Ariz. Admin. Code § 18-11-215

Current through Register Vol. 30, No. 50, December 13, 2024

Section R18-11-215 - Numeric Water Quality Standards for Non-WOTUS Protected Surface Waters

A. E. coli bacteria. The following water quality standards for Escherichia coli (E. coli) are expressed in colony-forming units per 100 milliliters of water (cfu / 100 ml) or as a Most Probable Number (MPN):

E. coli	FBC AZ	PBC AZ
Geometric mean (minimum of four samples in 30 days)	126	126
Statistical threshold value	410	576

B. pH. The following water quality standards for non-WOTUS protected surface waters pH are expressed in standard units:

pH	DWS AZ	FBC AZ, PBC AZ, A&Ww AZ, A&Wc AZ	AgI AZ	AgL AZ
Maximum	9.0	9.0	9.0	9.0
Minimum	5.0	6.5	4.5	6.5

C. The maximum allowable increase in ambient water temperature, due to a thermal discharge is as follows:

A&Ww AZ	A&Wc AZ
3.0° C	1.0° C

D. Suspended sediment concentration.

1. The following water quality standards for suspended sediment concentration, expressed in milligrams per liter (mg/L), are expressed as a median value determined from a minimum of four samples collected at least seven days apart:

2. The Director shall not use the results of a suspended sediment concentration sample collected during or within 48 hours after a local storm event to determine the median value.

A&Wc AZ	A&Ww AZ
25	80

E. Dissolved oxygen. A non-WOTUS protected surface water meets the water quality standard for dissolved oxygen when either:

1. The percent saturation of dissolved oxygen is equal to or greater than 90 percent, or

2. The single sample minimum concentration for the designated use, as expressed in milligrams per liter (mg/L) is as follows:

Designated Use	Single sample minimum
	concentration in mg/L
A&Ww AZ	6.0
A&Wc AZ	7.0

The single sample minimum concentration is the same for the designated use in a lake, but the sample must be taken from a depth no greater than one meter.

F. The tables in this subsection prescribe water quality criteria for individual pollutants by designated use:

Ariz. Admin. Code § R18-11-215

New Section made by final rulemaking at 29 A.A.R. 302, effective 2/20/2023.