Do you need to know when dam gates will be opened?

Do you need to know when dam gates will be opened?

Spring is here, and that (hopefully) means rain. 

We've been in a drought for so long that it feels like the days when the Brazos River Authority water supply reservoirs released substantial amounts of water are long past. But one heavy rain event could change that, and you can be notified wherever you are, whenever that happens. 

"When we have above normal rainfall to swing the system from drought conditions to full reservoirs, it typically coincides with flood events," said Aaron Abel, BRA water services manager. "We can have flood events in any month in the Brazos River Basin, but typically they coincide with our wetter months of the year (April through June) and then again in the fall (October to November)."

The three reservoirs owned and operated by the BRA were built for water supply: Possum Kingdom Lake, Lake Granbury, and Lake Limestone. Therefore, as much water as possible is kept in each reservoir to ensure the water is available to meet a wide range of needs. 

Water supply is used to generate the electricity that lights our homes and businesses and to supply thirsty cities with drinking water. The precious resource is also essential for agriculture, industry, and mining. Part of maintaining each structure, and prolonging the life of each dam, is ensuring water doesn't flow over any of these structures. Therefore, during times of heavy rain, water must be released when the reservoir becomes full to prevent damage to these vital and massive structures. 

There is no extra space to allow for floodwaters; often, if the lake is full, whatever water flows into the reservoir must also be released from the dam in real time. 

Texas lakes often serve a dual purpose. Many flood control lakes also hold water supply. However, supply lakes are not necessarily built to aid in flood control. 

While the three BRA lakes are used as storage reservoirs, they are not designed to provide flood control. Floodwater released from Lakes Possum Kingdom and Granbury is temporarily stored in Lake Whitney. But, there are no U.S. Army Corps of Engineers flood control reservoirs downstream of BRA's Lake Limestone, located on the upper Navasota River in Limestone, Robertson, and Leon counties. Water released from Lake Limestone flows down the Navasota River to where it joins the Brazos and then down the Brazos River to the Gulf of Mexico.

Many factors are considered in determining from which location water supply releases are made. These can include current lake levels, the amount of water flowing into the lakes, the amount of water being used locally from the lakes, the travel time for released water to reach its destination, and the amount of water that would be lost to evaporation or absorbed by the stream channel. 

Ultimately, these release decisions are made to maximize the beneficial use of the water supplies while seeking to balance adverse impacts.

The BRA does not release water from its reservoirs based on weather forecasts. Doing so could make flooding worse downstream or unnecessarily waste water supply.

The BRA lake offices work closely with the Central Office, the West Gulf River Forecast Center, the U.S. Army Corps of Engineers, emergency management officials and many other entities in making release decisions.

Being notified

For those living near the Brazos or Navasota Rivers, knowing when the BRA planned to open gates for water releases downstream has been a safety necessity. Farmers and ranchers might need to move cattle or equipment away from flood-prone areas. Homeowners might want to move patio tables, and chairs settled near the river. Or recreationists might reschedule fishing trips or canoe travel to a later date when flows subside. As a result, for decades, the BRA has offered a way for members of the public to receive notifications of gate changes at each of its three reservoirs.  

Through an automated system, the BRA can send a text, email, and/or phone call to anyone signed up to receive an alert. Individuals interested in receiving notifications can customize when and how often they receive a downstream notification from the call system. For instance, a person can sign up and select to receive alerts only when 15,000 cubic feet per second or higher is released from Lake Granbury's DeCordova Bend Dam. Or a person can choose to be notified at all release levels at Lake Limestone's Sterling C. Robertson Dam. 

And since every gate opening at Possum Kingdom Lake's Morris Sheppard Dam generates a large release downstream, a person can sign up for all or none of those updates. The gates at Possum Kingdom Lake are an "all or none" type release, unlike the other two reservoirs, which have the ability for incremental releases. The COC (controlled outlet conduit) at Possum Kingdom Lake fully opened only releases 3,000 cfs and therefore is considered a low-flow release, not warranting an alert. In addition, the watershed between Possum Kingdom Lake and Lake Granbury is shallow, allowing for that slight bump in flow. 
Each BRA reservoir has an alert horn that sounds at the dam prior to a gate opening, alerting those fishing downstream of an imminent gate opening.

The Brazos River Authority will, of course, continue its practice of keeping its website homepage – brazos.org – updated with real-time information regarding the current release rate from each of its three dams. BRA employees also will continue its practice of posting release-change information on its Facebook page and Twitter account. 

The alerts, which have been in place since before Lake Limestone's creation, are not meant to serve as a flood warning system. Texas' weather can change instantly, and everyone must be prepared when enjoying the water. Everyone is responsible for monitoring local news outlets, National Weather Service broadcasts, and other information to remain fully aware of potentially hazardous conditions.

Those interested in signing up for the downstream notification call list can fill out a form here.

There is great natural beauty to enjoy when you live close to a river or reservoir, but the tradeoff is staying aware of and being prepared for flooding.