Town council has authorized an expenditure of $21,000 for a preliminary floodplain mapping work plan that could lead to some easing of restrictions on development in Harriston.
In the fall of 2013 council considered a comprehensive staff report on the status of floodplain mapping in Harriston.
At the time it was pointed out current mapping is based on conditions that existed in the 1980s and early 1990s.
CAO Bill White explained that “different bridges of different sizes” were in place at the time and other characteristics of the watershed have changed.
In addition, current flow rate models were based on the once-in-a-hundred-year Hurricane Hazel flood levels.
“The flows may include a significant ‘tolerance’ level so that engineers were sure to model the maximum extent of any potential flood. The conservation authority would like to increase stream modeling rainfall collection information to gain more confidence on the exact flows that are used to model the storms needed to produce the mapping,” the report states.
“I really believe there is a chance that flood plain mapping is not accurate and may be too broad. Some properties may not actually be in the flood plain,” said White.
Council has allocated $50,000 toward the flood mapping project in the 2014 budget and to this point has used very little, if any, of the funds, said White.
In the 2015 budget, a work plan will be presented to finalize an amount needed to proceed with the work required to accurately identify floodplains in Harriston and address rural stormwater management concerns, the report states.
