The complex process of restoring lakes

The article delves into the challenges and complexities involved in restoring lakes, particularly in urban settings like Bengaluru. It critiques the unrealistic expectations set by policymakers regarding the restoration of lake water to potable quality and offers a more nuanced understanding of what lake restoration should focus on.

Key Points of the Analysis:

1.     Potable Water Standards in Lakes:

o    The Karnataka State Pollution Control Board (KSPCB) conducted a study of 110 lakes in Bengaluru, none of which meet potable water standards. This highlights the current pollution levels in the lakes, which are mainly due to the nature of inflows like wastewater, stormwater mixed with sewage, and raw sewage.

o    Potable water quality requires the highest water standards, free from toxins, carcinogens, and harmful microorganisms. However, achieving these standards in lakes, especially in urban areas, is extremely difficult due to contamination from natural and man-made surfaces.

2.     Sources of Water Pollution in Bengaluru’s Lakes:

o    Lakes in Bengaluru are polluted by three main sources:

§  Treated/partially treated wastewater from sewage treatment plants.

§  Rainwater mixed with sewage (Combined Sewer Overflows - CSOs).

§  Raw sewage entering through open stormwater drains.

o    Even if wastewater is prevented from entering lakes, runoff pollution (from roads, buildings, etc.) ensures that the water will not meet potable standards. The stagnant nature of lake water further degrades water quality through biochemical processes.

3.     Cost of Restoration and Challenges:

o    Restoring lake water to even secondary treatment levels comes at a significant cost, with treating 1 million liters of wastewater estimated at ₹1 crore, along with ongoing operation and maintenance costs.

o    Common restoration techniques include setting up sewage treatment plants, constructing wetlands, and using sedimentation ponds to treat combined sewage overflows. However, these efforts alone may not elevate the lakes to potable water standards.

4.     Misleading Perceptions of Restoration Success:

o    The study shows that all 110 lakes fall under the categories D (suitable for wildlife and fisheries) and E (suitable for irrigation, industrial cooling, or controlled waste disposal). None of the lakes are fit for swimming (Category B) or can be used as a source of potable water, either with or without treatment.

o    Biological Oxygen Demand (BOD) levels in category D or E lakes indicate how much oxygen is required for decomposing organic material in the water. Reducing BOD from high levels (like 30 mg/l to 15 mg/l) is significant progress, but it may not reflect in the category change, leading to a misleading perception that no progress has been made.

5.     Setting Realistic Expectations:

o    The article emphasizes the need to set realistic expectations for lake restoration, pointing out that the goal should not be to achieve potable water quality in urban lakes. Instead, the focus should be on tangible improvements in water quality, biodiversity, and the livelihoods of local communities.

o    The process of restoration should involve:

§  Identifying the problem.

§  Prioritizing issues with stakeholder input.

§  Baseline assessments of challenges.

§  Estimation of achievable goals based on available funds.

§  Realistic expectations and sustainability planning.

6.     Complexity of Lake Restoration:

o    Lake restoration is inherently complex and cannot be achieved with a one-size-fits-all approach. It requires phased targets, collaboration among stakeholders, and a comprehensive understanding of local ecological conditions.

o    The goal should be to turn lakes into healthy ecosystems that may not provide drinking water but contribute to the environment, biodiversity, and local communities.

Key Insights and Takeaways:

1.     Challenges of Urban Water Bodies:

o    Urban lakes like those in Bengaluru face serious contamination challenges from multiple sources. Restoring these lakes to potable water standards is unrealistic due to the nature of inflows and the cost of treatment.

2.     Financial and Technical Constraints:

o    Restoring lakes comes with high financial costs for treatment and infrastructure, and even then, the improvements may not be sufficient to meet potable water standards. The treatment of runoff and stormwater is particularly challenging in densely populated urban areas.

3.     Misleading Progress Metrics:

o    The current system of categorizing lakes (Categories A to E) does not reflect the incremental progress that can be achieved in lake restoration. Even significant improvements in water quality may not change a lake’s category, leading to misconceptions about the success of restoration efforts.

4.     Sustainable Restoration Goals:

o    Lake restoration should aim for more sustainable outcomes, focusing on creating vibrant, healthy ecosystems rather than on making the water potable. Lakes can serve multiple functions, such as wildlife habitats, recreational spaces, and sources of irrigation or industrial cooling, even if they are not drinkable.

5.     Stakeholder Engagement:

o    The process of lake restoration should involve stakeholder participation, including local communities, policymakers, and environmental experts. Setting realistic goals with the input of stakeholders is crucial for the sustainability of restoration efforts.

Conclusion:

The restoration of lakes, particularly in urban settings, is a complex and costly process that requires realistic expectations from policymakers and stakeholders. While potable water standards may not be achievable, the focus should be on incremental improvements in water quality, biodiversity, and the livelihoods of local communities. The success of restoration efforts should be measured by environmental health and the sustainability of the interventions, rather than solely by water quality standards.