Many of us actively work to ensure we create and maintain a healthy habitat for wildlife across the country, particularly in our area and in Cranleigh’s Waterways. We start with the most fundamental element: the water in the rivers, streams, ponds, and lakes. Good quality water fosters an environment where invertebrates thrive, supporting small and larger fish, and providing drinking water for mammals and birds. By prioritizing water quality, we unlock the potential for everything else to flourish. You can dive deeper into this topic by clicking here.
A group of dedicated individuals, backed by Surrey Wildlife Trust and The River Wey Trust, actively monitors and improves the wildlife habitat in the area by testing the water in various waterways around Cranleigh. The group extends their thanks to Councillor Liz Townsend for her support in funding the test kits. They employ a testing system developed in Canada by Water Rangers, a not-for-profit organisation (not to be mistaken for Power Rangers!). This group has successfully trained over 25,000 people and collected more than 200,000 data points from over 5,000 water bodies. Learn more about Surrey Wildlife Trust by clicking here and about Water Rangers here.
Volunteers conduct water tests that include qualitative assessments of Cranleigh’s waterways—checking color, opacity, and surface scum alongside quantitative measurements like hardness, pH, phosphate content, and nitrate content. Armed with a small kit, they venture out monthly to take measurements and input the data into a computer system, which is then analysed by post-graduate students at Surrey University.
This identifies patterns and trends, enabling us to detect variations in readings along stream flows and pinpoint the sources of unexpected results. For those who love digging into data, the system also allows the extraction of detailed information. Below, an example illustrates the trends at a specific location, where peaks in phosphate and nitrate levels stand out clearly.
Some Results So Far…
An example of Data from the Dashboard can be seen above, but the Cranleigh Water Rangers have made various other findings within Cranleigh’s Waterways.
Redcroft Walk: Monitoring at this location identified a spike in nitrates within the water along with an increase in conductivity. Increased conductivity in waterways is usually due to high concentrations of chemicals dissolved in the water.
At Knowle Park, an increase in conductivity and alkalinity was detected within the water. Alkalinity measures the amount of calcium carbonate within the water. It is important as it provides an indication of how much change in acidity the water is able to buffer. Fish and other aquatic animals rely on water being within an acidity range that they can tolerate.
The team have reported their past findings to Surrey Wildlife Trust. An increase in volunteers would allow for more consistency in testing and reporting. Where spikes in chemicals are found the Environmental Agency will come out and retest to validate findings.
If you are interested in viewing the condition of these waterways, you can do so on the Water Ranger’s website Here. A Dashboard and interactive map can be found with all tested submissions from the waterways in Cranleigh.
Challenges and Problems for our Waterways
Two of the primary challenges for water bodies when striving to maintain a good wildlife habitat are Nitrates and Phosphates.
Agriculture drives the majority of nitrate inputs into water, accounting for about 70% of the total, while sewage effluent follows as a secondary source, contributing 25 to 30% nationally. Nitrate concentrations typically peak in the drier, arable-heavy southern and eastern regions of England. It is also important to note that nitrates are added naturally to water from rotting vegetation.
Nitrates sometimes climb to toxic levels, hindering aquatic animals’ ability to survive, grow, and reproduce. Nitrate pollution also disrupts freshwater chemistry by reducing dissolved oxygen concentrations, which can promote the formation of reduced compounds like hydrogen sulphide, amplifying toxic impacts on aquatic life.
Phosphates enter into waterways from human and animal waste, phosphorus-rich bedrock, laundry and cleaning wastewater, industrial effluents, and fertilizer runoff. When too much phosphate accumulates in the water, algae and weeds explode in growth, potentially choking the waterway and depleting vital dissolved oxygen. This happens as algae and plants die off in the absence of photosynthesis and aerobic bacteria consume them. The fallout can kill off fish and aquatic organisms—not from elevated phosphate levels or poisoning directly, but from the chain reaction of algal overgrowth and the subsequent plunge in dissolved oxygen.
In the Cranleigh area, 10 volunteers actively monitor water quality at 11 locations, logging 131 observations since November 2023. This is typically over the last weekend of the month, ensuring the data aligns across the region for meaningful correlation.
How does this impact you?
The reduction in wildlife variety in Cranleigh’s Waterways immediately impacts residents and visitors to Cranleigh by limiting the creatures they can see. Decreasing biodiversity threatens the area’s overall appeal. Harmful bacteria, viruses, and parasites building up in the water can cause health issues, with children often facing the greatest risk. Potentially toxic chemicals accumulating in our waterways may potentially contaminate drinking water, and many of these toxins can trigger long-term health problems.
The interconnectedness of these watercourses increases the cost for Thames water to treat. A further issues arises in that not all of their treatment works have the correct filters. As waterways are monitored and cleaned the need for these filters are reduced.
The Water Rangers actively ensure that a spike in pollutant concentration within the water supply gets identified early. Then action is taken to determine the source and take reasonable actions to prevent future contamination.
How are the Tests Undertaken?
Learning how to undertake the tests is easy with the normal kit shown above, and the protocol is below.
- Go to your site.
- Hang the thermometer in the shade. Record air temperature.
- Attach reacher stick. Rinse the sample cup 3 times. Take a water sample 15cm below the surface.
- Put the conductivity meter in the water. Wait until values stabilize. Record conductivity and water temperature.
- Take a phosphate sample and after 5 minutes, compare the result to the chart, and record.
- Take a nitrate sample and after 3 minutes, compare the result to the chart, and record.
- Dip in a teststrip. Record chlorine, pH, alkalinity & hardness.
- Add context and observation data.
- Wipe off your sample cup and reacher stick with your towel.
- Pack up your testkit!
The testing kits are not cheap and constitute a considerable financial cost; for this reason, volunteer numbers are constrained. However, if you are interested in getting involved with or joining our testing team, please contact us at membership@cranleighsociety.org.
If you would like to see other information from us, please visit our blog.
