Floating Solar on an Irrigation Reservoir Upstream of a Ramsar Wetland
A state renewable energy corporation proposes a 60 MW floating solar plant on a 340-hectare irrigation reservoir, covering 100 ha (about 29 per cent) of the water spread with anchored pontoon arrays. The reservoir irrigates 12,000 ha of command and supplies drinking water to two towns. It lies 4.5 km upstream of a wetland notified as a Ramsar site and within the eco-sensitive zone of a wildlife sanctuary whose boundary is 1.1 km from the shoreline; the reservoir hosts wintering waterbirds. The utility states that solar photovoltaic projects need no environmental clearance and wants to start anchoring before the monsoon, because the drawdown period is the only window for bottom anchoring. Fisherfolk cooperatives hold fishing leases in the reservoir. The 220 kV evacuation line crosses 2.3 km of revenue forest land.
1. Solar PV is generally outside the list of projects requiring prior Environmental Clearance under the EIA Notification 2006 as amended. Explain why that does not settle the approvals question, and set out the clearances that must precede anchoring.
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An EIA exemption is only one gate. It does not displace other statutes, each with its own authority and trigger:
- Wildlife (Protection) Act 1972, sections 29 and 33A: any activity in a sanctuary or its eco-sensitive zone needs Wild Life Board/NBWL clearance. At 1.1 km from the boundary, the site is inside the eco-sensitive zone.
- Eco-sensitive zone notification under the Environment (Protection) Act 1986: the specific prohibited and regulated list for this sanctuary governs construction, anchoring and lighting.
- Forest (Conservation) Act 1980: the 2.3 km forest stretch of the evacuation line needs stage-I and stage-II clearance, or rerouting. Record any rights under the Forest Rights Act, including Gram Sabha consent.
- Irrigation and dam-safety authority: permission to occupy the reservoir surface, with mooring loads, clearance from the spillway, intake and dam crest, and drawdown-rated anchors. Check applicability of the Dam Safety Act 2021.
- State Pollution Control Board: consent to establish and operate for construction-phase discharges, sewage and diesel generating sets.
- Fisheries department and lease-holders: a written arrangement on access, netting lanes and compensation.
- Electrical Inspectorate/CEA: approval of the evacuation scheme.
Sequence these before anchoring; the monsoon window is a scheduling convenience, not an exemption.
2. Assess the ecological and operational consequences of 29 per cent surface coverage and recommend design and monitoring conditions, including whether a phased build-up is justified.
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Ecological: large coverage cuts wind-driven mixing and light penetration, so surface temperature rises and dissolved oxygen can drop, favouring algal blooms; littoral sediments are disturbed by anchors in the drawdown zone; open-water waterbirds, which the Ramsar values depend on, avoid cluttered water; fish assemblage and fishing grounds shift. At 29 per cent, these effects are large enough that they cannot be assumed harmless.
Operational: arrays near the intake or spillway are a trash and safety hazard; moorings must be designed for the full drawdown range and flood flows; cables at low water and maintenance-boat access need a year-round plan; evaporation savings claimed at full coverage are reduced by the gaps actually left.
Recommendation: cap coverage at roughly 10–15 per cent of water spread, keep a 100 m littoral margin and 300 m clear of intake, spillway and dam crest; build in two 50 ha phases, with a mandatory review before phase two; collect two years of baseline dissolved oxygen, temperature, chlorophyll and bird counts, then monitor quarterly; agree numeric triggers (for example, dissolved oxygen below 5 mg/L or a defined bird-count decline) that require a block to be de-moored. Phasing costs little compared with a stranded asset or a stop-work order and preserves the option to stop.
3. The utility argues that the drawdown window forces immediate anchoring. How do you sequence the project, and what is the core recommendation?
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Split the project so the statutory chain and the physical window stop competing.
- Onshore works, the pooling substation, and the evacuation line go first. Reroute the 2.3 km forest stretch now, since forest clearance is the longest-lead item and the cheapest thing to avoid.
- In parallel, commission a full-year ecological and hydrological baseline that includes a complete drawdown cycle, and file the wildlife and eco-sensitive zone application.
- Anchor only after the wildlife clearance and irrigation permission are in hand, using a single-season pilot block of about 10 ha rather than the full 100 ha.
- Negotiate the fisheries arrangement and the drinking-water priority protocol before any pontoon is placed.
Core recommendation: do not let a physical window dictate the legal and ecological sequence. Quantify the cost of a one-season delay against the cost of a stop-work order after anchoring - demobilisation, mooring removal, litigation and the loss of the pilot's learning. A one-year slip in a 25-year asset is small; an illegal occupation of a reservoir inside an eco-sensitive zone is not recoverable. State this arithmetic explicitly in the note.