The Milton Country Park management Team published this notice regarding Todd’s Pit Lake:

Following confirmation from the Environment Agency that we have blue-green algae present in Todd’s Pit Lake, we are now suspending all water activity until further notice.
Blue-green algae can be toxic to people and animals so please DO NOT enter the water or allow your dogs in the lake or near the water margins.
Dickerson’s Lake is unaffected and you may still allow your dogs to swim in this lake. Fishing can continue for our members on Dickerson’s Lake, Deep Pool and Hall’s Pool only.
Those who are due to take part in a water activity in the next month or so will be hearing from us and refunds given in due course. Please bear with us as we are dealing with a high level of communications around this.
Blue-green algae is a natural occurrence which can last for weeks or even months and so it is hard to predict how long this situation will continue for. We will be carrying out further tests and will keep the public informed on progress.
Milton Country Park Management Team