3.0 Pike Lake Catchment: Riparian Conditions
3.1 Pike Lake Headwater Drainage Features Assessment
3.1.1 Headwater Sampling Locations
The RVCA Stream Characterization program assessed Headwater Drainage Features for the Pike Lake catchment in 2017. This protocol measures zero, first and second order headwater drainage features (HDF). It is a rapid assessment method characterizing the amount of water, sediment transport, and storage capacity within headwater drainage features (HDF). RVCA is working with other Conservation Authorities and the Ministry of Natural Resources and Forestry to implement the protocol with the goal of providing standard datasets to support science development and monitoring of headwater drainage features. An HDF is a depression in the land that conveys surface flow. Additionally, this module provides a means of characterizing the connectivity, form and unique features associated with each HDF (OSAP Protocol, 2013). In 2017 the program sampled 19 sites at road crossings in the Pike Lake catchment area (Figure 33).
3.1.2 Headwater Feature Type
The headwater sampling protocol assesses the feature type in order to understand the function of each feature. The evaluation includes the following classifications: defined natural channel, channelized or constrained, multi-thread, no defined feature, tiled, wetland, swale, roadside ditch and pond outlet. By assessing the values associated with the headwater drainage features in the catchment area we can understand the ecosystem services that they provide to the watershed in the form of hydrology, sediment transport, and aquatic and terrestrial functions. The headwater drainage features in the Pike Lake catchment are predominantly natural and wetland features. Figure 34 shows the feature type of the primary feature at the sampling locations.
3.1.3 Headwater Feature Flow
The observed flow condition within headwater drainage features can be highly variable depending on timing relative to the spring freshet, recent rainfall, soil moisture, etc. Flow conditions are assessed in the spring and in the summer to determine if features are perennial and flow year round, if they are intermittent and dry up during the summer months or if they are ephemeral systems that do not flow regularly and generally respond to specific rainstorm events or snowmelt. Flow conditions in headwater systems can change from year to year depending on local precipitation patterns. Figure 35 shows the observed flow condition at the sampling locations in the Pike Lake catchment in 2017.
3.1.4 Headwater Feature Channel Modifications
Channel modifications were assessed at each headwater drainage feature sampling location. Modifications include channelization, dredging, hardening and realignments. The Pike Lake catchment area had a majority of features with no channel modifications observed, two locations had mixed modifications and one had been historically channelized. Figure 36 shows the channel modifications observed at the sampling locations for the Pike Lake catchment.
3.1.5 Headwater Feature Vegetation
Headwater feature vegetation evaluates the type of vegetation that is found within the drainage feature. The type of vegetated within the channel influences the aquatic and terrestrial ecosystem values that the feature provides. For some types of headwater features the vegetation within the feature plays a very important role in flow and sediment movement and provides fish/wildlife habitat. The following classifications are evaluated no vegetation, lawn, wetland, meadow, scrubland and forest. Figure 37 depicts the dominant vegetation observed at the sampled headwater sites in the Pike Lake catchment.
3.1.6 Headwater Feature Riparian Vegetation
Headwater riparian vegetation evaluates the type of vegetation that is found along the adjacent lands of a headwater drainage feature. The type of vegetation within the riparian corridor influences the aquatic and terrestrial ecosystem values that the feature provides to the watershed. Figure 38 depicts the type of riparian vegetation observed at the sampled headwater sites in the Pike Lake catchment. The majority of the headwater drainage features are classified as having natural riparian vegetation with only four features having altered vegetation typically in the form of ornamental grass or agricultural crops in the riparian zone.
3.1.7 Headwater Feature Sediment Deposition
Assessing the amount of recent sediment deposited in a channel provides an index of the degree to which the feature could be transporting sediment to downstream reaches (OSAP, 2013). Evidence of excessive sediment deposition might indicate the requirement to follow up with more detailed targeted assessments upstream of the site location to identify potential best management practices to be implemented. Sediment deposition ranged from none to substantial for the headwater sites sampled in the Pike Lake catchment area. Figure 39 depicts the degree of sediment deposition observed at the sampled headwater sites in the Pike Lake catchment. Sediment deposition conditions ranged from no sediment deposition to substantial levels of deposition.
3.1.8 Headwater Feature Upstream Roughness
Feature roughness will provide a measure of the amount of materials within the bankfull channel that could slow down the velocity of water flowing within the headwater feature (OSAP, 2013). Materials on the channel bottom that provide roughness include vegetation, wood structure and boulders/cobble substrates. Roughness can provide benefits in mitigating downstream erosion on the headwater drainage feature and the receiving watercourse by reducing velocities. Roughness also provides important habitat conditions for aquatic organisms. Figure 40 shows that the feature roughness conditions at the sampling locations in the Pike Lake catchment were variable ranging from moderate to extreme roughness conditions.
