Months after great crested newts forced delays to work on Ilkeston Station, flooding concerns have set it back again, pushing opening to late 2015.
Erewash MP Jessica Lee has called the county council's reason for delay "woefully inadequate".
Flooding risks in the car park had not been "foreseen" at the time the plan was submitted, the county council said.
Work was originally due to start in June but higher than expected numbers of newts - a protected species - were found at the site, pushing back the start date to this month.
The county council has now announced Â£3m of additional work is required to raise the car park by three metres and build drains and culverts to alleviate flooding in extreme weather.
Councillor Andy Botham said the cost of the work cannot exceed the Â£9.1m allocated for the project and work will not start until savings or a "cheaper solution" is found.
He said he expects work to start in the spring.
"Building a train station is a complicated business. We have had to look at the flood prevention work which we hadn't foreseen," he said.
But Ms Lee said it was "well-known" the area floods and the council should have factored that in.
"Either Derbyshire County Council are using this as an excuse or they are incompetent. Either way, they are letting local people down.
"People are not stupid and will see this as a woefully inadequate reason for delay," she said.
She said she is raising the matter directly with Transport Secretary Patrick McLoughlin.
Ilkeston is thought to be the largest town on the rail network without a station.
Work to build a new railway station in Derbyshire has been delayed for a second time.