CREEK CHARACTERISTICS
Central Mill Creek
(Highway 401 to Grandy’s Pond)
- Significant groundwater discharge between Highway 401 and Downey Road (County Road 35)
- Groundwater discharge from 2004 to 2009 higher than long-term average “attributed to the higher water level in the Capital Paving Phase 1 pond through those 6 years, and the resulting higher groundwater levels across the site”.4
- Significant groundwater discharge from upstream end of Grandy’s Pond for approximately 2,000 m. upstream to rear Gore, Lots 5/6
- Low gradients
- Bordered by an extensive Class I wetland floodplain
- High flood peak attenuation due to upland, floodplain and channel storage
- Flows through peaty and heavily forested wetlands
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- More than ten intermittent and permanent tributaries, originating in small upland marshes, providing drainage from extensive wetlands
- Runs, riffles and pools abundant in many areas, although flats dominate (see chart below)
- Bankfull flows at Flats 1 and 2 less than 1 year; suggest creek able to maintain a consistent and balanced sediment load
- Pavement layer strength and relative bed stability values indicate a trend in streambed stability, but streambed progressively less stable from Riffle 1 to Flat 2
- May indicate creek progressively less competent in transporting sediment load as the load moves downstream from the first Riffle
- Creek classified as a C5 (Rosgen’s classification) – i.e. a single thread channel with a wide floodplain, moderate width to depth ratio, high sinuosity, and low slope
- Land use and floodplain vegetation are important factors in protecting creek
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Figure 23. In the Central Reach, Mill Creek flows through peaty and heavily forested wetlands
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