Saturday, September 9, 2017

Alahalli Lake Report

Authored by Shreyas Sati and Alana Helin as part of the BIOME Trust Wetlands & Lakes Project

Alahalli Lake, also called Avalahalli Lake, is on 23 acres and is located in the southern part of Bangalore next to Amruth Nagar Main Road and Nandi Gardens Apartment Complex. It was observed during our visit on 8 September 2017 that the lake is not frequented by local residents but is used as a point of transit from one point to another. There is a small walking path on the northern boundary and partly on the eastern boundary which is currently submerged by water. No other amenities exist in this lake. Neither STPs nor wetlands exist in this lake. In total, there are 6 inlet points and 1 outlet from the lake. All the 6 inlets flow directly into the lake without treatment. The volume of inflow through the inlets is significant but could not be determined.


Alahalli MyMap.png

Overview and Observations
Alahalli Lake is located in Anjanapura township, Bangalore.

Lake Area
23 acres
Neither STPs nor Wetlands exist in this lake

Alahalli Lake & Neighborhood Development Trust (ALNDT), the local corporator K. Somashekar, Pavitra Foundation, PROMAC Industries, and a few residents nearby have put efforts in the direction of rejuvenating the lake. Together they have spent about Rs. 20 lakhs for de-weeding, constructing a 100 meter walking path, repair and maintenance of fences, operation and maintenance. There are six inlet points, all flowing directly into the lake without being treated, and one outlet from the lake which flows to Vaderahalli lake.

We observed that the health of the lake is very poor from the point of view of the quality of lake water. We could see algal growth on the majority portion of the water and is a breeding ground for various organisms. We also observed gas bubbles coming out of water as a result of anaerobic reactions. Along the northern boundary of the lake, from 2 broken chambers, we could see wastewater flowing into the lake through the surface of the walking path (POI 1). Due to these reasons, people may not like to use the lake for any recreational purposes.

It was also pointed out that a irrigation structure is in the lake along the western edge (POI 2). This structure was used to take water from the lake from irrigation in the past.

Despite the ongoing problems, the ALNDT is working hard to educate people in the neighborhood about the ecological benefits and the need of a healthy lake. They are also trying to mobilize resources from government authorities and private parties for rejuvenation of the lake.

The Lake
Six inlets where water would enter Alahalli Lake were identified and are summarized below.
Naala 1
Discharges directly into the lake through a culvert without any treatment from the Amruth Nagar Main Road.

Naala 2
Discharges directly into the lake under a bridge without any treatment from houses and apartments of Alahalli.

As seen in the bottom photo, a small grassy bund slows the sewage inflow and allows for some settling to occur before the water flows into the main water body.
3 & 4
Naala 3 & 4
Discharges directly into the lake through a culvert without any treatment from small houses/apartments, which are to the east of the lake.
Naala 5
Overflow from Kembathalli Lake discharges directly into Alahalli Lake through a culvert without any treatment.
Naala 6
Discharges directly into the lake without any treatment from Gollahalli.

The outlet from the lake is an open channel in the SW corner of the lake. The weir has been demolished by nearby residents who feared flooding by high water levels.
Outlet channel from Alahalli Lake

Buildup of algae on the surface was very apparent on the majority of the lake.

Near the northwest entrance, there are multiple pictures of gods placed next to a peepal tree.

The lake trust has hired two labourers for maintenance at an approximate cost of Rs 20,000/- per month. These labourers regularly use a trash boom to remove debris from the lake while on a small coracle.

No STP exists in the lake premises.

The Wetlands
No wetlands exist in the lake.

Contact Info
ALNDT Member: Anand Yadwad : +91 98802 44380,

References & Resources

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