The changing water quality of lakes—a case study of Dal Lake, Kashmir Valley

Abstract

Lakes throughout the globe have been gravely altered or degraded at a pace much more significant than their restoration. In the heart of Srinagar, the summer capital of Jammu and Kashmir, Dal Lake, has witnessed extreme loss in water quality during the last four decades because of anthropogenic pressures. The lake is unique in that over 50,000 people inhabit the lake itself in houseboats, dongas, or islands within the lake. These people derive their livelihood from the lake in terms of tourism, agriculture, fishing, and vegetable farming. The countless ways people use the lake have led to an extreme load of pollution in the lake. Encroachment in and around the lake has led to the loss of volume of water in the lake and consequently increased the concentration of pollutants. Discharge of untreated sewage, agricultural runoff, and sediments from adjoining catchments have further degraded the lake water quality. The changes in water quality are clear from the physio-chemical properties of the lake waters. While transparency and dissolved oxygen in the lake have decreased drastically during the last 40 years, the concentration of harmful substances like phosphates, nitrates, and chlorides has increased. The hardness of water has also increased due to higher levels of carbonates and bicarbonates in the lake. This paper details the changes in the water quality of Dal Lake over the recent past. The paper analyses the strategies that can be implemented to manage the lake and restore its quality if appropriately implemented.

Full text

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Environ Monit Assess (2022) 194:228
https://doi.org/10.1007/s10661-022-09869-x
The changing water quality oflakes—a case study ofDal
Lake, Kashmir Valley
RohitashwKumar· SabahParvaze·
MirBintulHuda· SaqibParvazeAllaie
Received: 24 November 2021 / Accepted: 17 February 2022
© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2022
and sediments from adjoining catchments have further
degraded the lake water quality. The changes in water
quality are clear from the physio-chemical properties of
the lake waters. While transparency and dissolved oxy-
gen in the lake have decreased drastically during the last
40 years, the concentration of harmful substances like
phosphates, nitrates, and chlorides has increased. The
hardness of water has also increased due to higher levels
of carbonates and bicarbonates in the lake. This paper
details the changes in the water quality of Dal Lake over
the recent past. The paper analyses the strategies that can
be implemented to manage the lake and restore its quality
if appropriately implemented.
Keywords Dal Lake· Pollution· Water quality·
Restoration· Physio-chemical parameters·
Anthropogenic activities
Introduction
Freshwater is a limited but essential constituent of
Earth’s hydrosphere. It is necessary for the survival of
humans, maintaining ecosystem functions, the exist-
ence of plants and animals, and for development and
sustainment of economy (Loucks & van Beek, 2017).
The services provided by freshwater systems are
multitudinous, yet humans have failed to protect and
maintain these over the years. Anthropogenic factors,
such as climate change, urbanisation, pollution from
industries and agriculture, nutrient loadings, sewage
Abstract Lakes throughout the globe have been gravely
altered or degraded at a pace much more significant
than their restoration. In the heart of Srinagar, the sum-
mer capital of Jammu and Kashmir, Dal Lake, has wit-
nessed extreme loss in water quality during the last four
decades because of anthropogenic pressures. The lake is
unique in that over 50,000 people inhabit the lake itself
in houseboats, dongas, or islands within the lake. These
people derive their livelihood from the lake in terms of
tourism, agriculture, fishing, and vegetable farming. The
countless ways people use the lake have led to an extreme
load of pollution in the lake. Encroachment in and around
the lake has led to the loss of volume of water in the lake
and consequently increased the concentration of pollut-
ants. Discharge of untreated sewage, agricultural runoff,
R.Kumar· S.Parvaze(*)
College ofAgricultural Engineering andTechnology,
SKUAST-Kashmir, JammuandKashmir, Srinagar190025,
India
e-mail: sabah.parvaze@gmail.com
R. Kumar
e-mail: rohituhf@rediffmail.com
M.B.Huda
National Institute ofTechnology, JammuandKashmir,
Srinagar190018, India
e-mail: huda_07phd13@nitsri.net
S.P.Allaie
Sam Higginbottom University ofAgriculture, Technology
andSciences, UttarPradesh, Prayagraj211007, India
e-mail: saqib.parvaze@gmail.com

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discharge, and incursion of invasive plants and ani-
mals have led to rapid degradation of water quality
(Ho & Goethals, 2019). The effects are more pro-
nounced in developing countries where rapid popula-
tion growth, rural–urban migrations, and economic
and political developments result in extraordinary
stress over land and water resources (Starkl et al.,
2018; Xu etal., 2019). The water resources of Kash-
mir valley, especially the lakes, are no exception to
this change. Dal Lake, located in the summer capital
of Jammu and Kashmir, has borne the brunt of human
apathy. Pollution has not only ensnared the lake
waters but is jeopardizing its very existence. The lake
has been destroyed over the past four decades due to
excessive sewage discharge, encroachment, and weed
infestation.
Dal Lake is the second-largest and the most famous
lake of Jammu and Kashmir. The lake was once one
of the most beautiful lakes in the world (Lawrence,
1895). However, today the statement is hardly believ-
able, as the lake has been affected to a calamitous
extent in terms of both ecology and hydrology (Ganaie
& Hashia, 2020). Dal Lake has already shown the
impacts of warming temperatures, variation in hydro-
logical regime, excessive nutrient load, and invasion
of non-native species. Discharge of untreated sew-
age from several point and non-point sources has
completely deteriorated the water quality of the lake
(Mushtaq et al., 2020a). The impact has been exac-
erbated by deforestation, grazing, agriculture, and
change in land use and land cover patterns in the lake
catchment (Rashid etal., 2017). These activities have
increased the sediment and nutrient load in the lake
waters, causing loss of water quality. In addition, large-
scale encroachment and discharge of human wastes
from houseboats have led to severe weed infestation of
the lake (Khan & Ansari, 2005; Zargar et al., 2012).
The rapid and unchecked growth of weeds, particularly
Azolla pinnata, has severely affected the lake’s water
quality and aesthetic value (Ali, 2019; Kundangar &
Abubakar, 2004). Although many locals draw their
livelihood from the lake through agriculture, tourism,
fisheries, etc., these activities have become a hazard to
the lake (Ahmad etal., 2020).
The concentration of various pollutants in the lake
water further increases due to lower hydrological
inflows to the lake (Mushtaq etal.,2020b). Water that
used to flow to the lake is diverted for irrigation and
drinking at many places. Conversion of land under
water into dry land by expanding floating gardens
is another important cause of degradation. At many
places, the lake has been encroached and replaced
by residential areas by the local community. Fur-
thermore, climate change in the Kashmir Himalayas
has led to a significant reduction in the cryosphere,
causing reduced streamflows which are an important
constituent of the lake water inflows (Parvaze etal.,
2016; Romshoo etal., 2015).
Several studies have been conducted to assess the
water quality of Dal Lake from time to time. How-
ever, due to the dearth of long-time and continuous
historic data, the changes in water quality of the lake
have not been studied. During the past three decades,
the lake’s water quality of has changed to a drastic
extent. From being famous for its crystal-clear waters
to being deemed unsuitable for consumption and
domestic purpose, the lake waters have seen a com-
plete transformation. This paper aims to assess the
change in water quality parameters of the lake since
the 1970s with respect to the available literature on
the catchment. Changes in water quality in the light
of previous research over the last four decades have
been studied. Important factors contributing to the
depletion and degradation of the lake water quality
have been documented. The paper also explains the
strategies needed to implement in order to restore the
lost glory of Dal Lake.
Location andextent
Dal Lake is an urban-type lake of the Kashmir Hima-
layas in the Srinagar city of Jammu and Kashmir. It
lies between 34°5′ and 34°9′ N to 74°49′ and 74°53′
E at a mean altitude of 1583m above mean sea level.
Figure1 shows the location of Dal Lake and its catch-
ment area, which was extracted from the digital eleva-
tion model (DEM) of the basin using ArcGIS soft-
ware. The lake catchment comprises mountain ranges
on the North and Northeast side, while it is enclosed
by flat arable land on other sides. The catchment is
characterized by rugged terrain with high relief. It is a
multi-drainage basin having a total area of 24 km2, and
the is catchment spread over 337 km2 (Rashid etal.,
2017). The lake has a total water holding capacity of
15.45 million meter cube (Mm3), and the open water
spread of the lake is nearly 10.5 km2. Dal Lake has
been the cradle of civilization of Kashmir valley and

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is considered the “liquid heart” of Srinagar (Masoodi
& Kundangar, 2018). It has found its place amongst
the most beautiful National heritage sites of India. It
plays a vital role in the region’s economy as it forms
the livelihood of numerous people of Srinagar city.
The lake is one of the most important tourist destina-
tions as well as a significant source of fish, vegetables,
and recreation to the locals. The lake waters also form
an important portion of the water supply to the Srina-
gar city.
Climate
The climate of Srinagar city is sub-Mediterranean type
(Mir et al., 2016). A single meteorological observa-
tory in the catchment is maintained by Sher-e-Kashmir
University of Agriculture Science and Technology
(SKUAST), Srinagar since January 1985. Based on the
SKUAST (1985–2019) data from, July is the warmest
month with a mean maximum temperature of 29.7°C
and a mean minimum temperature of 17.2 °C. Janu-
ary is the coldest month with a mean maximum tem-
perature of 6.4°C and a mean minimum temperature
of −2.4 °C. Precipitation occurs in the form of snow
and rain. The normal annual precipitation (1985–2019)
of the catchment is 844mm. Annual potential evapo-
transpiration (PET) is 880 mm and exceeds annual
precipitation (Parvaze et al., 2021). Monthly normal
of maximum temperature, minimum temperature, and
precipitation are presented in Fig.2.
Methodology anddata collection
To identify the relevant existing literature in accord-
ance with the objective of this study, a thorough
evaluation of all relevant studies of the water qual-
ity of Dal Lake up to the year 2021 was conducted.
The following keywords were used to search the
main scientific databases: Scopus, ScienceDirect,
Springer, and Google Scholar: Dal Lake, Himalayan
lake, water quality, and climate change. This search
focused on papers that allowed for the identifica-
tion of assessment and change in water quality vari-
ables used in the various studies. In all, 62 of the 98
articles examined allowed for the extraction of the
required information. Secondary data were gathered
from different government and scientific reports,
local NGO reports, and prior research pertaining to
Dal Lake in Srinagar.
Fig. 1 Location of study
area

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Issues concerningthelake
Like global inland water bodies, Dal Lake is beset
with problems arising predominantly due to anthro-
pogenic activities. The problems facing the lake can
be summarized as below:
• Reduction in the lake areas owing to encroachments
by communities and floating gardens.
• Decrease in the water holding capacity due to sil-
tation, primarily caused by the degradation of the
catchment area.
• Increased pollution because of the mushrooming
number of Dal dwellers and floating gardens, dis-
charge of raw sewage and solid wastes from the
bordering areas and within the settlements, and
the houseboats and agricultural return flow from
the catchment into the lake.
• Reduction in the number of inflow channels and
water channels within the lake causing reduced
circulation.
• Nutrient enrichment of the lake water and sedi-
ment causing extreme weed growth and changes
in the biodiversity of the lake.
Hydrology andwater balance ofthelake
Lakes in the Kashmir valley have undergone seri-
ous changes due to anthropogenic pressures. This is
particularly true of Dal Lake. Besides being a world-
renowned tourist destination, the lake serves impor-
tant ecological and socio-economic interests of
the Kashmir valley. However, changes in the water
quality of the lake have been a serious concern for
researchers recently. Changes in the water quality of
any aquatic system are incomplete without taking into
consideration the change in water balance. There have
been no significant changes regarding water balance
in the lake. Lake storage has been nearly the same for
the last four decades. However, during the last two
decades, an important component of inflow has been
sewage, which has affected the water quality to a sig-
nificant extent. Decrease in inflow from nallahs and
increase in sewage inflow maintain the water balance
but has led to a catastrophic change in the water qual-
ity of the lake.
The hydrology of Dal Lake is complicated due to
the huge diversity of the catchments contributing to
its inflow. These include the urban catchment of Sri-
nagar city, adjoining agricultural and mountainous
catchments. Presently, the lake comprises an open
water area and lake interiors comprising marshy land
and floating gardens (Fig.3). The open water area is
divided into three sub-basins: the Hazratbal basin in
the north, the central Bod Dal basin, and the Gagribal
basin in the south. Nigeen Lake on the west of Dal
Lake appears to be a detached arm of the main lake.
The sources of the lake include several streams and
springs. Telbal Nallah is a large perennial stream that
Fig. 2 Temperature,
precipitation, and potential
evapotranspiration normals
of Dal Lake catchment
from 1985 to 2019 (Parvaze
etal., 2021)

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drains the Dachigam National Park on the eastern
side of the lake and enters it from the northern end
(Fig.3). Another major source of inflow is the Botkol,
draining the northern and north-western catchment. It
also collects water from the Sindh Extension Canal,
and irrigation overflows and enters the lake from the
north-western end. Several smaller streams like the
Meerakshah Nallah also add water to the lake. Inflow
to the lake is also contributed by many springs arising
from its bed as well as outwash from the surrounding
mountains. Water flows out of the lake through two
principal outlets — a weir and lock system at Dalgate
and the Nallah Amir Khan connecting Nigeen lake
with Anchar lake via Khushalsar lake. A significant
amount of flow from the incoming streams is diverted
for agricultural purposes through a composite canal
network.
Although complete water balance studies for the
Dal Lake have not been reported, the first rainfall-
runoff balance was mentioned in the Enex Con-
sortium Report (Enex, 1978). The study period
was 1964 to 1976, during which maximum flow
occurred in 1976 and minimum flow in 1974. Water
balance was studied for these 2years, and the aver-
age annual inflow to the lake was estimated at 292
Mm3. The average annual rainfall of the basin for
the study period was 872mm. Telbal nallah contrib-
uted 80% of this flow, while 20% was contributed by
precipitation and drainage from the lakeside catch-
ments. Detailed water balance for the lake was first
presented in 1988 (Ishaq & Kaul, 1988a). An exten-
sive study on the annual water balance of Dal Lake
was undertaken during 1970–1980 and monthly
water balance from August 1981 to July 1982. The
study segregated the bottom inflow component for
the lake. The average inflow to the lake during the
study period was approximately 338.7 Mm3, out of
which 232.1 Mm3 (68.5%) was contributed by the
surface inflow into the lake, 9.1 Mm3 (2.7%) by
precipitation on the lake, and 95.9 Mm3 (28.3%) by
underwater springs. The major portion of outflow
from the lake was through Dalgate outlet and Nal-
lah Amir khan, forming 329.6 Mm3 (97.3%), while
evaporation formed only 9.1 Mm3 (2.7%). The
Jammu and Kashmir Lakes and Waterways Devel-
opment Authority (JKLAWDA, 2010) included a
Fig. 3 Drainage network
of Dal Lake (Amin etal.,
2013)

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component of sewage present in the lake as well as
sewage inflow into the lake. The water budget given
by JKLAWDA is presented in Fig.4. However, the
report emphasised that there has been no change
in the lake storage. Recently, chemical and isotope
mass balance approach was used to study the water
budget of Dal Lake (Saleem & Jeelani, 2017). Total
monthly inflow and outflow from the lake were 0.95
Mm3, out of which groundwater contribution to the
lake was 29.9%. Surface runoff into the lake formed
65.2% of the total inflow, while precipitation con-
tributed only 5.6% (Saleem & Jeelani, 2017).
Change inphysio‑chemicalparameters ofthelake
Transparency
In any aquatic system, the degree of light penetration
has a significant impact on the biological processes
and consequently, its productivity. One of the earli-
est documented studies reports that Dal Lake exhibits
varying transparency values in different seasons (Mir,
1977). Transparency is minimum during spring and
summer, while it increases to a significant extent in
winter. The changes in the transparency of the lake
Fig. 4 Water budget for
Dal Lake during 2006–2010
(JKLAWDA, 2010)

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were attributed to several factors, like plankton popu-
lations and extraneous materials, by other researchers
(Kaul, 1977; Vass & Zutshi, 1979). These researchers
also reported similar seasonal fluctuations in transpar-
ency. Mean depth of visibility in the lake had reduced
from 1.96 m in 1987 (Sarwar & Zutshi, 1987) to
1.49 m in 2005 (JKLAWDA, 2005). The value has
further dipped to 1.46 m in 2013 (Mushatq et al.,
2013) and 1.32m in 2020 (Gulzar et al., 2020).Lake
transparency has decreased to a significant extent.
Inflow of raw sewage and sediments into the lake
has reduced the visibility depth. The effect has been
worsened by eutrophication and profuse weed growth
in the lake (Lucas etal., 2009). Moreover, land use
land cover changes in the lake catchment have further
added to the sediment load in the lake.
pH
Dal Lake has been an alkaline lake. pH values of
the lake vary between 7.4 to 8.9 throughout the year
(Khanday etal., 2018; Sharma etal., 2015). pH values
have shown a fluctuating tendency since 1987. Trisal
(1987) estimated the pH of the lake to be between
7.4 and 9.5 at various locations, with an average of
8.4. The average value in 1990 was estimated at 8.7
(Zutshi & Ticku, 1990). pH values decreased to 8.2
in 1997 (JKLAWDA, 1997) and 2010 (JKLAWDA,
2010) but were reported to be higher, i.e., 8.4 in 2017
(Rather & Dar, 2020a). pH is a crucial parameter
for determining whether the lake waters are suitable
for different purposes. The pH of the lake has been
alkaline in the past and remains so. However, seri-
ous fluctuations in its value are a sign of the possibil-
ity of a gradual change in the well-buffered aquatic
system (Kremleva & Moiseenko, 2017). This can be
attributed to high levels of pollution loads in the lake,
which increase with time.
Conductivity
Conductivity is closely related to the trophic status of a
water body, being low in oligotrophic (being deficient
in nutrition) and high in eutrophic ones. Conductivity
values during 1998–1999 fluctuated between 122 and
759 µS in different basins of Dal Lake (JKLAWDA,
1997). Earlier, Kaul (1977) reported conductivity
values between 95 and 240 µS in the various basins,
while Trisal (1987) recorded a range of 270 to 490 µS.
Recent studies state that the conductivity values of the
lake vary between 300 and 642 µS (Chashoo et al.,
2020; Ruhela et al., 2020). For shallow lakes, like
Dal Lake, conductivity is an important pollution indi-
cator (Das et al., 2006) and assess the trophic status
of aquatic systems (Ozguven & Demir Yetis, 2020).
Increasing conductivity values of the lake waters can
be attributed to a heavy load of silt, sewage, and fer-
tilizers in the inflow streams of the lake. In addition,
crop areas and human inhabitations around the lake,
coupled with changes in land use and land cover of
the lake catchment have led to the gradual increase
of conductivity values of lake waters (Stenfert Kroese
etal., 2020).
Carbonates and bicarbonates
Carbonates and bicarbonates jointly determine the over-
all alkalinity of an aquatic system and are employed to
distinguish between soft and hard water bodies. Water
with alkalinity values exceeding 90mg/l is hard water
(Moyle, 1945). Dal Lake water was classified as hard
water by Trisal (1987). Alkalinity values of the lake
at the time were in the range of 70–134mg/l. During
the years 1998–1999, alkalinity varied between 37 and
249mg/l, thus suggesting a rise in the hardness of water
over the previous decade (JKLAWDA, 2005). Recent
data on the Dal Lake reveals that alkalinity remains
over 90mg/l for most of the year. Thus, the lake fits
into a typical hard water type (Ahmad et al., 2020).
Bicarbonates were reported throughout the year, while
carbonates contributed mainly during the warm period
when pH was high. Bottom water had only bicarbonates
(Shah etal., 2019).
Dissolved oxygen
Oxygen is a crucial element for regulating the metabolic
activities of aquatic organisms and also acts as an indi-
cator of the lake condition (McCormick & Reid, 1961).
The distribution of oxygen in deep waters is dependent
upon the presence or absence of stratification (Lohri
etal., 2013). Dal Lake is a shallow water body that dis-
plays negligible fluctuations in the oxygen levels from
the surface to bottom (Mushtaq etal., 2018). The dis-
solved oxygen (DO) and the thermal cycle of the lake
have been found to be closely related (Trisal, 1987). DO
values are high during winter while low during summer.
In 1987, mean annual DO values at different lake sites

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were 0.8–12.05mg/l. Deweeding only increases the DO
values temporarily (Kundangar, 2003; Zutshi & Ticku,
1990). Annual DO values of the lake have decreased
from 7.4mg/l in 1997 to 6.9 mg/l in 2017 (Rather &
Dar, 2020a). Dissolved oxygen levels in Dal Lake have
declined significantly since the 1990s. Thriving weeds
and profuse growth of macrophytes in the lake because
of increased nutrient load are the primary cause of this
decline. Respiration by bacteria and aquatic animals, as
well as the oxygen demand for macrophytes and their
decomposition causes the free oxygen to be used up
rapidly. A decrease indissolved oxygenhas been one of
the most significant impacts of lake pollution (Mushtaq
etal., 2018).
Cationic elements
Calcium and Magnesium are the most abundant diva-
lent cationic elements in the Dal waters (Trisal, 1987;
Trisal & Kaul, 1983). The usual cation progression for
the lake water is Ca > Mg > Na > K. According to the
Ohle’s classification, Dal Lake is a calcium-rich lake
(Ohle, 1934). Seasonal fluctuations of cationic ele-
ments in the lake have been reported. The concentra-
tion of calcium and magnesium is high during summer
(Ishaq & Kaul, 1988b). The concentration of sodium
and potassium in the lake shows marked fluctuations.
While sodium fluctuates without any trend, potassium
concentration is highest during early spring and low-
est during summer. Maximum calcium ion concentra-
tion in the lake water in recent times has not exceeded
100 mg/l and magnesium ion concentration remains
below 30mg/l. However, the values are very low as
compared with previous observations. Ishaq and Kaul
(1988a, b) reported calcium ion concentrations of up
to 432 mg/l and magnesium ion concentrations of
upto 92 mg/l. The lake shows a significant increase
in the concentration of all cationic elements over the
last three decades (Mushtaq et al., 2018; Rather &
Dar, 2020a). High concentration of calcium and mag-
nesium in Dal Lake is because of their leaching from
agricultural soils (Ishaq & Kaul, 1988b). Increase in
the cation concentration of the lake may be attributed
to the increase in use of chemical fertilizers in the
nearby cropped areas. Farming practices followed in
the lake catchment are responsible for increased leach-
ing of these ions into the lake water. Elevated levels of
Mg2+ can also be a consequence of the decomposition
of macrophytes (Kumar, 1990; Ohle, 1934).
Nitrates
Researchers in the 1970s and 1980s (Kaul, 1977; Kaul
etal., 1978; Trisal, 1987) reported only small quanti-
ties of inorganic nitrogen in most basins of Dal Lake.
Only the Brarinambal area was reported to have very
high concentrations of nitrate-nitrogen (NO3
−N) and
Ammoniacal nitrogen (NH3-N). Nitrate-nitrogen was
reported as the most profuse source of nitrogen in
the lake ecosystem, with concentration levels shift-
ing between 80 and 650μg/1. Other forms of nitrogen
were present in traces. However, data for 1998–1999
reveal a significant increase in inorganic nitrogen in
the lake, indicating the lake to be under considerable
pollution stress (Mushtaq etal., 2018; Rather & Dar,
2020a). The increase in the concentration of nitrates
in Dal Lake is due to an increase in the amount of
organic wastes in the lake and their subsequent decom-
position. Greater decomposition of organic matter in
lakes speeds up the release of ammoniacal nitrogen in
the water (Richards etal., 1965). Another reason for
this increase may be the surge of bottom ammoniacal
nitrogen to the surface by human activities, namely,
dredging and de-weeding operations. It may also be
ascribed to quick fertilizer overflow and direct dump-
ing of raw sewage from in and around the lake. The
rise in nitrate concentration in the lake may be due to
leaching and surface runoff of nitro-phosphate fertiliz-
ers from an adjacent cropped area into the lake as well
as from domestic sewage from homes and houseboats
being dumped into the lake (Mustapha & Omotoso,
2008).
Total phosphorous
The concentration of total phosphorous in the lake has
shown an increasing trend. Earlier research reported
low concentrations of total phosphorous as well as
phosphorous loading into the lake (Enex, 1978; Ishaq
& Kaul, 1989, 1990). Total phosphorous is trapped
in the sediments, especially in the top layer. This is
attributed to the sedimentation of this mineral after
precipitation. The concentration of total phosphorous
has increased from 0.1 to 0.4 mg/l in 1997 to about
6mg/l in 2017 (Rather & Dar, 2020a). Similar results
have also been put forth by other researchers (Ahmad
et al., 2020; Mushtaq et al., 2018; Rather & Dar,
2020b). Phosphorus is regarded as the pivotal limit-
ing nutrient, leading to eutrophication of freshwater

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systems (Rabalais, 2002). It is a vital nutrient that
causes eutrophication and is needed by algae in mea-
gre quantities (Schindler et al., 2016). The potential
cause might be the growing degrees of eutrophication
in the Dal Lake system. The notable increment in total
phosphorus is because of extreme drainage from float-
ing gardens as well as from agricultural catchments
through Telbal and Botkol streams. Phosphate also
passes in the lake water through domestic wastewater,
explaining the expedited eutrophication.
Chlorides
Varying amounts of chlorides (Cl−) are present in
almost all-natural water bodies. The amount of chlo-
rides in a water body is dependent on the geochemi-
cal conditions of the catchment area (Adimalla &
Venkatayogi, 2018). However, the presence of chlo-
rides in an aquatic system is an indication of pollu-
tion by sewage (Edokpayi et al., 2017). Chloride
concentrations of Dal Lake have increased multi-old
since the last two decades. From a mean concentra-
tion of 2–2.7 mg/l in 2007, the values have shown
a steep increase up to 10.3 mg/l in 2017 (Mushtaq
etal., 2018; Rather & Dar, 2020a, c). An increase in
Cl− concentration is harmful for the lake vegetation
and results in increased corrosion. It further indicates
a heavy load of organic wastes in the water, which
leads to excessive consumption of dissolved oxygen
by bacteria affecting the ecosystem of the lake. The
drastic increase in Cl− concentration in lake waters is
because of the drainage of raw sewage into the lake.
As the number of Dal dwellers in the lake interiors,
as well as the houseboats, increased significantly in
the past two decades, the inflow of sewage has also
increased (Dar etal., 2020).
Effects ofwater quality changes onlake ecosystem
Over the years, Dal Lake’s water has shown con-
siderable changes, and at present, the lake is under
immense stress. A foul smell exudes from several
sections of the lake. The pressure of human dwell-
ings along the shores, as well as its interiors, have
been identified as one of the fundamental causes
leading to environmental degeneration of the lake
(Rohini, 2016). With the increase in population,
especially the urban, the pressure on the lake and its
environs as possible settlement zones, besides agri-
cultural activities within floating gardens and con-
verted land, has intensified (Ganaie & Hashia, 2020;
Mushatq etal., 2013). Projected population statistics
report an extraordinary increase during the previous
two decades. This has brought about the unlawful
invasion and the reclamation of vast expanses of the
water surface from the lake basin as floating islands
or gardens used for vegetable farming, residences,
hotels, and market sites (Ahmad etal., 2020; Rather
& Dar, 2020b). Despite increased surveillance by
the government and restrictive measures, illegal
encroachment continues. From the above factors, it
is obvious that the picturesque Dal Lake, promoted
as an aquatic plaza the world over, is dying under
the heightened human impact in its drainage basin.
The condition of the lake in the immediate proxim-
ity of sewage outfalls has attained a serious stage.
Though the pace of pollution differs from basin to
basin, the impact of advancing human actions is felt
throughout the lake, rising in unwanted variations,
led by extensive environmental deterioration. There
is an urgent need to check passage of sewage from
the catchment, and effectively halt the establish-
ment of floating gardens, which is still going on in
many areas of the lake.
The variations in the biodiversity of the lake are
prominent. The bacterial population has multiplied
remarkably especially in the houseboat neighbour-
hoods and adjoining Boulevard and Gagribal due to
faulty sanitary system, impaired land management
practices in the adjacent vegetable gardens cou-
pled with direct discharge of grey waters (Rashid
et al., 2017; Sultan etal., 2020). Among the phy-
toplankters pollution indicator species viz., Cyclo-
tella, Melosira, Microcystis, Achnanthes, Nitzchia,
Euglena, Phacus, and Oscillatoria are prominent.
Similarly, zooplankters viz., Keratella, Brachionus,
Chydorus, and Cyclops are the leading and indica-
tor species (Gulzar etal., 2020).
Pollution management ofthelake
Solid wastes, sewage, and their management
Dal Lake in Srinagar is an example where human
endeavours have degraded the lake beyond the point of
natural recovery. Encroachment, silting, weed infestation,

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and extensive disposition of liquid and solid wastes by
the populace in the lake and on the periphery have turned
this lake into a waste sink of which solid waste is one of
the culprits (Chashoo et al., 2020; Ruhela et al., 2020).
Moreover, the dumping of huge loads of oxygen using
components of solid waste has culminated in a drop in
dissolved oxygen concentration of lake waters, and at
many places in the lake, it has led to anaerobic conditions
(Badar & Romshoo, 2008).
A substantial number of houseboats are stationed
in Dal and Nagin Lake. Most of these are anchored
from Dal gate to Nehru Park, opposite Boulevard
Road for tourism and other commercial purposes.
The visitors, along with owners, inhabit these boats
during the tourist season and discard the solid waste
produced into the lake. Thus, these houseboats turn
into a consistent point source for pollution of Dal
Lake (Ganaie & Hashia, 2020). Apart from these
houseboats, numerous settlements with inhabitation
have also been established in the lake areas, which
are also contributory to an enormous quantity of solid
waste resulting in the pollution of the lake and subse-
quent deterioration (Mushatq etal., 2013).
Besides the above point sources within the lake,
the inhabitation around the lake, the gardens, com-
mercial centres, and the markets on the bordering
pathways add to the littering and subsequent dumping
of solid waste in lake waters either directly or through
the drains flowing into the lake.
The organic elements of the garbage and food
waste result in the deficiency of dissolved oxygen
levels of the lake and the inorganic constituents
especially nitrogen and phosphorus add to the nutri-
ents resulting in weed growth. In addition, the float-
ing matter, containing plastic bags, paper, tin cans,
glass bottles, metal pieces etc., affects the ambi-
ence of the lake. Dal Lake had been, over decades,
used as a container of substantial loads of inflows,
including raw human waste (Nengroo etal., 2017).
A strategy to check the flow of wastewaters as sew-
erage system and decentralized sewage treatment
has been conceptualized and constructed. Looking
at the peculiar climatic conditions, the inadequacy
of vast areas of land, insufficiency of electrical
power, and the uneven topography, pumping of sew-
age to one place where it can be treated have been
avoided, and treatment by fluidized aerobic bed
(FAB) has been approved (Chashoo et al., 2020;
Qayoom etal., 2021). The technology employs both
dispersed and attached microbial growth in biore-
actors accompanied by tube settlers and centrifuge
with a chemical treatment to produce effluents of
standards suitable for discharge in the lake body.
Design of a pumping system (minimal) has also
been included.
At present, three sewage treatment plants (STPs),
proposed by the Alternate Hydro Energy Centre of
Indian Institute of Technology (IIT), Roorkee (AHEC,
2000), are functioning at three locations around the
lake. These are located at Habak, Hazratbal, and Lam
areas around the lake. These STPs discharge treated
sewage into the lake. There is a significant difference
in the physio-chemical properties of the treated sew-
age and raw sewage as presented in Table1.
Dal Lake, however, needs more STPs and appro-
priate management for the disposal of solid wastes
in its vicinity. Hyper-eutrophic areas like Nehru
Park and Nigeen basin need new STPs as well as the
upgradation of existing ones. These STPs, because
of their inability to perform many times and faulty
seepage, have led to an increase in lake eutrophica-
tion (Qayoom etal., 2021). For at-site treatments,
small-scale waste-water treatment plants can be
established for communities or individual homes.
Harvesting and deweeding
Dal Lake holds a vivid and mixed growth of macro
flora, which in some sections has developed into
dense layers to make up a practically impenetrable
mass (Kumar etal., 2020). The most protracted cov-
erage is of submerged species and floating forms,
Table 1 Quality of raw sewage and treated sewage of STP,
Hazratbal (Qayoom etal., 2021)
Parameters Inflow Outflow
COD (mg/l) 280 56
BOD (mg/l) 100 20
Total Solid (mg/l) 415 83
TDS (mg/l) 275 55
TSS (mg/l) 137 28
pH 6–6.5 7.8
DO (mg/l) <1 <1.6
Nitrogen(mg/l) 45 9
Ammonia(mg/l) 15 3
Chloride(mg/l) 75 15

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which have become a nuisance. The abundance of
macrophyte vegetation in Dal Lake is not merely
owing to uninterrupted supply of nutrients from the
catchment but also because of many diverse benefi-
cial conditions such as shallow depth of the basin and
its gradual slope, nutrient-rich sediments, optimum
light, and temperature conditions during the growth
period, minimum wave effect and the existence of
diverse perennial species which are adapted to effi-
cient utilization of the prevailing environmental con-
ditions (Rehman et al., 2016). It is well recognized
that aquatic macrophyte communities are “habitat
opportunists”; hence, it is difficult to dislodge a com-
munity once it is established in a particular lake or a
part of it.
In order to boost the use of Dal Lake for aquatic
sports, navigation, and other needed purposes, an
argument has been made for removing extra biomass
of macrophytes by mechanical harvesting. However,
there is no refuting that in some places of the lake,
weed growth is enormous, presenting a degraded
view of the ecosystem. Unfortunately, while recom-
mending the use of machines for weed cutting, the
part played by macrophytes as an indispensable part
of the freshwater ecosystem performing various func-
tions has been completely disregarded. Further, it
should be mentioned that the most satisfactory and
reasonable management technique would be a restric-
tion of macrophyte vegetation in Dal Lake rather than
its elimination. It is rightly acknowledged that mac-
rophytes are bio-indicators of pollution. They ade-
quately eliminate minerals from the sediment nutrient
pool and thus aid in pollution abatement by function-
ing as nutrient pumps and serving as biological sinks.
The resident community of Dal uses macrophytes
in many forms, which include food, fodder and
medicinal plants. The macrophytes also make up the
primary source of food in the aquatic food chain and
maintain the most convenient breeding, resting, and
sheltering place for macrofauna, consisting of fish
and other organisms, besides upholding consider-
able loads of periphyton on which a wide number of
aquatic animals depend. Inhibition of sediment sus-
pension and oxygenation of water through photosyn-
thesis are alternative functions of macrophytes. But it
is still a fact that enormous growth of macro vegeta-
tion in a lake disrupts transport, impedes irrigation,
increases sedimentation by trapping silt particles and
affects recreation. Accordingly, what is required is
to estimate both the advantages and disadvantages
of adopting mechanical harvesting to control aquatic
vegetation and then select the method that is most
helpful to the system without generating unwanted
changes that may be more harmful and difficult to
control.
Among many in-lake rehabilitation methods, bio-
mass removal using mechanical weed harvesting
has been executed in Europe and the USA to some
extent of success. In many situations, harvesting of
weeds is accompanied by the application of chemi-
cals. Use of chemicals in Dal Lake is not advocated
because of multiple uses of its water.
Aquatic plant control, rather than elimination,
is the most rational management procedure. Entire
eradication of plant cover and full-scale harvest-
ing should be evaded at all costs. Shallow lakes
like Dal Lake are extremely susceptible to shifting
from a stable vegetative state to a non-vegetative
one. The vegetative state is tougher to disturbances,
but excessive weed removal can neutralize their
stability and cause turbid waters with algal blooms
(Masoodi & Kundangar, 2018). Weed harvesting
has to be selective, i.e., limited to definite zones
only. Lake areas that are convenient for fish, fod-
der, and food plants should not be exposed to repeat
harvesting. Harvesting should be carried out before
blossoming, fruiting, and formation of propagules
in plants. Regular monitoring should be initiated
during harvesting operations involving the follow-
ing aspects: Vegetation maps need to be developed
for analysing variations in cover and frequency of
different species. A correlation can be made with
earlier vegetation maps. Aerial photographs and
satellite imageries will be extraordinarily advanta-
geous. The efficiency of machines and men need to
be noted periodically. The re-establishment of vege-
tation and changes in the community structure must
be monitored. Phenology of diverse aquatic plants
must be recorded. Any variations in predominant
species after de-weeding must be noted regularly.
Dredging of lake sediments
Decrease of nutrient load from catchment through col-
lection and treatment of sewage may have a meager
consequence on the improvement of Dal Lake envi-
ronment, since, during the times of increased eutroph-
ication for many decades, a considerable amount of

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phosphorus and nitrogen has been adsorbed by the
sediment (Mushtaq etal., 2013). Therefore, any reduc-
tion of outside loading is generally taken care of by
internal loading, thereby restricting the response of
the lake to the cutback of nutrients coming into the
system from the neighbouring area. Nutrients coming
from catchment and other extraneous sources are par-
tially accepted by biological life but substantial loads
of these are accumulated in sediments that are dis-
charged back to water over a course of time. Although
internal loading is a crucial source of nutrients in Dal
Lake, no data are available on the amount of nutrients
released from the sediments.
The deep sediment–water interaction, probably enor-
mous impact of siltation, and the presence of vast patches
of solid landmass along the north-eastern border nega-
tively influence the natural functioning of the Dal Lake
ecosystem (Mir etal., 2018). Dredging of lake sediments
can be employed as a reclamation approach to bring
about the elimination of nutrient-rich sediments, deepen-
ing of silted lake areas to enhance water flow, removal
of shoals and solid land mass, and cutback of emergent
vegetation.
Dredging can be specified as a rewarding lake res-
toration approach if there is a pre-implementation
evaluation of the lake setting, useful equipment is
selected, disposal locations are defined before the
dredging begins. Therefore, the designing of the lake
deepening project should take into deliberation many
components such as the extent of deepening based on
the area to be dredged out, the dumpsite, and the use
of the lake area, which is to be dredged out.
Shoreline development
The prominence of the shoreline of a water body is
an unambiguous indicator of the ecological status of
the same, and Dal Lake is no anomaly. The shore-
line, specifically from Dal-gate to Naseem Bagh,
has evolved over the years as the much-pursued sta-
tion both for tourist-associated enterprises as well
as for residential expansion (Rather, 2012). For any
management strategy of the Dal-Nagin Lake to be
useful, the impact of the tourist and the resident
community on Dal and Nagin lakes has to be inves-
tigated and visualized (Mir, 2017). An estimate of
the expected uses, and the impact, has to be evalu-
ated so that prospective development of the shore-
line is identified in distinct perspective.
Research and monitoring programme
The lack of a precise plan for the comprehensive mon-
itoring and control of the lake is now being understood
extremely strongly. For illustration, despite afforesta-
tion programs, there are many areas of the catchment
where erosion processes remain intense. The small silt
basin formed at the lake’s northern end cannot fully
impede incoming silt and usually fills up. Invasion
by weeds and plankton has followed dredging for silt
removal (Mushtaq etal., 2015). Harvesting of invad-
ing macrophytes, either by hand or by harvesters, has
not been a success story either. The weeds proceed to
multiply faster and set up hurdles to navigation and
recreation. Conservation programs are confined to
afforestation of the catchment to control silt move-
ments, dredging of the lake, and weed removal.
Invasion by alien species, extreme siltation and
waste discharge, habitat loss, and competition with
more economically significant species has taken a
toll upon the local Dal flora and fauna. However,
biodiversity monitoring has been trivial in the area
(Chowdhury, 2018; Mukhtar & Chisti, 2013). A
few individual bird counts and studies on a few spe-
cies apart, little information of the lake’s biodiver-
sity exists. Species counts, production information,
nutrient pools, food web characteristics, species
inter-dependences, feeding and breeding patterns,
habitat dynamics, and much more need to be stud-
ied over the long term to understand the impact of
various management plans upon the lake’s health
and biological diversity.
With such a scenario, there is a revealing call to
plan an ultimate research program for the lake hold-
ing regarding ongoing restoration programs, man-
agement procedures, and gaps in the interpretation
of the Dal Lake ecosystem.
Public awareness program
The accomplishment of any project depends upon
the engagement, assistance, and collaboration of the
individuals who are “Project-Affected.” It is there-
fore a prerequisite that the project of this nature be
participatory and carries the support of the resident
populace who will be directly affected by the imple-
mentation of the project. This demands that infor-
mation be formed at all levels about the demand and
intentions of the conservation project and how it will

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be advantageous to the local population in terms of
better living conditions and quality of life (Ali, 2014).
It should also present information on the present posi-
tion of the lake, need for its cleaning, saving the rich
bio-diversity, and maintaining ecological balance in
the lake system. It should also inform people regard-
ing the steps that are being taken by the government
and other agencies in the area of lake conservation
and how they can participate to make it a peoples’
movement (Jeelani & Kaur, 2014). In order to gener-
ate confidence in the local population, it should also
provide information regarding the progress of the
project implementation.
Future research needs
Although various studies have been carried out on Dal
Lake, most of these focus upon distinct aspects of the
lake. Overall management and monitoring studies from
the management and viable development point of view
are sadly lacking. Limnological studies indicate water
and sediment chemistry and planktons. Various fields
in the study of the lake’s ecosystem need to be cov-
ered. Some of the significant future research demands
include geological investigations of the catchment and
the lake bed; hydrological examinations incorporating
the strengthening of meteorological structure in the
lake catchment; the impact of snowfall, snow-melt, and
rainfall on temporal flow into the lake; role of ground-
water flow from the area neighbouring the lake to it
and vice versa; description of springs in the catchment
and their characters; detailed applications of the catch-
ment identifying soil types, elevation, drainage lines,
land use, and their impact on flows in the drains pour-
ing into the lake; impact of activities in the catchment
on the volume of surface and groundwater flowing into
the lake; hydraulic modelling of the catchment and
the lake; and modelling of the lake circulation, pollu-
tion, macrophytic and plankton growth. Also, a thor-
ough water balance of the system must be worked out
before other aspects conditional upon the water body’s
hydrology are studied.
Conclusions
The water quality of Dal Lake has undergone mon-
strous anthropogenetic pressure for the last four dec-
ades. Houseboats, STPs, hotels, agricultural practices
around the lake, floating gardens, lake encroach-
ment, and other non-point sources have degraded
the water quality as well as aesthetic properties of
the lake. Over the years, the concentration of harm-
ful substances, phosphates, chlorides, and nitrates has
increased tremendously. Concentration of total phos-
phorous has increased from 0.1 to 0.4mg/l in 1997
to about 6 mg/l in 2017. Similarly, chlorides have
shown a steep increase from 2–2.7mg/l 329 in 2007
to 10.3 mg/l in 2017. Other elements like calcium
and magnesium have also witnessed an increasing
trend in the lake. Lake alkalinity and pH are chang-
ing due to which lake waters have been found unfit
for drinking and domestic consumption. Dissolved
oxygen levels, on the other hand, have shown sig-
nificant decline in the lake over the last few decades.
Annual DO values of the lake have decreased from
7.4 mg/l in 1997 to 6.9 mg/l in 2017. The lake has
become hyper-eutrophic at several places, which has
severely affected the lake ecosystem. Changes caused
due to these factors have affected the lake water qual-
ity to such an extent that these cannot be corrected
naturally, and if proper and timely measures are not
implemented, the chances of lake survival are bleak.
Therefore, there is an urgent need to address the prob-
lems associated with lake restoration, management,
and conservation by both authorities and the local
population. A participatory approach-based conserva-
tion plan taking into consideration the restoration of
water quality and quantity, considering all stakehold-
ers, is the need of the hour to stop the lake from dying
an untimely death. Various aspects of lake hydrol-
ogy, chemistry, and geology need to be investigated
for sustainable management of the lake. The impact
of pollution and water quality change on the biodiver-
sity of the lake is the most neglected component of
research and needs to be investigated.
Acknowledgements The authors are thankful to Water Resources
Management Centre at National Institute of Technology, Srinagar
and College of Agricultural Engineering and Technology, SKUAST-
Kashmir, for providing all facilities to carry out the research.
Availability of data and material The data cannot be made
available because of the policy of data providing agency.
Declarations
Ethics approval Not applicable.

Environ Monit Assess (2022) 194:228
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Consent to participate The authors express their consent to
participate for research and review.
Consent for publication The authors express their consent
for publication of research work.
Conflict of interest The authors declare no competing inter-
ests.
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