Investigators were able to contain much of the oily substance using specialist equipment on Friday and Saturday after reports of a leakage emerged on Thursday.Wildlife living in the area was badly affected by the spill, believed to have emanated from Riverside Park, in Huntingdon, and the RSPCA was called to rescue six swans that had been caught up in the incident. The birds were taken to a rescue centre to be cleaned. Today (Tuesday), the Environment Agency said it was carrying out tests on the pollutant to establish what it is and where it came from. Once complete, the substance will then be removed from the water along with the protective spill kits and booms. A spokesman for the Environment Agency said: We are monitoring the river pollution from Huntingdon Riverside Park. The oily substance has been captured within booms placed in the river and contained until it can safely be removed. The locks are open for navigation. We are continuing investigations to allow us to accurately identify the substance and how it was able to reach the river. We are aware of various reports via social media. If anyone has any information we would ask them to report it to our incident hotline number 0800 807060. In the immediate aftermath of the incident, access to the locks around Huntingdonshire was suspended but, with the pollutant contained, the emergency measures were lifted and boaters able to continue using the Great Ouse as normal.