Nottawasaga River to be reconfigured to protect properties in Angus

 New Tecumseth Free Press November 18, 2013

The preferred solution to head-off future hazards to existing properties on Nottawasaga Drive and on Concessions 3 and 4, immediately north on Brown’s line in Angus, is to reconfigure the Nottawasaga River channel and floodplain so it migrates away from the eroding valley wall, according to the recommendations contained in 105 page Class Environmental Assessment (EA) Study.

The EA, produced by PARISH Geomorphic Ltd. and Terraprobe Inc, was commissioned last February by the Township because “human safety and the integrity of property may be compromised by the predicted future meander pattern of the Nottawasaga River adjacent to these existing developments.

Mitigative measures need to be considered to ensure the long-term stability of these properties and the safety of the people who occupy the dwellings on these properties.” Within the focus area, the Brown’s Line homes and houses in the southeast corner of Nottawasaga Drive are under the most direct threat

There are four options, including the a)”do-nothing” which was a required alternative. The others include b) Stabilize the eroding valley walls in situ; c) Construct a cut-off channel and re-align the river away from the eroding valley wall; and d) Reconfigure channel and floodplain to promote the river to migrate away from the eroding valley wall.

The preferred solution is a mix of options ‘c’ and ‘d’ as combined they would have the least impact on the “natural river processes, the least impact on Lake Sturgeon habitat, and the most sustainable option to mitigating the identified erosion hazard.” The estimated cost for the recommended option is about $337,000, not including a $300,000 contingency.

The financial estimates do not include excavation and removal of approximately 15,000m3 of fill by the municipality or other interested parties, because it can be “utilized at other local development sites requiring clean fill. Under this assumption, the excavation costs would be offset by the revenue generated by the sale of the clean fill to recipient development sites.”

Other features of the EA Study below:

The Nottawasaga River flows north from the Niagara Escarpment and Oak Ridges Moraine, through the Minesing Wetlands, and into Nottawasaga Bay, an inlet of Georgian Bay (Lake Huron), at Wasaga Beach. Angus sits on high bluffs along the Nottawasaga River. The middle reach of the river extends downstream from its confluence with Innisfil Creek, through Nicolston Dam and then urban Angus, to just upstream of Minesing Swamp. Lands along the Middle Nottawasaga River Valley are typically well-drained and support extensive potato and sod farms, but away from the river, drainage is less effective and large tracts of land support swampy, lowland forest.

Agricultural is the primary landuse throughout the subwatershed, although urban development near Angus and Barrie has increased over the past few decades. Warmwater fish species, such as pike and bass, are common in the Nottawasaga River, and the waterway also provides a migratory corridor for rainbow trout and Chinook salmon that spawn in the upper watershed. Lake sturgeon, which are rare in Ontario, also spawn in the Nottawasaga River, downstream of Nicolston Dam.

The Nottawasaga River Valley is designated as “Greenlands” in Simcoe County’s Official Plan, and consists of Red Pine Coniferous Plantation and Fresh-Moist White Cedar-Mixed Hardwood Forest communities on the slopes and tablelands associated with the valley system. This study also documented the presence of several common mammal and bird species, and documented that the Ontario Breeding Bird Atlas Database had noted breeding of two colonial bird species – Bank Swallow (Riparia riparia) and Cliff Swallow (Petrochelidon pyrrhonota) – within the vicinity of the study area. Two provincially threatened bird species have been documented in the vicinity of the study area – Whip-poor-will (Caprimulgus vociferous) and Cerulean Warbler (Dendroica cerulea). In 1953, the land use in the study area was dominated by agricultural activities.

A large portion of the area appears to have supported row crops, and was largely devoid of forested area, except the river valley and a swath of forest between Brown’s Line and Willoughby Road. By 1978, coniferous forests, presumably plantations, dominated the west side of the river along and other agricultural lots apparently were left to become scrub forest. For the most part, the area remained rural over this period. Besides rapid residential expansion along the river, the main difference between the 1978 and 2010 photographs is the position of the channel. The report will be presented to Essa council on Wednesday night.