DISTRIBUTION AND BIOTIC EFFECTS
OF NUTRIENTS IN FLATHEAD LAKE, MONTANA
A Report on Research Work Done in
1973-1975 with the Support of the
Environmental Protection Agency and
the State of Montana Department of
Health and Environmental Sciences.
Submitted by the Investigators:
John F. T1bbs
University of Montana
Department of Zoology
M<«soula, Montana
Arden R. Gaufin
University of Utah
Department of Biology
Salt Lake City, Utah
Jack A. Stanford
North Texas State University
Department of Biological Sciences
Denton, Texas
UNIVERSITY OF MONTANA BIOLOGICAL STATION
January 1975
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FLATHEAD LAKE NUTRIENT STUDY*
SUMMARY AND CONCLUSIONS
Phosphorus concentrations reported in this study are about 1/10 of
previously reported values. Sensitivity limits of the phosphorus.methods
used in this study (0.01 mg/1 P) were not low enough to accurately deter-
mine phosphorus concentrations in the drainage. Nevertheless, low phos-
phorus concentrations were shown to be important in controlling phyto-
plankton production. Nitrogen concentrations did not affect phytoplankton
production. Although phosphorus inputs to the lake are sufficient to
support nuisance pelagic blooms of algae, such blooms did not occur. The
best estimate of these inputs are 1,400 and 100 pounds per day from the
Flathead and Swan Rivers, respectively. High concentrations of iron plus
constantly oxygenated water and/or large suspended sediment inputs are
apparently responsible for the lack of blooms. Either or both of these
factors may physically remove phosphorus from the lake's photic zone.
In addition, the suspended sediments decrease light penetration and may
actually precipitate algae. Because of these factors, it is impossible
to estimate the amount of phosphorus the lake can annually assimilate
before changes occur in algal species composition and production.
Because of the importance of suspended sediments to the present lake
ecosystem, it is imperative that any factors which may change suspended
sediment inputs to the lake be controlled.
Water Quality Bureau data not included in this report indicate the
following contributions to the lake from sewage treatment plants in pounds
per day: Kalispell - 105; Whitefish - 42; Columbia Falls - 11; Bigfork -
6. Thus, the total phosphorus contributed to the lake by sewage treat-
ment plants (162 pounds per day) is about 11% of the total, Because of
these relatively minor contributions from the sewage treatment plants
and the uncertainty of the assimilative capacity of the lake, phosphorus
removal at the sewage treatment plants in the Flathead drainage is not
desirable at this time. However, because the lake is not limited by
nitrogen, and because the population in the drainage is increasing, the
feasibility of phosphorus removal should be determined for existing and
planned sewage treatment plants.
*(This page written by MT WQB)
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EPA Region VIII LU""!7
Denver, Co!::. j
table of contents
Acknowledgements p v
Introduction p 1
The Present Study p 4
The Study Area p 5
Materials and Methods p 9
Phytoplankton Standing Crop p 9
Chemical Analysis of Dissolved Solids p 10
Algal Assay and Experimental Nutrient Additions p 11
In Situ Chemical, Thermal Light, and Turbidity Profiles p 12
Results p 13
Thermal Regime p 13
Turbidity and Light Penetration p 15
Net Phytoplankton p 20
Water Chemistry p 27
Algal Assay p 30
Discussion p 33
Literature Cited p 43
Appendix 1. Average Net Phytoplankton Count at Each Station 7 pp.
on Each Sampling Date
Appendix 2. Tabulation of all Chemical Data 35 pp.
ii.
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TABLES
Table
1.
Summary of Selected Flathead Lake Water Chemistry
P
5
Table
2.
Morphological Features of Flathead Lake
P
7
Table
3.
Methods Used and Minimum Detectable Concentrations
P
11
of Various Parameters Monitored
Table
4.
Species List of Net Phytoplankters Ennumerated
P
21
Table
5.
Summary of Chemical Data
P
28
Table
6
Comparison of Data from Midlake Samples
P
33
Table
8
Nitrate and Phosphorus Loading
P
36
iii.
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FIGURES
Fig.
1.
Map of Flathead Lake showing sampling stations
P
6
Fig.
2.
Thermal regime from August 1973 to September 1974 at
P
14
the Midlake Station (2)
Fig.
3.
Turbidity isopleths as measured on 7 June, 1974 at a
P
18
point midway between Stations 2 and 3. Contours re-
present relative per cent transparency of water as
measured by submarine transmissometer.
Fig.
4.
Turbidity plume movements across the Lake
P
20
Ftg.
6.
Tabellaria - Oscillatoria dynamics in relation to
P
22
light at Yellow Bay (station 1)
Fig.
7.
- - - at Midlake (station 2)
P
23
Fig.
8.
- - - as Skidoo Bay (station 4)
P
24
Ftg.
9.
- - - at Big Arm Bay (station 7)
P
25
Fig.
10.
- - - at North End (station 13)
P
27
Fig.
11.
Depth readings of light, turbidity and Tabellaria
P
27
fenestrata cells per liter at Midlake (station 2).
Water transparency is represented by width of graph
on each datum (1 mm equals approximately 2 per cent
transmission)
Fig.
12.
Seasonal dynamics of nitrate (as NO^) arid silica
P
31
(as SiO ) at Yellow Bay (station 1)
2
FLg.
13.
Seasonal dynamics of nitrate (as NO^) and silica (as SiC^)
P
32
at Midlake (station 2)
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ACKNOWLEDGEMENTS
A project involving as many different activities as this one has may
be expected to call upon help from individuals with a variety of talents.
Many have been helpful to us. We wish especially to thank Drs. A. Horpe-
stad, M. Botz, and Mr. D. Nunnallee of the State Department of Health and
Environmental Sciences; Mr. D. Hanzel of the Department of Fish and Game;
Drs. T. Bahr and B. Ball of the Institute of Water Research, Michigan
State University; Dr. G. W. Prescott of the University of Montana Biological
Station; Messrs. D. Potter, G. Voerman, M. Roh, C. Servheen, T. Seastedt,
S. Loken, and Mmes. S. Turk, L. Potter and S. Munson assisted the progress
of the project in many ways.
v.
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INTRODUCTION
Flathead Lake and the Flathead Drainage have drawn nationwide public
attention in recent years. The region has long been famed for its natural
beauty and the quality of its environment; these considerations have made
the Flathead desireable to land speculators and subdividers among others.
Changes in land use, increased areas of lands used exploitively and in-
creasing affects on the environment by ever larger resident and tourist
populations have begun to cause concern for the future of the drainage.
It is seen, as well, that in the future the lake and its drainage
will require sound management based on real information concerning changes
in the environment which have happened in the past, which are occurring
at present, and which may be desireable or tolerated in the future.
A number of state and federal agencies have undertaken studies of
various aspects of importance to management of land use and water quality
In the drainage. A few recent studies deserve note: Cunningham and
Werth, 1973; University of Montana School of Forestry, 1974; Reynolds, 1974.
Other earlier studies are reviewed in the compilation by Seastedt and Tibbs,
1974.
Settlement in the region by European man occurred late in the 19th.
Century. Prior to the 1820's the land was wilderness and belonged to
Indians of the Salish Tribal Nation. The rate of settlement was slow but
steady, and was enhanced by the coming of the Great Northern Railroad in
1891. Lumber was, and remains, a principle industry of the area. The
Stillwater, Whitefish, Flathead and Swan Rivers served as transport systems
for the earliest lumber center, Somers, located on the northwest shore of
Flathead Lake.
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Flathead Lake served as a transport system from Poison to points north
until a road was built along the west side of the lake. Steamboats carried
passengers and cargo to points along the lake and upper Flathead River.
The Flathead River system remained largely unmodified until the con-
struction of Kerr Dam below Poison in 1938. The dam regulates the upper
ten feet of Flathead Lake and has a capacity of 1,219,000 acre-feet
(Montana Water Resources Board, 1968).
The Flathead drainage system was significantly modified by the Hungry
Horse Reservoir. This dam began operation in 1953 on the South Fork of the
Flathead River; the dam has a capacity of 3,468,000 acre-feet (ibid). The
dam regulates much of the spring run-off on the South Fork, reducing the
flow of the Flathead River during this period. Conversely, the dam dis-
charges water during other periods of the year, correspondingly Increasing
the volume of the Flathead River.
The geological processes which have resulted in the present rugged
terrain of the Flathead drainage have been discussed by many investigators;
current reviews can be found in Silverman (1971) and Johns (1970). Fields
(1971) is a useful source book on the geology of the region.
Two major occurrences have been responsible for present land structure
The first and most significant event, was the great crustal deformation
that occurred in the Late Cretaceous Period, and which is responsible for
the mountain formation in the area. Pre-Cambrian sediments predominantly
Ravalli quartzite and Peigan limestones compose much of the present mountal
formations. The second factor responsible for much of the present land
conditions, lakes and drainages, was the massive glaciation, especially
the last glacial advance of the late Wisconsin age. The moraines left by
this last ice movement are directly responsible for the formation of Lake
Mary Ronan and Flathead Lake's present configuration (Smith, 1966).
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3.
Konizeski (1968), reports that Whitefish Lake is also of similar origin.
He further states that the Flathead arm of Glacial Lake Missoula 'innun-
dated the entire Kalispell Valley to an altitude of 4,200 feet. Sand, silt,
and clay accumulated in the glacial lake to a thickness of several hundred
feet and covered older deposits, (Konizeski, 1968). These lacustrine
deposits, then, along with numerous moraines and glacial debris, compose
much of the subsoils in the lower areas (below 3,400 feet). Konizeski
found that Tertiary and Quaternary deposits were as much as 4,800 feet
deep in the Kalispell Valley.
Soils formations in the Flathead drainage have had only about 12,000
years to form. Before that the glaciers had removed pre-existing soils.
Soils are usually thin except where there are aluvial, lacustrine or
aeolian deposits of silt, sand, or clay.
A brief review of the fauna and flora of the region is given in
Seastedt and Tibbs (1974). Also discussed at some length therein are
<: 11matological and population data, and the effects that increasing popu-
lations and attendant increases of rural and domestic sewage may have on
lakes in the Flathead drainage. In their study of the land use and water
quality of the Flathead Drainage, Seastedt and Tibbs (1974) discuss water
quality studies on streams and tributaries of Flathead Lake, chemical
constLtuents of natural waters in the Drainage as known-to the time of
that report, and with that information and estimated projections based on
waste water, farming practices, forest management and other land uses,
attempted to assess nutrient loading in Flathead Lake. It will be seen
below that those 1974 estimates were high.
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4.
THE PRESENT STUDY
Limnological investigations of Flathead Lake began around 1890
(Forbes, 1893). The physical and biotic processes involved in controlling
primary production of Flathead Lake are nevertheless poorly understood.
Previous studies (Potter and Baker, 1961; Morgan 1968, 1971) have reported
high phosphorous and nitrogen values in the photic (photosynthetic) zone
(Table 1). According to these data, the Lake should support heavy biomass
or green algae or perhaps bluegreen algae instead of the observed low
densities of phytoplankton organisms which are primarily diatoms. Lake
hydrodynamics, however, or low concentrations of some other nutrients may
be responsible for the present apparent oligotrophic nature of Flathead
Lake (G. W. Prescott, personal communications).
Seastedt and Tibbs (1974) have suggested that dissolved solid con-
centration is increasing in tributary rivers primarily due to cultural
activities in the drainage basins. Area land planning and management
reports have emphasized maintenance of high water quality standards as
prerequisite to preserving the high quality of Flathead Lake (Seastedt and
Tibbs, 1974; Dils, et al., 1973).
The present study was undertaken to describe seasonal dynamics of
various physical and chemical parameters involved in plankton community
metabolism and to relate findings to nutrient loading trends previously re-
ported. The importance of various chemical parameters, especially phosphor-
ous and nitrogen, to standing crop dynamics of net phytoplankton was evaluated
,in relation to physical parameters such as light, turbidity, circulation,
and temperature. The major objective was compilation of baseline data and
clarification of basic hydrodynamics so that the limnology of Flathead Lake
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5.
might finally progress from a formative beginning to a status providing
capability for informed management.
Table 1. Summary of selected Flathead Lake water chemistry as reported
by previous investigators. All data in mg/L-^
Potter and
Baker, 1961
Morgan
1967
Morgan
1968
Morgan
1969
Ivory
1971-72
Alkalinity
89.7
90.0
87.5
80.0
83.8
Total Iron
0.60
0.10
0.05
0.05
0.02
Nitrate-Nitrogen 0.05
0.16
0.12
0.19
0.06
pH
8.0
8.3-7.8
8.2-8.7
9.3-8.8
8.0-8.4
Ortho-Phosphate
0.20
0.16
0.11
0.15
0.035
Silica (SiO,)
-
5.0
A.7
4.5
4.6
THE STUDY AREA
In discussing preliminary observations on factors influencing plankton
communities in Flathead Lake, Potter and Stanford (1974) described the
geology, history, and general morphology of the Lake and its drainage basins;
only pertinent information is repeated here. Flathead Lake is located in
northwestern Montana in the upper Flathead River drainage. Most inflowing
wnter is received at the Lake's north end via the Flathead and Swan Rivers
(Fig. 1) although there are numerous small streams entering along the
west and, especially, the east shore, their combined volume is insignificant
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6
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7.
in comparison to that recruited from the 7,000 acre drainage area of the
two tributary rivers. Average flow of the Flathead and Swan Rivers is
9,774 and 1,159 cfs respectively. The outlet is at the southern end of
the Lake where the upper 3 vertical meters of Lake level is controlled
by discharges from Kerr Dam for power generation. Morphological features
of Flathead Lake are summarized in Table 2. Bottom contours are being
mapped in detail, but are not yet available (C.A. Silverman, personal
communication); however, the eastern half of the Lake averages about twice
as deep as the western half (Fig. 1). A deep trench, attaining depths of
100 meters or more in places, extends south along the east shore from
Yenne Point to the Narrows and Skidoo Bay. The northeastern area of the
Lake is rather uniformly shallow (10-30M) due to deposition of sediments
by the Flathead River. The flow of the river is thought to extend
generally along the western shoreline, deflected . toward the center some-
what by Angel Point. The Swan River flows through large Swan Lake and a
small hydroelectric impoundment Just before entering Flathead Lake; these
function as sediment sinks and, therefore, except during those years of
highest runoff, the River is always very clear and contributes very little
sediment to the Lake.
Table 2. Morphological features of Flathead Lake, Montana from (Potter and
Stanford, 1974).
Maximum length 45.5 Km
Mean breadth 10.5 Km
Maximum depth 110.3 m
Mean depth 13.5 m
Area 475.6 Km^
Area of islands 14.3 Km
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8.
Table 2. (continued)
Volume
24.9 Km3
Length of shoreline
301.9 Km
Shoreline development
3.9
Insularity
3.0%
Mean Retention Time of water
2.37 years
All of Poison Bay is less than 6m deep, but a surprising dropoff of
60-80 meters occurs only 100 meters or so north of the Narrows area.
The long fetch of the lake's valley allows strong winds which keep
the lake surface rough much of the time, especially in winter. This
characteristic surface turbulence and the Lake's great volume work together
to keep the lake from freezing over for appreciable lengths of time. Ice
pack lake-wide occurs only once in every four to seven years, usually in
March (D. Hanzel, personal communication). The Lake is a clear blue during
fall and winter but turns greenish-brown as the amounts of seston increase
in spring, primarily due to clay turbidity from Flathead River discharge.
The water is again quite clear by mid- to late summer as turbidity settles.
In this study, thirteen sampling stations were established, ten on the
Lake and one each on inflowing and outflowing rivers (Fig. 1). The location
of each stations was as follows (station names underlined):
1. in middle of Yellow Bay; maximum depth, 27 m.
2. over deepest point in Lake, roughly midway between Yellow Bay
and Wildhorse Island and referred to as Midlake station;
maximum depth, 110 m.
3. in middle of Lake between Yenne Point on the east shore and Angel
Point on the west shore; maximum depth, 60 m.
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9.
4. in middle of Skidoo Bay; maximum depth, 60 m.
5. in Poison Bay midway between the Narrows and the outflow;
maximum depth, 6 m.
6'. in outflow area of Flathead River at Poison; maximum
depth, 5 m; flowing water.
7. in middle of Big Arm Bay; maximum depth, 35 m.
8. at Mouth of Flathead River; maximum depth 10 m, often
flowing water.
9. in middle of Bigfork Bay; maximum depth, 3 m.
10. Flathead River at Holt Bridge; maximum depth, 8 m;
flowing water.
11. about 200 m from Painted Rocks on the Lake's west shore;
maximum depth, 50 m.
12. Swan River at bridge in town of Bigfork; maximum depth,
2 m; flowing water.
13. midway between mouth of Flathead River and Angel Point
on Lake's North End; maximum depth1, 30 m.
Stations 8 and 9 were inaccessible during low water periods of late
winter and early spring. The Flathead River above the Lake meanders
and when lake level is maxium, water is backed several kilometers up
the river channel. Flow intensity and depth varies seasonally at
station 10. Some additional sampling was done in various tributary
creeks and at intermediate stations on the Lake during spring runoff.
MATERIALS AND METHODS
Phytoplankton Standing Crop.
Net phytoplankton was quantified at least monthly, weather permitting,
at Stations 1, 2, 3, 4, 5, 7, 11, and 13. Samples were obtained at 5 meter
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10.
intervals from surface to 40 meter level (or bottom) using a 3 liter Van
Dorn water bottle. All 3 liters were filtered through a No. 20 mesh plankton
bucket to concentrate plankton; samples were preserved immediately with
formalin. Algae were enumerated in a one ml Sedgewick-Rafter cell using
the method of Welch (1948, pg 286). Dr. G.W. Prescott (U. Montana Bio-
logical Station) and Dr. Forest M. Begres (Eastern Michigan U.) kindly
verified taxonomic identifications.
Chemical Analysis of Dissolved Solids
Water samples were obtained as often as possible for chemical analysis
from lm and 40 m at deep water stations, or from 1 m and 20 m or less at
shallower stations with the same Van Dorn water bottle. Occasionally
samples were obtained from intermediate or greater depths. All samples
were analyzed for alkalinity, hardness, (Mg. Ca, and total) silica, carbon
dioxide, and pH content immediately after collection. These analyses were
conducted at the Biological Station laboratory at Yellow Bay. Duplicate
samples were cooled and shipped by bus to the Montana State Department of
Health and Environmental Sciences laboratory in Helena for analysis of
total phosphorous, ortho-phosphate (P0^) and nitrate (NO3) content. Monthly
samples from same depths were filtered through 0.45 micron aperture Millipore
filters, then preserved with concentrated nitric acid (1 ml per 100 ml water)
and sent to the Helena laboratory for trace analysis of total iron, zinc
and copper. Occasional samples were sent for analysis of cadmium, cobalt,
total Kjeldahl nitrogen, and total carbon. The chemical methodology used
and threshold level of detection for each parameter is summarized Jn tnble 3.
One set of midlake samples was sent to the Institute of Water Research
laboratory at Michigan State University for analytical quality check.
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11.
Al^al Assay and Experimental Nutrient Additions
Algal assays using the Selenastrum bottle test (EPA, 1971) were
utilized to elucidate limiting nutrients in Flathead Lake. Water samples
were obtained from either Yellow Bay or from Midlake stations and
immediately shipped to Helena for assay. Experimental in situ additions
of phosphorous as Nal^PO^'I^O were undertaken using cylindrical polyethelene
bags after the method described by Shindler (1971). The bags were lm wide
by 10m long and suspended from a wooden frame near shore in Yellow Bay.
The bags were filled by divers carrying the open ends through the water
column. Nutrients were added as frozen solutions which were allowed to
thaw at various depths within bags. Net phytoplankton and chemical water
samples were obtained as above prior to nutrient addition and again after
a week's time. Changes in net phytoplankton number and species composition
and chemical differences were recorded. Several experiments were attempted
during May and June, 1974, but only 2 were successful due to problems of
maintaining the bags' vertical position in the water column during wind
storms. Experimental conditions of the successful attempts are summarized
wLth results.
Table 3. Methods used and minimum detectable concentrations of various
parameters monitored. Unless an electronic probe was sued,
methods are those given in Taras, et al. (1973).
PARAMETER
METHOD
MIN. DETECT. CONC'N.
Total P
Persulfate Digestion to P0^
Stannous Chloride Reduction
30pg/l (P04-P)
Total N
Kjeldahl Digestion
no3
Phenoldisulfonic Acid Reduction 10pg/l (NO-j-N)
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12.
Table 3. (continued)
PARAMETER
Fe, Co, Zn, Cu
Total Carbon
Silica
Alkalinity
Hardness
Carbon Dioxide (Free)
pH
Dissolved Oxygen
Conductivity
Redox
METHOD
Atomic Absorption (Perkin-Elmer)
C02 Analyzer (Beckman, Model 914)
Molybdosilicate Reduction
Brom-cresol Methyl Red Titration
EDTA Titration
Methyl Orange Titration
Leeds-Northrup, Hydrolab Surveyor 5
Hydrolab Surveyor 5
MIN. DETECT. CONC'N.
lOjig/1
0.5mg/l
0.4 mg/1
0.5 mg/1
In situ Chemical, Thermal, Light, and Turbidity Profiles
Depth profiles to 100 m of temperature, dissolved oxygen, pH, conductivity
and oxidation-reduction potential were obtained as often as wind conditions
would allow at all stations using a Hydrolab "Surveyor-5" in situ apparatus.
For logistical reasons special effort was made to obtain these data at
Stations 1, 2, 4, and 13 at least monthly. Data on light were gathered
using a secchi disk and a Kahlsico submarine photometer. Levels of light
extinction were of most interest. Turbidity was studied intensively during
the spring runoff period of April-July, 1974. A Kahlsico turbidimeter
deployed by an electrical winch on deck was used to measure relative trans-
parency of water at various depths to 60m.
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13.
RESULTS
Preliminary data were gathered during July and August, 1973, but the
major research effort encompassed a sampling period from 15 September,
1973, to 20 September, 1974. Sampling was hindered or impossible on some
occasions due to wind and rough water. Inclement weather was responsible
for some inconsistency in the sampling schedule reported herein.
Thermal Regime
Seasonal dynamics in thermal character of the water column at the
Midlake stations are illustrated in Figure 2. Thermal stratification
began in early summer, 1972; the thermocline gradually sank, the water
mass turning over in November. Winter stratification was weak due to wind
circulation; the Lake was essentially homeothermos at 2.2° + 0.2° C from
late January to early April. A thermal circulation began again in late
April and May and it was followed by construction of the summer thermo-
cline in June, 1974. Flathead Lake is clearly dimictic with spring and
fall mixing periods throughout the water column.
Data supplied by Delano Hanzel of the Montana State Department of
Fish and Game (Personal Comm.) demonstrated that the 1973 and 1974 summer
isotherms were very unstable. Variations of up to 3° were recorded by
towing a recording thermister for some distance (approx. 100m) at a
constant depth. Thermal conditions were most constant throughout the
water column on daily or weekly bases during winter and spring, 1974.
Conditions given in Figure 2 prevailed at all stations with some
variation at the more shallow stations. Modification of the thermal regime
by river discharge was observed at stations 8, 9, and 13. Poison Bay was
homeothermos at surface temperatures throughout the study except on rare
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15.
calm days in Spring and Summer. Thermal regimes were not carefully
monitored at river stations. The seasonal thermal cycle in the Flathead
River above the lake was probably very similar to that reported during
1972-72 by Stanford (1974).
Turbidity and Light Penetration
Depth of light penetration in Flathead Lake was dramatically affected
seasonally by varying climatic and biotic processes. Secchi disk and sub-
marine photometer readings were affected by the density of seston in the
water column. A secchi disk reading of 14.3 m (47 ft) was observed at
Midlake station in November, 1973; incident light was recorded as deep as
55 m. Thus, the Lake appeared deep blue in color due to backscattering
blue wave lengths of the visable light spectrum. Seemingly continuous
winter cloud cover and surface turbulence reduced secchi disk readings to
around 10 m, but the clarity of the water was not changed much as light
penetration was routinely recorded to 45-50m in deeper areas of the lake.
Springtime growth of phytoplankton, discussed in detail below, further
reduced light availability, but turbidity resulting from upstream snow melt
in May and June severely limited light penetration. Secchi disk readings
were less than one meter and light became extinguished at 23 m in the Lake's
pelagic region and at lesser depths in littoral areas near the mouth of
the Flathead River.
Flooding due to spring snow-melt is an annual occurance in the upper
Flathead River drainage. Subsoils are predominantly montmorillanite and
kaolinite clays ; erosion of these clays by tributary streams during periods
of rapid snow-melt results in heavy sediment loading in the Flathead River.
Bank erosion by the River itself contributes large amounts of suspended
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16.
solids. The Flathead River discharge into Flathead Lake is therefore
typically very turbid during spring runoff.
The 1973-4 winter snowfall in the upper Flathead River drainage
surpassed all records. A brief pulse of turbid runoff began in April as
large amounts of snow at lower altitudes melted; the major spring dis-
charges, however, began in late May and continued until late June. This
prolonged runoff provided an excellent opportunity to document development
of clay turbidity in Flathead Lake.
The extreme north end of the Lake became turbid due to the late April
pulse of high discharge. Patches of turbid water were observed as far
south on the Lake as Yenne Point. This early pulse receded by early May
allowing the limited turbid area at the north end to clear up noticeably.
Major turbid discharge by the Flathead River began on 28 May as warm
weather prevailed. The River rapidly approached flood stage, discharging
30-50,000 cfs during the first week of June. Peak flow was recorded on
8 June; thereafter the flow of the River began to recede and to clear
slowly. The Swan River also delivered heavy runoff to Swan Lake and by 10
June turbid water was passed completely through Swan Lake and on downstream
to Flathead Lake. The Swan River discharge to Flathead Lake was decidedly
less turbid, however, than the Flathead River effluent.
A large turbidity plume was immediately evident as discharge from the
Flathead River increased. Aerial and surface reconnaissance of plume
development was undertaken. Turbid river water and clear lake water strongly
resisted mixing; interface areas were easily observed on the leading edge
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17.
of the plume. Logs and other debris accumulated at the interface zone,
apparently held there by downward movements of density currents. This
mixing resistance caused the warmer turbid water to slide out over colder,
clear water. This phenomenon was documented on 7 June when the plume had
reached a point midway between station 2 (Midlake) and 3 (Yenne Point).
Turbidity-depth profiles obtained in the plume, at the interface, and in
clear water south of the plume are summarized in Figure 3. The 15 per cent
transmission contour roughly corresponds to the interface area. It was'
seen that there was no tendency for turbid river water to flow under clear
lake water and maintain continuity through the lake basin as has been
reported in some deep reservoirs (Ruttner, 1966), Similar observations
wore made at other areas on the lake. Progressive movements of the plume
across the lake surface are illustrated in Figure 4. Flathead River water
was discharged directly toward Angel Point along the west shore. Mixing
resistance slowed movement of the sediment into the cold, deep water of
the eastern half of the Lake. Therefore interface areas were always
observed extending southwesterly across the lake. Because of the current
pattern, the Midlake station and Yellow Bay were the last areas to become
turbid. By 11 June turbid water reached the Narrows and moved into
Poison Bay. The constriction in the Narrows caused the plume to spill
into Skidoo Bay and move back up the east shore. By 18 June backwelling
turbidity joined the trailing edge of the plume and the entire Lake appeared
turbid. At all times light transmission was more restricted at the northern
.nid wostern shores than it was on the eastern shore areas.
The affect of turbidity on the clarity of the water column was best
documented at the Midlake station (Figure 5). Intense turbidity moved in
at the surface on 18 July. The water column cleared slowly as clay particles
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TUHBIDITY
/- INTERFACE
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%
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20.
were dispersed or settled to the lake bottom. On 18 August the upper 60
meters (instrument cables were only 60 meters long) was dramatically
transparent, and almost devoid of seston. A secchi disk reading of 13.1 m
was recorded on 18 September. Similar turbidity regimes were recorded at
other stations. Turbidity contours were extremely unstable and similar to
the situation described for the isotherms above. Although sediment traps
were not utilized, the sedimentation rate must have been greater in more
turbid areas along west shore. In general, however, clearing of surface
waters was evident over all of the lake by early August. By mid-August
the Lake was again blue in color.
Secchi disk and light data are summarized in relation to phytoplankton
dynari.cs at various stations in Figures 6 through 11.
Net Phytoplankton
Seasonal dynamics in standing crop of net phytoplankton followed
patterns previously reported (Morgan 1968, 1971). Total phytoplankton
counts were, however, much higher. Bacillariophyceae were always the
most numerous net plankters. Total net phytoplankton counts were less than
3
50 x 10 per liter in fall and until midwinter; however, by February counts
3
began to increase, later reaching more than 800 x 10 per liter during the
spring circulation period in April. Counts decreased in May and were re-
duced even below fall and winter numbers when turbidity moved over the Lake
in June and July.
Gaufin (1974) has listed nearly 600 phytoplankton species (identifications
verified by Drs. G. W. Prescott and Ruth Patrick) as representatives of the
indigenous flora in Flathead Lake. Only a few of these species, however have
been reported to be abundant in previous studies (Morgan, 1968, 1971; Moghndam,
1969; Ivory, 1973). We found only nine species to have specimens present in
-------
21.
our samples In numbers greater than 500 per liter (Table 4). Of these
Tabellarla fenestrata was almost always the most abundant, out-numbering
other net plankters 4 to 1. Oscillatoria aquatica were quite abundant
during the spring phytoplankton bloora; this small, filamentous blue-green
alga has not previously been reported in the flora of Flathead Lake.
Table 4. Species list of net phytoplankters enumerated. They are listed
as they most commonly occurred, in decreasing order, with the
most abundant at the top.
Tabellaria fenestrata (Lyngb.) Kutz var. fenestrata
Asterlonella formosa Hess. var. formosa
Fragillaria crotonensis Kitton var. crotonensis
Oscillatoria aquatica Lyngb.
Melosira ltalica subsp. subartica Muller
Synedra spp.
Rhizosolenia eriensis H. L. Smith
Dinobryon sertularia Ehrenberg
Dinobryon bavaricum Imhoff
Net phytoplankton species composition was similar at bays and at open
water stations. Spring peak counts for TT. fenestrata were very similar
except at the North End where April turbidity adversely affected production
(Fig. 6-10). Seasonal dynamics of 0^. aquatica lagged just behind T. fenestrata,
but intensity of the bloom varied. At North End and Skidoo Bay counts were
low (Fig. 8 and 10); at Yellow Bay and the pelagic stations (Midlake, Yenne
Pt, and Painted Rocks) maximum counts were about the same, ranging between
-------
Light-Tabellaria-Oscillatoria dynamics in Yellow Bay.
Fig. 6
500
400 -
__ 10m
c
o
to
o
m
m
. 20m
*
m
*
£
Light extinction
/ j
Bottom
.* /
* a
* B
% B
» B
300
200 J-
100
Q>
.O
C
D>
n
B>
o
o
c
a
(t>
n
X
©
Oct Nov
1973
Dec
Jan
1974
Feb
Mar
Apr
May
Jun
Jul
Aug
Sept
-------
t~* i. ^ n u ~ ca j 5 cixAdLon
dynamics at Midiake.
500
400
u
0>
03
U
u
in
a
c
0)
100
T
200 t
Oct Nov Dec Jan Feb Mar Apr
1973 1974
Ma/ Jun Jul Aug Sept
-------
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept
1973 1974
-------
500
o
u
0)
c
o 200
re
4-1
05
-------
Light-Tabellaria-Oscillatoria dynamics at North End.
Fig. 10
10m
20m
Light extinction
Bottom
/
%
%
/*
/
tilling.
us
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept
1973 1974
-------
80 x 1C>3 per liter and 120 x 10^ per liter (Figs. 6 and 7); however,
at Big Arm Bay counts reached more than 140 x 10 per liter and did not
immediately decrease as June turbidity limited light availability
(Fig. 9). Little variation in counts was observed due to sampling depth;
net phytoplankton was about evenly distributed in the water column
sampled at all stations. Mean values for the counts of the most abundant
taxa are summarized for each station on all sampling dates in Appendix 1.
Generally peak counts, for all phytoplankters enumerated, occurred in
April also. The Dinobryon species were not present in counts until late
spring and persisted through the turbid period. Fig. 11 illustrates
depth profiles of turbidity in relation to available light and standing
crop of T. fenestrata at Midlake station during early summer 1974.
Water Chemistry
In situ chemical-depth profiles to 100m with Hydrolab Surveyor 5
revealed that dissolved oxygen, conductivity, pH, and oxidation-reduction
potential (ORP) remained quite constant lake-wide throughout the study.
Dissolved oxygen was always present in concentrations near saturation
regardless of depth, even during summer stratification. Per cent
saturation values between 80 - 110 were regularly recorded. No more than
5 per cent variation within the water column was ever recorded at any
station. Similarly, pH ranged from 7.8 - 8.1 and variations of not more
than 0.5 pH units were recorded in any one depth profile. Conductivity
was always 155-170 micromho per cm and no change was observed during the
turbid period. ORP values varied from 3.7 - 5.7 millivolts. No seasonal
dynamics could be documented for any of these parameters.
A listing of all laboratory chemical data is presented in Appendix 2.
Annual ranges in data are given for each station in Table 5. Alkalinity,
-------
23MA Y 3-JUN / lJUN ' 12-JUN 12&-JUN 1 2-AUC
/--
10-
20-
£
jXg 30
Q
40
50
60
600X10
3
250X10
3
<30X 10
3
-------
Table 5. Summary of Chemical Data, Sept. 1973 to Aug. 1974. mg 1-1
No. Station pH Total Total Nitrate Phosphate Total Silica Total
Name (in situ) Hard Alkal (a3 NO^) (as PO^) Phos.CPO^) (SiO?) Iron
1.
Yellow Bay
7.8-8.2
83-107
78-91
A
0
H»
1
o
<.03
<03-.05
1.3-4.1
2.
Midlake Deep
7.8-8.2
87-95
79-90
A
0
H
1
¦>
O
<.03
<.03-.09
1.7-4.1
3.
Yenne Point
7.8-8.2
85-99
79-87
<01-.38
<.03
<.03-.05
1.6-3.9
4.
Skidoo Bay
7.8-8.2
86-96
79-88
<.01-.41
<.03
<.03-.06
1.8-4.4
5.
Poison Bay
7.8-8.2
81-97
79-88
<.01-.20
<.03
<.03-.06
1.9-5.5
6.
Fit R. at Pisn
7.8-8.2
81-98
78-90
<.01-.67
<.03
<.03-.05
1.4-6.5
7.
Big Arm Bay
7.8-8.2
86-96
78-87
<.01-.28
<.03
<.03
1.7-4.6
8.
Fit. R. Mouth
7.7-8.4
86-101
71-90
<.01-.80
<.03
<.03-.25
2.3-5.4
9.
Big Fork Bay
7.7-8.3
75-106
73-98
.01-.23
<.03
<.03-.21
2.1-6.7
10.
Fit R. at Holt Bg.
7.2-8.4
83-97
81-97
.01-.91
<.03-.07
<.03-.54
2.0-6.5
11.
Painted Rocks
7.8-8.3
84-93
77-C8
.01-.34
<.03
<.03
1.8-4.1
12.
Swan R. at Big Fk.
7.8-8.4
72-97
70-103
.01-.98
<.03
<.03-.36
2.6-7.0
13.
North End
7.6-8.4
84-95
78-87
.02-.35
<.03
<.03-.07
1.7-4.1
See Appendix 2
-------
29.
hardness, and CO2 values indicate that Flathead Lake water is well buffered
and moderately hard. Some discrepancies occurred between laboratory and in
situ pH values indicating that shifts in the carbonate-bicarbonate system
may have occurred during sample storage in laboratory refrigerators.
However, these variations may have been entirely due to instrument error.
Alkalinity and hardness data agree well with previous studies. No
significant seasonal dynamics in alkalinity or hardness data were recognized.
Nitrogen and phosphorous data are most significant. Nitrate values
ranged between 0.01 and 0.40 mg per liter at lake stations. Seasonal trends
were similar at all lake stations with higher values being recorded gen-
erally during spring and fall circulation periods (Figs. 12 and 13).
Nitrate values were much higher at the inflowing river stations. However,
concentrations in samples from outflowing waters at Station 6 (Flathead
River at Poison) were quite similar seasonally to those from lake stations.
Phosphorous was rarely above minimum detectable concentrations at lake
stations and Station 6. Unbound, inorganic PO^ concentrations were never
detectable. Total P was higher at inflowing river stations on occasion
but the annual averages were near the detectable limits of 0.03 mg per
liter.
Comparison of data from duplicate sets of samples from Stations 1,
2, and 3 (Yellow Bay, Midlake, and Yenne Point) which were analyzed at
both the Institute of Water Research (Michigan State U.) and at the Helena
Laboratory are given in Table 6. IWR utilized a more sensitive method of
phosphorous detection (IWR, unpublished) and recorded very low concen-
trations. Nitrate values agreed fairly well. Total carbon was quite low
as might be expected considering the low net phytoplankton counts obtained
at the same time (Appendix 1).
-------
30.
Silica (SiC^) concentrations were fairly low (1.3-2.5 tn per liter)
during winter and spring months. However, large amounts were apparently
carried into Flathead Lake by heavy spring discharges as values reached
6.0-7.0 mg per liter during June and July. Seasonal dynamics of silica
(SiC^) at Yellow Bay and Midlake stations are illustrated in Figures 12 and
13. Other lake stations followed similar trends. The inflowing rivers and
river mouth areas reached higher values during spring runoff.
Copper, cobalt, zinc, manganese and cadmium concentrations were always
quite low, but detectable, at all stations at which samples were analyzed
for these elements. Total iron, however, was always surprisingly high, with
values ranging between 0-0.22 mg per liter (Table 5).
Algal Assay
Phosphorous concentrations greater than 0.003 mg/1 added to filtered
Flathead Lake water stimulated growth of Selenastrum in bioassay experiments.
Nitrogen additions had no stimulatory effect. Nitrogen and phosphorous
spikes added together stimulated growth irrespective of nitrogen concentration,
but in direct proportion to phosphorus addition.
In situ phosphorous additions of 0.5 rag per liter also stimulated
growth of indigenous algal flora (Table 7). No significant shifts in species
composition were observed through the experimental period, however,
Tabellaria fenestrata continued to dominate net phytoplankton, but total
numbers were greater in response to phosphorous spikes.
-------
4.0
'n 3.0
$
w 2.0
hJ
M
(O
1.0
0.40
Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
1973
1974
Fig. 12
-------
4.0
'n 3.0
v
t>0
a
H 2.0
M
10
1.0.
Sept Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
1973
1974
Fig. 13
-------
33.
Table 6. Comparison of data from midlake samples collected 25/11/74 and
analyzed by IWR and Montana State personnel.
Station Depth Nitrate Total Total
Nitrogen Phosphorus Carbon
mg/l-N
mg/l-P
ma/l-C
IWR
State
IWR
State
IWR
1-Yellow Bay
lm
0.01
0.01
0.004
0.01
21
1-Yellow Bay
25m
0.01
0.01
0.007
OvQl
21
2-Midlake
lm
0.01
0.03
0.004
0.01
20
2-Midlake
40m
0.01
0.05
0.03
0.01
20
3-Yenne Point
lm
0.01
0.01
0.005
0.01
20
3-Yenne Point
40m
0.01
0.01
0.004
0.01
20
DISCUSSION
Previous reports of species compositions of dominant Flathead Lake net
phytoplankton are different from that reported here in two respects.
Tabellaria quadrisepta Kunds. was listed by Morgan (1968, 1971) and Ivory
(1973) as the most abundant phytoplankter rather than T. fenestrata.
Apparently Morgan incorrectly identified the diatom. We did observe T.
quadrisepta on occasion and this species appears on Gaufin's (1974) indigenous
species list; it was never abundant, however, during our study. We were,
however, quite surprised to find the unreported blue green alga, Osclllatoria
aquatlca in such high numbers at all lake stations. Other bluegreen
populations have been observed in Flathead Lake but only in rather stagnant,
isolated shoreline areas probably in response to localized nutrients seepage
from septic tanks (U. Mont. Biol. Stat., unpubl. data). No evidence of
limnetic bluegreen blooms have been reported previously. 0. aquatica occurs
-------
34.
as small, inconspicuous filaments, but we had no difficulty making counts.
It seems unlikely that this plankter could have been overlooked in previous
studies if it were present in similar densities. Morgan (1968, 1971)
and Ivory (1973), however, concentrated plankton by centrifuging 500 ml
samples through a Forrest plankton centrifuge. This method breaks up
algal colonies and destroys many of the more delicate cells (Gaufin,
unpubl. data). It is possible that the rather fragile strands of
0. aquatica could have been broken by centrifugation and not recognized
by Morgan nor by Ivory. Moghadam (1969) studied primarily diatom taxonomy
and her acid-boiled, hyrax-mounted preparations of diatom frustules pre-
vented examination of other algae. Young (1935) would have reported ().
aquatica if it had occurred. It is unclear whether this plankter is
a new arrival in Flathead Lake, whether its earlier smaller populations have
now become appreciable, or whether it has merely been overlooked by
previous investigators. Perhaps it is only abundant in certain years, re-
sponding to some uncommon combination of environmental stimuli. The
abundance of 0. aquatica during 1973-1974 clearly establishes the alga
as an important phytoplankter in the Lake and further investigation of
its ecology is warranted.
Peak standing crops of net phytoplankton were higher in the present
study than reported by Morgan (1971). This may not be due to increased
productivity since 1969. Rather It may be that Morgan's centrifugation
process may have biased counts by destroying diatom colonies and possibly
even substantial numbers of cells. Furthermore, Morgan's small sample
size (500 ml) may not have adequately sampled the sparcely distributed
plankton populations. Our counts were derived from sedimentation of 3
.liter samples. No damage and little or no loss of cells was encountered;
our counts were quite reproducible.
-------
Net phytoplankton species composition and population dynamics in
addition to low limnetic phosphorus concentrations reported here characterize
Flathead Lake as oliogotrophic according to Vollenweider's (1970)
classification scheme. The limnology of the bays corresponded well with
that of the open water areas indicating that the Lake functions as a unit.
However, areas around the mouth of the Flathead River were more dramatically
influenced by river discharges. Spring nutrient circulation, warming
temperatures, and increasing photoperiod stimulated net phytoplankton bloom
in the bays and pelagic areas alike with slightly higher intensity in Big
Arm Bay. Notably, phytoplankton density was similar throughout the 40 ra
photic zone. Turbidity severely reduced net phytoplankton production in
early summer. An apparent lack of nutrient additions during high spring
discharges was strongly indicated by the failure of net phytoplankton to
re-establish populations in late summer and fall after the water column
began to clear. Chemical analysis also showed that there were no additions
of nutrients except for silica which was always present in fairly high
concentrations. The lack of increase in conductivity was especially in-
dicative of the inert nature of the materials causing the turbidity.
Notice, however, that at all stations except Big Arm Bay, standing crops
were rapidly decreasing in May before the onset of severe clay turbidity,
indicating that a nutrient limitation had already occurred. Unfortunately
chemical data did not reveal a significant corresponding nutrient dynamic
in detectable concentrations.
Concentrations of phosphorus in Flathead Lake observed in the present
study were dramatically lower than previously reported. It is surprising
that validity of previous data has not been seriously questioned since the
-------
36.
phosphorous concentrations in Flathead Lake reported by Potter and Baker
(1961), Morgan (1968, 1971) and even USGS (1970) data upon which Seastcnd
and Tibbs (1973) based their loading predictions compare nicely with values
given for grossly enriched Lake Washington (Edmonson, 1969) and western
basin of Lake Erie (Cole, 1973). Out nitrate nitrogen data, however, were
quite similar to previous values.
Based on AO year average flow data in the Swan and Flathead Rivers
at Flathead Lake (USGS, 1972) and chemical data gathered during the study
we calculated the approximate nitrate nitrogen and total phosphorus input
into the Lake during the period August 1973 to August 1974 (Table 8). If
we may assume this nutrient input and metabolism of nutrients within the
Lake has been fairly constant over the last 2.37 years (ie. corresponding
to mean water retention time), it is apparent that about two thirds of the
NO^-N that entered the lake via the rivers was not discharged. Phosphorous
loading data were based on maximum possible concentrations; on most occasions
total phosphorus was found to be less that the minimum detectable con-
centrations, but loading calculations were made giving less than detectable
concentrations a value of 0.03 mg per liter even though they were
probably much lower. As with nitrate nitrogen, about two thirds of the
total phosphorus entering the Lake was not discharged. Note, however, that
virtually all of the phosphorus was organically bound; very little free PO^
Table 8. Nitrate and phosphorus loading in Swan River and Flathead River
above and below Flathead Lake, 1973-4. Figures are in metric
tons expressed as N and P.
Swan R.
Nitrate
168
Phosphorus
18
Flathead R. at Holt Bridge
789
232
Total Input
Flathead R. at Poison
957
352
180
251
Loss within Flathead Lake
605
71
-------
was detected in river discharges and no phosphorus left the Lake in that
form (Appendix 2), at least in our detectable range. Probably all phorpliorus
leaving the lake was organically bound in living phytoplankton biomass dis-
charged downstream. Unfortunately, we were unable to obtain organic
nitrogen data. USGS (1970) data indicated that two thirds of nitrogen in
Flathead River lake discharges during 1969-70 was organically bound. The
figures in Table 8 do not include recrutiment of nitrate-nitrogen or
phosphorus from other potential sources such as lake surface precipitation,
shoreline septic tank seepage and shoreline agricultural runoff.
Nitrate nitrogen concentrations increased during fall and spring
circulation periods at lake stations; this suggested nitrate release from
sediments or recirculation of sedimented nitrogen as nitrate from profundal
areas of the Lake. No seasonal dynamics in phosphorus could be demonstrated
at lake stations. Seasonal dynamics must have occurred, however, correspond-
ing to net phytoplankton blooms. Phosphorus dynamics were likely in the
range of <.001-009 mg per liter as indicated by the total phosphorus values
obtained in samples analyzed by Institute of Water Research. Pechlaner (1970)
reported spring diatom bloom in Lake Erhen (Sweden) followed phosphate
phosphorus concentrations of not more than 0,010 mg per liter. Planktonic
diatoms such as those abundant species in Flathead Lake are known to main-
tain bloom populations on very low concentrations of phosphorus and
Asterionella formosa has been shown to take up inorganic phosphorus in
concentrations of as little as 0.0001 mg per liter (Mackereth, 1953).
Silica and trace metals appeared to be present in sufficient amounts not
to be limiting to phytoplankton production at any time in Flathead Lake.
Inorganic phosphorus was always near minimum detectable concentration,
even in river discharge into Flathead Lake during spring runoff; the upper
Flathead River drainage apparently does not release much soluble inorganic
-------
38.
phosphorus. Cultural additions of phosphorus are increasing (Seastead and
Tibbs, 1973), but it appears that all inorganic phosphorus is organically
bound before it reached the Lake. Phosphorus cycles rapidly in lakes and there
is some evidence that phytoplankton can utilize complex organic phosphorus
metabolites directly without conversion to free phosphate (Lean, 1974).
Rapid cycling of very low phosphorus concentrations must occur in the photic
zone of Flathead Lake, especially during the spring when the greatest net
phytoplankton production occurred.
Sediments from cores taken in Flathead Lake were analyzed for total
phosphorus. The Montana State Department of Fish and Game kindly assisted
us with the coring operation. Samples from the surface of the cores as
well as from various depths in the cores were analyzed to provide infor-
mation on the possible present and past accumulations of phosphates in
these sediments. Only one of the twenty samples revealed more than a trace
of phosphorus. We conclude that phosphorus which may be released from
Lake sediments would provide only insignificant amounts of that nutrient
in the water.
Our phosphorus and nitrogen data indicate Seastead and Tibbs (1973)
may have greatly overestimated loading of these nutrients in Flathead River
discharges. Our calculations only approximate nutrient budgets for Flathead
Lake. Seasonal organic nitrogen data are needed along with knowledge of
phosphorus and nitrogen released from sediments, precipitation nutrient
additions at Lake surface, and phytoplankton nutrient assimilation rates.
However, our loading estimates strongly suggest that nitrogen is present in
sufficient concentrations to support additional phytoplankton biomass. Lack
of available phosphorus is apparently a large factor in suppressing phyto-
plankton production. These conclusions were supported by algal assay experi-
ments .
-------
39.
During the 1973-4 study period, roughly 70 metric tons of phosphorus
and 605 metric tons of nitrate nitrogen were either permanently tied up in
biomass and/or lost to Lake sediments. Again, this is based on the assumption
that the ratio of nitrate-nitrogen and total phosphorus received to that
discharged was constant and directly related to annual dynamics "of the same
nutrients within the Lake during the time for which the calculations were
made. Presumably, most of this phosphorus was bound in bottom sediments in
such form that resuspension was severely limited, because total phosphorus
values were always very low or undetectable in the water column. Much less
may be said about nitrogen, due to lack of organic nitrogen data. It is
clear, however, that substantial amounts of nitrogen were also tied up by
lake processes.
Chemical and physical hydrodynamics provide plausible explanations for
nitrogen and especially phosphorus losses. In the presence of dissolved iron,
phosphorus will precipitate as iron phosphate, as long as oxidizing (aerobic)
conditions exist (Sridharan and Lee, 1974). Our dissolved iron and oxygen
data indicate similar conditions existed in Flathead Lake. Inorganic
phosphorus complexed as iron phosphate in bottom sediments could not be re-
suspended unless an anaerobic (reductive) mud-water interface developed.
Furthermore, reducing conditions or a paucity of dissolved iron would have
to exist between the sediments and the photic zone before any released
phosphate could be utilized by phytoplankton. Dissolved total iron was
always fairly high during the study and there was no evidence that surface
sediments or any part of the water column were ever in a reducing (anaerobic)
condition anywhere in the pelagic area of Flathead Lake. It appears, then,
that as long as iron is available, phosphate could be precipitated and lost
from the functioning Lake ecosystem.
-------
40.
The annual clay turbidity observed in Flathead Lake may also be
playing a major role in phosphorus cycling. Lee (1970) and Wildung and
Schmidt (1973) have shown that phosphorus may be adsorbed to the surface
of fine clay particles. In fact, Golterman (1974, personal communication)
has shown that phosphorus concentrations may be reduced to levels severely
limiting primary production by phosphorus sorption of montmorillonite and
kaolinite clay turbidity. Considering the similar clay turbidity and the
manner in which we have described the plume to spread over the lake surface
and then sink, clay sorption and permanent sedimentation of phosphorus may
well account for some phosphorus losses. The very low standing crops of net
phytoplankton observed after the photic zone cleared of turbidity suggests
primary production was nitrient limited. Nitrate as well as phosphorus con-
centration was quite low at that time. Lee (1970) points out, however, that
nitrogen has less afinity for clay sorption than does phosphorus. During the
turbid period we observed seston in clumps composed of organic detritus and
phytoplankton adhering to an inorganic (presumably clay) substrate. There-
fore, the clay turbidity may also function as a floculation agent, clearing
the water column of seston. Large amounts of organic nitrogen and phosphorus
could be lost to the lake sediments in this manner. By means of such "stripping"
phenomena the turbidity is very likely the most important hydrodynamic feature
of the Lake in terms of maintaining very high transparency of water during
late summer, fall and winter.
In order for the spring growth of net phytoplankton to begin, regener-
ation of available phosphorus and nitrogen in photic zone had to occur. Re-
circulation of Nitrate released in profundal areas of the lake is a possi-
bility, but most of the nutrient probably was derived from tributary rivers
during fall and winter. Regardless of source, nitrate regeneration in
-------
41.
photic zone is documented here. Unfortunately we did not have analytical
capability to monitor spring phosphorus dynamics which must have been in
range of 0.0001 to 0.009 mg per liter.
The occurance of the blue green alga, Oscillatoria aquatica< is very
significant in regard to nutrient availability. Certain species of
Oscllatoria are known to be capable of nitrogen fixation and often sustain
high population densities in presence of very low nitrogen and phosphorus
concentrations (Hutchinson, 1974). Nuisance bluegreen blooms often follow
spring blooms of diatoms which have reduced nitrogen and phosphorus to low
concentrations (Hutchinson, 1957). Bluegreens, such as Oscilatoria and
Anabaena are better competitors for very low phosphorus and can fix their
own nitrogen (Shapiro, 1973). Pechlaner (1970) has documented a spring
diatom outburst in Lake Erhen (Sweden). The bloom was stimulated by in-
creasing photoperiod, 0.02 mg per liter PO^-P, and 0.15 mg per liter NO^-N.
Bluegreen algae (Anabaena flos-aquae and Aphanizomenon flos-aquae) began
to diminate when nutrients were reduced to 0.003 mg/1 PO^-P and 0.015 mg/1
NO^-N. This pattern closely resembles that observed in Flathead Lake;
except that in the latter case bluegreen algae (Oscillatoria aquatica)
production decreased as turbidity ensued, apparently limited by low light
and nutrients. Should turbid conditions not have occurred, intense primary
production may have continued into summer months with bluegreens dominating
the plankton community.
The present study has documented spring turbidity movement and con-
sequences, demonstrated phosphorus limitation, and documented diatora-
Oscillatoria standing crop dynamics in relation to light and water chemistry.
However our efforts toward defining nutrient (P and N) budgets for the Inke
-------
were only moderately successful. Further study of assimilation rates,
sediment release and sorption and phosphorus dynamics are badly needed.
We failed to consider nannoplankton organisms which Kalff (1977) has
shown often are major primary producers in oligotrophic lakes. We have
no estimate for the amounts of phosphorus the Lake might assimilate on an
annual basis before changes in algal species composition and production
occur. Documentation of the true phosphorus dynamics requires analytical
capability in .1 - 10 ug/liter range. It is clear, however, that discharges
from Flathead River do contain phosphorus concentrations well within range
necessary for nuisance pelagic blooms of bluegreens to develop should the
physical mechanisms of phosphorus loss be overcome.
Edmondson (1972), Shindler (1974) and Shindler et al. (1972) have
convincingly shown that the eutrophication process is most dependent on
phosphorus because nitrogen is usually present in sufficient concentrations
or, if not, bluegreen algae can fix their own. Also, they have proven that
total primary production in phosphorus sensitive lakes is related to the
ratio of phosphorus added to phosphorus lost by natural processes. Therefore,
in such lakes, especially those which are deep enough to stratify, primary
production will become phosphorus limited when phosphorus input is eli-
minated. Management of primary production in Flathead Lake hinges on further
understanding of actual phosphorus dynamics in the Lake as well as its
tributaries and a quantitiative knowledge of the Lake's ability to maintain
a phosphorus deficit. G. W. Prescott (personal communication) was certainly
correct in observing earlier that phosphorus is probably the mainspring of
primary production in Flathead Lake. Critical values, however, are an
order of magnitude lower than he supposed.
-------
A3.
LITERATURE CITED
Cole, R. A. 1973. Environmental changes in Lake Erie and their future
impact on lake resources. Inst. Wat. Res., Mich. St. U., Tech. Rep.
No. 32.3, 98 pp.
Cunningham, W. P. and L. F. Werth. 1973. A resource Inventory'method for
land use planning in Montana. Mont. Dept. Nat. Res. Cons. -78pp.
Dils, R. E. et al. 1972. A study of forest management practices on the
Flathead National Forest, Montana. Unpubl. Report for Kalispoll
Chamber of Commerce, Kalispell, Mont., 70 pp.
Edmondson, W. T. 1969. Eutrophication in North America, jln Eutrophica-
tion: Causes, consequences, correctives. Nat. Acad. Sci., Washington,
D. C., 661 pp.
. 1972. Nutrients and phytoplankton in Lake Washington.
in Likens, G. E., ed., Nutrients and eutrophication: The limiting
nutrient controversy. Amer. Soc. Limnol. and Oceanogr., Spec.
Symposia, 1:172-193.
Fields, 'R. W. 1971. Geology of Western Montana, Vol. II, N. W. Montana
and Glacier National Park. Department of Geology, University of
Montana, Missoula.
Forbes, S. A. 1893. A preliminary report on the aquatic invertebrate
fauna of the Yellowstone National Park, Wyoming, and of the Flathead
region of Montana. Bull. U. S. Fish Comm. for 1891, 11:207-258.
Gaufin, A. R. et al. 1975. Flathead Lake: A status report. .In press.
EPA Ecological Research Series.
-------
44.
Hutchinson, G. E. 1957. A treatise on limnology. Vol. II. John Wiley
and Sons, Inc. New York, 1115 pp.
Ivory, T. M. 1973. Phytoplankton production of Poison Bay, Flathead
Lake, Montana. Unpubl. Ph.D. dissertation, U. of Utah, Salt Lake
City, 206 pp.
Johns, W. M. 1970. Geology and mineral deposits of Lincoln and Flathead
Counties, Montana. Bur. Mines and Geol. Bull. 79, 182 pp.
Kaliff, J. 1972. Net plankton and nannoplankton production and biomass
in a north temperate zone lake. Limnol. and Oceanogr., 17:712-720.
Konizcski, R. L. et al. 1968. Geology and ground water resources of the
Kalispell Valley, Northwestern Montana. Mont. Bur. of Mines and
Geol. Bull. 68, 42 pp.
Lean, D. R. S. 1973. Phosphorus dynamics in lake water. Science,
197:678-680.
Lee, G. F. 1970. Factors affecting the transfer of materials between
water and sediments. U. Wis., Wat. Res. Cen., Lit. Rev. No. 1, 45.
Mnckereth, F. J. H. 1953. Phosphate utilization by Asterionella formosa
Hnss. J. Exptl. Bot. 4:296-313.
Mogh.-ulnm, F. 1969. Ecological and systematic study of plankton diatom
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U. of Utah, Salt Lake City, 206 pp.
Montana Water Resources Board. 1968. Inventory Series, Montana Register
of Dams. Publ. No. 3, 75 pp.
Morgan, G. R. 1968. Phytoplankton productivity of the east shore area
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-------
45.
. 1971. Phytoplankton productivity vs. dissolved nutrient
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Utah, Salt Lake City, 107 pp.
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in Lake Erhen (Sweden). Limnol. and Oceanogr. 15:113-130.
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43:338-348.
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Univ. of Motnana. V+123 pp.
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-------
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Montana, 74 pp.
Sridharan, N. and G. F. Lee. 1974. Phosphorus studies in lower Green
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Vollenweider, R. A. 1968. The scientific basis of stream and lake eu-
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CSI/68. No. 27 (miceogr.). 182 pp.
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sediments. EPA-R3-73-024, 185 pp.
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5:91-163.
-------
APPENDIX 1:
Average net phytoplankton count
at each station on each sampling date
-------
>iean Raw Councs per liter - Yellow Bay
PHYTOPLANXXER
Date T
.fenestrata
A.forsosa
F.crotonsis
Meiosiria spp.
Syned
8/x/73
16,379
<1,000
<1,000
<1,000
<500
17/x/73
16,440
4,008
1,115
3,488
652
29/xi/73
5,630
4,423
3,204
3,832
851
B
m
18/1/74
43,584
12,877
8,150
6,744
2,273
ll/IV/74
421,034
110,727
16,777
13,590
2,961
O
rH
rH
-*
22/IV/74
489,840
129,554
14,584
7,729
3,843
17/V/74
469,359
53,210
18,621
7,926
6,073
6/VI/74
192,712
8,896
6,008
5,551
1,696
o
cu
60
27/VI/74
34,063
1,807
3,060
1,388
523
tfl
5/VII/74
28,443
5,814
3,864
2,373
1,174
<
18/VII/74
15,759
4,695
2,730
<1,000
<500
CD
4J
c
3
O
u
s
cfl
p5
D«25m
Dynobryon spp 0. ac^uatica R.eriensis
<1,000
-
1,210
-
2,041
<500
7,366
581
7,219
961
10,193
3,761
32,157
<500
69,797
<500
65,365
<500
120,993
-
43,409
-
3,844
-
7,651
-------
MEAN RAW COUNTS PER LITER
PHYTOPLANKTER
Date
T.fenestrata
A.formosa
F.crotensis
Melosira
.l/xi/73
21,282
4,311
3,346
2,064
?l/xi/73
12,167
5,199
1,661
2,128
L8/I/74
24,498
15,756
3,797
7,446
L5/II/74
72,788
20,078
3,113
8,791
21/11/74
75,303
20,447
4,173
13,808
9/IH/74
160,639
37,995
14,091
16,925
Z9/III/74
193,361
54,045
10,798
12,018
Ll/IV/74
406,729
116,158
16,673
22,429
22/IV/74
489,128
108,268
16,725
11,755
17/V/74
389,492
63,238
12,205
5,893
ll/VI/74
238,922
7,697
17,071
1,000
27/VI/74
25,099
2,136
3,909
4,610
5/VII/74
17,236
2,542
4,645
18/VII/74
11,793
7,282
3,350
-
Deep Water - D=110m
Synedra spp
1,121
3,181
3,927
1,540
1,685
4,399
1,350
8,654
6,144
1,871
1,793
1,000
1,016
<1,000
O.aquatlca
1,352
<1000
7,3111
4,716
5,090
9789
21,549
60,630
77,699
40,473
4,343
8,300
<1000
D.bavarlcum
<1,000
<1,000
<1,000
<1,000
<1,000
<1,000
<1,000
<1,000
4,251
5,680
74,807
24,896
10,561
961
-------
MEAN RAW COUNTS PER LITER - Skldoo Bay - D=60m
PHYTOPLANKTER
Date
T. fenestrata
A. f onnosa
F. cro
tonensis
Melosira
Syndedra spp Dynobryon R.erensis
0.aquatica
A/XI1/73
30,039
7,095
5,
687
6,006
536
<1000
24/1/74
58,505
22,135
6,
794
13,188
734
6850
8/II/74
80,076
19,450
7,
044
12,021
960
3220
21/11/74
110,931
18,855
6,
321
12,321
1,829
7/III/74
152,917
32,819
9,
685
17,737
1,101
5650
22/111/74
133,154
4,532
3,
685
7,850
508
5339
ll/IV/74
386,500
62,473
17
,106
16,115
2,599
7046
ll/V/74
450,308
33,595
15
,826
9,528
1,864
21,987
29/V/74
251,698
11,874
11
,784
5,035
1,565
15,431
13/VI/74
153,978
5,480
8
,644
14,077
859
14,362
27/VI/74
85,945
8,023
4
,880
4,308
1,572
13,263
li/VII/74
60,075
15,008
7
,175
4,152
621
4,816
-------
MEAN RAW COUNTS - POLSON BAY - D=6m
PHYTOPLANKTER
Date
T.fenestrata
A,Formosa
F.crotensis
Melosira spp
Svndedra spp Dvnobrvon R.erensis
O.aauatica
ll/X/73
34,888
6,441
11,017
536
<1000
4/XII/73
25,848
22,882
4,661
1,271
4,231
24/1/74
73,661
31,470
13,362
918
<1000
8/II/74
52,813
6,554
9,986
367
<1000
21/11/74
176,732
34,719
7,119
8,898
508
2,542
7/III/74
150,798
50,906
16,378
15,848
480
<1000
22/111/74
88,816
3,220
1,130
ll/IV/74
278,163
83,238
23,758
7,613
586
16,115
ll/V/74
453,412
43,787
24,012
7,768
2,825
29/V/74
136,207
5,254
4,209
480
13/VI/74
133,679
9,266
2,825
6,073
27/VI/74
51,655
5,122
5,028
18/VII/74
66,105
4,407
734
-------
MEAN RAW COUNTS PER LITER - YEKNE POINT D=80m
PHYTOPLANKTER
Date
T.fenes trata
A.formosa
F.crotensis
Melosira
Svndedra spp Dvnot>rvon
R.erensis O.aquatica
9/XI/73
38,069
9,336
2,683
3,041
847
4,972
15/XI/73
31,866
5,799
2,909
5,558
960
4,294
30/1/74
51,455
8,117
3,390
10,946
437
8701
11/11/74
66,952
15,286
2,712
8,478
433
1807
9/III/74
160,975
28,691
7,881
11,285
508
847
26/111/74
185,200
45,215
12,976
9,153
1,041
17/IV/74
435,633
48,808
16,146
10,735
3,239
17,902
23/IV/74
553,218
49,359
14,047
11,098
1,995
13,200
22/V/74
215,020
8,832
5,292
4,901
1,200
10,283
ll/VI/74
164,333
8,531
9,451
4,990
1,017
8,152
17/VII/74
56,942
17,430
4,350
1,751
904
7,208
-------
MEAN RAW COUNTS PER LITER - BIG ARM BAY D=40m
PHYTOPLANKTER
Date
T.fenestrata
A.formosa
F.crotensls
Melosira 9pp
Syndedra spp Dynobryon R.erensls
O.aquatica
9/XI/73
15,675
8,787
2,043
2,741
1,094
8,382
4/XII/73
10,237
4,191
2,088
3,839
3,587
2,990
13/XII/73
16,595
26,725
2,655
4,919
6,942
4,799
24/1/74
31,778
19,826
4,421
8,739
4,542
6,935
15/11/74
107,835
44,096
9,382
26,572
2,512
6,107
7/III/74
203,835
82,370
20,201
14,097
3,457
-15,914
29/111/74
355,430
84,780
16,906
8,783
4,675
51,048
15/IV/74
467,829 .
121,655
15,793
9,488
6,122
137,819
29/V/74
258,877
8,413
16,447
5,162
<1,000
72,555
13/VI/74
193,471
4,786
19,176
110,070
4,244
198,584
-------
MEAN RAW COUNTS PER LITER - NORTH END D=30m
PHYTOPLANKTER
Date
T.fenestrata
A.formosa
F.crotensis
Melosira spp
Syndedra spp Dynobryon R.erensis
0.aquatica
18/X/73
26,131
11,695
3,691
2,429
423
3,107
15/XI/73
31,753
15,099
2,542
4,197
3,540
4,237
26/XI/73
46,523
12,990
2,674
6,421
5,214
<1,000
11/11/74
109,359
15,012
5,415
11,445
4,939
6,017
9/III/74
198,363
41,588
12,467
9,741
1,288
5,508
26/111/74
239,414
64,341
12,494
9,605
2,198
6,189
17/IV/74
395,675
67,754
14,588
11,985
2,010
7,542
23/IV/74
259,891
21,768
7,919
6,751
3,550
6,642
22/V/174
98,128
1,000
4,783
2,034
10/VI/74
103,467
6,059
4,675
4,548
955
6,723
17/VII/74
61,237
10,254
7,119
3,408
725
3,757
-------
APPENDIX 2:
Tabulation of all Chemical Data.
-------
DATE dH Si
(1) Yellow 3av
T !Sr3m
T Phos
ADc Co^ No^ 0 Phos
T. K. T Fe Cu Zn ... Mn Co,
'//QaDepth
2-VII
73
;
.01
.OA
.01
1
21.8
S
.01
.03
.01
16.5
D
..0-VII
73
[
.01
.04
.01
21.5
-
S
103
.07
.04
19.0
D
'2-VII
73
[
.02
.02
.01
20.0
S
.03
.03
.02
15.0
D
J9-VII
73
[
.02
20.5
S
.02
D
3-IX
73
.02
17.5
S
.02
17.5
D
4-IX
73
.05
8.0
27
21-X
73
.02
18.0
1
8-X
73
.04
12.5
1
.08
13.0
10
.02
7.5
27
i
-------
(1) Yellow Bay II T Phos two
iATE pH Si T Hard Ca Mg Alk CNo^ 0 Phos T. K. T Fe Cu Zn Mn Co/Cd^. ^
L7-X-
73
2.1
8.6
91
3
.17
0
12.5
1
2.2
87.
89
5
.19
0
9.0
26
23-X-
73
8.0
1.7 "
92
86
3
0
<.01
-
1
7.7
1.7
88
86.7
4.8
.06
<.01
27
30-X-
73
8.1
1.9
86
87
3.0
.04
<.01
9.C
1
8.1
2.1
86
86.5
3.0
.09
.10/.01
9.0
10
5-XI-
73
7.3
2.2
90.4
86.2
4.5
.19
.io/<.o:
6.0
1
7.6
2.2
95.8
86.4
4.5
.17 .
X)4/< .01
5.0
30
19-XI-
73
7.4
1.8
85.0
62.0
23.0
85.7
2.9
.10
j07/<.01
6.0
1
7.5
1.9
85.8
62.0
23.8
86.0
3.2
.11
<.01
6.0
25
30-XI-
73
7.4
1.8
88.2
61.9
26.3
85.8
3.2
.06
<.01
5.5
.05
<.01
<.01
1
7.48
1.9
87.0
62.5
24.5
84.5
2.7
.07
<.01
5.5
.06
<.01
<.01
25
17-XII
73
.04
,01/<.01
5.2
.01
<01
<.01
1
.07
.02/
5.1
0
.01
<.01
25.
9-1-
74
| 8.3
1.3
89.8
63.' 0
23.8
85.5
3.3
.04
01/<.01
1
i
i 1.0
!
.06
<.01
jj.01
¦
! !
I i
I
1
-------
DATE dH Si T Hard Ca Vq ahx Yelfe^ -^No3 0 ?hos T. K. T Fe Cu Zn Mn Co,
9-1-
74
8.3
1.7
90.0
63.6
23.6
86.5
3.8
.06
<.01
4.0
.06
<.01
<.01
25
18-1-
74
8.25
2.2
88.9
62.4
26.5
85.5
3.5
.03
.02/
3.0
.06
<.01
.01
1
8.25
2.3 '
88.0
63.8
24.2
85.2
3.3
.06
.Ol/c.Ol
3.0
.01
<-01
-
25
4-II-
74
8.3
1.6
88.5
65.5
23.0
86.5
4.0
.13
<.01/
2.5
0
<.01
.01
1
8.15
2.0
91.0
63.0
28.0
85.8
4.0
.1.2
<.01/
2.5
.30
<.01
<.01
25
.12
<.01/
2.0
.03
<.01
.01
15
21-11-
74
8.2
2.58
92.0
71.0
21.0
84.0
3.5
.11
.01/
<.01
1.5
.02
<.01
.01
1
8.2
2.58
93.0
72.0
21.0
84.5
3.5
.08
<.01/
<.01
2.0
.01
<.01
.01
25
25-11-
74
.04
<.01/
.02
1.5
0
.01
<01
1
.03
.03/
.02
2.0
.10
<.01
.01
25
1 1
w
M 1
1
00 1
-------
(1) Yellow Bay T Phos foui
)ATE pH Si T Hard Ca Fig ALk Co^ No^ O Phos T. K. T Fe Cu Zn Mn Co/Cd^ ^
29-11:
1L
8.2
2.7
95.0
67.0
28.0
86.7
3.0
.29
<.03
2.4
20
8- IV-
74
8.35
1.9
83.5
66.0
17.5
85.9
2.0
.04
<.03
3.0
1
8.25
2.1 '
83.9
66.0
17.9
85.9
2.5
.22
<.03
3.0
.04
<.01
<.01
20
11-IV
74
8.4
2.0
92.5
64.9
27.6
86.0
3.0
.02
»28/<.03
2.8
.03
<.01
.01
1
8.2
2.2
91.0
66.0
25.0
86.2
3.0
1.9
.03/
3.0
.09
<.01
.01
20
13-IV
74
.09
$3/<.03
3.0
1
22- IV
74
8.2
3.15
-
60.9
-
85.8
3.5
.04
<.03
3.0
.04
<.01
<.01
1
I
8.1
3.0
-
64.0
-
85.5
3.0
.04
<.03
3.0
.04
<.01
<01
25
17-V-
74
8.5
3.3
90.5
69.0
21.5
89.0
3.0
0.0
<.03
5.5
0
<.01
<.01
1
8.5
3.0
88.5
68.0
20.5
88.0
4.0
0.0
<.03
5.3
.02
<.01
<01
25
11-VI
74
7.7
3.4
91.0
67.0
24.0
86.0
4.0
9.6
<.03
10.0
.02
<01
<.01
0
<.01/
1
8.2
3.0
90.5
67.3
23.2
86.5
4.0
0.0
<.03
7.0
.02
<.01
<.01
0
<.01/
25
.04
2.6 / <;0 3
3.0
4
27-VI
74
8.15
-
86.0
62.0
24.0
82.3
4.0
0
-
0
11
.01
0
O1/SD0Z
1
i
1
8.1
-
86.5
63.0
23.5
81.5
5.0
-
.02
11
.01
0
<01/<00L 25
-------
CD Yellow Bay T Phos f
DATE pH Si T Hard - Ca Mg Alk Cc>2 No3 0 Phos T. K. T Fe Cu Zn Mn Co/Q3Depth
5-VII
74
8.0
-
84.5
66.5
18.0
80.8
3.5
-
0
<.01
.03
0
<.01/
<001
1
8.1
-
90.0
69.5
20.5
84.5
3.5
-
0
<.01
.02
0
If
25
15-vi:
74
.01
.04
<.01
0
M
25
0
<.01
.02
0
II
1
18-Vi:
74
: 8.1
-
86.5
60.5
26.0
80.5
3.5
-
0
11
.01
0
II
1
7.85
-
91.5
64.0
27.5
84.0
4.0
-
0
<.01
.01
0
If
25
-------
C2) Mid lake Deep T Phos
ME pH Si T Hard Ca Mg Alk Col No. 0 Phos T. K.
Fe Cu Zn Mn
Co/0dDepth
one
D-VII
73
I
.01
.02/.02
21.0
S
.03
.OA/.01
10.0
D
2-VII
73
I
.03
OA/.01
70.5
S.
.01
.02/.02
18.5
D
9-VII
73
I
.03
18.0
S
.OA
18.0
D
3-IX
73
.06
17.0
S
7-IX
73
.02
15.5
1
.OA
6.5
AO
>8-X-
73
.06
13.5
1
.07
13.0
10
.11
6.0
AO
:3-x-
73
7.6
2.2
88
87
4.2
.08
<.01
-
1
7.5
1.8
88
87
A.5
.12
<.01
1
AO
31-X-
73
8.1
2.1
87.4'
87
2.9
.OA
<.01
10.0
1
!
!
i 1 , i
i - ~ :
! i
-------
(2) Midlake Deep T Phos
DATE pH Si T Hard Ca Mg aUc Co^ Ko"3 O Phos T. K. T Fe Cu Zn Mn
31-X-
73
8.0
2.3
88
88
5.0
.14
<.01
6.0
!
j 40
8-XI-
73
8.15
2.1
87.0
63.5
23.5
87.0
3.7
.22
04/<.01
6.5
!
i
! 1
1
8.15
2.2 '
86.9
62.3
24.6
86.0
4.0
.09
,04/<.01
5.0
40
8.0
2.3
87.0
63.4
23.6
87.5
4.1
80
9-XI-
73
7.6
1.9
90.3
65.9
35.6
85.7
80
21-XI-
73
7.4
1.8
87.7
63.9
23.8
85.5
5.0
.23
<01
6.0
.03
<.01
<.01
1
7.5
1.7
87.4
66.7
20.7
85.7
4.0
.31
<.01
6.0
.37
<.01
<.01
40
7.5
1.8
87.5
66.4
21.1
85.4
7.0
.40
<.01
5.5
.09
<.01
<.01
80
7-XII
73
7.5
2.1
87.5
62.8
24.7
85.8
4.0
5.0
1
7.5
2.1
87.5
62.8
24.7
85.8
4.5
5.0
40
7.5
2.1
87.5
62.8
24.7
85.5
3.2
5.0
80
18-1-
74
8.15
1.7
87.5
64.7
22.8
85.5
3.0
.04
.02/
3.0
.04
<.01
.01
1
8.25
2.1
90.0
63.0
27.0
85.0
3.0
.07
.02/
3.0
0
<01
<01
40
4-II-
74
8.35
1.5
90.5
68.0
21.5
84.5
3.0
.17
.07/
2.5
.01
<.01
.01
1
8.35
1.8
94.5
67.5
27.0
87.5
3.0
.23
<.01/
2.5
0
<.01
.01
40
-------
{2) Mldlake Deep T Phos three
DATE pH Si T Hard Ca Mg Alk Co^ No3 0 Phos T. K. T Fe Cu Zn Mn C°/caDa3th
15-11-
I 74
8.20
2.28
91.0
66.0
25.0
85.5
3.0
.12
<01/
<.01
2.5
.01
<.01
.01
1
8.30
2.30
90.0
68.0
22.0
85.0
3.0
.12
.09/
.01
2.5
0
<.01
.01
40
21-11-
74
8.1
1.99
94.0
73.0
21.0
85.5
3.5
.01
.01/
<01
2.0
0
<01
.01
1
8.30
2.40
89.0
70.0
19.0
85.5
3.5
.11
<.01/
<.01
2.0
.01
<.01
.01
40
25-11-
74
.03
<.01/
.05
1.5
0
<.01
<.01
1
i
!
1
t
.05
<.01/
.03
2.0
0
<.01
.01
40
28-11-
74
8.0
2.7
95.0
65.0
30.0
88.0
5.0
.21
.03/
.06
2.5
0
<.01
<.01
1
8.2
2.5
95.0
64.0
31.0
88.0
4.0
.23
.01/
<.01
2.5
0
<.01
.01
40
7-III
74
8.0
2.95
88.0
62.0
26.0
86.0
3.0
.06
.03/
<.03
.30
2.5
0
<.01
<.01
1
.06
.05/
<03
.01
2.5
-
20
8.1
3.08
88.0
62.0
26.0
87.0
2.5
.06
<.03
.01
2.5
.01
<.01
<.01
40
10-11]
74
7.9
2.5
88.5
63.0
25.5
86.0
2.0
.14
.06/
<.03
<.01
2.2
.02
<.01
.01
1
8.25
3.0
88.0
63.0
25.0
86.5
2.5
.15
<.01/
<.03
II
2.2
.02
II
II
40
21-11]
74
8.1
2.64
93.5
68.5
25.0
89.5
3.0
.11
.03/
<.03
.04
2.0
.02
1
8.3
2.7
93.5
66.0
27.5
87.0
3.0
.17
<.01/
<.02
<.01
2.0
.02
40
-------
(2) Midlake Deep T Phos fo
DATE pH Si T Hard Ca Mg ALk Co2 Nc>3 0 Phos T. K. T Fe Cu Zn Mn ^/C^Depth
29-11
74
: 8.1
2.1
89.8
70.0
19.8
85.8
3.0
.08
<.03
2.5
.02
<.01
.01
1
8.3
2.35
93.2
69.0
24.2
85.5
3.5
.20
.03/
2.4
.02
<.01
40
8-IV-
74
8.3
1.8 '
89.0
65.0
24.0
85.7
3.0
.16
<.03
3.0
0
<01
<.01
1
8.1
2.3
88.0
67.5
20.5
85.2
3.0
.04
<.03
3.0
.01
II
It
40
11-IV
74
8.3
1.9
88.5
68.8
19.7
86.6
2.5
.31
<.03
3.0
.02
It
tl
i
8.2
2.5
92.0
68.5
23.5
87.0
3.0
.02
.18/<.03
3.0
.09
<.01
.01
40
2 2-IV
74
8.2
2.6
6
61.8
-
86.0
3.0
.04
03/<.03
3.0
.04
II
II
1
8.1
3.0
-
64.5
-
85.0
3.0
.04
.03/<.03
3.0
.02
II
It
40
8.15
3.2
-
60.0
-
85.0
3.0
.04
<.03
3.0
.03
II
<.01
60
17-V-
74
8.7
2.8
91.0
75.0
16.0
88.0
4.0
0.0
<.03
5.2
0
It
It
1
8.4
3.0
91.0
73.0
18.0
87.5
4.0
0.0
<.03
4.2
.02
<.01
<.01
40
6-VI-
74
0.0
<.03
8.0
10
11-VI
74
8.2
3.8
91.0
67.0
24.0
85.0
3.5
4.7
<.03
10.0
.03
<.01
<.01
0
<.01/
1
7.9
3.5
89.0
66.5
22.5
86.5
4.0
-
0
It
It
0
II
25
27-VI
74
8.1
88.0
67.0
21.0
83.0
4.0
-
0
.03
.01
0
< .01/
<.oc
1
1
-------
t pnos
JATE pri oi T Hard Ca Mg Alk Co^ No^ 0 Phos T. K. T Fe Cu Zn Mn
Co/QWh
five
.2-VI-
74
4.7
<;03
-
2.5
<.01
.02
.02
<.01/
10
'.7-VI-
74
7.85
-
93.5
67.0
26.5
85.0
5.0
-
.01
<.01
<.01
0
<.01/
<.001
40
i-VII-
74
8.05
- '
87.0
61.0
26.0
80.5
3.0
-
.01
.03
If
0
II
1
8.15
-
92.5
66.0
26.5
86.5
3.5
-
.01
.03
<01
0
II
40
M !
> r-
1
00
8.0
-
80.0
57.5
22.5
78.5
3.5
-
0
<.01
II
0
II
1
8.0
-
95.5
63.0
32.5
85.5
3.0
-
0
II
II
0
II
40
.24
<.01
.04
0
40
}
.
-------
(3) Yenne Point T Phos
DATE pH Si T Hard Ca Mg aUc No^ 0 Phos T. K. T Fe Cu Zn Mn Co,
21-VI
73
¦I
.01
.03/.03
19.5
S
.01
.01/.01
19.0
D
29-VI
73
:i
-
.02
20.0
s
.06
19.0
D
2 7-IX
73
.07
14.2
1
.11
6.0
40
08-X-
73
.09
13.5
1
.03
12.5
10
.11
6.5
40
18-X-
73
2.0
86
80.5
4.0
1
2.1
85
89
5.5
40
9-XI-
73
7.2
2.0
90.0
65.3
24.7
84.0
.13
.06/<.01
7.0
1
7.3
2.2
88.9
63.9
25.0
84.7
-
.17
.54/<.01
6.0
40
15-XI
73
7.4
1.6
87.9
64.7
23.2
85.7
85.5
5.5
4.0
.11
<.01
7.0
1
7.6
1.8
88.0
63.9
24.1
.11
.01/<.01
6.5
40
-------
(3) Yenne Point T Phos two
JATE pK Si T Hard Ca Mg Alk Co^ No^ 0 Phos T. K. T Fe Cu Zn Mn Co/03-^..
15-XI
73
7.7
1.9
89.3
63.0
26.3
86.0
4.0
.16
.02/<.01
6.0
75
30-1-
74
8.35
1.6
88.0
65.0
23.0
84.5
-
0.0
0.0
2.0
0
<.01
<.01
1
8.2
1.7'
96.0
73.0
23.0
83.5
-
0.0
0.0
2.0
.02
II
II
40
11-11
74
8.15
2.34
89.0
66.0
23.0
86.0
-
.18
.02/
.03
2.5
.04
<.01
II
1
8.15
2.90
89.5
63.0
26.5
84.8
-
.17
.02/
.04
2.5
.05
II
II
40
25-11
74
.07
.01/
.03
2.0
0
<.01
.01
1
.12
.01/
<.01
2.0
0
<.01
.01
40
LO-III
74
8.2
3.4
87.0
62.0
25.0
85.0
2.5
.16
.03/<.02
.08
2.2
.04
<.01
<.01
1
8.35
3.2
88.0
63.0
25.0
86.0
2.5
.38
.05/<.02
.02
2.2
.03
II
.02
40
26-111
74
8.1
2.1
92.0
69.5
22.5
87.0
3.0
.05
<.03
2.5
.02
II
<.01
1
8.1
2.2
96.0
72.0
24.0
86.5
3.5
.08
<.03
.08
2.5
.02
II
11
40
17-IV-
74
8.27
3.2
-
65.5
-
85.5
-
.04
<03
3.5
.10
II
II
1
8.17
3.2
-
69.8
-
85.5
-
.07
<.03
3.1
.03
II
<01
40
2 3-IV-
74
8.2
2.8
-
61.0
-
87.5
3.0
.04
.03/<.o:
3.0
0
.01
11
....
1
t
i
7.9
3.2
-
63.0
-
86.0
3.0
.04
,03/<.02
3.0
.0! <.01
!
1
I
40
-------
(3; Yenne Point T Phos thi
DATE pH Si T Hard Ca Mg Alk Co2 Nc>3 0 Phos T. K. T Fe Cu Zn Mn C°/cdDepth
22-V-
74
8.1
3.6
99.0
62.5
36.5
88.5
4.0
.06
.03/
5.0
.02
<.01
<.01
l
20
8.1
3.5'
90.0
63.0
27.0
88.0
4.0
0.0
<.03
5.0
.05
It
ft
40
10-VI-
74
8.2
3.9
87.0
65.5
21.5
86.5
4.0
-
0
II
It
0
<.01/
1
7.9
3.0
89.0
63.0
26.0
88.0
4.0
-
0
tt
ft
0
If
40
17-VI1
74
7.85
-
81.0
58.5
22.5
80.0
3.0
-
.01
f 1
.01
0
<.01/
<.oo:
1
7.9
-
92.0
63.5
28.5
86.0
3.5
-
0
ft
<.01
0
if
40
-------
ME pH Si
T Ha:
rd Ca
Mg
(<
Alk
Skid
^2
oo Bay
No3
T Pho:
0 Pho:
3 T. K.
T
one
Fe Cu Zn Mn c°/cdDepth
7-VII
73
I
.01
<01
20.5
s
2-VII
73
I
.03
<.01
20.5
s
.02
.02/.01
20.0
D
9-VII
73
I-
.02
20.0
S
.03
18.5
D
o-ix-
73
.03
17.5
D
!6IX-
73
.01
15.0
1
.01
6.5
40
.O-XI-
73
7.7
1.9
86.0
64.5
21.5
86.5
3.5
.09
.04/<.0]
7.5
1
7.7
2.1
87.5
64.0
23.5
85.5
4.0
.29
.03/<.0]
7.3
40
7.6
2.4
87.0
66.0
21.0
85.9
4.5
.33
.02/<.0]
6.3
70
!2-XI-
73
7.5
1.8
88.0
65.5
22.5
85.8
3.0
.12
<.01
6.0
.03
<.01
.01
. 1
7.5
1.8
86.5
65.0
21.5
86.0
3.9
.29
<.01
6.0
.04
II
<.01
40
7.45
2.2
89.5
65.2
24.3
85.2
4.0
.41
<01
5.5
.03
II
It
80
8.3
2.1
86.5
»>
6^.0
24.5
85.0
2.5
.03
.02/
3.0
0
II
.01
i
1
-------
9 (4) Skldoo Bay t Phos
DATE pH Si T Hard Ca Mg Alk Cc>2 Nc>3 0 Phos T. K. T Fe Cu Zn Mn
24-1-
7 4
8.2
2.1
87.5
63.5
24.0
85.5
3.0
.08
-
3.0
0
<.01
<.01
40
9-II-
74
8.2
6.3
90.0
65.0
25.0
85.5
3.0
.08
.01/
3.0
.04
ft
1 1
1
8.25
6.3'
89.5
70.0
19.5
85.0
3.0
.11
.01/
3.0
0
11
II
40
21-11
74
8.2
2.98
91.5
68.0
23.5
84.5
4.0
.08
<.01/
<.01
2.5
0
<.01
<.01
1
8.3
2.28
87.0
65.5
21.5
85.5
4.0
.09
<.01/
<.01
2.5
.02
If
f f
40
7-III-
74
8.2
3.32
87.0
62.5
24.5
86.0
3.0
.03
<.03
.01
2.5
.01
<.01
<.01
1
8.1
4.13
87.0
62.0
25.0
86.0
3.0
.11
<.03
.01
2.5
0
ft
II
40
8.2
4.34
8 .5
62.0
24.5
86.0
2.5
.06
<.03
.01
2.5
0
II
II
80
22-111
74
8.1
2.65
94.0
72.0
22.0
88.5
4.0
.26
.05/
<.03
<.01
2.5
.02
II
II
1
8.2
2.9
97.0
76.0
21.0
87.5
3.5
.10
.06/
<.03
It
2.5
.01
ft
II
40
11-IV-
74
8.3
.17
89.8
69.0
20.8
86.5
3.5
.11
.05/
<.03
3.0
.02
II
II
1
8.2
2.4
91.0
70.0
21.0
85.5
4.0
.13
<.03
3.0
.05
<01
.01
40
11-V-
74
8.3
3.0
-
66.5
-
86.3
3.0
0.0
<.03
3.0
0
tt
<.01
1
8.3
2.75
-
66.0
-
85.5
3.0
0.0
.04/
<.03
3.0
.02
If
II
40
29-V-
74
8.2
3.15
90.5
67.0
23.5
85.5
3.0
0.0
<.03
8.0
.02
II
tl
0
1
-------
2ATE
T Hard
(4) Skidoo Bay
Mg N Mk Ut>2 1
T Phos
No3 oHpEos T. K.
T Fe Cu Zn Mn
three
Co/0aDepth
^-VI-
TA
0
<.03
-
.03
<01
.01
. 0
.01/
1
L3-VI-
74
8.2
-
90.5
63.0
27.5
85.5
4.0
-
0
<01
<.01
0
<.01/
1
8.5
- '
90.5
65.0
25.5
85.5
4.0
-
0
<.01
II
0
II
40
27-VI-
74
8.15
-
89.0
66.0
23.0
81.0
4.0
-
.01
It
.01
.02
<.01/
<.00]
1
8.05
-
90.5
73.0
17.5
84.5
4.5
-
0
«
It
.01
II
40
18-VII
74
8.1
-
85.0
60.0
25.0
80.0
3.5
-
0
II
<.01
0
II
1
8.1
-
91.5
62.5
29.0
87.5
3.5
-
0
II
.01
0
II
40
.14
<.03
-
.05
II
II
0
<.01/
5
.04
n
-
2.7
.02
.07
.07
II
10
.13
ii
-
.07
<.01
<01
0
II
20
1
i
1
I
I
1
1
-------
(5) Poison Bay t Phos one
DATE pH Si T Hard Ca Mg Alk Co2 No3 O Phos T. K. T Fe Cu Zn Mn c°/°dDepth
22-VI]
73
I
.01
.01/.01
21.0
s
26-IX-
73
.07
14.5
1
.03
14.2
5
10-XI-
73
7.7
2.1
90.5
64.5
26.0
84.5
4.0
.07
. 05/<.o:
4.0
1
7.7
2.0
88.0
63.0
25.0
85.9
4.0
.11
.32/<.o:
4.0
5
4-XII
73
7.5
2.2
87.5
62.5
25.0
85.3
4.0
3.5
1
7.5
2.0
88.0
63.0
25.0
85.5
4.0
3.5
5
24-1-
74
8.2
1.9
88.0
63.0
25.0
86.0
3.0
.01
.02/
2.5
0
<.01
.01
1
8.3
1.9
90.0
66.5
23.5
86.0
3.0
.09
.01/
2.5
0
tl
11
5
8-II-
74
8.25
5.52
90.0
65.0
25.0
84.5
3.5
.13
.01/
2.5
0
It
If
1
8.25
5.70
89.0
65.0
24.0
85.0
3.5
.08
.01/
2.5
0
<01
<.01
4
21-11
74
8.15
2.28
92.5
73.8
18.7
84.5
3.5
.08
<.01/
.01
2.0
.02
<.01
.01
1
8.35
2.33
93.3
72.0
21.3
85.0
3.5
.01
.01/
V
2.0
0
If
tf
5
7-III-
74
8.3
2.65
87.0
62.0
25.0
86.0
2.5
.13
<.03
.20
2.0
If
<01
<.01
1
8.2
2.53
87.0
62.5
24.5
88.0
3.0
.06
.03/<.o:
.25
2.0
0
If
ft
5
-------
C5) Poison Bay t Phos two
>ATE pH Si T Hard Ca Mg Alk Co^ No^ 0~Pfios T. K. T Fe Cu Zn Mn c°/cdDeDth
22-113
74
8.1
2.9
92.5
74.0
18.5
87.0
3.0
.20
.04/<.0:
.28
2.5
.01
<.01
<.01
l
8.2
3.05
96.5
75.5
21.0
86.5
3.5
.20
.05/<.o:
.27
2.5
.01
II
II
4
11-IV-
74
8.15
1.6'
90.0
67.9
22.1
85.5
3.0
.13
.06/<.o:
3.0
.02
II
If
1
8.1
2.1
86.5
66.9
19.6
85.1
3.0
0.0
<.03
3.0
.03
II
11
3
11-V-
74
8.1
2.8
-
68.0
-
86.5
3.0
0.0
<.03
3.0
0
II
II
1
8.3
2.95
-
67.5
-
86.0
3.0
0.0
<.03
3.0
0
II
II
5
29-V-
74
8.2
3.6
89.0
65.0
24.0
85.0
3.5
.04
<.03
8.0
1.3
<.01
<.01
.01
<.01/
1
8.2
3.4
94.0
65.0
29.0
85.0
3.5
0.0
<03
6.0
.01
II
II
0
II
5
13-VI-
74
8.1C
-
89.0
61.5
27.5
85.5
4.0
-
II
II
<.01
II
II
1
8.05
-
89.5
61.5
28.0
86.5
3.5
-
0
II
tl
0
II
5
27-VI-
74
7.9
-
86.5
64.0
22.5
81.0
5.0
-
II
<.01
<.01
11
<.01/
< .oo:
1
8.25
-
91.0
67.0
24.0
79.0
4.5
-
0
II
.01
0
it
5
18-VI1
74
8.1
-
83.0
57.5
25.5
76.0
3.5
-
0
tl
.01
II
it
1
8.0
-
82.0
59.0
23.0
76.0
3.0
-
.01
.03
<.01
0
11
5
12-VI-
74
.01
<.01
.03
0
<.oi/ j
I
i
3
-------
C6) Below Poison Bridge ip p]tqs
DATE pH Si T Hard Ca Mg Alk Co2 No3 0 Phos T. K. T Fe Cu Zn Mn GVO^Depth
26-IX-
73
.11
14.1
1
.04
-
3
LO-XI-
73
7.5
2.3'
88.0
64.0
24.0
85.3
3.4
.13
.04/<.01
4.0
1
7.6
2.3
86.8
62.8
24.0
85.3
3.5
.25
.09/ <.01
4.0
3
16-xri
73
8.4
1.4
88.0
63.0
25.0
85.5
2.7
.01
.03/<.01
3.0
.04
<.01
<01
1
7.9
1.8
88.0
52.5
25.5
85.5
3.2
.05
.02/<.o:
3.0
.02
M
.01
5
14-1-
74
8.1
2.0
90.0
63.5
25.5
87.5
3.0
.05
<.01/
.03
-
0
II
II
1
8.1
1.7
88.5
64.0
24.5
86.5
3.0
.03
.01/<.0]
-
0
II
II
3
24-1-
74
8.35
1.8
87.0
64.5
22.5
86.0
2.5
.0
<.01
2.5
II
<.01
.01
1
8.4
1.9
91.0
62.0
29.0
84.5
2.5
.04
.02/
2.5
0
II
II
3
3-II-
74
8.3
6.30
85.9
65.0
20.9
84.5
3.5
.12
.01/
2.5
(1
fl
1
8.2
6.45
93.0
64.9
28.1
84.5
3.5
.07
<.01/
2.5
.03
<.01
.01
3
21-11-
74
8.25
2.80
91.2
68.0
23.0
85.5
4.0
.01
.01/
<.01
2.0
.02
If
II
1
8.35
2.90
89.0
61.0
28.0
84.5
4.0
.02
<.01/
ft
2.0
.02
It
If
3
7-III-
74
8.2
3.08
88.0
63.0
25.0
90.0
3.0
.08
.o3/<.o:
.02
2.0
.02
<.01
<.01
1
-------
(6) Below Poison. Br Idea T Phos ^
jATE T Hard AUc Co~ No_ 0 Phos T. K. T Fe Cu Zn Mn Co/Cd-
'-III-
74
8.1
2.48
88.0
62.0
26.0
86.0
3.0
.14
.05/<.03
.18
2.0
0
.01
.01
3
.8-111
74
.18
<.03
<.01
2.0
.01
1
'.2-III
74
8.0
3.13
97.5
66.3
31.2
87.0
3.5
.18
.03/<.03
<.01
2.5
.24
II
.01
1
8.1
2.85
98.0
64.5
33.5
85.0
3.5
.15
o
V
O
.67
2.5
<.01
<.01
.01
3
.13
<.03
.35
2.0
.03
3
LI-IV-
74
8.3
2.3
88.5
68.0
20.5
86.0
3.0
.22
<.03
3.0
.02
<.01
<.01
?
!-V-
74
8.3
2.75
-
70.0
-
86.0
3.0
0.0
<.03
4.0
0
fl
II
2
1-V-
74
8.15
2.75
-
62.0
-
85.7
4.5
.67
<.03
4.0
.01
If
II
2
Ll-V-
74
8.25
2.55
-
66.5
-
86.5
3.0
0.0
<.03
3.0
0
ft
It
2
!9-V-
74
8.2
3.2
91.5
66.0
25.5
87.0
3.5
.05
.03/<.03
6.0
.03
II
II
0
<.01/
2
r
M
>
i
8.2
-
88.0
61.5
26.5
86.0
4.0
-
0
<.01
<.01
0
II
2
!7-VI-
74
8.1
-
86.5
63.0
23.5
81.0
3.5
-
.02
II
.01
II
<.01/
<.001
2
1
> ^
1 I
00 |
8.0
-
85.5
66.0
19.5
82.0
4.0
-
.01
It
.04
0
II
1
.8-VII
74
8.1
-
83.0
64.0
19.0
78.5
3.0
-
0
.07
.01
0
If
2
...
I
1
-------
Kf) nigarm pay t trios
DATE pH Si T Hard Ca Mg Alk Cc>2 No3 0 Phos T. K. T Fe Cu Zn Mn
09-VI]
73
I
.01
.03/.01
21.5
s
.01
.01/<.0]
19.0
D
04-IX-
73
.02
15.5
D
26-IX-
73
.06
14.2
1
.13
6.5
35
9-XI-
73
7.5
1.9
86.9
63.5
23.4
85.7
-
.09
.08/<.0]
7.0
1
7.5
2.1
89.4
64.0
25.4
85.5
-
.06
.05/<.0]
7.0
27
30-XI-
73
7.52
1.9
88.2
63.0
25.2
86.6
3.0
0
<.01
5.5
.05
<.01
<.01
1
7.55
2.0
88.5
62.5
26.0
86.3
3.0
0
<.01
5.5
.06
tf
tt
30
18-XII
73
8.3
1.5
89.5
63.0
26.5
-
4.0
.05
.02/
4.8
0
fl
tt
1
8.4
1.8
89.9
62.5
27.4
-
4.0
.01
.03/
4.6
tf
<.01
.01
35
24-1-
74
8.15
1.7
89.0
66.0
23.0
84.5
3.0
.10
<.01/
2.5
0
ft
<.01
1
8.25
1.9
86.5
63.5
23.0
84.5
3.0
.08
.01/
2.5
tt
tf
.01
40
L5-II-
74
8.2
2.15
89.0
67.0
22.0
85.0
3.0
.08
<.01/
<.01
2.0
.01
<.01
f 1
1
8.3
2.55
90.0
68.5
21.5
85.0
3.0
.08
.03/
11
2.0
.04
ft
ft
35
-------
C7) Bigarm Bay T Phos two
1ATE pH Si T Hard Ca Mg Alk Oo^ Nc>3 0 Phos T. K. T Fe Cu Zn Mn Co/G^nenth
1-111-
74
8.1
3.08
87.0
63.0
24.0
87.0
2.5
.06
.03/<.0:
.02
2.5
0
t1
O
V
<.01
1
8.1
2.50
87.0
62.0
25.0
87.0
3.0
.12
.o6/<.o:
<.01
2.5
If
il
II
25
>9-111
74
8.2
2.45
89.0
70.0
19.0
85.8
3.0
.28
.03/
3.2
0
.01
<.01
1
8.25
2.5
88.8
75.0
13.8
85.8
3.0
.07
<.03
3.2
tl
<.01
II
25
15-IV-
74
8.3
2.9
95.8
66.8
29.0
86.5
-
0.0
<.03
3.0
.06
II
II
1
8.25
3.0
90.2
66.0
24.2
87.0
-
0.0
<.03
3.0
.04
II
.01
30
29-V-
74
8.35
3.1
90.0
67.0
23.0
87.0
3.0
0.0
<.03
8.0
0
<.01
<.01
0
.01/
1
8.1
2.8
92.0
68.0
24.0
86.5
4.0
0.0
<.03
5.0
.02
II
H
.01
II
35
L3-VI-
74
8.1
-
90.5
64.0
26.5
85.5
3.5
-
0
II
II .
0
II
1
7.8
-
89.5
64.5
25.0
87.0
4.0
-
II
<.01
<.01
II
II
35
L8-VII
74
8.15
-
81.0
59.0
22.0
80.0
2.5
-
0
tf
.01
0
:. 01/
<001
1
8.0
-
89.0
63.5
25.5
86.0
3.5
-
.01
II
<.01
0
II
35
1
1
i
!
-------
uu; tio-Lt Bridge T Phos two
1ATE pH Si T Hard Ca Mg Alk Co^ No^ 0 Phos T. K. T Fe Cu Zn Mn C^OciDepth
25-11-
74
.28
.01/
.04
1.0
0
<01
.01
1
.27
.01/
.02
1.0
It
It
II
6
3-III-
74
8.35
3.95
87.0
70.0
17.0
85.0
3.0
0.0
.02/
.06
3.0
0
If
<.01
1
8.25
4.05
85.0
70.0
15.0
85.0
3.0
.40
.02/
.02
3.0
II
< .01
II
5
6-III
74
8.2
3.45
85.5
61.0
24.5
86.0
3.0
.30
.04/
<03
< .01
2.2
.04
II
II
1
7.8
3.3
85.0
61.0
24.0
85.0
3.0
.30
.06/
<.03
2.2
.01
II
< .01
5
3-IV-
74
8.1
3.1
93.5
66.0
27.5
84.5
-
.22
<.03
-
II
.01
.01
1
8.25
3.4
97.0
79.5
17.5
97.0
-
.27
.03/
<.03
-
0
<.01
II
5
2 4-IV-
74
8.0
5.4
-
56.0
-
84.5
3.0
.18
.03/
3.0
1
8.0
5.3
-
56.5
-
84.5
3.0
.13
.03/
3.0
5
29-IV-
74
7.85
6.5
-
72.0
-
82.5
5.0
.20
.05/
5.0
.02
.01
<.01
1
3-V-
74
8.15
5.2
-
62.0
-
82.5
4.0
2.2
.03/
5.0
.01
<.01
II
1
8.15
5.8
-
65.3
-
82.5
4.0
.91
<.03
5.0
0
If
f 1
5
L6-V-
74
8.2
5.3
-
64.0
-
86.9
5.0
.10
.10/
<.03
3.0
1
8.2
5.5
62.0
-
86.5
5.0
.09
.03/
3.0
5
-------
CIO) Holt Bridge T Phos
DATE dH Si T Hard Ca Nig ALk Co^ No^ O Phos T. K. T Fe Cu 'Zh Mn
30-VI]
73
T
.08
13.0
s
04-IX-
73
.03
14.5
s
.02
-
D
15-XI]
73
8.2
2.0
98
67.7
30.3
93.7
3.0
.06
.01/<01
2.0
0
.01
.01
1
8.1
2.2
98
68.0
30.0
94.8
3.0
.03
.01/
-------
DATE rjll Si T riard
{3} M.^fork Pay
Nig Alk Co
No,
T Phos
O Phos
T. K.
Fe Cu Zn Mn
Co/0dDepth
26-111
74
8.3
3.8
104.0
77.5
26.5
98.0
4.0
.05
.04/
2.5
.03
<.01
.02
1
L7-IV-
74
8.1
6.4
106.0
83.5
-
97.5
-
.13
.21/
<.03
3.5
3.0
.04
ii
<.01
1
23-IV-i
74
8.1
6.7'
-
68.5
-
98.3
4.0
.13
.03/
3.0
.02
it
It
1
22-V-
74
8.1
6.2
99.5
77.0
22.5
90.0
5.0
0.0
.03/
<.03
5.0
.01
<.01
It
1
10-VI-
74
7.8
5.4
87.0
64.0
23.0
78.0
3.5
13.
<.03
10.0
.03
11
<.01
0
<.01/
2
17-VI1
74
8.1
-
75.0
56.5
18.5
72.5
3.2
0
.04/
<.03
-
.01
II
11
0
<01/
<.001
2
1
I,
1
A
a
1
-------
DATE oH
(9) Bigfork Bay T Phos ont
Si T Hard Ca Mg Co^ No3 0 Phos T. K. T Fe Cu Zn Mn c°/cdDepth
08-VI1
73
I
.01
.04/.01
20.0
s
21-VI]
73
I
.02
.02/.01
19.5
s
30-VI1
73
I
.03
20.0
s
2 7-IX-
73
.07
14.6
1
.03
14.0
3
18-X-
73
2.8
88.0
91
3.5
.11
0
11.0
1
.17
0
11.0
3
9-XI-
73
7.5
2.1
88.2
65.0
23.8
84.6
-
.18
.03/
-------
{?/ Flathesd River Mouth T Phos two
DATE pH T Harci CS~""~TE% aIV IX>2 No3 0 Phos T. K. T Fe Cu Zn Mn Co/°dDepth
1
>
1
CM
rsj
8.2
5.5
100.0
68.0
32.0
90.5
4.0
.09
<.03
4.0
.11
<.01
<.01
5
i
25-V-
: 74
8.1
5.1
93.0
66.0
27.0
89.0
4.0
7.5
1
30-V-
74
.27
.25/
8.0
.03
.01
II
.01
<.01/
1
.24
.09/
8.0
.09
<.01
It
0
II
25
10-VI-
74
7.8
5.0
85.0
60.5
24.5
76.0
3.5
3.4
.12/
8.0
.04
II
<.01
.01
II
1
7.9
5.4
81.0
58.0
23.0
76.5
3.5
11.
-
8.0
.21
II
II
II
It
8
8.25
5.1
95.0
65.0
30.0
89.0
3.5
7.5
5
26-VI-
74
8.0
-
70.0
51.5
18.5
65.0
3.5
-
1
17-VI]
74
- 8.1
-
78.0
54.0
24.0
71.5
3.0
-
0
<.01
<.01
0
<.01/
<.001
1
7.8
-
77.0
55.0
22.0
71.5
3.0
-
0
<.01
0
<.01/
<.001
8
1
i
j !
1 1
! i
i. i I
-------
(8) Flathead River MoutR 1> phos 01
DATE pH Si T Hard Ca Mg Alk Co^ No^ 0 Phos T. K. T Fe Cu Zn Mn Co/Cd^^^
08-VI3
73
I
.01
.01/.01
21.0
s
.01
<01
20.0
D
21-VII
73
I
.02
.01/.01
20.0
S
.01
.03/.01
18.5
D
27-IX-
73
.13
11.0
1
.16
11.0
8
L8-X-
73
2.5
86.7
88.7
5.0
.56
0
7.0
1
2.7
88.0
88.0
4.0
.46
0
7.0
9
3-XI-
73
7.5
2.3
82.5
62.9
20.4
82.3
-
.33
.02/<.01
2.0
1
7.5
2.6
84.5
63.9
21.4
82.5
-
.58
.14/<.01
2.5
8
26-XI-
73
7.55
2.0
97.0
69.7
27.3
87.8
5.0
.51
<.01
1.0
.05
<.01
<.01
1
7.55
2.2
95.7
67.2
28.5
88.0
5.0
1.0
.04
II
II
5
30-1-
74
8.2
2.1
93.5
66.5
27.0
89.5
-
-
-
1.5
.01
II
.01
1
8.15
2.3
93.0
69.0
24.0
88.8
-
.20
.01/
1.5
.10
<.01
n
7
J2-V-
74
8.2
5.7
101.(
70.0
31.0
91.0
4.0
.08
.03
4.0
.19
II
<.01
1
-------
(10) Holt Bridge T Phos thn
DATE dH Si T Hard Ca Mg Alk Cc>2 Nc>3 O Phos T. K. T Fe Cu Zn Mn c°/°dDepth
22-V-
74
.10
<.03
9.0
1
.10
<.03
9.0
3
3-VI-
74
8.2
4.7
78.0
58.0
20.0
78.0
3.0
.31
.11/
8.0
.02
<.01
<.01
0
<.01/
1
8.1
5.0
79.0
58.0
21.0
77.0
3.0
.30
.03/
<.03
8.0
.05
<.01
<.01
0
<.01/
5
7-VI-
74
7.9
4.1
81.0
57.5
23.5
77.0
3.5
.31
.16/
8.0
.03
If
If
If
ff
1
7.8
5.2
81.0
57.0
24.0
77.0
4.0
.26
.16/
8.0
11
ft
If
If
H
5
19-VI-
74
.27
.54/.04
1
21-VI-
74
7.8
-
65.0
41.0
24.0
60.0
2.5
-
0
.04
<.01
0
ff
1
26-VI-
74
8.0
-
75.0
52.0
23.0
66.0
3.0
-
1
27-VI-
74
.20
/.03
.02
<.01
<.01
0
<.01/
<001
1
7.7!
75.5
59.0
16.5
67.5
4.0
.16
-
-
.02
<.01
.01
0
<.01/
<.001
5
16-VI]
74
8.1!
-
77.0
57.0
20.0
74.5
3.0
.13
<.03
-
0
it
ft
If
11
1
7.9
-
76.0
56.0
20.0
74.0
4.0
.13
<.03
-
.01
it
.01
0
ff
5
-------
(11) Pairtt6d R6dka t phos one
WTE pH Si T Hard Ca Mg Alk Cc^ No^ 0 Phos T. K. T Fe Cu Zn Mn
Co/CdDepth
26-IX-
73
.03
14.2
1
.17
5.5
40
08-X-
73
.07
13.5
1
.02
13.0
10
.09
6.5
40
31-X-
73
8.If
1.9
92.0
87.5
3.7
.0
<.01
6.0
1
8.1
1.8
91.0
86.8
3.7
.01
<.01
9.5
40
9-XI-
73
7.6
1.9
89.7
65.7
24.0
85.3
-
.11
.07/
<.01
7.0
1
7.6
2.3
90.9
65.0
35.9
84.8
-
.25
.10/. 05
5.0
40
20-XI-
73
7.3
2.1
86.2
63.0
23.2
85.7
3.0
.24
<.01
6.0
.06
<.01
<.01
1
7.3
2.0
87.4
63.9
24.3
85.7
4.0
.34
<.01
5.5
.03
If
If
40
6-XII
73
7.6
1.9
87.0
62.0
25.0
85.0
3.0
5.0
1
7.6
1.9
87.0
62.0
25.0
84.5
3.0
5.0
40
7.6
1.9
87.0
62.0
25.0
84.5
3.0
5.0
80
11-11
74
8.3
2.28
90.5
72.0
18.5
84.7
-
.08
.02/
.02
2.0
.04
<.01
.01
i <
1
1
-------
(11) Painted Rocks t phos
DATE pH Si T Hard Ca Mg Alk Cc>2 Nc>3 0 Phos T. K. T Fe Cu Zh - Mn
11-11
74
8.3
2.70
88.0
73.0
15.0
84.5
-
.09
.01/
.02
2.0
.22
A
O
.01
40
7-III-
74
8.2
3.25
87.0
63.0
24.0
88.0
3.0
.09
<.03
.01
2.5
0
II
<.01
1
.18
.03/
<.03
2.5
20
8.25
3.18
88.0
61.5
26.5
87.0
3.25
.13
<.03
<.01
2.5
0
<.01
<.01
40
10-111
74
8.1!
2.8
88.0
63.0
25.0
88.0
2.0
.13
.04/
<.03
.01
2.4
.01
it
If
1
8.15
2.74
88.0
63.0
25.0
87.0
2.5
.06/
<.03
.02
2.4
.02
1!
.01
40
29-111
74
8.2
1.95
93.0
69.0
24.0
86.0
3.0
.06
.03/
2.5
.07
<01
<01
1
8.1
2.45
90.8
65.0
25.8
86.3
3.0
.04
<.03
2.5
.01
fl
If
40
15-IV-
74
8.1
3.2
89.0
69.5
19.5
86.4
-
0.0
<.03
3.0
.01
>» .
1
8.3
3.0
90.5
74.5
16.0
85.9
-
0.0
<.03
3.0
.04
<.01
<.01
40
22-V-
74
7.9
3.9
88.0
68.0
20.0
85.0
3.0
0.0
< .03
5.0
0
II
II
1
8.2
3.2
91.0
64.5
26.5
86.0
4.0
0.0
<.03
5.0
.03
II
It
40
10-VI
74
8.2
3.9
87.0
63.5
23.5
85.0
3.0
8.0
<.03
10.0
ft
<.01
<.01
0
<.01/
1
8.15
3.2
91.0
63.0
28.0
86.0
3.5
12.
< .03
6.0
.04
tl
It
0
40
17-VII
74
8.0
-
82.0
60.0
22.0
78.5
3.0
0
.03/
<.03
'
-
0
11
II
0
<.01/
<.001
1
-------
(12) Swan River T Phos
)ATE pH Si T Hard Ca Mg Alk Co^ No^ 0 Phos T. K. T Fe Cu Zn Mn
D4-IX-
73
.04
17.0
s
31-XI-
73
7.8
3.3
90.0
92.7
4.3
.05
<.01
10.0
1
7.5
3.3
94.0
95.0
5.5
.06
<.01
9.0
4
L5-XII
73
8.0
2.6
97.0
66.5
30.5
92.5
3.0
.02
.01/
2.5
0
.01
<.01
1
15-1-
74
8.1
3.1
97.0
70.9
26.1
94.5
4.0
.12
/.01
1.0
.02
<.01
II
1
25-1-
74
.03
0.0/
-
1
29-1-
74
8.05
3.5
91.0
67.5
20.5
89.0
4.0
.38
.01/
2.0
0
<.01
.01
1
30-1-
74
.33
<.01/
1.0
.01
II
II
1
5-II-
74
7.85
3.3
93.5
69.0
24.5
91.0
3.5
.57
<.01/
2.0
0
II
tl
1
25-11-
74
.08
<.01/
.06
1.5
0
<.01
.01
1
3-III-
74
8.2
6.65
96.0
67.0
29.0
97.0
3.0
.39
.05/
.07
2.0
0
tl
<01
1
OS
M
M
M
1
8.25
6.35
97.5
68.0
29.5
103.0
4.0
.17
.08/.03
<.01
1.5
.04
It
tt
1
21-111
74
,24
<.03/
.03
.08
2.0
.03
1
LI-IV-
74
8.25
5.3
97.0
79.5
17.5
97.0
-
.09
<.03
-
.02
.01
<.01
24-IV-
74
8.3
6.4
-r>
, 64-. 5
-
98.0
3.3
.08
.03/
3.0
4.0
'
1
]
1
-------
(12) Swan River T Phos tw
DATE pH Si T Hard Ca Mg Alk 0=>2 Nc>3 0 Phos T. K. T Fe Cu zn Mn C°/CdDept±i
29-IV-
74
8.1
8.1
-
79.8
-
97.0
5.0
0.0
<.03
6.0
.02
<.01
<.01
1
3-V-
74
8.0
7.0
-
65.5
-
65.5
4.5
2.8
.07/
<03
3.0
0
rf
If
1
16-V-
74
6.6
8.15
-
64.5
-
90.5
5.0
0.0
<.03
3.0
1
30-V-
74
.07
.03
8.0
.03
<.01
<.01
.01
<.01/
1
.04
<.03
8.0
.04
tt
If
.01
II
3
3-VI-
74
8.2
6.4
88.0
62.0
26.0
87.0
3.0
-
-
8.0
.17
it
II
0
II
1
7-VI-
74
7.9
6.5
87.0
64.0
23.0
85.5
3.5
0.0
<.03
8.0
.05
<.01
<.01
II
II
1
8.1
6.1
87.0
61.0
26.0
85.0
3.5
.98
<.03
8.0
.05
II
If
II
II
3
21-VI-
74
7.7
-
58.0
36.0
22.0
56.0
3.0
-
0
.04
ff
0
f 1
1
26-VI-
74
8.1
-
79.5
58.0
21.5
68.0
4.5
.05
/ <. 03
-
.03
<.01
.01
.01
<.01/
<.001
1
16-VI1
74
- 7.7
-
72.5
54.0
18.5
70.0
3.5
0
<.03
0
II
ff
0
II
1
19-VI-
74
.09
.36/
<.03
1
-------
(13) North End T Phos one
3ATE pH Si T Hard Ca Mg Alk Co^ No^ O Phos T. K. T Fe Cu Zn Mn
27-IX-
73
.08
14.2
1
.08
7.5
25
18-X-
73
1.9'
88.0
86.0
3.3
-
1
2.1
84.0
85.5
4.5
-
23
15-XI-
73
7.8
1.7
85.4
65.9
19.5
84.9
6.0
.09
.01/
<.01
6.0
1
7.8
1.8
85.7
65.0
20.7
84.5
5.0
.13
<.01
5.5
25
26-XI-
73
7.6!
2.0
88.3
63.1
25.2
85.0
4.0
.22
<.01
5.5
.02
<01
<.01
1
7.65
2.1
89.7
64.1
25.6
84.6
5.0
.22
<.01
5.5
If
If
II
30
11-11
74
8.2!
2.40
89.0
65.0
24.0
84.0
-
.15
.01/
.02
2.0
.04
II
.01
1
8.3!
3.05
91.5
69.0
22.5
84.0
-
.02
.01/
.04
2.0
.04
<01
30
10-111
74
8.2
3.0
88.0
62.0
26.0
85.5
2.0
.15
.06/
< .03
<.01
2.2
.01
It
<.01
1
8.2!
3.25
89.0
63.0
26.0
85.0
2.5
.16
.07/
<03
2.2
.03
II
.01
25
26-11]
74
8.1!
2.45
94.0
74.5
19.5
87.0
3.5
.12
.06/
< .03
< .01
2.5
.01
< .01
II
1
8.2
33.!
90.5
68.0
22.5
86.0
3.5
.35
.18/
.19
.05
2.5
.01
If
< .01
30
17-IV-
74
8.2!
4.3
-
71.4
-
85.6
-
.11
< .03
3.0
.03
11
_J
fl
J
1
!
t i
1
X
-------
(13) North End T Phos twc
DATE pH Si T Hard Ca Mg Alk Cc>2 Nc>3 0 Phos T. K. T Fe Cu Zn Mn C°/CdDepth
17-IV-
74
8.1
3.5
-
69.5
85.8
-
.04
<.03
3.0
.04
<.01
<01
20
23-IV-
74
8.3
4.0
-
63.5
-
85.0
3.0
.09
.03/
3.0
.03
It
II
1
8.0
4.S
-
66.0
-
84.0
3.0
.18
.03/
3.0
.01
rr
rr
30
22-V-
74
8.2
4.5
88.0
67.0
21.0
85.0
3.5
.04
<.03
5.0
.02
ti
it
1
8.2
4.6
90.0
76.0
14.0
86.0
4.0
.04
<03
5.0
.03
<.01
<.01
30
10-VI-
74
8.15
4.1
85.0
59.5
25.5
84.0
3.5
.40
<.03
10.0
.05
11
ti
0
<.01/
1
8.0
4.1
83.5
61.0
22.5
81.0
3.5
.12
<.03
6.0
30
17-VI]
74
7.8
-
80.0
57.5
22.5
78.0
3.0
.05
<.03
-
.01
<.01
<.01
0
<.01/
<.001
1
8.1
-
90.0
64.0
26.0
86.0
3.0
.06
ff
-
0
.01
0
fl
30
11-VI-
74
.13
<.03
.08
<.01
.02
0
<.01/
1
------- |