N.H. Code Admin. R. Env-Wq 1703.23 – Conversion Factors For Metals

(a) Dissolved metal shall be determined by multiplying total recoverable metal by the conversion factor listed in Table 1703-2 for that metal, shown in equation form as follows:
Dissolved Metal = Total Recoverable Metal x Conversion Factor
(b) Total recoverable metals shall be determined by dividing dissolved metals by the conversion factor listed in Table 1703-2, shown in equation form as follows:
Total Recoverable Metal = Dissolved Metal / Conversion Factor
(c) The conversion factors in Table 1703-2 shall be used as translators to go from the dissolved metals criteria listed in Table 1703-1 to permit limits expressed as total recoverable metals by dividing dissolved metal by the conversion factor.
(d) If the hardness of the receiving water is different than 20 mg/L, then aquatic life criteria for hardness-dependent metals shall be calculated as follows:
1. (1) The equations in Env-Wq 1703.24(a) and (b) shall be used in conjunction with the coefficients shown in Table 1703-3 to calculate the total recoverable metal for freshwater;
2. (2) The equations shown in (a) and (b), above, shall be used in conjunction with the factors shown in Table 1703-2 to convert total recoverable metal to dissolved metal or dissolved metal to total recoverable metal;
3. (3) For hardness less than 20 mg/L, a hardness of 20 mg/L shall be used in the equations; and
4. (4) For hardness values greater than 400 mg/L, a hardness of 400 mg/L shall be used in the equations.
(e) Table 1703-2 shall be as follows, provided that the conversion factors for cadmium and lead shall be no greater than 1.0:
Table 1703-2: Factors to Convert Total Recoverable Metals to Dissolved Metals
FRESHWATER
Conversion Factors
MARINE
Conversion Factors
Acute
Chronic
Acute
Chronic
Arsenic
1.0
1.0
1.0
1.0
Cadmium
1.136672 - [(Ln Hardness)(0.041838)]
1.101672 - [(Ln Hardness)(0.041838)]
0.994
0.994
Chromium (+3)
0.316
0.860
-
-
Chromium (+6)
0.982
0.962
0.993
0.993
Copper
0.960
0.960
0.83
0.83
Lead
1.46203 - [(Ln Hardness)(0.145712)]
1.46203 - [(Ln Hardness)(0.145712)]
0.951
0.951
Mercury
0.85
0.85
0.85
0.85
Nickel
0.998
0.997
0.990
0.990
Selenium
-
-
0.998
0.998
Silver
0.85
-
0.85
-
Zinc
0.978
0.986
0.946
0.946

Source. (See Revision Notes #1, #2, and #3 at chapter heading for Env-Wq 1700) #12042, eff 12-1-16; ss by #14203, eff 2-26-25