Research over the next four years will examine the impact of nutrients flowing in from surrounding catchments and how to prevent an influx into the system.

Their work will inform ACT government investment in improving the health of the lake, thanks to $1.5 million in research funding.

Professor Fiona Dyer said, in addition to toxic algal species preventing access to the lake for months at a time, there was global concern that living in close proximity to algae increased instances of motor-neuron disease.

"There's very much a public-health risk associated with the algal blooms," Professor Dyer said. "And we also lose the lake as an amenity."

The study will look at how run off from private and public spaces, including roofs, streets and sport fields, impacts lake health and the best measures to prevent it.

Professor Dyer said a pilot study of water entering a Tuggeranong catchment from a sport field showed high concentrations of nutrients coming off the grounds.

"We fertilise these sports fields to make them great for playing sport on but the question is, 'could we optimise the amount of fertiliser that's used on them so it's mostly taken up by the grass?'," she said.

Professor Dyer said, prior to University of Canberra's initial waterways study five years ago, the assumption was that nutrients had built up in Lake Tuggeranong over the 50 odd years since it was constructed and that was causing the blooms.

Their research showed there was five times as much nutrients coming into the lake as what had built up over time.

"So you've got this constant supply of nutrients coming into Lake Tuggeranong that are pretty much driving those algal blooms in the system. Until you stop what's coming in from all the streams that are feeding the lake itself, you're not going to make any difference to those algal blooms," Professor Dyer said.

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The research grant is part of a significant ACT government funding boost to the ACT Healthy Waterways program, with an additional $14 million committed through to June 2023.

The funding will allow construction of 11 water-quality assets in Belconnen and Tuggeranong, two areas where waterways were identified as having declining levels of health in 2021.

Infrastructure will include floating wetlands to remove pollution, in addition to the three built since June last year.

Money will go towards engaging with landowners to reduce fertiliser use in catchment areas and expanding the activities of a community-based program, The Leaf Collective, that helps prevent leaves and grass clippings from polluting storm water.

Its program will be expanded across Canberra and will continue until June 2023.

Minister for Water, Shane Rattenbury said continuation of the waterways program would deliver positive outcomes for the environment and for community wellbeing, and was part of the plan for a sustainable, resilient and liveable Canberra.

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