The Mansagar Lake in Jaipur, Rajasthan, and the Kaikondrahalli Lake in Bengaluru, Karnataka, have been successfully restored using two very different approaches. The restoration of Mansagar was achieved under a public private partnership (PPP) model while Kaikondrahalli was restored through a multi-stakeholder socially inclusive model. Both approaches have successfully revived the lakes and the ecologies dependent on them. They have also provided local communities with aesthetic and recreational spaces that are also sources of revenue.
a. Mansagar
Stopping any further pollution was the first prerequisite for the restoration of Mansagar lake. This required diversion of highly polluted drain water from Brahmpuri and Nagtalainalas drains. A 1.5-km channel was constructed as part of the initiative to divert drain and storm water into a 7-metre-deep sedimentation basin constructed on the east side of the lake. Using boulders, sand and dredged mud, a natural filter was created forthe incoming waste by building a bund at the end of the depression. The waste passes through this bund, leaving behind large-sized pollutants, then moving into two chambers, which have vegetation in them. This strategy significantly lowers the Biological Oxygen Demand (BOD) of water and makes it clean enough to sustain flora and fauna.
Work was carried out simultaneously to dredge the Mansagar Lake. This increased the lake’s depth from 1.5 mt to more than 3 mt. It was important to lower the lake depth significantly so as to increase its storage capacity. The dredged mud was used to build embankments within the lake. Two sewage treatment plants were also constructed to treat 7 million litres of waste daily and discharge the treated water into the lake. The Mansagar Lake, which used to dry up in the summer before the restoration effort, now remains perennially full. To attract flora and fauna, five nesting islands were created to attract migratory birds, fish were introduced and giant bubblers were installed to provide regular oxygen supply to the lake.
b. Kaikondrahalli
The BBMP used a phased approach for lake restoration, primarily because it did not have access to adequate funds to begin with. The phased approach ensured regular availability of funds for the project. Phase I, which lasted from December 2009 to March 2011, began with demarcation of the lake’s boundaries. This was necessary to enable a precise mapping of the lake and to stop any encroachment. The mapping was done in coordination with the revenue department, which is the custodian of land records. Revenue surveyors conducted a survey, leading to the establishment of the lake’s boundaries. Lake encroachers were then served eviction notices through the tehsildar. With the lake administratively secured and cleared of encroachments, the next step wasto stop pollution. As the inflow of sewage was a major reason for the lake’s degradation, the inflow was diverted through a pipeline.
These two steps effectively stopped further degradation of Kaikondrahalli. The next step was aimed at de-silting of the lake. The unruly vegetation growth in the lake was cleared before de-wedding and de-silting of the lakebed. These efforts increased the lake’s depth by an additional metre and increased its storage capacity by 54%. The restoration drive also involved the development of inlets and outlets to improve the flow of water, embankments and revetments, and a pathway around the lake.
In Phase II (September 2011 to March 2012) a fence was constructed around the lake in line with its administratively and cartographically demarcated boundary. Thereafter,the lake periphery was afforested to improve water quality and prevent soil erosion. As the dumping of items such as flowers and idols during religious festivals was also a major source of pollution in the lake, separate ponds were constructed for these activities, enabling citizens to continue with their cultural and religious practiceswithout harming the lake.
Kaikondrahalli was then developed into an aesthetic and recreational urban space, with facilities like walking/jogging pathway around the lake perimeter, a 2.5-km cycling track, an amphitheatre for cultural performances, and pergolas and toilets.
The BBMP regularly engaged with the local community throughout the implementation of the restoration project. After project completion, the task of monitoring and maintenance was handed over to the local community. To this end, a tripartite agreement was signed between the following agencies:
1) Mahadevapura Parisara Samrakshane Mattu Abhivrudhi Samiti (MAPSAS), a society formed by local residents and concerned citizens with the objective of safeguarding Kaikondrahalli
2) United Way, a U.S.-based NGO that funds community action
3) BBMP
While MAPSAS was given the responsibility of maintaining the facilities at the lake, BBMP agreed to fund any major repair work. The maintenance responsibilities included security, gardening, cleanliness, maintenance of fences and lighting. All fishing activities in the lake were stopped. This gave the local community control over their commonproperty and enabled more effective monitoring and maintenance of the lake.
Revival of local ecosystems:
A notable and successful strategy in the restoration of Mansagar Lake was the use of treated storm water as a primary water source for lake revival. The sedimentation basin in the lake is an inexpensive treatment system that costs far less than treating sewage. Both the lakes have also revived the local ecology and attract a large variety of birds including pelicans, ducks, black cormorants, shikhrajuvs, rufoustreepie and many others.
References
1. http://www.downtoearth.org.in/content/mansagar-lakes-fate-hangs-balance
2. Indicator of bacterial presence in water.
3. Shelter structures for protection from rain and sun.