Thomas Brook Watershed

The 760-hectare Thomas Brook Watershed, a sub-watershed of the Cornwallis River Watershed, is located in Kings County, part of Nova Scotia's fertile Annapolis Valley. Agricultural intensity is greater in the lower reaches of the watershed and mainly consists of forages, cereals, specialized crops and livestock. See map.

Agricultural production in the watershed is focused on crops such as grain, silage and grain corn, forages, nursery stock and strawberries. In addition there are livestock operations including dairy, beef and hobby farms. Urban expansion in the surrounding area has increased the watershed's rural residential population.

Thomas Brook is a small stream, with a main channel less than six kilometres long and rarely wider than two metres. It originates at the top of the steep forested escarpment of the North Mountain, and drains into the Cornwallis River which flows east to the Minas Basin. The brook is fed by rainfall, drainage from seasonal streams, and seepage originating throughout various geological formations along the North Mountain escarpment.

Much of the soil in the watershed is imperfectly drained. Shallow parent material, topography and the forest ecosystem affect drainage at the upper levels, and rapid runoff from snowmelt can lead to spring flooding. The coarse soils of the lower slopes and level portions of the brook are susceptible to leaching and summer moisture deficiencies. Drought-like conditions were in effect from 1996 to 2001.

Intense land-use pressure from both agricultural and residential sources has led to a decline in surface water quality in the Thomas Brook Watershed. Concerns include E. coli and phosphate loading. Recent investigations indicate that high nitrate-nitrogen concentrations in groundwater can seep into surface waters during the summer months. These findings have been the catalyst for the development of a Nutrient Management Strategy for the province of Nova Scotia.

Four BMPs were studied within the Thomas Brook Watershed as follows:

  • Nutrient management planning
  • Cattle exclusion fencing with off-stream watering
  • New dairy farm facilities
  • Runoff retention pond
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