Digswell Lake was made in 1810 and formed part of the Digswell House park. Then, as now, the Lake was fed by underground springs and discharged over a weir into the River Mimram.
The Digswell Estate, including the lake, was sold by the Trustees of the 7th Earl Cowper in 1919 to Ebenezer Howard, the founder of Welwyn Garden City; between the wars the lake was rented out to the local fishing bailiff who bred trout and let out rods for fly fishing. Digswell House and its lake were separated when Bessemer Road was constructed in the mid-1950s.
In 1957, Digswell Lake Society was formed and leased seventeen acres of woodland and ornamental parkland from the Welwyn Garden City Development Corporation. In 1985 the Society purchased the freehold of this area from the Commission for the New Towns