Knowing Drought

Kicking off the New Year with rain across the Brazos River basin allowed those who rely on water – aka all of us – to exhale some of the rising concern as drought severity levels climbed these past few months.

It’s not as if a drought is unexpected. Like the devastating floods that drop anchor in Texas, drought, too, arrives without welcome like a whisper during Sunday church service.

A majority of people likely equate drought to things they can see, such as the harsh cracks in the ground that zigzag across one’s well-manicured yard, widening and deepening as the days continue. Once that undesired yard décor has resealed, the drought’s passed on, right?

“From a wholesale water supply provider stance, the Brazos River Authority is typically the last part of the system to feel the effects of drought when it occurs. We’re the last to go into a drought, and we’re the last to come out of a drought too,” said BRA Water Services Manager Aaron Abel. “When it’s dry, you have the soil moisture that dries out, and then if dry weather continues, you start to see lower river streamflows, and finally you see lowered reservoir levels, which is when it begins to affect those who need the water. Coming out of a drought, it takes rain to wet the soil, and then soil moisture has to creep back up to capacity. Then you see runoff occur, then increased river streamflows, and finally, the reservoirs begin to fill back up.”

Water supply provider

Since droughts have the ability to affect every single household, it’s crucial the Brazos River Authority water supply system work to keep its lakes as full as possible, so when drought comes, water is there to access. Water conservation efforts remain an important lesson to teach the next generation to inspire continued understanding of the importance and value of water. Once the rain stops, there’s no way to refill the reservoirs tasked with supplying water to countless Texans.

October is usually one of the wettest months in Texas, but many parts of the state received little or no rain in that time. Nearly half (49.1 percent) of the U.S. was experiencing drought conditions as of Dec. 8, with the greatest coverage and most intense drought conditions located over the southwestern quarter of the continental U.S., according to the National Weather Service Climate Prediction Center.

The National Weather Service issued a La Nina Advisory, which states there is a 95% chance La Nina conditions will be present through February and a 65% chance La Nina will persist through April. Typically, the La Nina pattern brings warmer and dryer-than-normal conditions to Texas during the winter and spring. This translates to less rain and warmer temperatures leading to dry vegetation, creating an increased risk for wildfires, according to AgriLife Today.

Following the drought of the 1950s, the US Army Corps of Engineers and state organizations such as the Brazos River Authority built numerous reservoirs for both flood control and water supply. The stored water in the reservoirs provides access to water supply even in these exceptional drought conditions.

The BRA’s three lakes are water supply reservoirs, built to provide water: Possum Kingdom Lake and lakes Granbury and Limestone. These structures are most important come dry times as those throughout the watershed need water in their daily life. Daily operations work to ensure water gets to the part of the basin that needs it the most, whether that’s releasing water from a reservoir to go downstream or using water pipelines to move the water.

The BRA water supply system includes 11 reservoirs. Eight are owned and operated by the U.S. Army Corps of Engineers: lakes Whitney, Aquilla, Proctor, Belton, Stillhouse Hollow, Georgetown, Granger, and Somerville. And the BRA also operates and manages the Williamson County Regional Raw Water Line (WCRRWL), which delivers raw water from Lake Stillhouse Hollow to Lake Georgetown for use by three Williamson County providers: the cities of Georgetown and Round Rock, and Brushy Creek Municipal Utility District.

Drought stages

As a result of the drought experienced in 2011, the BRA began regularly assessing projected reservoir conditions to stay ahead of drought. Two graphics are posted on the BRA’s website each month, representing the potential for reservoir capacity and drawdown. One illustrates reservoir levels under extremely dry conditions, while the second projects reservoir levels under average conditions. These projections are also provided to the public on the BRA’s website here.

The graphics also indicate if any of the drought stages identified in the BRA’s drought contingency plan will be triggered. The drought contingency plan is a strategy or combination of strategies for monitoring the progression of a drought and preparing a response to potential water supply shortages resulting from severe droughts or other water supply emergencies.

It’s important the contract holders throughout the basin understand the varying drought stages so they know the efforts that will be needed to preserve the water supply during droughts, Abel said.

“We want to be able to stretch the existing supply as long as possible,” he said. “We don’t really know how long a drought is going to last. Just like every flood is different from every other flood, every drought is different from every other drought.”

Those who get their water from Lake Georgetown were the first in recent months to enter a drought stage.

In November, a Stage 1 Drought Watch was declared as the result of the drier than normal conditions in this portion of the Brazos River basin. One of the trigger points for the institution of drought contingency measures at Lake Georgetown is sustained pumping through the WCRRWL for a period of six months. The goal of the Stage 1 Drought Watch is to implement a voluntary reduction of five percent of water use that would have occurred in the absence of any drought contingency measures and to raise awareness of the developing drought situation.

Toward the end of 2020, Stillhouse Hollow Lake and Lake Granger were also approaching potential Stage 1 Drought Watches, Abel said. Lake Somerville may also find itself in Stage 1 in late January depending on rainfall, he said.

There are stages in the BRA’s drought contingency plan. Stage 2, among other things, includes a goal of 10% reduction in water use, and 20% in Stage 3. Forecasts help manage a precious supply of water and conservation efforts throughout the watershed stretch the resource through dry times.

Conservation

Stretching from New Mexico to the Gulf of Mexico, the Brazos River watershed is a vital resource to individuals, households, businesses, industry, agriculture, mining and so much more. Working together to protect that resource is a continuous process. The National Weather Service West Gulf River Forecast Center, BRA and Corps of Engineers work together in coordination with other agencies, such as the U.S. Geological Survey, to manage water releases across the Brazos River basin. Conserving water is a big task and not up to just one person.

Some conservation efforts naturally differ over seasons. During these winter months, any amount of rain goes a long way, Abel said. Most plants are dormant in the winter, and so grasses and native plants along the river and in the watershed aren’t growing or active, so they don’t use water from soils like they do in summer months, he said.

“In the summer, we may have a dry area upstream of a reservoir, and we get 1-2 inches and see no response in the watershed at all because all the water goes to the dry soils and plants,” he said.

Everyone can make a difference when it comes to extending the water supply through water conservation efforts. These efforts go the furthest when drought begins to creep its way across the Lone Star State. Reservoir levels may decline and could reach additional trigger levels requiring further actions under the BRA’s drought contingency plan. Learn about a variety of water conservation ideas here.