Representatives of the Quarry Swimming and Fitness Forum have drawn up a 31-page response to the authority's consultation report on 'future swimming provision for Shrewsbury'.
The council's official consultation closed on Friday, with about 2,000 people responding on the issue.
In a letter submitted to Shropshire Council, the forum questions data used in its consultation.
It reads: "We have grave concerns that the options report on which the council will largely base its decision regarding the future of the pool is significantly flawed.
"The report does not consider the importance of the accessibility of the different sites, overestimates usage at the Sundorne Sports Village, underestimates demand at a refurbished or renovated Quarry Pool, and, crucially, demonstrates that the proposed two pool solution will not have sufficient capacity to meet demand over the timescales required."
The options under consideration from the council include refurbishing or carrying out an extensive renovation of The Quarry.
Alternatively, the council has put forward options where a new pool could be built on the site of the existing pool, at Shrewsbury College, at Shrewsbury Sports Village, at land off Clayton Way, or on land at Ellesmere Road.
Stephen Gillian, a member of the forum, said he hoped the council would consider the contents of the report as they look to make their decision.
He said: "A lot of people have put in a lot of effort and we have done our best to produce a well considered and researched document.
"It is something we think should be helpful to the council in making up their mind."
The report also reiterates that the location should be in the town centre.
The forum also states: "Recent pool user surveys show that there is an unequivocal preference for a town centre location."
A decision on a preferred option is not expected until February 2016.