One of the key measures of water quality at the Yadkin Project is the level of dissolved oxygen (DO) in the water being released from the dams.
 
APGI is committed to continue enhancing the water quality in the Yadkin Project lakes and the Yadkin River. Recent data shows that technology installed by APGI at Narrows Dam has significantly improves dissolved oxygen levels downstream of the dam.

 

Water quality within the Yadkin Project lakes is generally considered to be good or fair. One significant challenge comes from runoff – soils and sediment that flow from neighboring communities into the Yadkin River add nutrients. High levels of nutrients lead to increased algae production and can result in lower dissolved oxygen levels.

 

State Regulation

Water quality at the Yadkin Project is regulated by the NC Department of Environment and Natural Resources, Division of Water Resources.

 

The Yadkin Project is subject to the following state standards related to dissolved oxygen levels: a minimum of 4.0 mg/L (measured instantaneously) and a minimum of 5.0 mg/L (daily average).

 

APGI has committed to invest up to $80 million to continue improving water quality at the Yadkin Project, beginning with a $40 million investment at High Rock Lake. APGI will install three “through-the-blade” aerating turbines at High Rock once the Federal Energy Regulatory Commission (FERC) issues a new license for the Yadkin Project. The engineering, planning, and model testing of the new turbines has already been completed.

 

Monitoring Dissolved Oxygen Levels

APGI closely monitors dissolved oxygen levels in the tailwaters of each dam. The monitors record dissolved oxygen and temperature data every 15 minutes, 7 days a week, between May 1 and November 30. This is the time when DO concentrations are of greatest concern. The monitors in the Narrows and Falls tailwaters have been operating since 2001, while monitors to the Tuckertown and High Rock tailwaters were added in 2003.
 
In March 2013, APGI provided state officials with a report summarizing the level of dissolved oxygen measured in the Yadkin Project tailwaters since 2007. The report shows that water leaving the Yadkin Project meets state standards for water quality 100% of the time.

 

Water enters the Yadkin Project at High Rock Lake with relatively low concentrations of dissolved oxygen. After traveling 38 miles down the Yadkin River and passing through four dams operated by APGI, the water quality improves significantly before it is discharged at the Falls Dam. In 2013, water discharged from High Rock Dam met the state standard for dissolved oxygen 78% of the time (based on daily average measurements). It met those same standards 100% when discharged from Narrows Dam and Falls Dam.

 

Read the press release.

Read the 2013 Dissolved Oxygen Report.

 

Controlling Hydrilla on the Yadkin Project Lakes

 

Alcoa is cooperating with North Carolina’s Aquatic Weed Control Program to control the growth of hydrilla, an invasive aquatic weed, on the Yadkin Project lakes.   After hydrilla was observed growing in Badin and Tuckertown lakes, Alcoa asked for assistance from the Aquatic Weed Control Program to implement control measures to reduce the areas of infestation and prevent widespread growth.

 

Alcoa worked with the Aquatic Weed Control Program, the NC Wildlife Resources Commission (NCWRC), and others to develop a Badin Lake Hydrilla Extirpation Plan. The Plan outlines a management approach that includes chemical (herbicides) and biological (grass carp) controls, vegetation surveys, and hydrilla tuber monitoring.

 

The short term goal of the Plan is to minimize the spread of hydrilla on Badin Lake and the long term goal of the Plan is to extirpate hydrilla from Badin Lake entirely.  Alcoa and the Aquatic Weed Control Program made the first application of an aquatic-use herbicide on Badin Lake in May 2012.  Additional herbicide applications on Badin Lake are planned in 2012.

 

Alcoa and its partners are also making preparations to introduce grass carp into Badin Lake later in 2012.  Grass carp are sterile fish that preferentially feed on hydrilla.  Because grass carp will also eat other submersed vegetation, such as water willow, Alcoa is working with NCWRC to construct exclosures, which will be placed in the lake to protect native aquatic vegetation.

 

Alcoa and the Aquatic Weed Control Program are also planning an extensive survey for hydrilla on Tuckertown Lake in 2012.