Tophill Low Nature Reserve is a fantastic 121 hectare site, flanking the River Hull near Driffield in East Yorkshire, which is owned and managed by Yorkshire Water.

Formally opened as a Nature Reserve in 1993, the site consists of two reservoirs with SSSI status for wildfowl, surrounded by a network of woodland, grassland, marshes and ponds.

Tophill Low has been identified as a Flagship Pond site by the Freshwater Habitats Trust due to the presence of UK Biodiversity Action Plan (UK BAP) priority species Greater Water-parsnip Sium latifolium. Classified as nationally scarce in the UK, and protected under Schedule 8 of the Wildlife and Countryside Act, Greater Water-parsnip, a large robust upright perennial, is found in wet ditches on fens and swamps. Once a common plant in East Yorkshire, it was believed to be extinct in the Holderness region until a small remnant population was discovered on Hornsea Mere. This was propagated on and re-introduced to Tophill Low, which is now possibly the biggest site in East Yorkshire.

The reserve is also home to good populations of amphibians including UK BAP priority species Great Crested Newts Triturus cristatus and Pool Frog Pelophylax lessonae. The Pool Frog was considered to be non-native to England before the mid 1990s when Pool Frog bones from mid-Saxon times where uncovered, along with records documenting the species presence in England prior to any known frog introductions. Tophill Low is considered to be the main site for Pool Frog in the North of England, with the main stronghold being in East Anglia.