Defra has made an ordinary drought order for South East Water covering the River Ouse and Shell Brook, after concluding that an exceptional shortage of rain threatens a serious deficiency of supplies in Sussex. The order modifies abstraction licence 21/128 and takes effect on 3 December 2025, expiring at midnight on 2 June 2026, consistent with the six‑month statutory limit for ordinary drought orders under the Water Resources Act 1991.
Two headline changes apply to the River Ouse at Barcombe. The minimum natural flow above which abstraction is authorised drops from 20 megalitres per day to 15 Ml/d. If Ardingly Reservoir falls below 45.7 metres Above Ordnance Datum, equating to usable storage under 500 Ml (the trigger level), the minimum natural flow above which abstraction is authorised falls further to 10 Ml/d.
Releases from Ardingly Reservoir into the Shell Brook are reduced while the order is in force. Both the defined augmentation release and the compensation release fall from 4,000 m3/day to 1,000 m3/day. This mirrors the winter drought permit granted by the Environment Agency on 22 September 2025, which sought to slow reservoir drawdown ahead of refill.
The order also adjusts the abstraction curve at Barcombe. Once natural flows exceed 40 Ml/d, higher daily abstraction is authorised than under the standard licence. The authorised daily maximum remains 90.2 Ml/d, but the point at which that cap is reached is reduced from natural flow over 196 Ml/d to over 184.89 Ml/d, or over 173.78 Ml/d when the trigger level at Ardingly Reservoir is reached.
Seasonal restrictions are temporarily lifted for the Upper Ouse take at Ardingly. Instead of the usual November–April window, abstraction under Schedule 4 is permitted for the duration of this order, aligning the licence with winter refill objectives already reflected in the company’s drought permissions.
The company must operate under an environmental monitoring plan set out in section 5.4 of the October 2025 Environmental Assessment Report (Johns Associates), and implement any additional monitoring required by the Environment Agency. Weekly reports to the Agency must cover monitoring results, compliance with the order and the operation of sources; records must be kept and provided on request.
Mitigation is tied to observed effects. South East Water must immediately notify the Environment Agency if indicators set out in Table 5.2 of the Environmental Assessment Report are observed during monitoring, and must implement the corresponding mitigation measures unless the Agency agrees otherwise in writing.
For clarity on liability, the order states that nothing in it authorises any event causing environmental damage for the purposes of the Environmental Damage (Prevention and Remediation) (England) Regulations 2015. Operators cannot rely on the existence of this order to appeal a remediation notice on the basis that an activity was permitted.
The measures sit alongside demand‑side actions already in place in South East Water’s area. A temporary use ban has applied in Kent and Sussex since 18 July 2025, and the company has separately applied for a non‑essential use drought order for businesses. Defra’s weekly drought updates continue to track the company’s position and reservoir storage at Ardingly.
The Secretary of State recorded that notices of the company’s application were properly published and served and that no objections were lodged. The licence, the Environmental Assessment Report and related documents are available for public inspection by appointment at the Environment Agency’s Worthing office, providing transparency on the monitoring and mitigation the company is required to deliver under this time‑limited instrument.