                           8.40-8.50 24.5-22 13.20-8.25 0.55 3.36-2.37            
      P. promelus 100.0%                                                
    Chlorine Stripped Sample C. dubia 60.0%                           8.10-8.30 24.5-22 13.20-7.30 ND 3.36-NA            
      P. promelus 55.0%                                                
    Both Cl2 & NH3 Stripped C. dubia 25.0%                           8.40-8.40 24.5-22 8.23-6.30 ND 3.36-2.02            
      P. promelus 5.0%                                                
6/21/94 to Midwest Original Effluent Sample C. dubia 0.0%                         1283 7.80-8.30 23.4-21.4 7.80-7.20 ND 8.96-11.65     8.66 #N/A    
6/22/94 Lab   P. promelus 5.0%                                                
8/29/94 to EPA   C. dubia 0.0% 0.0%                       1250 7.85-8.46 24.3-24.7 7.20-8.10 <0.02 17.8-NA 236 270 8.04 142    
8/30/94   No Mortality at <= 50% Effl. P. promelus 0.0% 6.7%                                              
09/05/1995 EA Original Effluent Sample C. dubia 30.0%   80.0%                     182-1.322 7.7-8.7 19.7-21.0 8.5-9.2 <0.01 17.0-22.9 248-256 270-284 8.07 95    
to Sparks, MD (C. dubia = 8-day Chronic; Hardness Impairment) P. promelus 50.0%   100.0%         12.5%     25.0%   26.2% 736-1,839 8.3+-0.25 23.6-26.0 4.2-8.3             3.82 0.32
09/11/1995   Ammonia Stripped Sample C. dubia 0.0%   70.0%                                            
    (C. dubia = 8-day Chronic; Hardness Impairment) P. promelus 0.0%   2.0%                                            
11/13/1995 EA Original Effluent Sample C. dubia   0.0% 100.0%   >100%       6.3%     12.5% 54.8% 186-1558 7.7-8.7 23.4-27.1 7.5-8.7 0 24.0 228 292 7.89 108 1.82 0.12
to Sparks, MD (C. dubia = 6-day Chronic; No Chlorination) P. promelus   100.0% 100.0%   62.5% 58.9%   25.0%     50.0%   38.6% 186-1567 7.1-8.6 23.5-26.0 4.5-8.5 0           2.59 0.19
11/14/1995   Ammonia Stripped Sample C. dubia   0.0% 0.0%                                            
    (C. dubia = 6-day Chronic; No Chlorination) P. promelus   0.0% 3.0%                                            
09/10/1996 EA Original Effluent Sample; CO2 Head Space C. dubia 0.0% 0.0% 70.0%   >100%       80.0%     100.0% 82.2% 162-1874 7.4-8.6 23.5-26.0 7.0-8.5 0 0.06-0.25 212-236 160-182 3.65 234 1.22 0.02
to Sparks, MD (C. dubia = 6-day Chronic; No Chlorination) P. promelus 0.0% 5.0% 10.0%   >100% >100%   50.0%     80.0%   93.9% 162-1625 7.4-8.3 23.2-26.0 5.6-8.2 0           1.06 0.02
09/16/1996   Ammonia Stripped Sample; CO2 Head Space C. dubia 0.0% 0.0% 20.0%                                            
    (C. dubia = 6-day Chronic; No Chlorination) P. promelus 0.0% 2.0% 2.0%                                            
03/04/1997 EA Original Effluent Sample C. dubia 20.0% 100.0% 100.0%   71.9%       25.0%     50.0% 47.7% 170-2040 7.9-8.3 19.7-20.8 8.6-9.2 <0.01 16.7-25.3 240-248 304-310 7.66 242 2.10 0.06
to Sparks, MD (C. dubia = 6-day Chronic; No Chlorination) P. promelus 95.0%                         212-2320 7.7-8.3 19.5-21.0 8.6-9.3                
03/10/1997   Ammonia Stripped Sample C. dubia 0.0% 0.0% 10.0%                                            
    (C. dubia = 6-day Chronic; No Chlorination) P. promelus 10.0%                                                
04/01/1997 EA Original Effluent Sample (No Chlorination)                                                    
to Sparks, MD 0 ppt Salinity P. promelus   100.0% 100.0%     63.2%   25.0%     50.0%   53.4%   7.6-8.2 24.0-25.7 6.9-8.3 <0.01 17.6-25.4 244-268 302-306 8.21 151 1.87 0.10
04/07/1997   1 ppt Salinity P. promelus   100.0% 100.0%     65.3%   25.0%     50.0%   53.5%                     1.87 0.10
    2 ppt Salinity P. promelus   100.0% 100.0%     61.9%   50.0%     80.0%   56.7%                     1.76 0.09
     4 ppt Salinity P. promelus   100.0% 100.0%     68.0%   50.0%     80.0%   58.0%                     1.72 0.09
    Ammonia Stripped Sample P. promelus   2.0% 2.0%                                            
08/23/1998 EA Original Effluent Sample C. dubia 0.0% 0.0% 12.0%   > 100% #N/A   100.0%       > 100% 61.6% 1,497-1,616 6.7-7.3 23.5-26.0 5.9-8.3 < 0.01 3.57-6.62 280-292 186-206 4.22 210 1.62 0.03
to Sparks, MD (Time of Flow Diversion to Theresa St. Plant) P. promelus 0.0% 0.0% 10.0%   > 100% > 100%   100.0%     > 100%   > 100%                     < 1.0 < 0.02
08/28/1998   Ammonia Stripped Sample C. dubia 0.0% 0.0% 20.0%   > 100% #N/A   100.0%       > 100% > 100%                     < 1.0 < 0.02
    (C. dubia = 8-day Chronic) P. promelus 0.0% 0.0% 7.0%   > 100% 100.0%   100.0%     > 100%   > 100%                     < 1.0 < 0.02
    Ammonia Add-Back to Orig. Conc. C. dubia 0.0% 0.0% 0.0%   > 100% #N/A   100.0%       > 100% 89.4%                     1.12 0.02
    (C. dubia = 8-day Chronic) P. promelus 0.0% 0.0% 5.0%   > 100% > 100%   80.0%     100.0%   > 100%                     < 1.0 < 0.02
02/23/1999 EA Original Effluent Sample C. dubia 10.0% 0.0% 10.0% > 100%  > 100%  > 100%     80.0%     100.0% 61.2% 1,408-1,438 7.3-7.4 22.7-26.0 3.7-8.9 < 0.01 16.1-32.7 260-272 258-280 7.98 178 1.63 0.07
to Sparks, MD (Time of Flow Diversion from NETP) P. promelus 85.0% 85.0% 85.0% 89.4% 88.0% 88.0%   80.0%     100.0%   87.2%                     1.15 0.05
03/01/1999   Ammonia Stripped Sample C. dubia 0.0% 0.0% 0.0% > 100%  > 100%  > 100%     100.0%      > 100% > 100%                     < 1.0  < 0.04
    (C. dubia = 8-day Chronic) P. promelus 5.0% 2.0% 7.0% > 100%  > 100%  > 100%   100.0%      > 100%    > 100%                     < 1.0  < 0.04
    Ammonia Add-Back to Orig. Conc. C. dubia 35.0% 60.0% 100.0% > 100% 96.0% 87.7%     < 80%     80.0% < 80%                     > 1.25 > 0.05
    (C. dubia = 8-day Chronic) P. promelus 100.0% 100.0% 100.0% < 80% < 80% < 80%   < 80%     < 80%   < 80%                     > 1.25 > 0.05
09/26/1999 EA Original Effluent Sample C. dubia 0.0% 0.0% 80.0% >100% >100% 100.0%   25.0%     50.0%   36.4% 1,365-1,522 7.5-8.5 19.5-25.9 6.3-9.0 <0.01-0.03 17.9-29.8 252-264 250-262 10.1 162.5 2.75 0.16
to Sparks, MD   P. promelus 90.0% 97.0% 100.0% 83.3% 62.5% 56.1%   25.0%     50.0%   55.1%                     1.81 0.11
10/01/1999   Ammonia Stripped Sample C. dubia 0.0% 0.0% 0.0% >100% >100% >100%   100.0%     >100%   >100%                     < 1.0 <0.06
      P. promelus 0.0% 2.0% 12.0% >100% >100% >100%   100.0%     >100%   >100%                     < 1.0 <0.06
    Ammonia Add-Back to Orig. Conc. C. dubia 100.0% 100.0% 100.0% 87.3% 84.2% <80%   <80%     80.0%   <80%                     > 1.25 > 0.07
      P. promelus 100.0% 100.0% 100.0% <80% <80% <80%   <80%     80.0%   <80%                     > 1.25 > 0.07
10/10/1999 EA Original Effluent Sample C. dubia 15.0% 10.0% 30.0% >100% >100% >100%   50.0%     80.0%   47.8% 1,230-1,440 7.1-8.7 19.9-26.0 5.7-9.3 <0.01 15.7-26.0 252-260 252-270 9.3 110.3 2.09 0.16
to Sparks, MD (C. dubia = 6-day Chronic) P. promelus 100.0% 100.0% 100.0% 65.2% 67.1% 58.8%   25.0%     50.0%   48.5%                     2.06 0.16
10/18/1999   Ammonia Stripped Sample C. dubia 0.0% 10.0% 20.0% >100% >100% >100%   80.0%     100.0%   84.7%                     1.18 0.09
    (C. dubia = 6-day Chronic) P. promelus 0.0% 0.0% 2.0% >100% >100% >100%   100.0%     >100%   >100%                     <1.0 <0.08
    Ammonia Add-Back to Orig. Conc. C. dubia 95.0% 90.0% 100.0% <80% 80.0% 80.0%   <80%     80.0%   22.4%                     4.46 0.35
    (C. dubia = 6-day Chronic) P. promelus 100.0% 97.0% 100.0% <80% <80% <80%   <80%     80.0%   24.6%                     4.07 0.32
File:  F:\MSExcel\San\Sampling\SurfaceWQ\ToxSum.xls  
 
  [1]   Effluent TUc was calculated as the reciprocal of the IC25 effluent toxicity concentration and is relative to plant effluent end of pipe.    
  [2]  Instream TUc was calculated as the Effluent TUc x (Qe/(Qe + Qs)), where Qe = plant effluent flow and Qs = upstream flow in Salt Creek.    
  NDEQ Proposed Limits:  
  Theresa St. Plant:  7Q10 summer = 13.7 cfs and TUc = 2.46 max. based on NOEC; 7Q10 winter = 21.7 cfs and TUc = 2.55 max based on NOEC.  
  Northeast Plant:  7Q10 summer = 43 cfs and TUc = 1.8 max. based on NOEC; 7Q10 winter = 50 cfs and TUc = 1.8 max based on NOEC.  
  In general, TUc shall not exceed 1.0 at the end of the chronic mixing zone; the City is allowed 100% mixing allowance with Salt Creek flow.