According to the files leaks were first detected in the year the facility opened, prompting decades of ad hoc repair efforts and radioactive materials being released to trace where water was escaping.

A December 1981 report prepared by the former Commonwealth Housing and Construction Department for officials at the Capital Territory Department shows fluctuating water levels and water loss were first recorded in December 1955.

Held in the ACT government archives, the report's first volume confirms leaks were recorded more than ten times in the 1950s, 1960s and 1970s, suggesting the current leaks reported in 2012 have existed throughout the life of the facility.

In 1956 remediation work was completed on the walls and floor of the outdoor diving pool and radio isotopes were released into the water. The material was later traced as far away as the Commonwealth Avenue Bridge.

Last month it was reported technicians investigated serious leakages throughout 1981, finding water was entering a large trunk sewer under the Constitution Avenue site. Archivists this week released another section of the report, showing the effect of leaks on Lake Burley Griffin was studied in 1960.

In 1972 radio isotope tracing was again used, confirming water was still leaking into the trunk sewer, located 6.78 meters below ground level and about 7 metres away from the diving pool.

The pool was closed in March this year after about 19 million litres of water was found to be leaking annually. Territory and Municipal Services Minister Shane Rattenbury said the amount was equivalent to the loss of the entire volume of an Olympic size pool every two weeks and was costing taxpayers $100,000 annually.

More than $260,000 had been spent in recent years to stop water entering the stormwater network.

The 1981 report suggests the leaks are related to construction problems in 1954. The company contracted to build the facility went into liquidation after foundations and pipe work had begun. A later contract had to be rushed to meet the deadline for opening the pools.

"Difficulties with the technical standards of both pool contractors were recorded by the supervision," the report said.

"The facility has continued to show signs of leakage in spite of detailed and costly remedial works by the Commonwealth. A review of previous works has... indicated successful repair. However this is followed at a later time by renewed leakage."

Technicians dug about 20 boreholes in the area and found a large "leakage dome" adjacent to the diving pool. Concrete testing at 12 locations found problems from porosity, tiles were found to have "chronic lifting problems" and shoddy repairs had made some problems worse.

The pool's balance tank was found to be leaking 5000 litres each day, while leakage from the diving pool was 3700 litres per day. Officials warned previous leakage amounts had ranged from 4200 litres per day to 100,000 litres.

Repair estimates in 1981 ranged from $5000 to upgrade joints in the diving pool to $12,000 for an excavation works. New concrete slabs and other remediation would cost $80,000 and an entirely new pool would cost more than $3 million.

The report describes the leaking pool complex as in a "serviceable condition" and says the most cost effective solution is to continue with minimal repairs and "accept the cost of any losses afterwards".

Plans continue for a new aquatic centre to be built next to Lake Burley Griffin. The Civic Pool will remain operational until the new facility is opened, sometime after the next term of the Legislative Assembly begins.