Smallbrook Meadows, a 50 acre nature reserve, extends for over a mile on the south side of Warminster along the River Wylye and its small tributary the River Were, also known as the Swan River. The majority of the land in the reserve comprises disused water meadows, six of them - agricultural grassland which was seasonally flooded in order to increase yields, of grass and hay - while the other main habitat is wet woodland, concentrated beside the River Wylye. Other features are a pond, some marshy areas, shallow ditches once used to irrigate the fields, an old orchard, and the rivers themselves, which are characterised by very clear water, since they flow over chalky soils, filtering out most particles.
Some of the old water meadows have become species-rich grassland, though others were subject to use of pesticides and fertilisers prior to creation of the nature reserve so here the plant diversity is much less. Notable wildflowers include southern marsh orchid, widespread in the wet meadows, heath spotted orchid, and stream water-crowfoot in the fast-flowing rivers. Bird and insect life is correspondingly varied, while water voles may occasionally be spotted.
The reserve is a popular place due to the proximity to Warminster; for walking, picnics in the summer, photography, and birdwatching. It contains over 2 miles of paths, and several hours could be spent exploring.
Smallbrook Meadows Nature Reserve is provided with a dedicated, free parking area along Smallbrook Road, half a mile southeast of Warminster town centre, approximately half-way along the reserve - to the west is the River Were, bordered by meadows and marsh, while to the east, the River Wylye, whose surroundings are more wooded. 800 feet east of the car park was once the site of Smallbrook Mill, a corn-milling operation complete with millponds, established here for many centuries, though little trace remains today. From the car park, one path heads east through the trees, staying on the north side of the river, later emerging into some rough grassland, though most visitors see only the western section of the reserve, along a wheelchair-accessible track which winds through a marshy area, past a pond dug in 1989, and across some drier grassland, to another entrance at the far side of the reserve along Weymouth Street. The westernmost fields border a boating lake and pleasure grounds, just before which is a junction with another path to the northeast that runs alongside the best wildflower meadow in the area, dotted with hundreds of orchids in the summer.