Chemical Water Quality Standards

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Chemical Water Quality Standards (Ohio Administrative code 3745-1-07)

Chemical Form Units1 Inside Mixing Zone Maximum Outside Mixing Zone Maximum Outside Mixing Zone Average
Ammonia-N (WWH) Total mg/l - - Table 7-2 Table 7-5
Ammonia-N (EWH) Total mg/l - - Table 7-3 Table 7-6
Ammonia-N (MWH) Total mg/l - - Table 7-2 Table 7-7
Ammonia-N (SSH2) Total mg/l - - Table 7-4 a
Ammonia-N (CWH) Total mg/l - - Table 7-4 Table 7-8
Ammonia-N (LRW) Total mg/l - - Table 7-2 - -
Arsenic Dissolved4 μg/l 680 340 150
Arsenic Total Recoverable5 μg/l 680 340 150
Cadmium7          
Chlorine(WWH, EWH, MWH, CWH) Total Residual μg/l - - 19 11
Chlorine(LRW) Total Residual μg/l - - 19 - -
Chlorine(SSH2) Total Residual μg/l - - b b
Chromium6          
Chromium VI Dissolved μg/l 31 16 11
Copper6          
Cyanide(WWH, EWH, MWH) Free μg/l 92 46 12
Cyanide(LRW) Free μg/l 92 46 - -
Cyanide(SSH2, CWH) Free μg/l 45 22 5.2
Dieldrin Total μg/l 0.47 0.24 0.056
Dissolved oxygen3 (WWH) Total mg/l - - 4.0 5.0
Dissolved oxygen3 (EWH) Total mg/l - - 5.0 6.0
Dissolved oxygen3 (MWH) Total mg/l - - 3.0c 4.0
Dissolved oxygen3 (SSH2) Total mg/l - - a a
Dissolved oxygen3 (CWH) Total mg/l - - 6.0 7.0
Dissolved oxygen3 (LRW) Total mg/l - - 2.0 3.0
Dissolved solids Total mg/l - - - - 1500d
Endrin Total μg/l 0.17 0.086 0.036
Lead6          
Lindane Total μg/l 1.9 0.95 - -
Mercury Dissolved4 μg/l 2.9 1.4 0.77
Mercury Total Recoverable5 μg/l 3.4 1.7 0.91
Nickel6          
Parathion Total μg/l 0.13 0.065 0.013
Pentachlorophenol7          
pH (WWH, MWH) - - s.u. - - - - 6.5-9.0
pH (EWH, CWH) - - s.u. - - - - e
pH(SSH2) - - s.u. - - - - a
pH(LRW) - - s.u. - - - - 6.5-9.0f
Selenium Dissolved4 μg/l - - - - 4.6
Selenium Total Recoverable5 μg/l - - - - 5.0
Temperature (WWH, MWH) - - 0F(0C) - - Table 7-14 Table 7-14
Temperature (EWH, CWH) - - 0F(0C) - - g g
Temperature (SSH2) - - 0F(0C) - - a a
Temperature (LRW) - - 0F(0C) - - 98(37) 94(34)
Zinc6          

1.  mg/l = milligrams per liter (parts per million); μg/l = micrograms per liter (parts per billion); s.u. = standard units; 0F =degrees Fahrenheit; 0C = degrees Celsius.

2.  SSH- This aquatic life habitat use designation is in effect only during the months of October to May

3.  Outside Mixing Zone Maximum means outside mixing zone minimum Outside Mixing Zone Average means outside mixing zone minimum twenty-four-hour average

4.  These criteria are implemented by multiplying them by a translator approved by the director pursuant to rule 3745-2-04 of the Administrative Code.

5.  These criteria apply in the absence of a translator approved by the director pursuant to rule 3745-2-04 of the Administrative Code.

6.  These criteria are water hardness dependent. See table 7-9 of OAC 3745-2-04.

7.  These criteria are water pH dependent. See table 7-10 of this rule.

a.  This criterion is the same as that for the aquatic life use designation in effect June to September. See footnote 2.

b.  No chlorine is to be discharged.

c.  The dissolved oxygen minimum at any time criterion for modified warmwater habitats in the Huron/Erie lake plain ecoregion, as identified in rules 3745-1-08 to 3745-1-30 of the Administrative Code, is 2.5 mg/l.

d.  Equivalent 25C specific conductance value is 2400 micromhos/cm.

e.  pH is to be 6.5-9.0, with no change within that range attributable to human-induced conditions.

f.  Acid mine drainage streams over sandstone geotype are exempt from the pH criterion.

g.  At no time shall the water temperature exceed the temperature which would occur if there were no temperature change attributable to human activities.


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Last updated: April 7, 2009.