Print PageConstruction was completed on the North Texas Municipal Water District (NTMWD) East Fork Raw Water Supply Project in 2009. A diversion pump station on the East Fork of the Trinity River provides flow through a 1,840-acre wetted surface area constructed wetland known as the East Fork Wetland. A conveyance pump station then pumps the wetland-treated water through 43.5 miles of pipeline to Lavon Lake to augment this surface water supply source. Start-up period operations during 2009 included many periods of irregular flows to accommodate completion of construction and planting efforts and establishment of the wetland vegetation. Operational interruptions as the result of periods of high rainfall resulting in high lake lakes required multiple efforts to manage water levels in the wetland cells. Wetland operations achieved flow-through conditions again by April 23, 2010.
The John Bunker Sands Wetland Center located centrally within the East Fork Wetland celebrated its Grand Opening on October 7, 2010. The Wetland Center will provide educational opportunities for children and adults.
Samples were collected weekly at several locations in the wetland for analysis of multiple water quality parameters. Flow is monitored continuously at three locations through the system. Mass balance calculations and linear regression analyses are conducted based on the accumulated data.
Results/Conclusions
Analysis of the water quality data collected during the start-up period indicates very good removal of both phosphorus and nitrogen through the East Fork Wetland and a strong correlation between mass loading and removal. Influent concentrations of total phosphorus (TP) averaged approximately 2 mg/L and were reduced to a mean concentration of less than 0.3 mg/L. Influent concentrations of total nitrogen (TN) averaged approximately 10 mg/L and were reduced to a mean concentration of about 1.4 mg/L. Percent mass removed for TP and TN were approximately 83 and 86 percent, respectively.
The start-up period for the East Fork Wetland has been a period of ongoing learning and changes including operational adjustments to address identified issues. Key operational issues resolved during the start-up period of the East Fork Wetland or requiring ongoing efforts include water level management within the wetland cells, management of diverted flows from the river and flow through the wetland, population control of destructive nutria, and remedial wetland planting efforts. However, even during this start-up period, the East Fork Raw Water Supply Project provided more than 14 billion gallons of high quality water supply to Lavon Lake from January 2009 through November 2010.
