The Beas Project, comprising two units namely, Unit-I – BSL Project and Unit-II – Beas Dam, is a part of the Master plan for the utilisation of the waters of the three eastern rivers viz. the Satluj, the Beas and the Ravi for irrigation and power-generation in an integrated manner. With the completion of Bhakra-Nangal Project, the waters of the Satluj (average flow 16,652 million cum or 13.5 million-acre feet) were fully harnessed. With the help of the existing Madhopur-Beas link which transfers, on an average, 2344 million cu m (0.9 million acre feet) of Ravi waters to the Beas, the Beas dam at Pong together with the Bhakra Dam enables India to harness about 92% of the average inflow of the three eastern rivers. With the completion of Beas-Satluj Link project, the figure has further risen to 97%.

The agency of departmental construction, initiated at the Bhakra Dam, was adopted for the construction of the Beas Dam also. Punjab Government constituted the Beas Control Board in 1961 to exercise efficient technical and financial control over all matters pertaining to the construction of the project. Consequent upon the re-organisation of the Punjab in 1966, the execution of the Project was vested with the Government of India, on behalf of the Partner States, who reconstituted the Control Board and named it as ‘Beas Construction Board’ (BCB).

The ‘Beas Construction Board’ under the Chairmanship of the Union Minister of Energy comprises, besides a full-time Secretary, headquartered at New Delhi, the Chief Ministers, Punjab, Haryana, Rajasthan and Himachal Pradesh; one Minister each from the States of Punjab, Haryana, Himachal Pradesh and Rajasthan; Deputy Ministers, Energy and Irrigation Government of India; Secretary, Department of Power, Ministry of Energy, Government of India; Secretary, Irrigation, Ministry of Agriculture and Irrigation, Government of India; Chairman, Bhakra and Beas Management Board; Chairman, Central Water Commission; Member (Hydro-Electric), Central Electricity Authority; Joint Secretary, Ministry of Energy, Government of India; Financial Adviser and Joint Secretary, Department of Power, Ministry of Energy, Government of India; Secretaries, Irrigation and Power, Punjab, Haryana and Rajasthan; Secretaries, Finance, Punjab, Haryana and Rajasthan; Secretaries, Colonization and Revenue, Rajasthan; Financial Commissioner-cum-Secretary, Revenue Department, Himachal Pradesh; Chairmen, State Electricity Boards, Punjab, Haryana, Rajasthan and Himachal Pradesh; General Manager, Beas Project; Financial Adviser and Chief Accounts Officer, Beas Project; Chief Engineers, Irrigation Works, Punjab and Haryana; Chief Engineers, Electrical (Power Stations and Transmission), Beas Project; and the Chief Engineer, Rajasthan Canal Project. A Board of Consultants for Beas Project was constituted under the chairmanship of Dr.A.N.Khosla consisting of some most eminent and experienced engineers from within the country and outside. The present scheme was gradually evolved through a detailed and systematic study of the various alternatives after seeking advice from United States Bureau of Reclamation (USBR)

The concept of Beas-Satluj link for diverting some water of river Beas into Satluj through two tunnels and an open channel to generate power and to increase the storage capacity of Bhakra reservoir (Gobindsagar) was conceived by Dr. A.N. Khosla, a brilliant engineer and dynamic leader in the profession and a close and trusted confidant of Jawaharlal Nehru.

The preliminary investigations for Beas Satluj Link Project were started in 1956, which led to the preparation of a preliminary Project report by the Project Organisation of the Punjab Irrigation Branch in November 1957.

The investigation work was taken up by the Project Circle of Punjab Irrigation in 1956 and a Project Report with a limited scope for providing irrigation to the Southern Punjab was accordingly prepared by the Project Administration of the Irrigation Branch. Punjab in November, 1957. This project was intended to form the first stage of the bigger scheme, which in its final stage envisaged construction of a 213.36 m (700 ft) high dam on the Beas River at Larji. The entire scheme was to be completed in three stages.

• Diversion Dam at Pandoh
• 11.26 km long tunnel from Pandoh to Riggar
• 19.31 km long open channel from Riggar to Sundernagar
• 4.824 km long tunnel from Sundernagar to the Alsed khad near the Malindi village.

In the second stage, the tunnel from Sundernagar to the Alsed khad was proposed to be extended to the power plant site on the right bank of the Satluj River. The power house was also to be constructed in this stage. In the ultimate stage, it was proposed to construct dam at Larji. However, the construction of a 213.86 m (700 ft) high dam at Larji was subject to its technical and financial feasibility.

Another proposal for the Beas Satluj Link was prepared in January, 1960. The proposal envisaged :

• A 131.06 m (430 ft) high concrete arch dam across the Beas River just below the junction of the Uhl River, about 6.43 km (4 miles) upstream of Mandi Town.
• 7.0 km long twin diversion tunnels for a total capacity of 849.5 cumecs discharging into the Suketi Reservoir.
• 134.11 m (440 ft) high earthern dam on the Suketi khad to create a reservoir in Suketi Valley.
• 14.966 km long twin power tunnels from the southern end of the Suketi Reservoir to the power plant on the Satluj River.
• A power plant with installed capacity of 1200 MW on the Right Bank of the Satluj River. The scheme had the potential to develop 625 MW of firm power at 100 percent load factor at the Satluj Power Plant and a live storage capacity of 3080 milion cubic metres (2.5 million acre ft) in the Suketi Reservoir, besides meeting the additional irrigation needs of Southern Punjab from the Bhakra Reservoir.

The proposed Suketi Reservoir covered an area of about 9308 hectares (23000 acres) in the Balh Valley and the fact of its submergence was viewed unfavourably by the Government of Himachal Pradesh. However, the scheme was abandoned because the feasibility of 134.11 m (440 ft) high dam in the seismic zone could not be properly established with the data available. Further studies indicated that a dam of 99.06 m (325 ft) height with a live storage of 1233 million cubic metres(1.0 x 106 acre ft) would submerge an area of 6475 hectares (16000 acres) only and would still retain a substantial power potential. Moreover, it was considered feasible to construct a rockfill dam of this height. But, on account of the objection of Himachal Pradesh Government to the submergence of the Balh Valley, this scheme was also held in abeyance.

The problems mentioned in para 3.1.1 and 3.1.2 indicated the necessity of having a direct link from the Beas to the Satluj River without any reservoir in Suketi Vally, so as to meet the immediate irrigation needs of erstwhile Punjab (now Punjab & Haryana) and to develop the optimum power potential at Bhakra, Pong and Satluj Power Plants. These power plants working in a grid would have given a total firm power of 733 MW. Such a scheme as a whole offered the best combination of works for the diversion of the Beas waters to the Satluj River without submerging the Suketi Valley. It was proposed to be completed in two stages. The first stage provided the work upto the Bumka/Bharari link, thereby the Beas water could be taken to the Satluj River through the Alsed/Bharari khad for additional irrigation and power from Bhakra Reservoir. The second stage provided the completion of Sundernagar Satluj Tunnel and the Satluj Power Plant for additional power from the 304.8 m (1000 ft) fall available at the tail end of the Beas Satluj Link.

• 42.67 m (140-ft) straight gravity type concrete diversion dam above river bed, 13.00 km upstream of Mandi Town.
• 7.62 m dia, 12.84 km long Pandoh Baggi Tunnel for a design capacity of 254.85 cumecs.
• 11.59 km long hydel channel with a capacity of 254.85 cumecs in head reach and 233.62 cumecs in remaining reach.
• Balancing reservoir of 6.165 million cubic metres (5000 acre ft) capacity at tail end of hydel channel or in Bumka Nalah.
• 8.53 m dia, 13.68 km long Sundernagar Satluj Tunnel for design discharge of 212.376 cumecs (7500 cusecs).
• Bumka/Bharari By-pass Link.
• 21.95 m dia, 76.2 m high differential type surge shaft with an internal riser of 7.62 m diameter.
• Satluj Power Plant on the right side of Satluj River with an installed capacity of 636 MW (Units of 106 MW each).

The features of the proposal of the final scheme as adopted for construction are as below: -

• Pandoh Dam: An earth-cum-rock fill type 76.25 m (250 ft) high diversion dam at Pandoh. Pandoh Dam – Top View
• Panodh Spillway: An orifice type gated chute spillway having 9939 cumecs (351000 cusecs) discharge capacity at maximum reservoir level 896.417 m (2941 ft) with flip bucket type energy dissipator at its downstream end. Pandoh Dam - Spillway
• Pandoh Baggi Tunnel: A 7.62 m finished dia, 13.11 km long tunnel with a design capacity of 254.85 cumecs. Baggi Control Works
• Sundernagar Hydel Channel: A 11.80 km long hydel channel. Sunder Nagar Hydel Channel
• Sundernagar Balancing Reservoir: A balancing storage of 3.7 million cubic metre capacity near Sundernagar.
• Sundernagar Satluj Tunnel: A 8.53 m finished dia, 12.35 km long power tunnel with design capacity of 403.52 cumecs.
• Surge Shaft: A 22.86 m main shaft, 125 m high Surge Shaft having riser of 7.62 m diameter.
• Dehar By Pass: A 6.71 m finished dia, 296.8 m long by pass tunnel followed by a chute of 533.4 m length with design discharge capacity of 212.376 cumecs.
• Dehar Penstocks: Three penstock headers of 4.877 m dia and each header bifurcating into two branches of 3.353 m dia.
• Dehar Power Plant: A power plant on Right Bank of Satluj river with installed capacity of 990 MW i.e. 6 units of 165 MW.

The idea of a storage dam across Beas River at Pong was first mooted by Mr. C.E. Blaker of the Punjab PWD Irrigation Branch in 1926. A committee, led by Mr. A.J. Willey, Consulting Engineer, to the United States Bureau of Reclamation, Dr. P.S. Pinfold, the Chief Geologist to Attock Oil Co., and Mr. W.H. Nicholson, Superintending Engineer of Punjab PWD Irrigation Branch was appointed by Punjab Government in 1927 to report on the possibilities of storage of surplus waters of the Punjab rivers and their tributaries. The committee, on the basis of Mr. Blaker’s report, recommended that in view of high floods which were likely to occur at that site, an economical storage would be difficult to arrange. The committee was also of the opinion that in view of the soft, though uniform foundation a shingle and boulder embankment might prove to be the most practicable proposition.

Interest in storage on the Beas was revived in 1955. Geological, hydrological, material and other investigations were accordingly carried out, resulting in preliminary report on the Beas Dam Project. In this report, an earth dam having live storage capacity of 6764 million cubic metres and dead storage of 925 million cubic metres was proposed. The dam was visualized to be an earth-cum-rockfill structure with a concrete spillway section. No power generation was contemplated in this preliminary report. Nevertheless, the power potential of the project was recognised.

Later on, after carrying out further investigations a more detailed report for the Beas Dam at Pong was prepared and submitted to Punjab Government in 1959. In this report, an earth-cum-rockfill dam, 100.6 m high above river bed level, was proposed alongwith a hollow butteress type concrete dam, with an overflow spillway. No power generation was envisaged at that stage although provision was made for the installation of two power penstocks in the non overflow section of the concrete dam.

Subsequent to the preparation of 1959 project report, considerable work on geological explorations, investigations for materials, preparations of preliminary designs, comparison of the economics of various types of layout of appurtenant works etc., was carried out. The Board of Consultants under the Chairmanship of Dr. A.N. Khosla, comprising some of the most eminent engineers from within the country and abroad contributed towards finalisation of project proposal. The advice of United States Bureau of Reclamation was also sought on various features of the project. Numerous hydraulic model tests were conducted at Central Water & Power Research Stations, Poona and Irrigation & Power Research Institute, Amritsar, as an aid to designs. The final scheme was gradually evolved through a detailed and systematic study of the various alternatives.

The Proposal of features of the final scheme as adopted for constructions are as below: -

• Dam: An earth-core-cum-gravel shell dam is 132.59 m (435 ft) above the deepest foundation level and 100.58 m (330 ft) above the deepest river bed. Beas Dam at Pong
• Diversion Works: The construction of the dam involved diversion of the river through five cement concrete lined tunnels which have been designated as T1, T2, P1, P2 & P3 from left to right. These tunnels each of 9.14 m (30 ft) finished dia, have an aggregate length of 5022.80 m.
• Outlet Works: Permanent intakes alongwith trashrack structures, etc., have been provided on bench at El. 374.90 m. The gates are normally operated from the control chamber floor at El.343.66 m and can also be operated from the hoist house, located above El.435.86 m in case of emergency. Each control chamber is connected to the hoist house through a vertical shaft. Upstream View of Beas Dam
• Penstock Works: Each of the three penstock tunnels P1, P2, P3 is equipped with 3.048 x 6.401 m (10 x 21 ft) fixed wheel type emergency gate operated by a hydraulic hoist of 150 tonne capacity. The gates are operated from hoist structures located on top of the dam, which are connected to the tunnels by means of vertical shafts. Downstreams of emergency gates, steel penstocks of 7280-mm inner dia have been installed in each tunnel of 9.14 m dia. Butterfly valves are provided at downstream end of each penstock branch.
• Spillway: An overflow type, gated chute spillway, with a discharging capacity of approximately 12375 cumecs (437000 cusecs) at the highest flood level El.433.121 m has been provided on the left abutment. Beas Dam - Spillway
• Pong Power Plant: Pong Power Plant (360 MW) is a multi storeyed re-inforced concrete framed structure having 143.04 m length 33.11 m width and 43.48 m height, located in the stilling basin downstream of penstock tunnels. Pong Power House
• Switch-Yard: The 220 kv switch-yard has been located close to the power plant to its right. Generators are connected to 3 phase step-up transformers for stepping up the generation voltage of 11 kv to 220 kv.