1. (1) Limits.

   1. (i) Toxic substances. The following limits shall apply in basin waters other than zones 2, 3, 4 and 5.

      1. (a) The concentration of a toxic substance in basin waters shall not exceed one twentieth of the TL₅₀ value at 96 hours, as determined by appropriate bioassays, except in designated mixing areas. Criteria for combinations of toxic substances will be based upon the same principle.

      2. (b) The substances listed below shall not exceed the specified limits or one twentieth of the TL₂₀ value at 96 hours, whichever is lower.

         	Limit mg/l
         Arsenic	0.05
         Barium	1.0
         Cadmium	0.01
         Chromium (hexavalent)	0.05
         Lead	0.05
         Mercury	0.005
         Selenium	0.01
         Silver	0.05

      3. (c) The concentration of a persistent pesticide^* in basin waters shall not exceed one one hundredth of the TL₅₀ value at 96 hours, as determined by appropriate bioassay.

   2. (ii) Oil. No readily visible oil.

      (b) Effluent quality requirements.

2. (1) Public safety. Temperature. Maximum 110° (43.3°C) where readily accessible to human contact.

3. (2) Limits.

   1. (i) Debris, scum or other floating materials. None.

   2. (ii) Toxicity. The following requirements shall apply in basin waters other than zones 2, 3, 4 and 5.

      1. (a) Not more than 50 percent mortality in 96 hours in an appropriate bioassay test with a 1:1 dilution. Wastes containing chlorine may be dechlorinated prior to the bioassay test.

      2. (b) Notwithstanding the results of the tests prescribed in clause (a) of this subparagraph, the substances listed below, being accumulative or conservative, shall not exceed the following specified limits in an effluent:

         	Limit mg/l
         Arsenic	0.1
         Barium	2.0
         Cadmium	0.02
         Chromium (hexavalent)	0.10
         Copper	0.20
         Lead	0.10
         Mercury	0.01
         Selenium	0.02
         Zinc	0.60

      3. (c) Persistent pesticides, not to exceed 1/100 of the TL₅₀ value at 96 hours as determined by appropriate bioassay.
   3. (iv) Odor. Not to exceed a threshold number of 250.
   4. (v) BOD. In zones 2, 3, 4 and 5, a waste shall receive not less than zone percent reduction in addition to meeting allocation requirements.

On January 26, 1972, the Delaware River Basin Commission adopted Interpretive Guideline No. 1, as Resolution No. 72-1, directing that the following numerical definitions be used as guidelines by the commission staff in administering sections 860.3(a), 860.4(a), (c), and (d) of this Part of the Water Quality Standards, and that they be administered in accordance with the procedures of the Basin Regulations—Water Quality.

(a) Stream quality objectives.