Flooding at Winchester City Mill
There has been a mill present on the site since at least the early 900’s, the current building was largely restructured in 1744. The City Mill is the oldest working water mill in the country. The Mill forms a natural bottle neck before the city bridge, constricting the main flow of the river into two channels which flow through the building and which provides the power for the waterwheel and machinery to operate.
But as much as the river is our friend, it can also be our foe.
The heavy rain fall over the winter of 2013/14 had a catastrophic impact throughout the UK. Here in Winchester, the City Mill straddles the main channel of the River Itchen as it passes through the City, funnelling the river into a bottle neck beneath the building and enabling us to harness the power of the river to turn the mill’s waterwheel.
Changes to the river levels are very important for us to monitor and it was with concern that we watched water levels along the River Itchen begin to gradually rise during December 2013. Following the heavy rainfall, which came with the severe storms over the Christmas period, the water meadows along the Itchen basin soon reached capacity. By 11 January, the river level was already too high to enable our volunteer millers to safely engage the mill machinery. In a matter of days, the flow level beneath the mill rose dramatically, washing up over the whole lower mill floor and flooding into the Mill’s island garden.
As the levels continued to rise throughout January, a major flood alert was declared in Winchester. The whole lower floor at the City Mill was completely underwater and we were forced to close the main museum due to the potential risk of damage to the building’s ancient structure. By 14 February, the river reached the highest level ever recorded locally by the Environment Agency.
Thankfully, by the last week of February, the levels upstream began to gradually recede and the flood alert was lifted in Winchester. Despite this, the river level here at the Mill remained dangerously high throughout March and in to April. By mid-April, we were able to undertake a structural survey to assess the damage to the building, the waterwheel and the mill machinery.
Repairs to the damaged waterwheel were finally completed on 18 April but the building suffered significant structural damage from large amounts of debris getting caught up beneath the building.
The repairs to the building has also included bringing forward a major project to replace the Mill’s weed screen, as well as major structural repairs to the lower floor which include replacing a 150 year old beam and pillar strut damaged by debris impact.
Now, in 2019, we're working with the Environment Agency to prevent potential damage in the future. The National Trust has pledged to fund the immediate flood resilience measures and any on-going work which will alleviate any risk of damage to the Mill during the next significant flood event.