The Holton catchment has substantial areas of woodland, largely managed by the Forestry Commission as well as a number of attractive meadows, notably Bernwood Meadows managed by BBOWT. The brook rises in the hills south of Brill before flowing under the M40 south of Boarstall, through agricultural land and pasture to join the Thame above Wheatley. Holton Brook is a stream with a number of tributaries. It receives effluent from three small sewage treatment works at Forest Hill, Horton-cum-Studley and Stanton Harcourt.
In 2015, the Environment Agency classified the Holton Brook as “moderate”. This classification is based on multiple factors, but the main drivers of the moderate status are the phosphate, invertebrates and macrophytes. All other measured factors are currently ranked as “high” or “good”. It is not surprising that phosphate is not good in this catchment due to the three sewage treatment works and multiple septic tank systems that drain in to the Brook. The 2027 objective for the Holton Brook is “good”, including phosphate levels, invertebrates and macrophytes. We hope to work with our partners to reach this objective.
You can find out more about the classification of rivers in our catchment by using the Environment Agency’s Catchment Data Explorer.
The river isn’t the only water that we are concerned with. There are multiple small waters including ponds, ditches and steams. All of which are highlighted on the map below.
Intensive water quality surveys carried out in 2015 have shown that phosphate levels remain very high in this catchment, and concentrated from STWs. Slightly elevated levels at the top of the catchment near Boarstall may reflect the lack of mains drainage. We have worked to engage the local community to ensure that personal sewage systems are maintained to the correct level. Elsewhere some of the streams show low levels of phosphates. However, those streams that have direct connection from the three STWs, and running into the main Holton brook, all show very high levels of phosphates and nitrates. Apart from increased nitrate and phosphate levels, the Brook generally has some nice habitat with excellent potential.
We currently have limited numbers of volunteers regularly monitoring in this area, and we are particularly interested in receiving regular water quality data and Riverfly surveys. You can find out more about our volunteer monitoring and how you could get involved in monitoring yourself here.
There are currently no groups that are working specifically on the Holton Brook. If you would like to get involved by starting a local group in your area, then please get in touch.