Thirty years of Dal Lake Pollution
WORLD ENVIRONMENT DAY – JUNE 5
BEAUTIFICATION, PRESERVATION AND CONSERVATION ARE THREE SEPARATE SUBJECTS TO BE TAKEN INDEPENDENTLY, WRITES DR. M. R. D. KUNDANGAR.
Aquatic ecosystem worldwide are being severely altered or destroyed at a rate greater than that at any other times in human history and far faster than they are being restored. Dal Lake ecosystem (Lat. 340 – 6′ N, 740-45′ E, alt. 1583m) situated in the heart of Srinagar, the summer capital of Jammu & Kashmir State is under tremendous anthropogenic pressure since more than three decades. The uniqueness of the lake is that 50,000 people live within the lake itself in various islands (hamlets) besides houseboats and doonga boats. The myriad ways in which people use the lake, along with the numerous pollutant-generating activities have stressed the lake ecosystem in diverse ways. These stresses have caused significant impairment to lake quality. Three major classes of stresses have been identified that has degraded its quality:
a) Excessive inputs of nutrients and organic matter, from point and non-point sources, leading to eutrophication
b) Hydrological and physical changes
c) Siltation from inadequate erosion control
Of these three categories, stress problems related to nutrient over enrichment and excessive plant production is probably the most common as an estimated load of 12.30x106 m3 of liquid waste with 18.17 tons and 25 tons of Phosphorus and inorganic nitrogen is enriching lake annually (Kundangar et al 2003).
Despite the fact, number of restoration plans by National and International agencies viz., Srinagar Master plan of 1971, Lake Area Master Plan by Stein (1972), Enex Consortium Report (Enex,1978), Dal lake Development Report by Riddle(1985), ODA(1989) Project Report under NLCP (1997) and Project Report of AHEC Roorke(2000), there has been no significant improvement in Dal lake environment but the lake conditions as a whole continue to deteriorate at an alarming rate thereby threatening the very existence of the lake beside posing serious health hazard to the people living within and around the lake.
This article provides the changes in the hydrochemistry and biodiversity of the lake during the last thirty years by comparing the earlier available data with the present.
The changes in the water quality are tabulated and the data reveals more than 70% decrease in water transparency, a major shift in oxygen regime(10.2mgl-1 to 6.8mgl-1), Ammonical.-nitrogen content(23.6 ugl-1 to 438 ugl-1),Total-Phosphorus(187.8 µgl-1 to 615 µgl-1) and Total dissolved solids(30.2 mgl-1 to 201 mgl-1) indicating thereby a drastic changes in the water quality which can be attributed to intensified release of nutrients due to soil erosion, runoff from immediate catchment, discharge of urban wastes including inorganic fertilizers. The higher values of Total dissolved solids is clear indication of continued siltation, failure of retention of silt by partially commissioned Settling basin and high ingress of sewage into the lake and mineralization process of organic matter.
The changes in the biodiversity where under the bacterial population has increased tremendously particularly in the house boat areas and near Boulevard and Gagribal due to inadequate sanitary system, poor land practices in the nearby vegetable gardens coupled with direct discharge of grey waters. Among the phytoplankters pollution indicator species viz. Cyclotella, Melosira, Microcystis, Achnanthes, Nitzchia, Euglena, Phacus, Oscillatoria etc. are dominant and a significant relationship has been recorded between the dominance of a particular algal classes and the proximity of wastewater disposal sites in Dallake. Likewise zooplankters viz., Keratella, Brachionus, Chydorus, Cyclops are the dominant and indicator species.
Table 1. Water quality changes in Dal lake during thirty years.
Parameters Unit 1974-1976 1985 1996-1997 2006-2007
Dissolved oxygen mg/l 10.25 8.7 8.6 6.8
Total alkalinity mg/l 69.5 85.6 104 115
Nitrate nitrogen µg/l 481 483 272 539
Ammonical nitrogen µg/l 23.6 37.0 362 438
Ortho phosphate µg/l 65.5 80.5 135 93
Total phosphorus µg/l 187.8 211.5 768 615
Total dissolved solids mg/l 30.2 32.2 119.8 201
Although the algal blooms are natural to freshwater lakes but the Dal lake waters with the advent of time and due to increased and unabated human incursions within and lake peripheries have witnessed frequent algal blooms. Recurrence of such blooms has become a regular phenomenon in the various basins of the lake. In 1991 the reddening of the lake waters due to Euglenoid bloom was first of its kind. According to Kundangar and Sarwar (1997) a close relationship was observed between chloride and nitrates which almost coincided with those of high euglenoid population. The authors opined that the lack of water flushing, nutrient enrichment and accumulation of free carbon dioxide were the possible causes of the euglenoid bloom in Dal lake. In April 1998 a bloom of cladophora was recorded in the Pokhribal zone of Nigeen basin of Dal lake which smelled like untreated sewage and chocked the waterways near the exit point of Nallha Amir Khan (Kundangar 1999).The author attributed the appearance of this ‘ blanket weed’ to the chemical enrichment due to incoming sewage. The same author in 1999 recorded the two algal blooms one of Volvocales and that of Microcystis aeruginosa in Hazratbal and Nehrupark basin respectively giving waters a lush green colour. The Microcystis bloom since then has remained perpetual in the lake basin and has engulfed the entire basin area. Besides these, Spirogyra bloom is of common occurrence in the Nigeen Lake particularly when the exit gate at Nallah Amir Khan remains closed.
Aquatic Weeds: .
Peculiar changes have occurred in this basin over a period of time arising out of human incursions. Not only the floating gardens are being expanded unabatedly but 1/3 of the lake area towards Saderbal side has been turned in to marsh supported by thick mats of Typha and Phragmites and subsequently into land mass.
Euryale ferox, an abundantly found macrophytes has almost vanished and hardly scattered plants could be seen interspersed with Nelumbo plants. Chara an alga of which eleven (11) species were recorded by Mukerjee (1934) is on the verge of extinction and hardly few plants could be recorded in undisturbed pockets of the lake. Azolla sp. the exotic species are now the new invaders to the lake and assumed the greater dimensions. The significant changes in the vegetational pattern of the Dal Lake and their prolific growth in the open areas are attributed to unabated inflow of effluents channels, drains, raw sewage and enrichment of the lake sediments particularly due to heavy load of organic nitrogen and phosphates.
Fish and Fisheries:
The fish population of Kashmir has been introduced from the Central Asian Highlands during the second inter glacial period. The fish species include the members of Schizothoracine, Sisordiae and Cobitidae. The notable fish species common in Dal lake were Schizothorax esocinus, S. niger, S. curvifons, S. micropogon, Labeo dera, Carassius carassius but during the last thirty years their number has declined sharply. The schizothoracides have been since out numbered by Carpiodes. The two fish species viz; Cyprinus carpio specularis and C. carpio communis, introduced in 1956 have got well established as they thrive in waters rich in nutrients and organic matter. The present day fish catch of Dal lake comprises more than 80% of the carp. The decline in fish diversity and yield is attributed to the changes in hydrological regime and loss of critical habitats. The changes in the species richness can also be attributed to heavy loads of incoming sewage thereby leading to increased eutrophication which has adverse impact on the growth and development of sensitive fish species like Schizothorax. The increased pollution levels are favourable for the prolific growth of aquatic vegetation, which seem to be more favourable for hardy species thereby altering the balance of species richness.
Restoring Dal the beauty
On the basis of recommendations of the various consultants from time to time, the measures taken by the concerned authorities include partial commissioning of settling basin at the mouth of lake to arrest the tremendous silt load form Telbal nallah(a perennial source of water), marginal dredging along the lake shore, retrieving of land masses including that of sediment and slush, improving of the water circulation by way of cut and conduit at Brarinambal, revamping of the exit gates, removal of illegal floating gardens and some hamlets within the lake, deweeding along the specified lake areas, aeration of the lake water at selected places, laying of sewers around the lake and setting up of few Sewage treatment plants. Yet the lake does not show any sign of improvement either in its water quality or overall lake ecology. The fact remains that the condition of the lake is deteriorating at an alarming rate and creating hue and cry among the people of all walks of life.
The reasons for the failure of restoration programme of Dal Lake are summarized as under:
a) Changing of the consultancies from time to time and non-availability of required funds in time.
b) Politicization of the issue of Dal lake conservation and diversion of funds at highest level of state administration.
c) Predominance and preferences on engineering works.
d) Winding up of an established Research and Development wing to reduce the scope of scientific surveillance and to avoid any sort of scientific contempt.
e) Adopting of such energy dependant wastewater treatment (FAB) technology, proven to be failure under Kashmir conditions.
90-98% increase was recorded in ortho-phosphate and total phosphorus respectively while 32% increase was recorded in nitrate-nitrogen during winter months. The author had cautioned about the adoption of this technology for Dal Lake prior to its installation.
The present studies carried out during the year 2008 (Table 3) regarding the functioning of FAB based STP, showed that the installed STP could improve the chemical parameters of incoming sewage partially as against the claims put forth by the Dal lake authorities in their health bulletin (April 2008). Interestingly, the nitrate nitrogen content of the treated sewage shows an increase by 44% thereby vividly indicating the malfunctioning of the STP installed and commissioned by the Dal lake Authority against the wishes of the considered scientific opinion.
In my view the situation where under the STPs are malfunctioning, will not only exacerbate the problem of pollution of Dal Lake but shall have catastrophic consequences; as the non-point sources of pollution are being made the point source of pollution. This is also manifested by an increase in the oxygen consumption in the hypolimnion, rise in the BOD, COD and the concentration of electrolytes, as well as in the concentration of chlorides, sulphides, phosphorus and nitrogen. The increase in the concentration of P and the optimal ratio between P and N shall have important effect on the primary production and structure of plankton community and aquatic Macrophytes in various parts of the lake and subsequent deterioration of water quality.
Table3. Efficiency of nutrients removal through FAB-STP (April 2008)
Parameters *Raw sewage *Treated Sewage *% removal **Raw sewage **Treated Sewage **% removal
COD (mg/l) 116 36 69 190 108 43.1
Po4-p (µg/l) 658 282 57 620 390 37
T.P (µg/l) 1660 342 79 1320 805 39
NH4-N (µg/l) 2283 999 56 2810 1392 50
No3-N (µg/l) - - - 680 1232 i.
*LWDA – Health Bulletin April 2008; ** Adnan & Kundangar (2008)
f) The unscientific and erratic deweeding practices have proved a cosmetic and temporary treatment without any relief to the ecology and health of the lake ecosystem.
g) The Houseboat waste management has remained still an unaccomplished job. The so called floating septic tanks installed in some houseboats during early nineties have proved only show pieces to mislead the people.
Suggestive restoration measures:
The restoration measures should lay emphasis on:
a) Catchment conservation whereby already identified and prioritized micro watersheds should be taken for control of soil erosion and regulate flow regimes.
b) Integrated water management into restoration whereby measures should be taken for enhancement of water holding capacity based on water and sediment balance; restore area under willow plantation, water lilies, vegetable gardens and other encroachment and take proper measures for improvisation of water quality.
c) Biodiversity conservation whereby achieving self sustaining native and endemic fish population through targeted restocking and enhancing diversity and abundance of Schizothorax. Moreover, emphasis should be laid to develop method to reduce the prolific growth of endemic and exotic aquatic plants species like lemna, Salvinia and Azolla.
The long term solution in my opinion to the problem under Kashmir conditions (where there is already energy crisis and severe winters) is the adoption of a proven Root Zone technology (Treatment compartments) for wastewater treatment. The Treatment compartments have been found to be efficient in reducing the nutrients (nitrogen by 70% and phosphorus by 73%) besides other chemical constituents. Construction of Treatment compartments for wastewater treatment in and around Dal Lake including other lakes in Kashmir valley will have several advantages compared to conventional secondary and advanced wastewater treatment systems and can go a long way in maintaining the present trophic status of the water body.
Moreover, the preparation of vegetational maps through latest available techniques seems to be a pre requisite in order to record the existing weed density prior to deweeding practices and that too under close scientific supervision. The desiltation of the settling basin has become inevitable to increase the efficiency of arresting of the incoming silt load. The retrieval and cleansing of chocked peripheral springs all along the Lake periphery and diversion of their fresh waters towards lake will certainly increase the required volume of the lake.
The utter failure of the local authorities to restore the lake on scientific lines for last more than three decades and their interest in civil engineering works alone besides political interferences impel the authors to suggest the handing over the entire Dal restoration programme to any international agency well versed with the lake restoration.
Let the authorities concerned understand the difference between beautification, preservation and conservation of a lake, which are separate entities. Attempts to show that Dal lake has neither shrunk nor has undergone any morphometric, changes besides changes in water chemistry and biological diversity over a period of time are misleading and far from truth.
[The article is an extract of the original research paper entitled,”Three decades of Dal lake Pollution-Restoration. By Adnan Abubakr and M.R.D. Kundangar, published in the journal of Ecology, Environment & Conservation- 15(4):2009 pp825-833].
(The author is associated with Lake Sciences & Water management Department, SSM College of Engineering & Technology, Pattan, Kashmir and can be reached at email@example.com)
Lastupdate on : Fri, 4 Jun 2010 21:30:00 Makkah time
Lastupdate on : Fri, 4 Jun 2010 18:30:00 GMT
Lastupdate on : Sat, 5 Jun 2010 00:00:00 IST
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