Lake Tecumseh Weir Project
Overview - Weir - Boat Portage - Environmental Monitoring - Studies - Construction
What caused flooding in the Back Bay area during 2011? (PDF)
What's New Here: Independent report summarizing the history and status of the Lake Tecumseh Weir Project - Caleb Kulfan is a junior at Prescott College in Prescott, AZ majoring in Environmental Studies. He was team leader of the AmeriCorps group who assisted us with the Lake Tecumseh restoration project back in 2010 and recently completed the attached report on the project for a Restoration Ecology class. The report gives a comprehensive overview and history of the project. Read the report (PDF) here.
Submerged Aquatic Vegetation Study: Researchers at the Christopher Newport News Center for Wetland Studies reported that in October 2011 Lake Tecumseh supported five species of SAV and covered on average 62% of samples measured. Species documented in the lake include water stargrass (Heteranthera dubia), Eurasian Watermilfoil (Myriophyllum spicatum), Coontail (Ceratophyllum demersum), Sago Pondweed (Potamogeton pectinatus), and Southern Naiad (Najus guadalupensis). SAV provides important habitat for aquatic organisms, fish, and waterfowl and was mostly nonexistent in the lake before establishment of the weirs.
Two low weirs placed in canals connecting Lake Tecumseh to Asheville Bridge Canal reduce the release of turbid water from the lake when winds and runoff increase.
Lake Tecumseh is a shallow 261 acre lake located next to the Atlantic Ocean in Virginia Beach, Virginia. For decades, water levels in the lake fluctuated due to wind-driven tides and a man-made canal connecting the lake to Back Bay estuary.
Why Lake Tecumseh?
Recent studies identified Lake Tecumseh as the leading source of suspended sediment to Back Bay, a nationally significant estuary. Wind-associated wave action within the shallow lake suspended bottom sediments and eroded shorelines. These fine sediments then drained from the lake into Asheville Bridge Canal and Back Bay Estuary. Suspended sediments negatively affect submerged aquatic vegetation, foul fish gills, and degrade waterfowl habitat. The low weirs between Lake Tecumseh and Asheville Bridge Canal now reduce the release of suspended sediment from the lake and will improve aquatic habitat for fish and wildlife.
How Is Recreational Boating Affected By The Weirs?
Prior to the weirs being constructed, boating in the lake was possible only half the year due to shallow depths caused by drainage from wind tides. The weirs will make it possible to navigate on the lake for an additional 190 days. The weirs would have blocked the traditional passage in and out of the lake from Asheville Bridge Canal; however, access is now possible by a winch powered boat trolley on rails. A trip between the two water bodies takes approximately 5 minutes and instructions for use are available by clicking this link BOAT PORTAGE USE INSTRUCTIONS. Boat travel within Asheville Bridge Canal remains unaffected by the weirs.
Will The Weirs Improve Water Quality?
Data suggest yes and to a significant degree. Studies indicate over 2,000 tons of sediment were discharged annually from the lake and the weirs prevent 90% of all discharge events affecting the Back Bay estuary. The weirs also reduce flow velocities inside the lake, helping to settle sediment suspended in the lake before it is released to Back Bay. Furthermore, the weirs complete recommendations contained in the City’s 1967 engineering study for the creation of Asheville Bridge Canal which specified a spillway be created to maintain water quality in the lake.
Will the Weirs Cause Flooding?
Flood risk studies by the U.S. Geological Survey (2004) (PDF - 743KB) and the City of Virginia Beach (2008) concluded no increase in flooding would occur in neighboring communities including Sandbridge, Ocean Lakes, Red Mill, and Lago Mar due to the large flood storage capacity provided by the 261 acre lake and the surrounding 600 acres of wetlands. Weirs are small overflow-type structures commonly used to raise the level of a river or stream and have traditionally been used to create mill ponds. The weirs will be submerged during floods and would not reduce flood absorption or flood flows into or out of the lake.
Won’t the Weirs Harm Fish and Wildlife?
Not according to the Virginia Department of Game and Inland Fisheries. Brackish water species like mullet, white perch, spot, gizzard shad, menhaden, croaker, striped bass, and others will continue to inhabit the lake and swim over the weir when it’s submerged. Freshwater fish species like largemouth bass and sunfish are expected to thrive in the lake while the current salt-tolerant species will continue to reside unharmed in Asheville Bridge Canal and Back Bay. Furthermore, stable water levels favor the establishment of emergent plants that provide cover for young -of-year fish and attract wading birds and waterfowl.
A list of local project supporters includes the Back Bay Restoration Foundation, The Honorable Barry Knight (VA Delegate 81st District), Hampton Roads Sanitation District, City of Virginia Beach, NAS Oceana, Friends of Back Bay, and Virginia Department of Game and Inland Fisheries. Construction of the weirs and boat portage were completed February 7, 2011.
Lake Tecumseh Weir Project Brochure (PDF)
For more information, contact contact Back Bay National Wildlife Refuge at 757-301-7329.
To report maintenance issues associated with the boat portage or weirs, contact Back Bay National Wildlife Refuge at 757-301-7329 or 757-416-8959.
Weir installed at Lake Tecumseh
Severe erosion of the berm and mass wasting of steep side slopes occurred prior to the project.
Side slopes and height were reduced and the berm's width increased in order to establish vegetation and stop erosion. The live stakes, rootwads, and coir fiber logs pictured here along the shoreline were also part of a comprehensive berm rehabilitation and erosion prevention plan.