U.S. ENVIRONMENTAL PROTECTION AGENCY
NATIONAL EUTROPHICATION SURVEY
WORKING PAPER SERIES
REPORT
ON
MINERAL COUNTY
NEVADA
EPA REGION IX
WORKING PAPER No, 813
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY - CORVALLIS, OREGON
and
ENVIRONMENTAL MONITORING & SUPPORT LABORATORY - LAS VEGAS, NEVADA
•ffG.f.O. 699-440
-------
REPORT
ON
WALKER LAKE
MINERAL COUNTY
NEVADA,
EPA REGION IX
WORKING PAPER No, 813
WITH THE COOPERATION OF THE
NEVADA ENVIRONMENTAL PROTECTION SERVICE
AND THE
NEVADA NATIONAL GUARD
SEPTETCER, 1977
-------
REPORT ON WALKER LAKE
MINERAL COUNTY, NEVADA
EPA REGION IX
by
National Eutrophication Survey
Mater and Land Quality Branch
Monitoring Operations Division
Environmental Monitoring & Support Laboratory
Las Vegas, Nevada
and
Special Studies Branch
Corvallis Environmental Research Laboratory
Con/all is, Oregon
Working Paper No. 813
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
September 1977
-------
i
CONTENTS
Page
Foreword i 1
List of Nevada Study Lakes iv
Lake and Drainage Area Map v
Sections
I. Introduction 1
II. Conclusions 1
III. Lake Characteristics 3
IV. Lake Water Quality Summary 4
V. Literature Reviewed 9
VI. Appendices 10
-------
11
FOREWORD
The National Eutrophlcatlon Survey was Initiated In 1972 In
response to an Administration commitment to Investigate the nation*
wide threat of accelerated eutrophlcatlon to freshwater lakes and
reservoirs.
OBJECTIVES
The Survey was designed to.develop, in conjunction with state
environmental agencies, Information on nutrient sources, concen-
trations, and Impact on selected freshwater lakes as a basis for
formulating comprehensive and coordinated national, regional, and
state management practices relating to point source discharge
reduction and nonpolnt source pollution abatement In lake water-
sheds.
ANALYTIC APPROACH
The mathematical and statistical procedures selected for the
Survey's eutrophlcatlon analysis are based on related concepts
that:
a. A generalized representation or model relating
sources, concentrations, and Impacts can be
constructed.
b. By applying measurements of relevant parameters
associated with lake degradation, the generalized
model can be transformed Into an operational
representation of a lake, Its drainage basin, and
related nutrients.
c. With such a transformation, an assessment of the
potential for eutrophlcatlon control can be made.
LAKE ANALYSIS
In this report, the first stage of evaluation of lake and
watershed data collected from the study lake and Its drainage
basin Is documented. The report 1s formatted to provide state
environmental agencies with specific Information for basin
plannlna [§303(e)]f water quality criteria/standards review
[§303(c)J, clean lakes [§314(a,b)], and water quality monitoring
[§106 and §305(b)] activities mandated by the Federal Water
Pollution Control Act Amendments of 1972.
-------
111
Beyond the single lake analysis, broader based correlations
between nutrient concentrations (and loading) and trophic
condition are being made to advance the rationale and data
base for refinement of nutrient water quality criteria for
the Nation's freshwater lakes. Likewise, multivariate evaluations
for the relationships between land use, nutrient export, and
trophic condition, by lake class or use, are being developed
to assist in the formulation of planning guidelines and policies
by the U.S. Environmental Protection Agency and to augment
plans implementation by the States.
ACKNOWLEDGMENTS
The staff of the National Eutrophication Survey (Office
of Research and Development, U.S. Environmental Protection
Agency) expresses sincere appreciation to the Nevada State
Environmental Protection Service for professional involvement,
to the Nevada National Guard for conducting the tributary
sampling phase of the Survey, and to those Nevada wastewater
treatment plant operators who provided effluent samples and
flow data.
The staff of the Department of Conservation and Natural
Resources, Division of Environmental Protection, State Environmental
Protection Service provided Invaluable lake documentation
and counsel during the Survey, reviewed the preliminary reports
and provided critiques most useful In the preparation of this
Working Paper Series.
Major General Floyd L. Edsall, the Adjutant General of
Nevada, and Project Officer Major Harold E. Roberts, who directed
the volunteer efforts of the Nevada National Guardsmen, are
also gratefully acknowledged for their assistance to the Survey.
-------
IV
NATIONAL EUTROPHICATION SURVEY
STUDY LAKES
STATE OF NEVADA
LAKE NAME
Lake Mead
Lahontan Reservoir
Rye Patch Reservoir
Lake Tahoe
.Topaz Reservoir
Upper Pahranagat Lake
Washoe Lake
Wildhorse Reservoir
Wilson Reservoir
Walker Lake
COUNTY
Clark (Mohave in Arizona)
Lyon, Churchill
Pershing
Washoe, Carson City,
Douglas (Placer,
El Dorado in CA)
Douglas (Mono in CA)
Lincoln
Washoe
Elko
Elko
Mineral
-------
Map Location
Bridgeport
Reservoir
WALKER LAKE
X Lake Sampling Site
5 10 M1.
Scale
-------
REPORT ON WALKER LAKE, NEVADA
STORE! NO. 3211
I. INTRODUCTION
Walker Lake was included in the National Eutrophication Survey
(NES) as a water body of interest to the Nevada State Environmental
Protection Service. Tributaries and nutrient sources were not
sampled and this report relates only to the data obtained from lake
sampli ng.
Walker Lake is a remnant of Lake Lahontan, a prehistoric inland
sea. The Carson River Basin Council of Governments (1974) reports
that the lake rapidly is receding and salinity will soon destroy
its productivity.
II. CONCLUSIONS
A. Trophic Condition:*
Survey data and field observations indicate that Walker
Lake is eutrophic, i.e., nutrient rich and highly productive.
Whether such nutrient enrichment is to be considered beneficial
or deleterious is determined by its actual or potential impact
upon designated beneficial water uses of the lake.
Chlorophyll a_ values in the lake ranged from 1.2 ug/1 to
7.0 ug/1 with a mean of 3.4 yg/1. Hypolimnetic dissolved oxygen
*See Appendix C.
-------
levels were depleted and hydrogen sulfide production was detected
at Station 02 during November. Of the 10 Nevada lakes sampled In
1975, none had higher median total phosphorus values (0.602 mg/1),
7 had higher median inorganic nitrogen levels (0.080 mg/1), and
none had higher median orthophosphorus values (0.574 mg/1), than
Walker Lake.
Survey limnologists noted some algal growth along the shore-
line during the March sampling date and reported algal blooms
over the entire surface of the lake during the August and November
sampling times.
B. Rate-Limiting Nutrient:
Algal assay results were not considered representative of
conditions in the lake at the time of sampling due to a change
in nutrient levels from the time of collection to the beginning
of the assay. Lake data suggest nitrogen to be the primary
limiting nutrient in Walker Lake throughout the sampling year.
-------
III. LAKE CHARACTERISTICS
A. Lake Morphemetry:*
1. Surface area: 153.78 km2.
2. Mean depth: 24.1 meters.
3. Maximum depth: 35.0 meters.
4. Volume: 3,700.470 x 106 m3.
B. Precipitation:
1. Year of sampling: 8.5 cm.
2. Mean annual: 10.7 cm.
*James B. Williams, Jr. (personal communication).
-------
IV. LAKE WATER QUALITY SUMMARY
Walker Lake was sampled three times during the open-water
season of 1975 by means of a pontoon-equipped Huey helicopter.
Each time, samples for physical and chemical parameters were
collected from three stations on the lake and from a number of
depths at each station (see map, page v). During each visit,
depth-integrated samples were collected from each station for
chlorophyll a. analysis and phytoplankton identification and
enumeration. During the first and last visits, 18.9-liter
depth-integrated samples were composited for algal assays.
Maximum depths sampled were 14.6 meters at Station 01, 30.8
meters at Station 02, and 14.6 meters at Station 03. For a
more detailed explanation of NES methods, see NES Working Paper
No. 175.
The results obtained are presented in full in Appendix B
and are summarized in III-A for waters at the surface and at
the maximum depth for each site. Results of the phytoplankton
counts and chlorophyll ^determinations are included in III-B.
Results of the limiting nutrient study are presented in III-C.
-------
CODE 3?11
NO
( 3/1 I'7? 1
AMI) CHFMICAL CnARACIEHISTICS
( 7/11/75 )
MAX
= 3 DEPTH
MANGE
MEDIAN (METEHS)
( ll/ 6/75 »
MAX
S«*« s 3 OEPTh
RANGE
PANGE MEDIAN (METEPS)
TEMPEHATURE (DEG CENT]
O.-l.S M nEPTH
KAX DEPTH**
PISSOLVFO 0«y,EN ("fi/L
O.-l.S M DEPTH
MAX DEPTH**
CONDUCTIVITY (lJMnO«)
O.-l.S M fiEiJTH
MAX DEPTH**
PH (STANDARD L'MITS)
O.-l.S M fiEPTH
MAX OfPTH**
1
6
3
6
3
3
TOTAL AL*ALINIT* I*G/L>
O.-l.^ " OEPTM 6
MAX DEPTH** 1
TOTAL P (MG/L)
n.-l.S M DEPTH
MAX OEPTH**
6
DISSOLVED OKTHO * (MG/D
O.-l.S M i?Et>TH 6
MAX DEPTH** 3
N02»N03 (MO/L)
O.-l.S M nEPTH
MAX DEPTH**
AMMONIA (MG/L)
O.-l.S tt (1EPTH
MAX DEPTH**
XJELDAHL N (MG/L)
O.-l.S » OEPTH
MAX DEPTH**
6
3
6
3
6
3
4.7- S.I
3.0- r.f<
4.0- a. 4
7180.-71H2.
7181. -7182.
9.4- 9. -5
9.4- 0.5
3360. -4000.
0.602-0.632
0.576-0.610
O.S^is-o.612
0.040-0.060
0.050-0.060
0.0^0-0.0*0
0.0?0-0.040
1. 600-3. SOO
2.100-2.300
4J7
6.0
5!!?:
9!b
372n.
0.615
0.6U
0.6AO
0.6ft4
o.oso
O.O^U
o.nto
o.o^o
2.1*0
2.?no
0.0-
11.0-
0.0-
11.0-
0.0-
11.0-
0. fi-
ll. 0-
0.0-
11.0-
0.0-
11.0-
0.0-
11.0-
0.0-
11.0-
0.0-
11.0-
o.n-
11.0-
l.S
TO.h
l.-i
30. H
1.5
30. «
1.5
30. *
1.5
30.6
1.5
30. fl
l.S
30.8
JO!K
1.5
30.8
l.S
30. H
6
3
6
3
4
2
6
3
6
3
6
3
6
3
6
3
h
3
6
3
19.2- 23.0
A. 4- 17.0
4.2- 7.8
2.4- 4.6
7092. -7095.
7097. -7101.
•*.»- 9.5
9.4- 9.5
3480. -5440.
3S40.-3760.
0.51H-O.S56
O.S26-0.648
0.458-0.512
0.506-0.574
O.OPO-0.040
0.020-0.030
0.030-0.060
0.0*0-0.170
1.HOO-2.SOO
2.000-2.500
20. P
12.6
7.2
4.4
7093.
7099.
9.5
9.5
3H80.
3580.
0.527
0.614
0.4H6
0.534
0.030
0.030
0.035
0.070
2.200
2.4QO
0.0- 1.5
7.0- 24.7
0.0- 1.5
7.0- 24.7
0.0- 1.5
14.6- 24.7
0.0- 1.5
7.0- 24.7
0.0- 1.5
7.0- 24.7
0.0- 1.5
7.0- 24.7
0.0- l.S
7.0- 24.7
0.0- l.S
7.0- 24.7
0.0- 1.5
7.0- 24.7
0.0- 1.5
7.0- 24.7
6
3
6
3
6
3
6
3
6
3
6
3
1
0
6
3
6
3
6
3
14.4- 14.6
11.6- 14.5
5.0- 6.8
0.0- 6.2
7067. -7079.
7069. -7079.
9.3- 9.4
9.4- 9.4
3040. -4680.
2480. -5360.
0.558-0.620
0.572-0.740
0.672-0.672
0.020-0.020
0.020-0.020
0.020-0.070
0.020-0.060
1.600-2.000
1.800-2.4QO
14.5
14.4
6.3
6.0
7078.
7075.
4.4
9.4
3670.
4280.
0.599
0.612
0.672
•»»••
0.020
0.020
0.060
0.060
1.800
?.ooo
0.0-
10.4-
0.0-
10.4-
0.0-
10.4-
0.0-
10.4-
0.0-
10.4-
0.0-
10.4-
l.S
30. S
30.5
l.S
30.5
l.S
30.5
l.S
30.5
1.5
30.5
0.0- 0.0
»•••-•*•*«
0.0-
10.4-
0.0-
10.4-
0.0-
10.4-
l.S
30. S
l.S
30.5
l.S
30. S
SECCHI OI«C
2.1- 2.4
0.9- 1.8 1.7
3.?- 3.7 3,7
« N = NO. OF SAMPLES
«« 14KIMUM DEPTH SAMPLED AT EACH slTt
= MO. OF SITES SAMPLED ON Ti-l« DATE
-------
B. Biological Characteristics:
1. Phytoplankton -
Samp!i ng
Date
03/17/75
07/09/75
11/06/75
Algal
Dominant Units
Genera Per ml
1. Pennate diatom 27
2. Chroomonas? 16
3. Tetraedron 5
Other genera —
Total 48
1. Chroococcus 19
Other genera —
Total 19
1. Navicula 6
Other genera —-
Total 6
-------
2. Chlorophyll a. -
Sampling Station Chlorophyll a
Date Number (ug/1) ~
03/17/75 01 2 8
02 2.5
03 2.5
07/09/75 01 1.2
02 1.7
03 3.6
11/06/75 01 7.0
02 4.6
03 4.9
-------
8
C. Limiting Nutrient Study:
The algal assay results are not considered representative of
the conditions in the lake at the time of sampling due to a change
in nutrient levels from the time of collection to the beginning
of the assay.
The mean inorganic nitrogen to orthophosphorus ratios (N/P)
in the lake data were less than 1/1 on the three sampling dates
suggesting primary limitation by nitrogen (a mean N/P ratio of
14/1 or greater generally reflects nitrogen limitation).
-------
V. LITERATURE REVIEWED
Carson River Basin Council of Governments. 1974. Regional Water
Quality Plan, Phase I, Existing Conditions, Walker River Basin,
Carson City, Nevada.
U.S. Environmental Protection Agency. 1975. National Eutrophica-
tion Survey Methods 1973-1976. Working Paper No. 175. National
Environmental Research Center, Las Vegas, Nevada, and Pacific
Northwest Environmental Research Laboratory, Corvallis, Oregon.
Williams, James B., Jr. 1974. Personal communication. Depart-
ment of Human Resources. Carson City, Nevada
-------
10
VI. APPENDICES
APPENDIX A
CONVERSION FACTORS
-------
CONVERSION FACTORS
Hectares, x 2.171 = acres
Kilometers x 0.6211 = miles
Meiers x 3.201 = feet
Cubic mclnrs x 0.107 x 10 = acre/fee I
Square kilometers x 0.3861 = square miles
Cubic motors/sec x 35.315 = cubic feet/sec
Centimeters x 0.3937 = inches
Kilograms x 2.205 = pounds
Kilograms/square kilometer x 5.711 - Ibs/squarc mile
-------
APPENDIX B
PHYSICAL AND CHEMICAL DATA
-------
STO»tT RETRIEVAL DATE 77/01/26
NATt EUTROPHICATION SURVEY
EPA-LAS VEGAS
/TYPA/AMBMT/LAKE
DATE
FROM
TO
75/03/17
75/07/11
75/11/06
TIME
OF
DAY
10 45
10 45
10 45
10 45
10 45
10 50
10 50
10 50
10 50
10 50
10 20
10 20
10 20
10 20
DEPTH
FEET
0000
0005
0010
0022
0036
0000
ooo*
0015
0025
0048
0000
0005
0015
0034
00010
WATER
TEMP
CENT
5.2
5.2
5.2
5.2
5.1
22.1
19.2
16.8
15.3
12.6
14.6
14.5
14.5
14.5
00300
DO
MG/L
6.8
5.4
4.6
6.6
4.8
7.4
7.2
4.4
4.6
6.8
6.2
6.4
6.2
00077
TRANSP
SECCHI
INCHES
84
70
144
00094
CNDUCTVY
FIELD
MICPOMHO
7182
7182
7182
7182
7182
7095
7093
7094
7095
7097
7075
7077
7075
7075
321101
38 35 45.0 118
tfALKER LAKE
32021 NEVADA
00.0
150141
1
1EPALES 04001002
0040 FEET DEPTH CLASS 00
00400
PH
SU
9.
9.
9.
9.
9.
9.
9.
9.
9.
«>.
9.
9.
9.
9.
40
45
50
SO
50
50
SO
50
50
50
30
40
40
40
00410
T ALK
CAC03
MG/L
3360
3520
3740
3780
3640
3760
5240
3760
3960
3760
3720
3040
3820
2480
00610 00625
NH3-N TOT
KJEL
TOTAL N
MG/L MG/L
0.020 2.000
0.020 1
0.020 ]
0.030 1
1 .600
.600
.900
0.020 2.200
0.030 2. 500
0.040 2.300
0.030
0.030
0.060 i
0.020K
0.050
0.020K
0.060
.800
.700
'.000
.700
.800
.600
.800
00630
N02&N03
N-TOTAL
MG/L
0.040
0.040
0.040
0.050
0.050
0.020
0.030
0.020
0.020K
0.020
0.020K
0.02AK
0.020K
0.020K
00671
PHOS-OIS
ORTriO
MG/L P
0.57*
0.610
0.574
0.574
0.604
0.512
0.466
0.490
0.490
0.50f>
0.672
DATE TIME DEPTH
FWOM OF
TO DAY FEET
75/03/17 10 45 0000
10 45 0005
10 45 0010
10 45 0022
10 45 0036
75/07/11 10 50 0000
10 50 0005
10 50 001S
10 50 0025
10 50 0048
75/11/06 10 20 0000
10 20 000^
10 20 0015
10 20 0034
0665
S-TOT
/L P
0.580
0.624
0.584
0.576
0.632
0.530
0.518
0.522
0.528
0.526
0.592
0.558
0.606
0.572
32217
CHLRPHVL
A
UG/L
2.8
1.2
7.0
00031
IMCDT LT
REHNING
PEKCENT
K VALUE KNOWN TO BE LESS
THAN INDICATED
-------
STORET RETRIEVAL DATE 77/01/26
NATL EUTROPHICATION SURVEY
tPA-LAS VEGAS
/TYPA/AM8NT/LAKE
321102
38 39 10.0 118 44 35.0 4
WALKER LAKE
32G11 NEVADA
1S0191
11EPALES 04001002
0105 FEET DEPTH CLASS 00
DATE
FROM
TO
75/03/17
7S/07/M
75/11/06
DATE
FROM
TO
75/03/17
75/07/11
75/11/06
TIME DEPTH
OF
DAY FEET
11 30 '0000
11 30 0005
11 30 0025
11 30 0060
11 30 0101
10 20 0000
10 20 0005
10 20 0015
10 20 0025
10 20 0050
10 20 0081
09 55 0000
09 5S 0005
09 55 0027
09 55 0065
09 55 0100
TIME DEPTH
OF
DAY FEET
11 30 0000
11 30 OOOS
11 30 002*
11 30 0060
11 30 0101
10 20 0000
10 20 0005
10 20 0015
10 20 0025
10 20 OObO
10 20 0081
09 55 0000
09 55 0005
09 55 0027
09 55 0065
09 55 0100
00010
WATER
TEMP
CENT
4.8
4.fl
4.7
4.7
4.7
21.5
19.9
18.1
16.4
11.4
8.4
14. A
14.6
14.5
14.9
11.6
00665
PHOS-TOT
MG/L P
0.606
0.602
0.600
0.698
0.614
0.534
0.520
0.526
0.530
0.576
0.614
0.610
0.606
0.628
0.606
0.740
00300 00077
DO TRANSP
<:£CCHl
MG/L INCHES
7.6 96
3.6
4.6
6.6
4.0
7.8 68
7.2
6.0
6.4
4.0
2.4
6.4 144
6.4
6.4
5.6
0.0
32217 00031
CHLRPHYL INCDT LT
A RFMNING
UG/L PERCENT
2.5
1.7
4.6
00094
CNDUCTVY
FIELD
MICROMHO
7181
7182
7182
7162
7182
7092
7093
7093
7095
7098
7101
7079
7079
7079
7079
7079
00400
PH
SU
9.50
9.50
9.50
9.50
9.50
9.40
9.40
9.40
9.40
9.40
9.40
9.40
9.40
9.40
9.40
9.40
00410
T ALK
CAC03
MG/L
3600
4000
3980
3920
3720
3760
3480
3700
3040
3700
3540
4680
3620
5080
3660
4280
00610
00625
NH3-N TOT KJEL
TOTAL
MG/L
0.040
0.030
0.030
0.030
0.040
0.030
0.040
0.040
0.030
0.050
0.170
0.060
0.060
0.060
0.050
0.020K
N
MG/L
3.500
2.700
2.500
2.500
2.300
1.900
1.400
2.000
1.900
2.200
2.500
2.000
2.000
2.000
1.800
2.000
00630
M02&N03
N-TOTAL
MG/L
0.050
0.060
0.050
0.060
0.060
0.020
0.030
0.020
0.030
0.030
0.030
0.020*
0.020K
0.020*
0.020K
0.020K
00671
PHos-nis
OR TrlO
MG/L P
0.598
0.590
0.600
0.564
0.612
0.480
0.512
0.518
0.508
0.582
0.574
•
K VALUE KNOWN TO BE LESS
-------
STOUI-T RETRIEVAL DATE 77/01/26
NATL E'JTROPHICATION SURVEY
EPA-LAS VEGAS
321103
38 45 15.0 Hfl 43 25.0 4
nALKER LAKE
32021 NEVADA
150191
/TYPA/AUBNT/LAKE
DATE TIi*E DEPTH
FBO"
TO
75/03/17
75/07/09
75/11/06
DATE
FRor«
TO
7b/03/17
75/07/09
75/11/06
OF
DAY
12 15
12 15
12 15
12 15
15 15
15 15
15 IS
15 15
09 25
09 25
09 25
09 25
09 ?«
TIME
OF
DAY
12 15
12 15
12 15
12 15
15 15
15 15
15 IS
15 15
09 25
09 25
09 25
09 25
09 25
FEET
0009
0005
0022
0039
0000
ooos
0015
0023
0000
0005
0015
0030
0048
DEPTH
FEET
0000
0005
0022
0039
0000
0005
0015
0023
0000
0005
001S
0030
0048
00010
WATER
TEMP
CENT
4.7
4.7
4.7
4.7
23.0
20.0
17.0
17.0
14.4
14.4
14.4
14.4
14.4
00665
PHOS-TOT
MG/L P
0.626
0.642
0.596
0.602
0.556
0.550
0.676
0.648
0.590
0.620
0.614
0.602
0.612
00300
DO
MG/L
3.0
6.6
7.0
5.4
4.2
6.4
6.2
4.4
6.0
5.0
5.6
5.2
6.0
32217
CHLRPHYL
A
UG/L
2.5
3.6
4.9
00077 00094
THANSP CNDUCTVY
SECCHI FIELD
INCHES MICROMHO
»4 7180
7182
7181
7181
36
126 7067
7079
7079
7079
7069
00031
INCDT LT
RFMNING
PERCENT
11CPALE* 04001002
0043 FEET DEPTH CLASS 00
00400 00410 00610 00625
PH T ALK NH3-N TOT KjEL
Sll
9.50
9.50
9.50
9.45
9.50
9.50
9.50
9.50
9.40
9.40
9.40
9.40
9.40
CAC03
MG/L
3840
3840
3640
3920
4000
5440
5360
3580
3540
3760
3740
3600
5360
TOTAL
MG/L
0.030
0.030
0.040
0.030
0.030
0.060
0.120
0.070
0.060
0.070
0.050
0.060
0.060
H
MG/L
2.300
1.700
1.900
2.100
2.100
2.«ofl
4.000
2.400
1.600
i.aoo
2.200
2.600
2.400
00630
N02&N03
N-TOTAL
MG/L
0.060
0.050
0.060
0.050
0.030
0.040
0.040
0.030
0.020K
0.020K
0.020K
0.020K
0.020K
00671
PHOS-DIS
ORTHO
MG/L p
0.608
0.602
0.586
0.596
0.45«
0.492
0.500
0.534
K VALUE KNOWN TO BE LESS
THAN INDICATED
-------
APPENDIX C
PARAMETRIC RANKINGS OF LAKES
SAMPLED BY NES IN 1975
STATE OF NEVADA
Mean or median values for six of the key parameters evaluated
in establishing the trophic conditions of Nevada lakes sampled are
presented to allow direct comparison of the ranking, by parameter,
of each lake relative to the others. Median total phosphorus, median
inorganic nitrogen and median dissolved orthophosphorus levels are
expressed in mg/1. Chlorophyll a_ values are expressed in yg/1. To
maintain consistent rank order with the preceding parameters, the
mean Secchi disc depth, in inches, is subtracted from 500. Similarly,
minimum dissolved oxygen values are subtracted from 15 to create
table entries.
-------
LAKE DATA TO BE USED IN RANKINGS
LAKE
CODE LAKE NAME
3201 LAKE MEAD
3202 LAHONTAN RESERVOIR .
3204 RYE PATCH RESERVOIR
3205 LAKE TAHOE
3206 TOPAZ RESERVOIR
3207 UPPER PAHRANGAT LAKE
3208 WASHOE LAKE
3209 WILD HORSE RESERVOIR
3210 WILSON RESERVOIR
3211 'JAUER LAKE
MEDIAN
TOTAL P
0.016
0.19S
0.094
0.005
0.057
0.173 '
0.403
0.114
0.049
0.602
MEDIAN
INORG N
0.340
0.350
0.050
0.040
0.165
0.125
0.130
0.320
0.120
0.080
500-
MEPN SEC
266.565
472.083
467.750
-3.269
376.000
470.000
494.555
439.400
197.333
405.333
MEAN
CHLORA
3.111
4.608
4.938
0.571
7.517
...
11.633
75.530
10.033
3.422
15-
HIN 00
11.400
10.400
10.000
10.200
14.600
3.600
7.200
14.600
11.400
15.000
MEDIAN
DISS ORTHO P
0.005
0.148 •
0.039
0.003
0.041
0.026
0.268
0.065
0.016
0.574
-------
PERCEMT OF LAKES WITH HIGHER VALUES (NUMBER OF LAKES WITH HIGHER VALUES)
LAKE
CODE LAKE NAME.
3201 LAKE MEAD
3202 LAHONTAN RESERVOIR
3204 RYE PATCH RESERVOIR
3205 LAKE TAHOE
3206 TOPAZ RESERVOIR
3207 UPPER PAHRANAGAT LAKE
3208 WASHOE LAKE
3209 UILD HORSE RESERVOIR
3210 WILSON RESERVOIR
3211 WALKER LAKE
MEDIAN
TOTAL p
89 (
22 (
56 (
100 (
67 {
33 (
11 (
44 (
78 (
0 (
8)
2)
5)
9)
6)
3)
1)
4)
7)
0)
MEDIAN
INQRG
11 (
0 (
89 (
100 (
33 (
56 {
4* (
22 (
67 (
78 (
N
1)
0)
8)
9)
3)
5)
4)
2)
6)
7)
500-
HEAN SEC
78 (
22 t
44 (
100 (
67 (
33 (
0 (
11 (
89 (
56 (
7)
2)
A)
9)
6)
3)
0)
1)
8)
5)
KEAM
CHLORA
88 (
63 C
50 (
100 (
38 (
—
13 (
0 (
25 (
75 (
7)
5)
4)
8)
3)
1)
0)
2}
6)
15-
MIN DO
39 (
56 C
78 (
67 (
17 (
89 (
100 (
17 (
39 (
0 (
3)
5)
7)
6)
1)
8)
9)
1)
3)
0)
MEDIAN
DISS ORTHO P
89 (
22 (
56 (
100 (
44 (
67 (
11 (
33 (
78 (
0 C
8)
2)
5)
9)
4)
6)
1)
3)
7)
0)
------- |