 Balderhead Reservoir was constructed upstream of two existing reservoirs, Blackton and Hury, and added to the storage capacity on the River Balder.Construction of the Balderhead dam began in 1961 and was finished in 1964, with the reservoir being filled during 1965.The dam, which was built of compacted boulder clay and shale, is high and long, and became, at completion, the highest earth dam constructed in the British Isles.