He said the Greens wanted to stop the causes of water pollution to ensure rivers are clean, rather than just treating the symptoms.
"There's no point spending money cleaning up rivers if you don't look at what's making them dirty in the first place," Shaw said.
"We will invest in the Sustainable Farming Fund, create a Transformational Farming Partnership Fund, support organic farming and growing, and establish a 'Good Food Aotearoa NZ' national sustainability accreditation scheme so that farmers aren't left high and dry.
"Revenue for those ventures will come from a nitrate pollution levy charged on dairy farmers who continue to pollute our soils and water."
Shaw said the Greens would also accelerate depreciation on infrastructure to help farmers pay down debt and free up capital to move away from intensive farming.
"World markets are crying out for sustainably-produced food, fibre and wood, and our dirty rivers undermine the clean, green brand that 80 per cent of our exports rely on.
"Many farmers already know that we can have both healthy rivers and a healthy economy, so we're helping them achieve that."