NicolasL

I’m not saying that grey water discharge is causing fish to die. However, there has been a big fish death event in west London in the past week (see picture of part of the clean-up). I am wondering about two things: 1. To what extent the housing crisis in London (which has led to many many more boats mooring alongside the towpaths bowtostern on canals such as the Paddington branch with no locks for many miles) is aggravating pollution levels? Is grey water really an issue? Is sufficient research being done and acted upon? 2. What more can CRT do given the eutrophic conditions (for whatever reasons) creating smelly and unsightly duckweed-covered and polluted canals. In west London year by year duckweed levels have increased notably.

Unfortunately I haven’t found much research but there is a detailed study of water quality in Regents Canal. I have copied the conclusion below. You can get the full paper via a link at the end of this post. 2017 study. 8. Conclusions and Recommendations There is no doubt that the water quality in the Regent’s Canal is extremely poor as seen by the observed results of physical-chemical water quality parameters. The results of the analysis highlight the fact that the Regent’s canal water undergo nutrients catchment and algae blooms increasing. The rate of chemical reactions increased, and the solubility of gases decreased in water due to the higher temperature. The excessive pH value (Table 4) indicates that the characteristics of the Regent canal water are alkaline. The alkalinity of water mostly shows that the concentration of carbonates, bicarbonate and hydroxide present in water which may include phosphate, silicates and other compounds. The higher pH value in watercourse may result in eutrophic water and groundwater brine (Chapman, 1996). The observed pH value indicates that the eutrophication process is gradually increasing in the Regent’s Canal water. According to the Hampstead London weather (2017) report, the mean temperature over the period was approximately between 15 °C and 19 °C, but the Regent’s Canal water temperature was recorded higher which is lead to plant growth and algal blooms (Figure 15(b) and 18 (b)). The Regent’s canal water is polluted because of conventional Drainage Systems in London. The Regent’s Canal water bodies are continuously receiving significant quantities of polluting substances from streets, pavements, and roads. The proposed best feasible SuDS component can tackle this water pollution problem by holding back the peak rainwater volumes and reducing the “flushing” effect on the drainage system (London Sustainable Drainage Action Plan, 2015). The measured excessive phosphorous in the Regent’s canal indicates that the Regent’s Canal water is polluted. The eutrophication process occurs in water due to the high concentration of phosphorous. According to the OECD (2008) report, the high concentration of phosphate in water is associated with Eutrophication process. In figure 15(b) and 18(b) shows that the algal blooms are gradually increasing due to the excessive presence of phosphorous in the Regent’s Canal water. Though, nitrate concentration level variate from one site to another but an overall concentration of nitrate was found lower than the expected level which is a positive outcome. Consequently, the organisms in the Regent’s Canal water becomes more stressed because of low solubility dissolved oxygen in the water. There have been several issues identified which are associated with water quality deterioration in the Regent’s Canal. Currently, London has around 47% green space which include 33% parks, woodland and farmlands and 14% private parks and domestic gardens but about 40% surface area is impermeable and 12% surface area consists of roads and streets (London Environmental Strategy, 2017). A growing trend of the total or partial demolition of old factories and warehouses which are replaced by new developments on the side of the Regent’s Canal in Islington site, there by altering the character of the water. The Hackney Council should take initiatives for the conservation of the Regent’s canal water quality. The urban development in London is significant causes of the loss of green space, the expansion of impermeable surfaces used for roads, roofs, pavements and increasing the risk of flooding (London Environmental Strategy, 2017). Sustainable Drainage System should be designed and implemented to mitigate the risk of local flooding, reduce pollution, increase green space and improve water quality (London Borough of Tower Hamlets, 2017). SuDS design, construction and long-term maintenance will help to achieve less runoff into the Regent’s Canal water and reduce the discharge of polluted water into water bodies through Combined Sewer Overflow (CSO) spills. The WFD suggest that contamination should be measured and regulated before discharge into watercourses (Ellis et al., 1985). Furthermore, new developments and re-development projects in Tower Hamlets, Islington, and Camden needs to be controlled by local Council. The local authority should be employed Sustainable Drainage System (SuDS) and implement legislation to control water pollution (Howell & Mackay, 1997). The Environmental Agency is not aware of the specific pollution problem associated with heavy metals, sewer misconnections and biological pollutions. In addition, The Environmental Agency should take effective action to enforce legislation or any effective monitoring system to back up that legislation (Faulkner et al., 1999). The Greater London Authority (2017) can act as a powerful advocate to find out the issues, set out policies and proposals and take effective action. Further investigations should be made to find out the sources of reactive phosphate and the reason of higher pH and temperature level than expected level in the Regent’s Canal. The five different boroughs along the canal should avoid to green space cover; reduce storm water runoff rate by using sustainable drainage system to mitigate water pollution. For example, the local authority should employ best feasible SuDS such as retrofit, Bioretention planters and Raingardens etc. The Bioretention planters and Raingardens designs collect runoff through an inlet or across a flush edge. The highway authorities should maintain SuDS in public road surface according to national standards requirements (London Borough of Camden SFRA, 2014). Further monitoring needs to cover seasonal variation and the best feasible SuDS approved by the SuDS Approval Body (SuDS Manual, 2007). Dumping is another kind of pollution source which is directly linked with human activity. In the above figure 12(b), 15(c) and 18(b) shows that people are dumping rubbish frequently into canal water. So, public behaviour and attitude should change, participation and awareness on the environment is the most key factor to reduce water pollution. However, it is tough to change people behaviour and attitude in short time. The best feasible method to prevent water pollution is to stop discharge of untreated water into the watercourse. Consequently, the remediation and mitigation process will be time-consuming and expensive. So, the new and practicable SuDS design techniques will aim to reduce the phosphate level, stop eutrophication and algae blooms in the Regent’s Canal water. https://www.google.co.uk/amp/s/www.researchgate.net/profile/M_Ali27/amp

It seems to be standard practice for boats to discharge grey water directly into the canal. Fairy liquid and many cleaning products are toxic to fish. This week we’ve witnessed thousands of fish dead in the Grand Union in West London. CRT is “investigating”. Academic water quality research has shown that London canals are highly polluted and boat discharges have vastly increased in the past few years. It seems that pollution from solid bow-to-stern temporary mooring is killing the canal and fish. Duckweed proliferates in phosphorous rich water. What can be done?