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3.0 Nichols Creek Catchment: Riparian Conditions

3.1 Nichols Creek Overbank Zone

3.1.1 Riparian Buffer Width Evaluation

Figure 7 demonstrates the buffer conditions of the left and right banks separately.  Nichols Creek had a buffer of greater than 30 meters along 98 percent of the left bank and 100 percent of the right bank.   

Figure XX Riparian Buffer Evaluation along Nichols Creek
Figure 7 Riparian Buffer Evaluation along Nichols Creek  

3.1.2 Ripariain Buffer Alterations

Alterations within the riparian buffer were assessed within three distinct shoreline zones (0-5m, 5-15m, 15-30m), and evaluated based on the dominant vegetative community and/or land cover type (Figure 8). The riparian buffer zone along the Nichols Creek was found to be dominated by forest and wetland conditions along the riparian corridor. 

Figure XX Riparian buffer alterations along Nichols Creek
Figure 8 Riparian buffer alterations along Nichols Creek

3.1.3 Adjacent Land Use

The RVCA’s Stream Characterization Program identifies six different land uses along Nichols Creek (Figure 9). Surrounding land use is considered from the beginning to end of the survey section (100m) and up to 100m on each side of the river. Land use outside of this area is not considered for the surveys but is nonetheless part of the subwatershed and will influence the creek. Natural areas made up 97 percent of the stream, characterized by forest, scrubland, meadow and wetland. Wetland habitat was dominant in the adjacent lands along Nichols Creek at 63 percent.  The remaining land use consisted of abandoned agriculture and residential areas.

Figure XX Land Use along Nichols Creek
Figure 9 Land Use along Nichols Creek

3.2 Nichols Creek Shoreline Zone

3.2.1 Instream Erosion

Stream erosion is the process by which water erodes and transports sediments, resulting in dynamic flows and diverse habitat conditions.  Excessive erosion can result in drastic environmental changes, as habitat conditions, water quality and aquatic life are all negatively affected.  Bank stability was assessed as the overall extent of each section with “unstable” shoreline conditions.  These conditions are defined by the presence of significant exposed soils/roots, minimal bank vegetation, severe undercutting, slumping or scour and potential failed erosion measures. The majority of Nichols Creek had low levels of erosion along the system (Figure 10). 

Figure XX Erosion levels along Nichols Creek
Figure 10 Erosion levels along Nichols Creek

3.2.2 Undercut Stream Banks

Stream bank undercuts can provide excellent cover habitat for aquatic life, however excessive levels can be an indication of unstable shoreline conditions.  Bank undercut was assessed as the overall extent of each surveyed section with overhanging bank cover present.  Figure 11 shows that Nichols Creek had low levels of undercut banks along the majority of the system with a few specific locations having moderate levels of undercut banks observed.  

Figure XX Undercut stream banks along Nichols Creek
Figure 11 Undercut stream banks along Nichols Creek

3.2.3 Stream Shading

Grasses, shrubs and trees all contribute towards shading a stream. Shade is important in moderating stream temperature, contributing to food supply and helping with nutrient reduction within a stream.  Stream cover is assessed as the total coverage area in each section that is shaded by overhanging trees/grasses and tree canopy, at greater than 1m above the water surface.  Figure 12 shows low to moderate levels of stream shading along Nichols Creek.

Figure XX Stream shading along Nichols Creek
Figure 12 Stream shading along Nichols Creek

3.2.4 Instream Woody Debris

Figure 13 shows that the majority of Nichols Creek had low to moderate levels of instream woody debris in the form of branches and trees along the system. Instream woody debris is important for fish and benthic invertebrate habitat, by providing refuge and feeding areas.

Figure XX Instream woody debris along Nichols Creek
Figure 13 Instream woody debris along Nichols Creek

3.2.5 Overhanging Trees and Branches

Trees and branches that are less than one meter from the surface of the water are defined as overhanging.  Overhanging branches and trees provide a food source, nutrients and shade which helps to moderate instream water temperatures.  Figure 14 shows the system has low levels of overhanging branches and trees along Nichols Creek. 

Figure XX Overhanging trees and branches along Nichols Creek
Figure 14 Overhanging trees and branches along Nichols Creek

3.2.6 Anthropogenic Alterations

Stream alterations are classified based on specific functional criteria associated with the flow conditions, the riparian buffer and potential human influences.  Figure 15 shows 80 percent of Nichols Creek remains “unaltered” with no anthropogenic alterations. Eighteen percent of Nichols Creek was classified as natural with minor anthropogenic changes while only two percent was considered altered.

Figure XX Anthropogenic alterations along Nichols Creek
Figure 15 Anthropogenic alterations along Nichols Creek

3.3 Nichols Creek Instream Aquatic Habitat

3.3.1 Benthic Invertebrates

Freshwater benthic invertebrates are animals without backbones that live on the stream bottom and include crustaceans such as crayfish, molluscs and immature forms of aquatic insects. Benthos represent an extremely diverse group of aquatic animals and exhibit wide ranges of responses to stressors such as organic pollutants, sediments and toxicants, which allows scientists to use them as bioindicators.  As part of the Ontario Benthic Biomonitoring Network (OBBN), the RVCA has been collecting benthic invertebrates at the O'Neil Road site on Nichols Creek since 2004. Monitoring data is analyzed for each sample site and the results are presented using the Family Biotic Index, Family Richness and percent Ephemeroptera, Plecoptera and Trichoptera.

O'Neil Road sample location
O'Neil Road sample location
Hilsenhoff Family Biotic Index

The Hilsenhoff Family Biotic Index (FBI) is an indicator of organic and nutrient pollution and provides an estimate of water quality conditions for each site using established pollution tolerance values for benthic invertebrates. FBI results for the Nichols Creek catchment sample location at O’Neil Road are summarized by year from 2004 to 2015.  “Fair” to “Poor” water quality conditions was observed at the Nichols Creek sample location (Figure 16) using a grading scheme developed by Conservation Authorities in Ontario for benthic invertebrates. 

Figure xx Hilsenhoff Family Biotic Index at the Nichols Creek O’Neil Road sample location
Figure 16 Hilsenhoff Family Biotic Index at the Nichols Creek O’Neil Road sample location
Family Richness

Family Richness measures the health of the community through its diversity and increases with increasing habitat diversity suitability and healthy water quality conditions. Family Richness is equivalent to the total number of benthic invertebrate families found within a sample.  The Nichols Creek site is reported to have “Fair” family richness (Figure 17).

Figure xx Family Richness at the Nichols Creek O’Neil Road sample location
Figure 17 Family Richness at the Nichols Creek O’Neil Road sample location
EPT

Ephemeroptera (Mayflies), Plecoptera (Stoneflies), and Trichoptera (Caddisflies) are species considered to be very sensitive to poor water quality conditions. High abundance of these organisms is generally an indication of good water quality conditions at a sample location.  The community structure is typically dominated by species that are moderately tolerant and tolerant to poorer water quality conditions.  As a result, the EPT indicates that the Nichols Creek sample location is reported to have “Fair” to “Poor” water quality (Figure 18) from 2004 to 2015.

Figure xx EPT at the Nichols Creek O’Neil Road sample location
Figure 18 EPT at the Nichols Creek O’Neil Road sample location
Conclusion

Overall the Nichols Creek sample location aquatic habitat conditions from a benthic invertebrate perspective is considered “Fairly Poor” from 2004 to 2015 as the samples are dominated by species that are moderately tolerant and tolerant to high organic pollution levels.

3.3.2 Habitat Complexity

Habitat complexity is a measure of the overall diversity of habitat types and features within a stream. Streams with high habitat complexity support a greater variety of species niches, and therefore contribute to greater diversity. Factors such as substrate, flow conditions (pools, riffles) and cover material (vegetation, wood structure, etc.) all provide crucial habitat to aquatic life.  Habitat complexity is assessed based on the presence of boulder, cobble and gravel substrates, as well as the presence of instream woody material.

Low to high habitat complexity was identified for Nichols Creek (Figure 19). Regions with increased habitat complexity were observed in the lower to upper reaches of the system within the catchment.  

Figure XX Habitat complexity along Nichols Creek
Figure 19 Habitat complexity along Nichols Creek

3.3.3 Instream Substrate

Diverse substrate is important for fish and benthic invertebrate habitat because some species have specific substrate requirements and for example will only reproduce on certain types of substrate.  The absence of diverse substrate types may limit the overall diversity of species within a stream. Figure 20 shows the overall presence of various substrate types observed along Nichols Creek.  Substrate conditions were highly diverse along Nichols Creek with all substrate types being recorded at various locations along the creek.  Figure 21 shows the dominant substrate type observed for each section surveyed along Nichols Creek.  

Figure XX Instream substrate along Nichols Creek
Figure 20 Instream substrate along Nichols Creek
Figure XX shows the dominant substrate type along Nichols Creek
Figure 21 shows the dominant substrate type along Nichols Creek

3.3.4 Instream Morphology

Pools and riffles are important habitat features for aquatic life.  Riffles are fast flowing areas characterized by agitation and overturn of the water surface. Riffles thereby play a crucial role in contributing to dissolved oxygen conditions and directly support spawning for some fish species.  They are also areas that support high benthic invertebrate populations which are an important food source for many aquatic species.  Pools are characterized by minimal flows, with relatively deep water and winter/summer refuge habitat for aquatic species.  Runs are moderately shallow, with unagitated surfaces of water and areas where the thalweg (deepest part of the channel) is in the center of the channel. Figure xx shows that Nichols Creek is highly variable; 23 percent consists of runs, 7 percent riffles and 70 percent pools. Figure 22 shows where the riffle habitat areas were observed along Nichols Creek.

Figure XX Instream morphology along Nichols Creek
Figure 22 Instream morphology along Nichols Creek

3.3.5 Vegetation Type

Instream vegetation provides a variety of functions and is a critical component of the aquatic ecosystem.  Aquatic plants promote stream health by:

  • Providing direct riparian/instream habitat
  • Stabilizing flows reducing shoreline erosion
  • Contributing to dissolved oxygen through photosynthesis
  • Maintaining temperature conditions through shading

For example emergent plants along the shoreline can provide shoreline protection from wave action and important rearing habitat for species of waterfowl.  Submerged plants provide habitat for fish to find shelter from predator fish while they feed.  Floating plants such as water lilies shade the water and can keep temperatures cool while reducing algae growth.  Narrow leaved emergents were present at 98% of the sections surveyed, algae was observed in 68% of sections, while free floating plants were observed in 11% of surveyed sections.   Broad leaved emergents were observed in 32% of sections, submerged plants in 93%, floating plants in 98% and robust emergents in 86% of sections surveyed. Figure 23 depicts the plant community structure for Nichols Creek. Figure xx shows the dominant vegetation type observed for each section surveyed along the Nichols Creek catchment.

Figure xx Vegetation type along Nichols Creek
Figure 23 Vegetation type along Nichols Creek
Figure XX Dominant vegetation type along Nichols Creek
Figure 24 Dominant vegetation type along Nichols Creek

3.3.6 Instream Vegetation Abundance

Instream vegetation is an important factor for a healthy stream ecosystem. Vegetation helps to remove contaminants from the water, contributes oxygen to the stream, and provides habitat for fish and wildlife. Too much vegetation can also be detrimental. Figure 25 demonstrates that Nichols Creek reach had normal to common levels of vegetation recorded at 51 percent of stream surveys.  Extensive levels of vegetation were observed along 34 percent of the systems length and were consistent with wetland areas dominated by European Frogbit.

Figure xx Instream vegetation abundance along Nichols Creek
Figure 25 Instream vegetation abundance along Nichols Creek 

3.3.7 Invasive Species

Invasive species can have major implications on streams and species diversity. Invasive species are one of the largest threats to ecosystems throughout Ontario and can out compete native species, having negative effects on local wildlife, fish and plant populations. Ninety five percent of the sections surveyed along Nichols Creek reach had invasive species. The invasive species observed in the Nichols Creek reach were European frogbit, poison/wild parsnip, phragmites and purple loosestrife.  Invasive species abundance (i.e. the number of observed invasive species per section) was assessed to determine the potential range/vector of many of these species (Figure 26). 

Figure XX Invasive species abundance along Nichols Creek
Figure 26 Invasive species abundance along Nichols Creek

3.3.8 Water Chemistry

During the stream characterization survey, a YSI probe is used to collect water chemistry information.  Dissolved oxygen (DO), specific conductivity (SPC) and pH are measured at the start and end of each section.

3.3.8.1 Dissolved Oxygen

Dissolved oxygen is a measure of the amount of oxygen dissolved in water. The Canadian Environmental Quality Guidelines of the Canadian Council of Ministers of the Environment (CCME) suggest that for the protection of aquatic life the lowest acceptable dissolved oxygen concentration should be 6 mg/L for warmwater biota and 9.5 mg/L for coldwater biota (CCME, 1999). Figure 27 shows that the dissolved oxygen in Nichols Creek was predominantly below the threshold for warmwater biota along most of the system. The average dissolved oxygen levels observed within Nichols Creek was 3.14mg/L.

Figure XX Dissolved oxygen ranges in Nichols Creek
Figure 27 Dissolved oxygen ranges in Nichols Creek
3.3.8.2 Conductivity

Conductivity in streams is primarily influenced by the geology of the surrounding environment, but can vary drastically as a function of surface water runoff. Currently there are no CCME guideline standards for stream conductivity; however readings which are outside the normal range observed within the system are often an indication of unmitigated discharge and/or stormwater input. The average conductivity observed within the main stem of Nichols Creek catchment was 419.95 µs/cm.  Figure 28 shows the conductivity readings for Nichols Creek.

Figure XX Specific conductivity ranges in Nichols Creek
Figure 28 Specific conductivity ranges in Nichols Creek
3.3.8.3 pH

Based on the PWQO for pH, a range of 6.5 to 8.5 should be maintained for the protection of aquatic life. Average pH values for the Nichols Creek catchment averaged 7.45 thereby meeting the provincial standard (Figure 29).

Figure XX pH ranges in Nichols Creek
Figure 29 pH ranges in Nichols Creek
3.3.8.4 Oxygen Saturation (%)

Oxygen saturation is measured as the ratio of dissolved oxygen relative to the maximum amount of oxygen that will dissolve based on the temperature and atmospheric pressure. Well oxygenated water will stabilize at or above 100% saturation, however the presence of decaying matter/pollutants can drastically reduce these levels. Oxygen input through photosynthesis has the potential to increase saturation above 100% to a maximum of 500%, depending on the productivity level of the environment. In order to represent the relationship between concentration and saturation, the measured values have been summarized into 6 classes:

  1. <100% Saturation / <6.0 mg/L Concentration. Oxygen concentration and saturation are not sufficient to support aquatic life and may represent impairment
  2. >100% Saturation / <6.0 mg/L Concentration. Oxygen concentration is not sufficient to support aquatic life, however saturation levels indicate that the water has stabilized at its estimated maximum. This is indicative of higher water temperatures and stagnant flows.
  3. <100% Saturation / 6.0-9.5 mg/L Concentration. Oxygen concentration is sufficient to support warm water biota, however depletion factors are likely present and are limiting maximum saturation.
  4. >100% Saturation / 6.0-9.5 mg/L Concentration. Oxygen concentration and saturation levels are optimal for warm water biota.
  5. <100% Saturation / >9.5 mg/L Concentration. Oxygen concentration is sufficient to support cold water biota, however depletion factors are likely present and are limiting maximum saturation.
  6. >100% Saturation / >9.5 mg/L Concentration. Oxygen concentration and saturation levels are optimal for cold water biota.
Figure XX A bivariate assessment of dissolved oxygen concentration (mg/L) and saturation (%) in Nichols Creek
Figure 30 A bivariate assessment of dissolved oxygen concentration (mg/L) and saturation (%) in Nichols Creek

Dissolved oxygen conditions on the Nichols Creek catchment are generally below levels to support warm and coolwater species (Figure 30).  Dissolved oxygen conditions are lower in most reaches which are dominated by wetland habitat.  Oxygen levels in wetland habitats are typically lower than they are in areas where the substrate is dominated by cobble and riffle habitat. 

3.3.8.5 Specific Conductivity Assessment

Specific conductivity (SPC) is a standardized measure of electrical conductance, collected at or corrected to a water temperature of 25⁰C. SPC is directly related to the concentration of ions in water, and is commonly influenced by the presence of dissolved salts, alkalis, chlorides, sulfides and carbonate compounds. The higher the concentration of these compounds, the higher the conductivity. Common sources of elevated conductivity include storm water, agricultural inputs and commercial/industrial effluents.

In order to summarize the conditions observed, SPC levels were evaluated as either normal, moderately elevated or highly elevated. These categories correspond directly to the degree of variation (i.e. standard deviation) at each site relative to the average across the system.

Normal levels were maintained along the majority of Nichols Creek, however there were elevated areas in the middle reach where two tributaries enter the main stem of Nichols Creek (Figure 31). 

Figure XX Relative specific conductivity levels along Nichols Creek
Figure 31 Relative specific conductivity levels along Nichols Creek

3.3.9 Thermal Regime

Many factors can influence fluctuations in stream temperature, including springs, tributaries, precipitation runoff, discharge pipes and stream shading from riparian vegetation. Water temperature is used along with the maximum air temperature (using the Stoneman and Jones method) to classify a watercourse as either warm water, cool water or cold water. Figure 32 shows where the thermal sampling sites were located along Nichols Creek.  Analysis of the data collected indicates that Nichols Creek catchment is classified as a warm water system with cool water reaches (Figure 33).  

Figure XX Temperature logger locations in the Nichols Creek catchment
Figure 32 Temperature logger locations in the Nichols Creek catchment
Figure XX Temperature logger data for the two sites in the Nichols Creek catchment
Figure 33 Temperature logger data for the two sites in the Nichols Creek catchment

Each point on the graph represents a temperature that meets the following criteria:
- Sampling dates between July 1st and September 7th
- Sampling date is preceded by two consecutive days above 24.5 °C, with no rain
- Water temperatures are collected at 4pm
- Air temperature is recorded as the max temperature for that day

3.3.10 Groundwater

Groundwater discharge areas can influence stream temperature, contribute nutrients, and provide important stream habitat for fish and other biota. During stream surveys, indicators of groundwater discharge are noted when observed. Indicators include: springs/seeps, watercress, iron staining, significant temperature change and rainbow mineral film. Figure 34 shows areas where one or more of the above groundwater indicators were observed during stream surveys and headwater assessments. 

Figure XX Groundwater indicators observed in the Nichols Creek catchment
Figure 34 Groundwater indicators observed in the Nichols Creek catchment

3.3.11 Fish Community

The Nichols Creek catchment is classified as a mixed community of warm and cool water recreational and baitfish fishery with 20 species observed. Figure 35 shows the sampling locations along Nichols Creek. 

Figure XX Fish community sampling results along Nichols Creek
Figure 35 Fish community sampling results along Nichols Creek

The following table contains a list of species observed in the watershed.

Table 7 Fish species observed in the Nichols Creek catchment
Fish SpeciesFish codeFish SpeciesFish code
banded killifishBaKilfathead minnowFhMin
blackchin shinerBcShifinescale daceFsDac
blacknose shinerBnShigolden shinerGoShi
bluntnose minnowBnMinhornyhead chubHhChu
brassy minnowBrMinIowa darterIoDar
brook sticklebackBrStinorthern pearl dacePeDac
brown bullheadBrBulnorthern redbelly daceNRDac
central mudminnowCeMudpumpkinseedPumpk
common shinerCoShirock bassRoBas
creek chubCrChuwhite suckerWhSuc
Fish sampling location along Nichols Creek
Fish sampling location along Nichols Creek

3.3.12 Migratory Obstructions

It is important to know locations of migratory obstructions because these can prevent fish from accessing important spawning and rearing habitat. Migratory obstructions can be natural or manmade, and they can be permanent or seasonal. Figure 36 shows that Nichols Creek catchment had several beaver dams, a debris dam and two natural grade barriers identified along Nichols Creek at the time of the survey in 2015.

Figure XX Migratory obstructions in the Nichols Creek catchment
Figure 36 Migratory obstructions in the Nichols Creek catchment

3.4 Headwater Drainage Feature Assessment

3.4.1 Headwater Sampling Locations

The RVCA Stream Characterization program assessed Headwater Drainage Features for the Middle Irish subwatershed in 2014. 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 2015 the program sampled 4 sites at road crossings in the Nichols Creek catchment area (Figure 37).  

Figure XX Location of the headwater sampling site in the Nichols Creek catchment
Figure 37 Location of the headwater sampling site in the Nichols Creek catchment

3.4.2 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 Nichols Creek catchment are primarily classified as wetland with one feature classified as channelized. Figure 38 shows the feature type of the primary feature at the sampling locations.

Figure XX Headwater feature types in the Nichols Creek catchment
Figure 38 Headwater feature types in the Nichols Creek catchment
A spring photo of the headwater sample site in the Nichols Creek catchment located on Derry Side Road
A spring photo of the headwater sample site in the Nichols Creek catchment located on Derry Side Road
A summer photo of the headwater sample site in the Nichols Creek catchment located on Derry Side Road
A summer photo of the headwater sample site in the Nichols Creek catchment located on Derry Side Road

3.4.3 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 39 shows the observed flow condition at the sampling locations in the Nichols Creek catchment in 2015.

Figure XX Headwater feature flow conditions in the Nichols Creek catchment
Figure 39 Headwater feature flow conditions in the Nichols Creek catchment

3.4.4 Headwater Feature Channel Modifications

Channel modifications were assessed at each headwater drainage feature sampling location.  Modifications include channelization, dredging, hardening and realignments.  The Nichols Creek catchment area had three features with no channel modifications observed and one site as having been recently dredged. Figure 40 shows the channel modifications observed at the sampling locations for Nichols Creek.

Figure XX Headwater feature channel modifications in the Nichols Creek catchment
Figure 40 Headwater feature channel modifications in the Nichols Creek catchment

3.4.5 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 wildlife habitat.  The following classifications are evaluated no vegetation, lawn, wetland, meadow, scrubland and forest.  Figure 41 depicts the dominant vegetation observed at the sampled headwater sites in the Nichols Creek catchment.

Figure XX Headwater feature vegetation types in the Nichols Creek catchment
Figure 41 Headwater feature vegetation types in the Nichols Creek catchment

3.4.6 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 42 depicts the type of riparian vegetation observed at the sampled headwater sites in the Nichols Creek catchment.

Figure XX Headwater feature riparian vegetation types in the Nichols Creek catchment
Figure 42 Headwater feature riparian vegetation types in the Nichols Creek catchment

3.4.7 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 moderate for the headwater sites sampled in the Nichols Creek catchment area. Figure 43 depicts the degree of sediment deposition observed at the sampled headwater sites in the Nichols Creek catchment.

Figure XX Headwater feature sediment deposition in the Nichols Creek catchment
Figure 43 Headwater feature sediment deposition in the Nichols Creek catchment

3.4.8 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, woody debris 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 44 shows the feature roughness conditions at the sampling location in the Nichols Creek catchment.

Figure Headwater feature roughness in the Nichols Creek catchment
Figure 44 Headwater feature roughness in the Nichols Creek catchment

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