CAG Report No. 11 of 2025 — Implementation of Smart City Mission, Government of Karnataka

Chapter-IV
56
Further, HDSCL stated (December 2023) that the Phase -I work was completed
in February 2023 and is under O&M period. In respect of Phase II, the work
order was awarded (June 2020) for ₹36.59 crore. Phase II physically 96 per
cent completed and total amount of ₹32.08 crore was paid to the contractor.
On review of the records, Audit made the following observations:
• As per the DPR and feasibility study reports, the main cause of pollution
of the lake was ingress of untreated sewage. As such, the success of the
lake’s rejuvenation depended upon arresting the sewage ingress into the
lake. The PMC, in its feasibility report, suggested diversion of sewage or
construction of STP to treat the sewage before letting it into the lake.
However, the project was conceptualised and executed without provision
for sewage diversion or construction of STP. Instead, DPR proposed in-
situ lake water treatment by providing aerators, rafters and
bioremediation44 of the lake water.
Out of four inlets to the lake, three inlets carried sewage into the lake.
During JPV (June 2024), Audit observed that ingress of sewage to the lake
from two inlets, viz., Amargol and Gamanagatti drains was continuing
resulting in foul smell and growth of Water Hyacinth (Exhibit 4.12 and
4.13).
Exhibit 4.12.: Ingress of sewage into
Unkal lake
Exhibit 4.13: Ingress of sewage into
Unkal Lake
• Enzyme usage at the sewage inlet of the lake had limited impact and could
not serve as an alternative to STPs. This was evident from the fact that
even after usage of bio enzyme the quality of the lake water (green colour
due to growth of phytoplankton) remained unchanged.
Thus, acceptance of faulty design that focused on in situ water quality
management through installation of rafters, trash barriers, bioremediation and
44 Detoxifying contaminants present in wastewater by biological means.