July in the Brazos River Basin is typically the driest month of the year, with average rainfall usually hovering around two inches or less. This year, however, tells a different story.
The basin has already experienced abnormally high rainfall this month (July 2025), significantly deviating from its characteristic mid-summer dryness. Most of the basin has seen anywhere from around 0.5 to 8 inches of rain. Isolated pockets of the basin have seen 10 to 20 inches, and that’s just the first half of the month.
“The highest rainfall totals from these recent rain events occurred in the west-central portion of the basin within the Little River sub-basin," said Chris Higgins, lead hydrologist with the Brazos River Authority.
Rain in one basin can be a blessing, while in another it can be a curse. The Lone Star State has 15 major river basins, which essentially define the major drainage areas for all the rivers and streams that flow across the state.
As of July 22, 2025, the Brazos River Authority Water Supply System is 99.7% full. The last time it was at or very near 100% full in July was in 2021.
During late July 2021, all reservoirs within the BRA Water Supply System were full except Georgetown Lake, which was about 2 feet below the top of conservation, said Aaron Abel, BRA water services manager. The BRA total system capacity in July 2021 was comparable to the current BRA total system capacity of around 99.7% full.
“Currently, all reservoirs within the BRA Water Supply System are at their operational full levels or are impounding water within their respective flood control pools except for Lake Limestone, which is currently about 0.54 feet below top of conservation or about 97% full.”
“It may be a surprise to most, but the BRA Water Supply System has been at or very near 100% full many times in the past,” Abel said.
Some of these periods over the last decade include:
• Fall 2018 to Summer 2019
• Portions of Spring 2017
• Fall 2015 through Spring 2016
• Spring to Summer 2015
There are 11 reservoirs in the BRA’s Water Supply System. Three are owned and operated by the BRA: lakes Possum Kingdom, Granbury, and Limestone. And eight are owned and operated by the US Army Corps of Engineers. They include lakes Proctor, Whitney, Aquilla, Belton, Stillhouse Hollow, Granger, Georgetown, and Somerville.
One of the biggest impacts in the basin due to rainfall this month comes in Williamson County, 20 miles north of Austin.
The area with the highest rainfall totals occurred in Georgetown Lake’s drainage basin along the North Fork San Gabriel River, Higgins said. The area has received 15 to 20 inches of rain.
One area just west of Liberty Hill along the border between Williamson and Burnet counties received 15 inches within 24 hours over the July 4th weekend, Higgins said. The runoff raised Georgetown Lake by 24 feet in a single day, prompting the BRA to remove the Stage 1 – Drought Watch from the reservoir, which had been in place since early April.
Georgetown Lake hasn’t been full since July 2019, marking six years since its last full capacity.
Hamilton, Lampasas, and Coryell counties, which are in the Stillhouse Hollow and Belton lakes watersheds, received notable rainfall amounts ranging from six to 15 inches, Higgins said.
While the Brazos River Basin rainfall removed drought watches, the same powerful weather systems brought devastating, catastrophic flooding and tragic loss of life to other parts of the Texas Hill Country, emphasizing the different impacts of heavy rainfall across different watersheds.
As of July 22, all eight US Army Corps of Engineers reservoirs were temporarily holding a combined total of about 175,000 acre-feet of water in their respective flood pools, Higgins said. The Corps continues to evacuate the flood pools of these multi-purpose reservoirs at various release magnitudes, which will help maintain above normal streamflow along the mainstem of the river for at least a month or more.
With Georgetown Lake now full, the transfer of water from Stillhouse Hollow Lake to Georgetown Lake through the Williamson County Regional Raw Water Line (WCRRWL) was discontinued. Additionally, the BRA also removed the Stage 1 - Drought Watch status from Stillhouse Hollow Lake.
No drought declarations are currently in effect within the BRA Water Supply System. The Williamson County Regional Raw Water Line (WCRRWL) delivers raw water from Stillhouse Hollow Lake to Georgetown Lake for the three Williamson County providers. Without the line, the supply stored in Georgetown Lake would not meet local needs. Thankfully, there is the neighboring Stillhouse Hollow Lake, which is roughly four times larger than Georgetown Lake and can help meet demand when needed.
Streamflow conditions along the mainstem of the Brazos River and its tributaries remain above normal for this time of year. Recent rainfall and associated releases from the mainstem reservoirs will likely help maintain elevated streamflow levels in the lower basin over the next month or so.
When heavy rains result in significant inflow, water releases from the Brazos River Authority reservoirs can occur. Fortunately, the Corps reservoirs are designed for flood control, meaning they can hold a substantial amount of water beyond their normal conservation pool.
The BRA’s reservoirs, meanwhile, are not designed to hold floodwater. Beyond the normal conservation pool, the water that flows into BRA reservoirs when they are full must be released downstream to safely manage dam facilities.
The US Army Corps of Engineers reservoirs, on the other hand, have the ability to store large volumes of water until it is deemed safe for release downstream. Whitney Lake, for instance, is the largest of the Corps reservoirs and is located on the Brazos River downstream of lakes Possum Kingdom and Granbury. Releases of floodwater from these two reservoirs are captured and contained in the flood pool at Whitney Lake.