Upland swamps are a distinctive type of freshwater wetland found in elevated headwaters of streams along the coast and tablelands of south-eastern Australia. Upland Swamps in the Sydney Basin Bioregion have been recognised as Endangered Ecological Communities and include a range of flora and fauna associated with waterlogged soils on Hawkesbury sandstone plateaus. There are ~1000 coastal upland swamps of varying size and complexity on the Woronora Plateau, NSW. Upland swamps account for ~5% of the catchment areas of the Metropolitan and Woronora Special Areas, which WaterNSW manages. These areas provide drinking water to over 5 million people across Greater Sydney. Upland swamps are important contributors to catchment hydrology because they absorb water when it rains and release runoff for long periods after rainfall has ceased. Many of these swamps overlie large deposits of metallurgical coal and are subject to longwall mining underneath. Typically, longwall mining causes fracturing of the impermeable bedrock below the swamp, causing a loss of water to underlying strata and out of the swamp. Few studies have been able to quantitatively monitor the impacts that longwall mining has on the water balance of upland swamps. WaterNSW has been advocating for enhanced recognition and protection of swamps in the Special Areas including the needs for improved modelling, monitoring and research. WaterNSW in partnership with Water Research Laboratory is conducting extensive monitoring at several upland swamps in the Special Areas, to better understand how swamps contribute to our water supply and how they help improve water quality by developing a water balance model that can be applied to other upland swamps in the area. To date we have shown how longwall mining has had an impact on the hydrology at one upland swamp, compared to nearby unimpacted swamps and no longer responds as a natural swamp.