An investigation has found Doncaster Council over-ordered thousands of new street lights costing them up to £700,000.
The SMART Light project has been carried out across the borough installing around 47,000 new street lamps in two phases along residential roads and key highways.
But an internal audit shows local authority bosses over-ordered 3,743 lamps costing the council hundreds of thousands of pounds.
A report which will be discussed by councillors on the audit committee on Thursday said the 'potential loss' of over £700,000 'could have been avoided' if the project was 'better managed'.
'Further concerns' were raised around 'continued issues', a 'lack of clarity' on figures being reported to highways bosses and 'missing lamps'.
The investigation found the project had 'poor planning' and two oversight teams were in place to scrutinise the scheme but were 'hampered by a lack of documentation' regarding any challenge and action taken.
Comments also included the scheme had 'poor data quality' as the actual number and locations of lighting columns 'was not properly known' before the project commenced'.
The report added the column inventory was 'out of date and inadequate' to commence the project and It was not updated before the scheme started due to 'the pressure to actually begin the project and achieve the savings' outlined.
The council has so far spent £13.3 million on the new lights which are more environmentally friendly and will save £1.4 million a year.
The project has been largely funded by finance firm SALIX interest free.
Around 1,419 of the lamps included in the order have not yet been paid for and negotiations are ongoing with the supplier.
Nicola Frost-Wilson, internal audit manager at Doncaster Council said: "Options to recover these monies and use these additional stocks are being considered and should be firmed up by the end of August 2018. These include negotiations with the supplier to take back some of the stocks ordered, options to convert stocks for use in other lighting schemes and sales of the stocks for use in the schemes of other authorities.
"As a result, the losses identified above are not final values. As these options are still being considered and are yet to be agreed.
"While there have been substantial errors within this project, the overall value of the scheme remains positive. Additional work on the new SMART Lights is continuing and the Street Lighting Team is passing on lessons learned from the Doncaster experience to other authorities embarking on similar projects."