AN INTERVIEW WITH dam5

 Blake Johnson, Interpretive & Outreach Ranger for the US Army Corps of Engineers at B. Everett Jordan Lake tells us all about the Corps’ operations at Jordan Lake Dam.
    

Blake Johnson grew up in Elizabeth City and began working with the US Army Corps of Engineers at Falls Lake as an intern in 2015. In 2016 He graduated from NCSU with a major in Environmental Technology & Management and with minors in Environmental Chemistry & Toxicology and Soil Science. He now works full-time as the Interpretive & Outreach Ranger for the US Army Corps of Engineers at B. Everett Jordan Lake where he specializes in in community outreach and engagement.

Blake, it was a pleasure for us to come out to the lake today and actually observe what goes on here, especially as it pertains to dam operations. Just to give us all an idea of the magnitude of the Corps responsibility here, what can you tell us about this seemingly boundary-less body of water?

Well for starters, the reservoir actually covers 13,940 acres with a shoreline of 180 miles at its desired water level of 216 feet (66 m) above sea level. Its development was prompted by a particularly damaging tropical storm that hit the region downstream in September 1945 with major flooding and wide-spread damage. Constructed at an original cost of $147,300,000, it is owned and operated by the United States Army Corps of Engineers, which dammed and flooded the Haw River and New Hope River between 1971 and 1982. Impoundment of the reservoir was started in September 1981 and the lake initially reached normal pool stage in February 1982. It is now estimated that just over $1 billion in flood damages have been averted as a result of the creation of Jordan Dam.

So how do you actually control the water level in the lake?

Good question -The Corps of Engineers control the discharge of waters leaving the dam by utilizing a series of gates, which open and close allowing more and less water out accordingly. The normal or goal lake level is 216ft mean sea level (msl) and the maximum level is 240ft (msl), after which the water behind the dam will enter a spillway which routes the excess water around the dam and into the river below.

The minimum discharge from the dam is about 200 cubic feet per second. In periods of severe drought this minimum level of discharge must be maintained in order to support the minimum river level downstream that companies and towns need to support their daily activities. And when there is drought the lake level will be lower. The balance of maintaining a satisfactory river level downstream and a sufficient lake level above the dam in order for the towns that rely on lake water can get the water they need is an important goal of water management. There are also concerns for recreation both in the lake and in the river below.

Can you give us a good example of how you react to forecasts of major flooding downstream (such as for Wilmington) if there is no similar flooding forecast for Jordan Lake at that same time?

Yes. We try to anticipate special weather events (such as hurricanes) as much as possible. We do follow projections, but it’s important that we monitor the actual conditions as well. What I mean by this is that we are always looking at both projections and what weather we are currently experiencing to be ready to make changes as needed.

In recent example, where we had to react to Hurricane Dorian, projections were calling for the Wilmington area to receive a lot of rain, so we made sure our releases were minimal so that waters leaving our dam would not contribute to further flooding downstream if they received plenty of rainfall. The lake was at our normal, desired pool stage at that time so we were well equipped to hold on to extra waters, preventing them from reaching downstream, if we received plenty of rainfall upstream as well.

Often when heavy rainfall events are projected, we are asked if we are draining the lake. While that’s a reasonable expectation on the surface, the problem with that thinking is that waters leaving our dam have just over a 200-mile journey before they reach the ocean. This means that if we were to “drain the lake” once we receive projections, additional waters would be making their way downstream just as those areas are expected to be hit with the hurricane, compounding potential flooding.  

 This is much more complicated than I imagined and so much is at stake here. What about Jordan Lake as a water resource for domestic uses. We know that Jordan Lake is an important source of water for several area towns and cities. Please tell us how that is monitored and controlled?

The towns that take water from the lake call or email us with their total withdrawals daily and most of the water they withdraw is used as municipal water supply and later treated and discharged or returned into the river below the dam. It is estimated that more than 300,000 people get their water from the lake every day.

You also might want to know that the average inflow into the lake is about 450,000 gallons of water per minute and that local towns and counties draw about 40 million gallons of water from the lake, daily. And you might also be interested in learning that the maximum sustainable yield of water that can be withdrawn from the lake daily in keeping with the lakes mission is 100 million gallons of water per day. In the summer months, there is significant evaporation of water from the lake and it is estimated that we lose more depth from the lake due to evaporation than our discharges.

You previously said that you specialize in in community outreach and engagement. I know that this is not quite the same thing, but knowing that many agencies and businesses may be impacted by the Corps decisions on lake levels and downstream discharges, what can you tell us about the Corps involvement in these matters?

We have a weekly phone conference between the Corps and various stakeholders surrounding the lake as well as upstream and downstream of the lake. There are five Corps Lakes in our Wilmington District. The Wilmington District covers most of NC and a small part of VA as well. These calls focus on lake operations – what current lake levels are, plans to increase or decrease releases, etc. The National Weather Service (NWS) usually participates in these conference calls to provide weather updates. In critical situations such as severe storms causing heavy rains and flooding (real or potential) there may be phone conferences 2-3 times per week.

Blake, before we talked I thought that there might be sensors in different parts of the lake that gave you water level readings. Now I realize that this is not the case. What can you tell our readers about this?

Waiting until the water level in the lake is too high or too low is not a good idea. Instead we rely heavily on stream gauge data to give us an idea of how waters are moving through the Jordan Lake watershed before these get into the lake and also downstream from the dam and into the Cape Fear watershed. The gauge data we rely on comes from the USGS which maintains gauges in many streams and rivers across the US.   Another valuable resource is the Southeast River Forecast Center (RFC) through the National Weather Service. The Southeast RFC compiles information obtained through USGS and presents prediction models, flood status, and historical data for specific points.

We also understand that much of this same data is available to the general public as well. For those of us that may be interested, can you tell us where we can get this data?

Sure. The information obtained through these is all publically available and can be found at waterdata.usgs.gov  and you can also visit visit the Southeast RFC at weather.gov/serfc.

This is all very interesting. Can you go into some additional detail as I believe our readers would like to learn as much as possible on this subject?

Okay. Water management decisions are based on many variables: soil saturation, rainfall forecasts, evaporation, water taken in by plants and trees, to name a few – and these are looked at downstream, upstream, and locally. We hold back water to reduce flooding downstream, as well as supply water to local and downstream communities in the event of drought.

A good example of our water management practices is how we handled the storms of last fall. In a span of several months, we were faced with Hurricanes Florence and Michael, and several other events with high instances of rainfall both upstream and downstream. The furthest out we get forecasts for such events is about a week, and even at that point it’s not super precise and fluctuates almost daily.

We do not perform drawdowns – that is, we do not lower our lake level below our desired pool stage (216 ft. msl.) to have more flood storage. If we were to do this, the areas most prone to flooding would be receiving the waters we released just as the worst of the rainfall were coming their way, exasperating the flood. During these severe storms, downstream communities received almost 20-inches of rain in a matter of about two days. Upstream areas received almost 10-inches of rain in that same time, so that when the rain from upstream made its way to Jordan Lake, we were keeping the dam gates closed to isolate some flooding to Jordan Lake while preventingfurther flooding downstream.

I understand that under normal conditions it takes a few days for water discharged from the dam to reach Fayetteville and upwards of a week before reaching Wilmington. Does this ever work to your advantage?

Yes it does. The advantage of the waters taking about a week, depending on the flow rate water is moving through the river, to make their way downstream is that we can begin to release waters when areas downstream are still in minor flood stage but expecting to be out of it in the next several days, that way the waters we’re releasing aren’t furthering flood conditions.

During our tour of your facilities you pointed out the tall tower at the dam and said it was involved in the production of electricity. Can you give us a little more information about this?

Some of the water that passes through the gates that are normally used to discharge water from the lake also passes through two generators that create electricity. Jordan Hydro owns and manages the hydroelectricity equipment. This electricity is then sent to the power grid. The electricity that these 2 generators create is enough to meet the power needs of about 1,700 homes. You might also find it interesting to know that these generators must be lifted vertically whenever the lake level rises to flood stage in order to prevent damaging the generators. No power can be generated when it is necessary to raise these gates.

Those of us that have visited the dam site can easily see that this dam is earthen. When I think of large dams I always thought these would be concrete dams. Are earthen dam weaker than concrete ones?

Many people think of large, concrete structures when they think of dams and think that surely, Jordan Lake’s Dam must be weaker and more porous in comparison when they see the earthen structure. However, this is not the case. When certain clays are compacted well enough, they are less porous than the typical concrete. Water will move through the structure of any dam, just very slowly.

Of course we still need to regularly monitor the dam face for signs of movement. If you look at the sides of the dam you will see a large number of tubes sticking up from it. These are called piezometers which are well-like structures that allow us to monitor how water is moving through the structure of the dam. There are about 100 piezometers here that are measured regularly.  

Thank you Blake. Another thing we were wondering about was water pollution as we are aware that this has been a chronic problem here for several years now and that there have been a few attempts to improve the water quality.

I need to tell you that both pollution control and water quality are primarily the responsibility of the State, namely the Division of Water Resources and yes these are both important and complicated issues. However even though it is not part of our mission to abate lake pollution, we do partner with other organizations such as Clean Jordan Lake in order to accomplish the common goal of outreach and educating the public on protecting Jordan Lake. The Corps also works with the NC Division of State Parks, the NC Forestry Service and the NC Wildlife Services Commission to achieve the total balance between managing and protecting the natural resources in and surrounding the Lake.

What can you tell us about the wildlife in the area around the lake?

As you might suspect, the lake and the surrounding controlled shoreline are both rich in many kinds of wildlife. But did you realize that many American Bald Eagles call Jordan Lake their home? Jordan Lake is one of the largest concentrations of Bald Eagles east of the Mississippi River. We have received reports of as many as 40 being observed at the same time. Much of the land surrounding Jordan Lake are game lands that are free and open to the public for hunting, provided they have a valid NC hunting license. The NC Wildlife Resource Commission does well in managing the forestland to provide excellent habitat for game species.

Blake, you have given us a great amount of information about your operations at the lake and dam, but in closing is there anything that the public can do to support you in your mission?

Yes there certainly several things that the public can do to help us. One really big thing that comes to mind is the conservation of water usage so that the municipalities that take water from the lake take only what is needed. Also, homeowners and businesses (including agriculture and livestock operations) that are near tributaries that feed into the Lake should practice good conservation of soils and runoffs and minimum use of fertilizers as well as properly store and dispose of waste.

JORDAN LAKE VISITOR ASSISTANCE CENTER
The Jordan Lake Visitor Assistance Center is located at Jordan Lake Dam and offers rotating exhibits on water supply, recreation, fish and wildlife conservation, flood damage reduction, water quality, and the construction and operation of the dam. Several miles of paths and trails provide access to forests, fields, the lake shore, and the river bank. The programming theme is water management (quality and quantity), and what it means to each of us. Program topics also include water safety, endangered species management, and the purposes, history, and impacts of B. Everett Jordan Lake.   They also provide free water safety and environmental educational programs for schools and groups and are available to participate in career days and other special programs.

Visitors can  walk across the dam and visit the tailrace where the waters of Jordan Lake are discharge into the Haw River below the dam.

Hours of Operation Daily M-F 8:00 am to 4:30 pm.
During weekends, call ahead for center timesdam6
Address: 2080 Jordan Dam Road Moncure, NC 27559 
Phone: (919) 542-4501

 

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