The water quality of this small creek has remained steady since 1996. Extensive water quality monitoring has revealed that the aquatic habitat tends to be poorer in the upstream area but has improved downstream due to the presence of a well buffered, natural stream channel as may be seen at the location of this earthcache. The presence of cold water indicator fish species (Brown Trout) shows that some sections of the stream have relatively high quality cool or cold water habitat.
The Oxbow Creek watershed is located within the Thames River watershed, which is a part of the Lake Erie watershed. Water from Oxbow Creek enters the Thames River downstream of the City of London, and takes 4 - 10 days to flow through to Chatham to reach Lake St. Clair. Approximately two weeks after entering the Thames River the waters of Oxbow Creek will reach Lake Erie.
Friends of Oxbow Creek was formed in 2003 to improve the quality of the environment in the watershed and in cooperation with the Upper Thames River Conservation Authority, and along with landowners trees and shrubs have been planted in at least 15 locations and works have been put in place in some areas of the creek to prevent shoreline erosion which has an effect of maintaining higher water quality as well.
Fish monitoring by the Upper Thames River Conservation Authority found brown trout indicating cold water conditions at some locations. In addition the Brown Trout population is augmented by stocking by the Thames River Anglers but there is evidence of successful spawning in Oxbow Creek as well. Much of of Oxbow Creek has the potential to function as a cold water stream with continued rehabilitation efforts.
STREAM ORDER: Ordering streams is based on the method developed by Strahler (1964) and is commonly used for grouping watercourses on similar characteristics such as stream size and flow. In doing so, single unbranched tributaries are classified as first order streams. A second order stream starts at the confluence of two first order streams and end at its confluence with another second order stream, forming a third order stream and so on. A smaller stream entering a higher- order does not change the order number. With increasing stream order comes increasing stream size, flow, habitat complexity, stream productivity and fish species diversity. Generally, first to third order streams are headwaters with high gradient with erosion potential. Fourth to sixth order streams are wider with riffle and pool areas, greater depositional substrate like sand, and the power to move larger wood material.
STREAM SLOPE
Stream slope is a major factor in controlling stream morphology including the rate of erosion and deposition of substrate in a watercourse. Watercourses with steep slopes are typically straighter with high velocities and erosion potential than those with low slopes. The resulting habitat characteristics in these streams are higher ratios of riffles and and larger substrate like cobbles and boulders in reaches with high slopes and high ratios of pools and fine substrates like sands and silts in those with low slopes.
Slope % Characteristics Substrate
0.0 – 0.3 Typically sinuous; greater pool to riffle ratio Sands and silts
0.3-1.0 Relatively sinuous; more or less even pool – riffle ratio Gravels and cobbles
1.0-5.0 Riffles out number pools; higher water velocities; less sinuous Large gravels, cobbles and boulders >
5.0 Riffles predominate; water velocities and erosional forces high; typically straight stream channel Boulders, cobble and hard clay
Note: A riffle is a short, relatively shallow and coarse-bedded length of stream over which the stream flows at lower velocity and higher turbulence than it normally does in comparison to a pool. As a result of the lower velocity and heightened turbulence, small ripples are frequently found. Riffles are usually caused by an increase in a stream bed's slope or an object in the water.
1. From your observations on the characteristics and substrate at this location, what is the slope percentage at this location?
2. Determine the Volume of Flow (cubic metres per second). To do this measure a 10 meter stretch along the edge of the creek. Find a relatively small floating object like a stick and time how long it takes to travel the 10 meters. If you have a partner, one can stand on the bridge and keep track of the time it takes for the stick to reach the bridge.
3. Using the following equation to determine velocity: Velocity = distance (divided) by time = meters (divided) by seconds
4. Standing on the bridge, determine the average depth of the creek.
5. Next approximate the width of the river. You can measure the distance as you cross the bridge. Multiply the width by the depth to determine the cross-sectional area of the flow in square metres (or feet). Next multiply this measure by your velocity to get the Volume of Flow (cubic metres per second) (or feet).
6. Please take a temperature reading of the stream water.
Forward the information determined above in an email or message to me. Logs risk being deleted if the logging requirements are not completed. This should be a fun outing while you have an opportunity to learn something new or refresh past knowledge.
References:
Ontario Anglers and Hunters website; Upper Thames River Watershed Report Card (Upper Thames River Conservation Authority) Oxbow Creek Watershed Project (Upper Thames River Conservation Authority