Sussex was on a "knife edge" today with heavy showers and strong winds poised to bring more chaos to the coast.
Flood warnings are in force throughout the county, but a new threat loomed today.
The Chichester area, devastated by massive flooding in 1994, was put on the alert for the first time.
The Environment Agency said the River Lavant springs had reached "flood trigger level".
Spokesman Ray Kemp put it bluntly: "Should there be persistent wet weather, then flooding will result."
The Met Office today said heavy showers and winds gusting to 40mph were on the way and would continue for the rest of the week. He added: "The region remains on a knife edge."
Agency hydrologists and engineers are on 24-hour alert to keep the Lavant system free from debris from the recent storm.
A multi-agency group, chaired by West Sussex County Council chief executive Paul Rigg, is already liaising to initiate emergency procedures put into place after the 1994 flood.
Mr Kemp said: "Pumping, sandbagging and road diversions will minimise disruption should flooding occur."
After the 1994 flooding the agency drew up plans to construct a new flood relief system for the Chichester and Pagham Rife valley areas.
Planning permission has been granted but the scheme is being delayed by a compulsory purchase objection.
Peter Midgley, the agency's Sussex manager, said: "Following extremely heavy rain in the last few weeks which has already brought devastation to Uckfield and Lewes, groundwater levels in the Lavant area have reached their first alert level."
West Sussex County Council will run a helpline on 01243 539970 to deal with flood inquiries.
The 1994 floods affected the Westhampnett, Hornet and St Pancras area of Chichester after the Lavant burst its banks. The disruption lasted three weeks.
Rain brought more flooding to some parts of East Sussex last night.
A section of the A272 at Buxted was under water this morning and traffic was also held up by a flood on the busy A259 at East Dean.
In Uckfield and Robertsbridge traders and residents maintained their sandbag defences in case rivers burst their banks again.
Both towns escaped further damage.
Most schools forced to close due to storm damage were reopening again today.
The Environment Agency has issued flood warnings for the River Arun from Billingshurst to Pulborough and Arundel to Littlehampton, the Rother from Midhurst to Pulborough, the Adur from Henfield to Upper Beeding, the Ouse from Lindfield to Isfield and Isfield to Barcombe, the Cuckmere from Alfriston to Exceat, Langney Haven, and Coombe Haven.
A severe flood warning has been issued for the River Rother at Mayfield.
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