River Basin Characteristics
The Brandy Brook watershed is approximately 28 miles in length and consists of approximately 23,200 acres from its headwaters to the discharge point in the St Lawrence while the Sucker Brook is approximately 22 miles in length and consists of approximately 29,550 acres from its headwaters to its discharge point in the St Lawrence. Both empty directly into the St Lawrence River to the northeast of the Town of Waddington, New York. Little Sucker Brook no longer naturally flows into the St Lawrence and instead flows through a channel that connects Little Sucker Brook to Sucker Brook.
Both outflows lie upstream from the Moses-Saunders Power Dam off of Barnhart Island that provides both powers and regulates the St Lawrence Seaway to allow for navigation by large vessels. The construction of the dam in the 1950s has created bays at the mouth of Brandy Brook, Sucker Brook and Little Sucker Brook. The mouth of Brandy Brook lies approximately 20.8 miles upstream from the dam and the mouth of Sucker Brook lies 22.7 miles upstream from the dam.
St Lawrence County exhibits distinct topographical changes within its borders. The northern 60 percent of the county is relatively flat with little relief and is called the lowlands. The southern 40 percent lies within the Adirondack Mountains and has distinct changes in elevation with a maximum elevation of 2,700 ft above sea level. The lowlands area, in which Brandy Brook and Sucker Brook are part of, is primarily agricultural in nature, mostly primarily dairy or commodity based farms. Although not residing within the boundaries of the Brandy Brook and Sucker Brook watersheds, St Lawrence County does have other industries such as mining, aluminum smelting, and colleges and universities.
New York State Department of Environmental Conservation (NYS DEC) has listed both Brandy Brook and Sucker Brook as having possible or suspected silt/sediment. These streams did at one time support walleye spawning, although the DEC regional fisheries raises concerns over whether these streams are capable of supporting walleye habitat because of the high turbidity. The primary concern by the NYS DEC is that this turbidity may impact future development of any fisheries activities. These streams are not listed as exceeding the 303d Total Maximum Daily Load criteria according to the 2009 Waterbody Inventory.
In building the sediment transport model for the Brandy Brook and Sucker Brook watersheds, USACE used the online version of the U.S. Department of Agriculture Water Erosion Prediction Project (WEPP) model as the preferred method to develop an erosion estimation and sediment transport model. Because the WEPP model is typically used for small watersheds, the main channels of the Brandy Brook watershed, the Little Sucker watershed, and the Sucker Brook watershed are not the watershed channels being defined. Instead, each individual tributary leading to the main channels in the area modeled with the WEPP program. The main channel could not be modeled because 1) the area is too large to be modeled using the WEPP program and 2) that by modeling smaller watersheds the locations of probable erosion and sediment supply can be more accurately identified and prioritized. Though the WEPP model only estimates the erosion and sediment supply and cannot predict definite quantities, by using uniform methods and input data a reliable comparison can be made of smaller segments of the watershed. In total approximately 154 individual sub-watersheds of the Brandy Brook (82) watershed and Sucker Brook (72) watersheds were modeled, representing 87 percent of the Brandy/Sucker Brooks watersheds.
The WEPP model requires the identification of the “minimum source channel length” in meters and the “critical source area” in hectares. Initially, Brandy Brook, Little Sucker Brook and Sucker Brook were all defined using the 300 m/20 ha parameters. Upon completion of the initial model runs, there were noticeable gaps in model coverage because of the larger defined lengths and areas. Once completed using the initial parameters, a secondary set of model runs were completed using in most cases a 60m minimum source channel length and a 4 ha critical source area. The use of the larger values does not negate the smaller watersheds created by the smaller values but instead incorporates them into the larger watershed areas.
The other parameters set for the model were the outlet point for the tributary (defined by USACE at a location that was as close to the main channel as allowed), the land use grid (selected with National Agriculture Statistics Service – NASS and National Land Cover Database – NLCD), the subcatchments (delineated via Topographic Parameterization – TOPAZ), and the soils (defined using USDA’s Soil Survey Geographic – SSURGO database).
Use and Applications
The objective was to develop a sediment transport computer model of existing conditions in the Brandy Brook, Sucker Brook, and Little Sucker Brook watersheds that will be turned over to the St. Lawrence County Soil and Water Conservation District. WEPP is a small watershed scale model developed to quantify the impact of land management practices in watersheds; the model is capable of identifying problematic areas, as well as running scenarios for improving conditions. The WEPP model can be run through an online interface and incorporates specific GIS data, field observations, and field data collection. It may be used as a decision-making tool and also assist in applying for Federal grants. Using the WEPP model, USACE identified 5 areas in which further model runs or further study may need to be considered. Some of these areas are single watersheds while others are multiple watersheds within largely agricultural areas. In addition to the 4 WEPP modeled areas, USACE has also made some recommendations based on field observations that potential have impacts on the sediment transport system.
For more information:
USACE, Buffalo District
1776 Niagara Street
Buffalo, NY 14207
Phone: (716) 879-4488