Natural water treatments and ‘grey water’ schemes could be used throughout Dorset to stop or reduce nutrient pollution running into Poole Harbour.
Dorset Council has been given a £4.63 million grant by the government to help tackle the problem.
It is not only affecting the natural health of rivers and the harbour but also slowing or stopping the development of thousands of homes.
Current rules mean that both Dorset Council and BCP Council are unable to approve any building projects in a catchment area which runs into Poole Harbour unless a neutral nutrient run off can be proved.
Dorset Council planning portfolio holder Cllr David Walsh says this has already affected 2,000 Dorset homes with another 3,000 in adopted local plans likely to be affected unless action is taken.
He told Dorset Council’s Cabinet that the increased levels of nutrients, including phosphate, has led to increase algal growth in Poole Harbour, which, in turn is having an effect on biodiversity.
Cllr Walsh says that much of the nutrients comes from farm land which is being tackled by the agricultural industry and the Environment Agency, although the new grant is expected to make a big difference for building projects with their wastewater management.
Among the ideas being suggested are the creation of new wetlands which will naturally filter water.
Grey water solutions for homes might include upgrades to septic tanks and poorly performing treatment plants to deliver reductions in nutrient flows as well as improve biodiversity and water management.
The cost of these has been estimated at £100,000 for a package treatment plant serving around six homes.
A report to the council says there may also be opportunities for improvements to water efficiency in homes which further reduces nutrient levels in the outflow from wastewater treatment works.
Cabinet member Jill Haynes, who lives in the Sydling valley, suggested the water companies could do better themselves in tackling the problems.
She complained about the 24-hour pumping of wastewater into local chalk streams, including sewage, as they sought to reduce water levels after winter rain – an operation which has continued since December in the valleys north of Dorchester.
“We need to be talking much more strongly to MPs and central government to ensure that money is put into the infrastructure so we are not left to deal with run off, not just to Poole Harbour, but our precious chalk streams,” she said.
Cllr Walsh agreed water management was “a big issue” with smaller treatment works, which were common in Dorset, only needing to meet a 95 per cent, rather than 100 per cent pure water target.
He said Dorset councillors were lobbying for extra money to improve treatment works with the government currently only promising financial help for the upgrading of larger treatment plants serving 20,000 or more homes.