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Nevada Administrative Code (Last Updated: January 6, 2015) |
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Chapter445A Water Controls |
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WATER POLLUTION CONTROL |
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Standards for Water Quality |
NAC445A.2152. Colorado Region: Lake Mead.
- The limits of this table apply to the body of water known as Lake Mead, excluding the area covered by NAC 445A.2154, Inner Las Vegas Bay. Lake Mead is located in Clark County.
STANDARDS OF WATER QUALITY
Lake Mead
PARAMETER
REQUIREMENTS
TO MAINTAIN
EXISTING HIGHER
QUALITY
WATER QUALITY
STANDARDS FOR
BENEFICIAL USES
Beneficial Usea
Livestock
Irrigation
Aquatic
Contact
Noncontact
Municipal
Industrial
Wildlife
Aesthetic
Enhance
Marsh
Beneficial Uses
X
X
X
X
X
X
X
X
Aquatic Life Species of Concern
Warm-water fishery.
Temperature
ΔTb - °C
DT
= 0
ΔT
≤ 2
*
pH - SU
95% of S.V. samples ≤ 8.8
S.V.
6.5 - 9.0
X
X
*
X
X
X
X
Dissolved Oxygen - mg/l
S.V. ≥ 5.0 in the epilimnion or average in water column during periods of nonstratification
X
*
X
X
X
X
Nitrogen Species
(as N) - mg/l
Total Inorganic Nitrogen
95% of S.V. samples ≤ 4.5
Nitrate S.V.
Nitrite S.V.
≤ 10
≤ 1
X
*
*
X
Total Ammonia
(as N) - mg/l
d
*
Chlorophyll a - µg/l
c
*
*
X
X
Suspended Solids - mg/l
S.V.
≤ 25
*
X
Turbidity - NTU
e
S.V.
≤ 25
*
X
X
X
Color - PCU
f
*
X
Total Dissolved
Solids - mg/l
Flow Weighted A-Avg. Concentration ≤ 723 measured below Hoover Damg
S.V.
≤ 1000
X
*
Chloride - mg/l
h
S.V.
≤ 400h
X
*
X
Sulfate - mg/l
h
S.V.
≤ 500h
*
E. coli - MF/100ml
30-day log mean
≤ 126
X
X
*
X
X
S.V.
≤ 235
Fecal Coliform -
MF or MPN/100 ml
≤ 200/400i
X
X
*
X
X
X
* = The most restrictive beneficial use.
X = Beneficial use.
a Refer to NAC 445A.122 and 445A.2142 for beneficial use terminology.
b Maximum allowable increase in temperature above water temperature at the boundary of an approved mixing zone.
c The requirements for chlorophyll a are:
1 Not more than 1 monthly mean in a calendar year at Station LWLVB 1.85 may exceed 45µg/l. Station LWLVB 1.85 is located at the center of the channel at a distance of 1.85 miles into Las Vegas Bay from the confluence of the Las Vegas Wash with Lake Mead.
2 The mean for chlorophyll a in summer (July 1-September 30) must not exceed 40 µg/l at Station LWLVB 1.85, and the mean for 4 consecutive summer years must not exceed 30 µg/l. The sample must be collected from the center of the channel and must be representative of the top 5 meters of the channel. Station LWLVB 1.85 is located at the center of the channel at a distance of 1.85 miles into Las Vegas Bay from the confluence of the Las Vegas Wash with Lake Mead.
3 The mean for chlorophyll a in the growing season (April 1-September 30) must not exceed 16 µg/l at Station LWLVB 2.7 and 9 µg/l at Station LWLVB 3.5. Station LWLVB 2.7 is located at a distance of 2.7 miles into Las Vegas Bay from the confluence of the Las Vegas Wash with Lake Mead. Station LWLVB 3.5 is located at a distance of 3.5 miles into Las Vegas Bay from the confluence of the Las Vegas Wash with Lake Mead.
4 The mean for chlorophyll a in the growing season (April 1-September 30) must not exceed 5 µg/l in the open water of Boulder Basin, Virgin Basin, Gregg Basin and Pierce Basin. The single value must not exceed 10 µg/l for more than 5 percent of the samples.
5 Not less than two samples per month must be collected between the months of March and October. During the months when only one sample is available, that value must be used in place of the monthly mean.
d The ambient water quality criteria for ammonia are specified in NAC 445A.118.
e Turbidity must not exceed that characteristic of natural conditions by more than 10 NTU.
f Color must not exceed that characteristic of natural conditions by more than 10 PCU.
g The salinity standard for the Colorado River System is specified in NAC 445A.1233.
h The combination of this constituent with other constituents comprising TDS must not result in the violation of the TDS standards for Lake Mead and the Colorado River.
i Based on a minimum of not less than five samples taken over a 30-day period, the fecal coliform bacterial level must not exceed a log mean of 200 per 100 milliliters, nor must more than 10 percent of the total samples taken during any 30-day period exceed 400 per 100 milliliters.
Ê The Commission recognizes that at entrances of tributaries to Lake Mead, localized violations of standards may occur.
(Added to NAC by Environmental Comm’n by R160-06, eff. 8-26-2008)