17. KONASANDRA LAKE

WATER QUALITY

Table 1 Water quality of Konasandra Lake with BIS limits

Water quality of Konasandra Lake is listed in Table 17. pH ranged from 8.69- 8.8.  Electric conductivity and total dissolved solids ranged from 718-825.67 μS/cm and 537.67-582 ppm respectively. Biological oxygen demand was slightly higher than the BIS permissible limit while chemical oxygen demand was found higher at inlet site (39.33 ppm). Nutrients such as nitrates and inorganic phosphates were in minimal concentration. The amount of hardness in water reflected less influence of sewage and other human disturbances on water quality of Konasandra. The main source of pollution was observed due to dumping of solid waste along with construction waste near the lake bed.

CURRENT THREATS (Refer Figure 17 and Plate 17)

1. Sewage inflow
2. Local human disturbances such as washing clothes, swimming, open defecation
3. Weed cover
4. Dumping of solid waste

18. KOTHNUR LAKE

WATER QUALITY

Table 2 Water quality of Kothanur Lake with BIS limits

Water quality variation among sampling sites of Kothanur Lake has been listed in Table 18. pH was highly alkaline in condition ranging from 9.12-9.13.  Electric conductivity and dissolved solids were well within the BIS standard for surface waters while the chloride concentration was found to be as high as 242 mg/L at inlet and 239 mg/L at outlet which revealed domestic sewage as the major source. Both the biological and chemical demand for oxygen was increased at both the sampling sites ranging from 21.22-22.58 ppm and 42-51 ppm respectively. The Lake immediate surrounding was occupied by apartments which led to the pollution into the Lake through sewage, dumping waste and washing vehicles. Even though the restoration work was in process, black, foul odor water was characteristic of untreated sewage inflow into the Lake which also carried plastic and other waste along with it.

CURRENT THREATS (Refer Figure 18 and Plate 18)

1. Sewage inflow,
2. Construction of apartment in lake bed, dumping of waste in surrounding area
3. Eutrophication, Algal bloom was observed
4. Sewage inflow even after restoration

19. MADIVALA LAKE

WATER QUALITY

Table 3 Water quality of Madivala Lake with BIS limts

Variation in water quality of Madivala Lake is listed in Table 19. Water quality results showed the significant organic pollution through biological and chemical oxygen demand which ranged higher than that of BIS surface standards. Nutrients did not vary much which could also add to Eutrophication of water. Among all variables total hardness and calcium hardness ranged in higher concentration i.e., 194-201.2 mg/L and 102.73-131.54 mg/L respectively which clearly showed the sewage and local human disturbances influenced the water quality. The fisherman revealed that the fish diversity has been declined and frequent fish death resulted due to increased organic concentration in lake. The built-up area in catchment has been increased which could increase the pollution load. Even though this lake has been restored, improper maintenance of lake has led to dumping of waste and spoiled the lake water.

CURRENT THREATS (Refer Figure 19 and Plate 19) 

1. Sewage inflow
2. Construction of apartment in lake bed
3. Dumping of solid waste surrounding lake
4. Local human disturbances such as washing clothes, swimming, open defecation

PLATE 19

20. MALLATHAHALLI LAKE

WATER QUALITY

Table 4 Water quality of Mallathahalli Lake

Mallathahalli Lake water showed higher values for all the chemical variables which affected the growth of aquatic organisms. pH at both the sampling sites was in high alkaline range while, nutrient concentration was ranged as 0.062-0.072 ppm of nitrates and 0.046-0064 ppm of inorganic phosphates. The increased amount of sewage from upstream built- up resulted in increased organic matter in water along with high amount of hardness in water (range, 278-302 ppm). In later period, the lake water turned gradually to green in color because of algal bloom and led to fish death during 2009. Although the restoration work is in progress, the aquatic weeds have massively spread across region and consequently a decrease in oxygen level was recorded.

CURRENT THREATS (Refer Figure 20 and Plate 20)

1. Sewage inflow
2. Construction of buildings, dumping of waste in surrounding area
3. Eutrophication, Algal bloom was observed
4. Fishing.

PLATE 20 

21. MALSANDRA LAKE

Table 5 Water quality of Malsandra Lake with BIS standards mentioned

Water quality of Malsandra at different sampling sites has been listed in Table 21. pH of water ranged from 8.9- 9.23 while the oxygen level was as well significantly high indicating photosynthetic activity. Biological oxygen demand and chemical oxygen demand was higher at site 2 than at site 1 which was near road construction and stone mining. Total hardness ranged for 108-136 mg/L whereas calcium hardness was recorded as high at both the sampling sites i.e., ranging from 72.34- 96.25 mg/L. The lake water is clear and very less or no sewage inflow was observed into the lake and thus, the ionic concentration and total dissolved solids values were within the permissible limits.

CURRENT THREATS (Refer 21 and Plate 21)

1. No defined lake boundary
2. Human disturbances such as washing clothes, Open Defecation.

PLATE 21

22. MUTHANALLUR LAKE

NAME OF THE LAKE	MUTHANALLUR KERE
GEOGRAPHIC DETAILS       LAT/LONG: 12°49'23"N   77°43'40"E
AREA (2002/2009)	110.8/106.4 ha
ORGANIZATION	BBMP
WARD NAME	Anekal taluk
STATUS	Clean/ No pollution
RESTORATION	NO
WATER CONDITION	Clean.

 

 

figure 6 : Google Earth image and area of Muthanallur Lake during 2004 and 2009 respectively.

WATER QUALITY

Table 6 Water quality of Muthanallur Lake with BIS limits

Sampling site	Muthanallur site 1 (MTR1)	Muthanallur site 2 (MTR2)	BIS standards for Surface waters
pH	8.75	8.1	6.5-9
Electric conductivity (μS/cm)	1218	901	<1200
Total dissolved solids (ppm)	954	890	<700
Dissolved oxygen (mg/L)	8.13	9.76	>5
Biological oxygen demand (ppm)	7.35	5.89	<5
Chemical oxygen demand (ppm)	24.7	21.78	<30
Nitrates (ppm)	0.08	0.064	--
Inorganic phosphates (ppm)	0.22	0.29	--
Total hardness (mg/L)	93	90.2	<200
Calcium hardness (mg/L)	61.5	60.1	<80
Chlorides (mg/L)	119	123	<250
Total alkalinity (mg/L)	249	234	<600

Muthanallur Lake water along with BIS limits has been listed in Table 22. The highest ionic concentration of 1218 μS/cm and lowest of 901 was recorded at site 1 and site 2 respectively. Except the slight high amount of biological and chemical oxygen demand, all the chemical variables were well within the BIS permissible limits which resulted in good water quality. Muthanallur was found less affected by any anthropogenic activities but certainly higher values of electric conductivity and total dissolved solids require immediate attention and conservation of lake.

CURRENT THREATS (Refer Figure 22 and Plate 22)

1. Washing clothes, Open Defecation
2. Sewage from Electronic city (Initial stage).

PLATE 22

23. NELAGADARENAHALLI/ NARASAPPANAHALLI LAKE

WATER QUALITY

Table 7 Water quality of Nelagedarahalli Lake with BIS limits

Nelakondossi Lake water quality (Table 23) reflected high contamination of water with Eutrophication status. Alkaline pH ranged from 8.36- 8.71. Electric conductivity and total dissolved solids were very high in concentration i.e., 10890- 11160 μS/cm and 7530- 7790 ppm respectively. Dissolved oxygen was found to be as low as zero at inlet site because of higher amount of sewage and industrial waste from nearby industries. The low oxygen was also due to massive growth of water hyacinth and thus the increased organic pollution. The lake bed occupied with small scale industries and water at one side was completely covered with plastic and other waste dumps. Chloride and hardness concentration were observed to be more than the BIS standard limits for surface water because of their high concentration let in to the lake. No fish were found at this high amount of pollution while inhabited water birds.

CURRENT THREATS (Refer Figure 23 and Plate 23)

1. No defined lake boundary
2. Washing clothes, Open Defecation,
3. Construction of buildings next to lake bed
4. Dumping of solid waste, Industrial waste.

PLATE 23

MACROPHYTE COVER

WASTE DUMPING IN LAKE

ENCROACHMENTS IN LAKE BED

24. NELAKONDODDI LAKE

WATER QUALITY

Table 8 Water quality of Nelakondoddi Lake with BIS limits

Water quality of Nelakondoddi Lake reflected a pristine water condition with conductivity, total dissolved solids, biological oxygen demand and chemical oxygen demand concentrations well within the BIS standards and lesser than the polluted water. Nitrates ranged from 0.256- 0.449 ppm awhile phosphates were 0.12-0.15 ppm.  Total hardness and calcium hardness ranged from 140-148 mg/L and 44.96- 49.97 mg/L respectively. The source of hardness in such lakes could be accounted for local human disturbances such as washing clothes. This lake is located in 10 km buffer zone of Bangalore BBMP boundary and in less populated region and thus less pollution.

CURRENT THREATS (Refer Figure 24 and Plate 24)
Local human disturbances, grazing

PLATE 24

25. RACHENAHALLI LAKE

WATER QUALITY

Table 9 Water quality of Rachenahalli Lake with BIS surface water limits

Rachenahalli water quality has been listed in Table 25. pH was slightly alkaline in condition. EC and TDS ranged to be moderately polluted i.e., 854.3- 885.67 μS/cm and 609-620 ppm respectively. A slight higher amount of organic matter revealed pollution status at both the sampling sites. Total hardness was high at both the sites i.e, range of 221.33-222.67 mg/L because of high amount of calcium and soap water into the lake. The lake was at one side, occupied with agricultural field and to the other side inflow from nearby built-up regions. The restoration has not yet completed which needs immediate attention to properly maintain the water body.

CURRENT THREATS (Refer Figure 25 and Plate 25)

1. Sewage and Agriculture inflow,
2. Fishing and local human disturbances
3. Improper maintenance.
4. Weed cover

PLATE 25

RESTORATION WORK – JUNE- JULY 2010

26. RAMAPURA LAKE

WATER QUALITY

Table 10 Water quality of Rampura Lake and BIS standard limits

Rampura water quality is listed in Table 26 which reflects severe pollution at both the sampling sites. Higher electric conductivity and dissolved solids was observed which ranged from 1578-1930 μS/cm and 1050- 1135 ppm at inlet and outlet respectively. Dissolved oxygen was found to be zero at both the sampling site because of no penetration of light as the whole lake is covered with water hyacinth. A part of city’s sewage inflow could be observed at Rampura Lake’s inflow region which is the main source of contamination of water.

CURRENT THREATS (Refer Figure 26 and Plate 26)

1. Local disturbances such as Dumping of solid waste,
2. Conversation of lake into land by filling up with soil,
3. Untreated sewage inflow,
4. Eutrophication,
5. Loss of Biodiversity

27. RAMASANDRA LAKE

WATER QUALITY

Table 11 Water quality of Ramasandra Lake with BIS standard limits

Chemical variation in water quality of Ramasandra Lake has been listed in Table 27.  This lake is situated in less populated region and thus less influence of sewage on water quality could be observed. Electric conductivity and total dissolved solids ranged from 466- 516.67 μS/cm and 343- 369 ppm respectively. Least concentration of BOD and COD was observed at grazing sampling site (6.05 ppm and 8.88 ppm) while highest of 14.23 and 30.99 ppm at inlet site. Total hardness was highest at outlet site reasoning the utilization of water for washing, agricultural waste runoff and other human disturbances.

CURRENT THREATS (Refer Figure 27 and Plate 27)
Grazing, Fishing, Sand mining, Agricultural run-off, Local human disturbances.

PLATE 27

RAMASANDRA LAKE PRIOR TO RESTORATION: February 2009

28. RAYASANDRA LAKE

WATER QUALITY

Table 12 Water quality variables of Rayasandra Lake with BIS limits

Water quality of Rayasandra along with BIS limits is listed in Table 28. Both the sampling site revealed alkaline pH range. Ioinc level and dissolved solids concentration was slightly higher at site 1 when compared to outlet site while hardness of water was higher at outlet due to interruption of human disturbances. The water quality could be categorized as clean to moderate pollution as the pollution causing variables such as chlorides and organic concentration are well within the BIS surface water quality standards.

CURRENT THREATS (Refer Figure 28 and Plate 28)

1. Local disturbances,
2. Untreated sewage inflow

Plate28

 29. SANKEY TANK 

Figure 13 Google Earth image and area of Sankey tank during 2000 and 2010 respectively.

WATER QUALITY

Table 13 Water quality of Sankey tank and BIS standards

Water quality of Sankey tank is listed dn compared with BIS permissible limits in Table 29. Even though this lake has been restored, the water quality reflects pollution status. Both the sampling sites had alkaline pH range. EC and TDS at inlet were higher than the outlet site i.e, 710 μS/cm and 584 ppm at inlet while, 393 μS/cm and 270 ppm at outlet. Except the calcium hardness, chlorides, total hardness and alkalinity were well within the required permissible limits. The inlet receiving untreated sewage was recorded which was also reflected through water quality at inlet site.

CURRENT THREATS (Refer Figure 29 and Plate 29)

1. Local human disturbances,
2. Untreated sewage inflow

PLATE 29

EUTROPHIC WATER

ALGAL BLOOM NEAR INLET

 30. SOMAPURA LAKE

WATER QUALITY

Table 14 water quality variation in Somapura Lake with BIS limits

Water quality of Somapura Lake has been listed in Table 30 which reflected clean to moderate water quality at all the sampling sites. Among all the variables recorded, electric conductivity was found to be high ranging from 1020.67- 1024 μS/cm which is slightly lesser than the BIS limits from surface standards. Apart from sewage inflow, the asphalted road in addition contributed to lake contamination with chloride concentration. Organic pollution was slightly higher at inlet with 12.88 ppm of BOD and 36 ppm of COD concentrations. The only pollution source found was sewage at inflow which if treated will help in balancing the ecosystem.

CURRENT THREATS (Refer Figure 30 and Plate 30)

PLATE 30