Restoration of Urban lakes:a case study from Bangalore

Dr Priyanka Jamwal (ATREE, Bangalore)

Prof. Laurence Carvalho (UKCEH, Edinburgh)

priyanka.jamwal@atree.org @Jamwalpriyankalaca@ceh.ac.uk @LacLaurence

mailto:priyanka.jamwal@atree.orgmailto:laca@ceh.ac.uk

Bangalore’s Lakes – The Challenge

Poor quality is threatening multiple

benefits derived from the city’s lakes:

o Groundwater recharge and quality of

borehole water

o Fisheries

o Irrigation water

o Green spaces for recreation

o Biodiversity refuge in city

Phenomenal Population Growth Inadequate STP capacity

The Problem

Solutions – Beacons of hope

Questions addressed in talk

1. What does monitoring data tell us about current status and future wastewater treatment needs?

2. What is the effectiveness of wastewater treatment?

3. Goals for lake restoration?

4. Recommendations

Bellandur Lake Untreated sewage

Jakkur LakeSewage plant AND wetland treatment

Untreated “Control” Site

Community Rejuvenation Site

Photograph: Aaditya Sood

Status of Jakkur & Bellandur Lakes

1. Water quality (BOD, DO, Pathogens)

2. Ecological health (Algae)

3. Methane and other greenhouse gas emissions

Jakkur vs Bellandur plots

Inflows OutflowsCW Inflows Outflows

Biological Oxygen Demand (BOD)

Jakkur Bellandur

Drinking Water Treatment & Recreational Use: BOD target ≤3 mg/l)

Dissolved Oxygen (DO) (Midday)

Fisheries Use: CPCB DO target >4 mg/l)

Jakkur DO (Sunrise)

• Oxygen declines at night below CPCB quality target

• Reduced habitat availability for fish

Pathogens – faecal coliforms

Inflows OutflowsCW Inflows Outflows

Jakkur Bellandur

Cyanobacteria in Jakkur Lake exceed WHO high risk threshold for recreational (bathing) use

Anne DobelPhytoplankton (algae)

Jakkur: Trophic status (Phytoplankton abundance)

Phosphate variation in Jakkur lake

P-threshold for ecological response (

Methane & CO2Stella White, Julia Drewer, Carole Helfter, Amy Pickard, Sumita Bhattacharyya

Bellandur Jakkur

0

2

4

6

Methane CO2 Methane CO2

Jakkur (close up)

Wastewater treatment also greatly reduces methane emissions

Questions

2. What is the effectiveness of wastewater treatment?

3. Goals for lake restoration?

• Upgradation of Lake STP- Additional technologies for removal of Nitrogen

• Addition of EM ‘Effective Microorganisms’ balls to reduce organic matter and nutrient loads

• Around 50 EM balls and 20 liters of EM Solution at the inlet and the outlet of lake

Interventions at Jakkur Lake

Jakkur Lake

Effectiveness of STP upgrade on inflow

Effectiveness of EM balls - Questionable

(mg/l)

(mg/l)

No significant improvement in lake water quality

(mg/l)

Aerators installed at HAL + Streams Inlet (BL3). Photographs taken on 04-02-2020

Intervention at Bellandur Lake – Aerators deployed at the Inlet

Aerators installed at Koramangala-Agara Inlet (BL4). Photographs taken on 04-02-2020

Intervention at Bellandur Lake – Aerators deployed at the Inlet

No significant improvement in lake water quality

Restoration Goals –Unclear

Restoration objectives as per detailed project report (DPR)- Bellandur Lake

• Improving trophic state (water quality).

• Enhancing recreational activities (e.g. swimming, boating, fishing, bird watching).

• Enhancing lake values (historic, conservation).

• Enhancing lake use (water source).

Effectiveness of the interventions

Use Details

Raw water source (untreated) (A)pH (6.5-8.5), BOD5 (≤2 mg/l), Dissolved Oxygen (DO) (≥6 mg/l)

Total coliforms (≤50 MPN/100 ml)

Recreation (organized bathing) (B)

pH (6.5-8.5), BOD5 (≤3 mg/l)

Dissolved Oxygen (DO) (≥5 mg/l)

Total coliforms ≤500 MPN/100 ml)

Drinking water source (treated) (C)pH (6-9), BOD5 (≤3 mg/l)

Dissolved Oxygen (DO) (≥ 4 mg/l)

Total coliforms (≤5000 MPN/100 ml)

Fisheries (D)pH (6.5-8.5)

Dissolved Oxygen (≥ 4 mg/l)

Free ammonia as N (≤1.2mg/l).

Irrigation (E)

pH (6.0 to 8.5)

Electrical Conductivity (≤2250 µmhos/cm)

Sodium absorption Ratio (SAR≤26)

Boron (≤2mg/l)

Designated Best Use - Water Quality Criteria

????

https://kspcb.gov.in/CPCB-Water-Quality-Index.pdf

C

Water Quality Index

https://kspcb.gov.in/CPCB-Water-Quality-Index.pdf

Indicator SDG Indicator Type Impact Impact SDG

Nutrients, Secchi, chlorophyll-a 6 Water Quality Ecosystem health 6.4

Dissolved oxygen 6 Water Quality Food: Fishery potential 2

Faecal coliforms and pathogens 6 Water Quality Public Health 3

Cyanobacteria 6 Water Quality Public Health 3

Mosquito larvae abundance 3 Public Health Public Health 3

Fish catch per unit effort (sustainable fishery) 2 Hunger Food: fishery sustainability 8

Macrophyte species and abundance 6 Ecological Health Well-being, crops, energy 3

Greenhouse gases 13 Climate Action Climate mitigation 13

Re-defining Restoration Targets

Sumita Bhattacharyya

PhD

Solving Bangalore Lakes problem

Step #1: Create

consensus

through

participatory lake

visioning

Step #2: Establish

quantitative/

economically

feasible

goals for restoration

Step #3: Build

an evidence-

base

of solutions and

foster learning

Step #4: Build

communities

towards an

integrated

“bluegreen-

grey water

infrastructureplan”

https://www.csei.org/insights

Technologies

Instream Treatment systems

Decentralised Treatment Systems

• Freshwater savings• Improved water quality

Improvement in water quality

Engagement with stakeholders and citizens Co-developing “Water solutions” workshop with stakeholders and business,

Engagement with Citizen Groups

http://blrlakesdashboard.org/atree/lakes/#/app/welcome

Citizen Dashboard

Solutions Workshop

Solutions for Bellandur & Jakkur

Bellandur Lake• STP treatment necessary to reduce organic

loading to reduce methane emissions and stop fire and foam

• Recovery a long-term process - CW and in-stream treatments will also be necessary. Aeration to speed up recovery

Jakkur Lake• P-recovery at STP

• Constructed wetland needs upgrading and maintained regularly

Nutrient reduction (especially P)• P-recovery at STP• Effective constructed wetlands for

NO3 removal

Solutions for reducing algal blooms

Other solutions• Aerate/mix water column to

favour more beneficial algae• Hydrogen peroxide treatment• Algal harvesting for biogas

generation

Organic Pollution

Nutrient Pollution

Restored Lake

General Recommendations

• On-going investment needed in both centralised and decentralised water treatment

• Water quality standards need to be comprehensive and updated to urban context of multiple use

• Monitoring needs to be outcome focused, not just episodic reporting

• Need for rapid, publicly available data to track water quality and ecological health

Acknowledgements

• Anne Dobel• Stella White• Carole Helfter• Julia Drewer• Amy Pickard• Dan Read• Iain Gunn

• Veena Srinivasan• Durba Biswas• Shashank• Sumita Bhattacharyya• Pavan Muttepawar• Chandan Gowda• Ramya• Richu• Malkan

priyanka.jamwal@atree.org @Jamwalpriyankalaca@ceh.ac.uk @LacLaurence

Further Information:

Dr Priyanka JamwalProf Laurence Carvalho

mailto:priyanka.jamwal@atree.orgmailto:laca@ceh.ac.uk