Low water levels at Boundary Creek-Smith Creek Wildlife Management Area

November 18, 2014

by Idaho Fish and Game Visitors to the Boundary Creek-Smith Creek Wildlife Management Area (WMA) near Bonners Ferry have noticed that water levels across the WMA are low this year. The lower than normal water level is making trapping and waterfowl hunting very difficult. Three primary causes have contributed to the lower than desired water levels. These include the need to repair two broken water control structures, lower than normal rainfall, and the need to implement a vegetation management practice known as moist soil management. Properly functioning water control structures normally allow WMA managers to fluctuate water levels throughout the wetlands. However, two of the control structures were not functioning properly and needed repairs. For this work to be completed, water levels across the WMA, and the slough that carries and distributes water, had to be drawn down. When the slough is drawn down, ground water seeps out of the wetlands and further lowers the water table and wetland levels. Wildlife Habitat Biologist Colleen Treese manages the Boundary-Smith Creek WMA. According to Treese, "Wetlands with stable water levels often see a decline in emergent vegetation and a loss of productivity over time. Therefore, the long-term management plan for the area includes drawing down each of the nine individual wetland cells once every five years on a rotational basis to increase productivity." Periodic drawdowns of wetland areas expose bottom sediments and generate aerobic decomposition. The mudflats in a drawn down wetland favor the germination of plants typical of early marsh succession. Without drawdowns, these plants are outcompeted by cattails. Vegetation produced in drawdowns creates an abundance of seed that is excellent food for waterfowl, enhancing waterfowl habitat and use. "The exposed mudflats and decomposition also support abundant invertebrate populations that provide important food sources for wildlife such as waterfowl and shorebirds", said Treese. "Water levels are then kept below full capacity the following year to avoid over flooding the new plant species so they can become established." With the wetland levels reduced to repair the water control structures, Treese used the opportunity to implement vegetation management practices on several wetland cells. Additional work included cattail control to reduce monoculture stands of cattail. Treese explained, "For effective cattail control, two dry seasons are required. During the first season, the cattails are dried up, mowed, and burned to remove the old growth. The following season, new growth is treated with herbicides to kill the cattail. Once the cattail growth is curtailed, a diversity of competing native vegetation species are planted that may replace the cattail." The combination of factors left the water levels on the WMA uncharacteristically low this fall. However, important management actions have been accomplished that will allow for better wetland and waterfowl habitat into the future. Idaho Fish and Game regrets any inconvenience this has caused to the Boundary Creek-Smith Creek Wildlife Management Area users, and thanks everyone for their patience. Conditions permitting, everyone should expect more normal water levels and wetland conditions next year. For more information regarding the Boundary-Smith Creek WMA, please contact Colleen Trese or J.J. Teare at the IDFG Panhandle Region Office, 208-769-1414.