This is the first part of a series by the San Antonio Report about the sustainability of area lakes. Read the second part here and the third part here.
These days it’s easy to see why Canyon Lake, located just 30 minutes north of San Antonio, got its name.
Algae blooms along the lake’s shorelines in green and yellow plumes, its growth exacerbated by the ongoing drought. Trees that have not seen sunlight since Canyon Lake submerged the small towns of Crane’s Mill and Hancock five decades ago poke out along the lake’s rocky cliffs, which are marred by a dark stain where the waterline usually sits.
The manmade reservoir beloved by San Antonio boaters, anglers and skiers is less than 70% full. It reached a historic low Aug. 27 amid record-setting heat at 892.69 feet above sea level; the previous low, set on Sept. 8, 2009, was 893.7 feet. While the lake’s level can fluctuate with small rain events in the area, it’s been steadily on the decline since early this summer.
Known for the massive dam that formed it, Canyon Lake was built in the 1960s by the U.S. Army Corps of Engineers, which still manages it.
The Guadalupe-Blanco River Authority (GBRA), which contributed to the dam’s construction costs and pays the federal government annually for operation and maintenance, handles the lake’s water resources. The GBRA uses the water both to operate several small hydroelectric plants downstream from New Braunfels and to supply water to both residential and municipal utility customers, including SAWS.
Today, Canyon Lake has 23 boat ramps, two marinas, campgrounds, hiking trails, golf courses and a country club. The small municipality of Canyon Lake, population 30,000, has sprung up on its shores, spurred by the tourism and recreation dollars brought in by the lake and its roughly 80 miles of shoreline.
But even as Canyon Lake’s business owners and residents say the low water levels haven’t had a big effect around the lake this summer, the lake itself tells another story.
Boats carefully navigate their way around the algae blooms and stumps to find the rich blue center of the reservoir. Getting the boats out on the water has been a challenge, with only a few of the lake’s boat ramps accessible due to the low water level.
As drought continues to plague the Central Texas area and development explodes across the Hill Country, predicting how future droughts will affect local lakes and those who live on their shores is becoming increasingly difficult.
Canyon Lake’s historic low goes beyond its impact on recreation and highlights why planning for more intense bouts of drought and more severe dumps of rainfall needs to happen now — or Texas could be faced with punishing consequences.
“Texas plans for the droughts of the past, not the droughts of the future,” said Robert Mace, the executive director and chief water policy officer at The Meadows Center for Water and the Environment at Texas State University. “With droughts expected to get worse with warming, the risk of Texas communities running out of water gets higher every year.”
The creation of Canyon Lake
The discussions that led to the creation of Canyon Lake were launched in the early 20th century following several devastating floods that saw the Guadalupe River swell to fatal levels. The lake was created to serve two purposes: flood control and water conservation.
The lake works like a large Igloo water cooler, holding and storing water that comes into it from the upper Guadalupe River. Meanwhile, it releases water back into the lower Guadalupe in a controlled way, like the dispenser tap of the cooler.
In recent years, Canyon Lake’s inflows have been historically low, Mace said.
Since June 29, there’s been no inflow into the reservoir from the river, Mace said. The average flow of the Guadalupe River at Spring Branch, just upstream of Canyon Lake, is about 353 cubic feet per second (CFS), according to the GBRA.
While the lake’s inflows have hit zero before — in 2014, 2013 and 2011 — the fact that the burgeoning Hill Country population is tapping surface water means demands on the river’s water won’t go away, Mace said.
“It’s a combination of a few things … happening upriver,” Mace said.
The consequences of low flows
Currently, Canyon Lakes outflows remain steady; it is releasing water into the lower Guadalupe River at roughly 120 cubic feet per second (CFS), considered to be a rate safe for recreational activities downriver.
But the lack of water flowing into the lake means much of the lake has grown stagnant, perfect conditions for algae blooms.
According to the EPA, algae blooms can reduce the ability of fish and other aquatic life to find food, can block out sunlight or clog fish gills, can create dead zones — areas in water with little or no oxygen where aquatic life cannot survive, and can even release harmful toxins that can paralyze or even kill animals who ingest them.
While the algae at Canyon Lake is likely not dangerous and is more just a hazard for boaters, anytime thick layers of algae occur in a body of water, these impacts can too, said Todd Sink a Texas A&M associate professor and Texas A&M AgriLife algae expert.
Apart from making recreation on the lake more difficult, slow or non-existent flows also impact ranchers or residents near the lake who depend on the lake being high to supply their wells and tanks, Mace said.
“If you’re a rancher and you’re relying on the flow to water your flock, that’s an issue,” he said. “There may be people relying on those flows for household uses. There’s environmental impact — whatever species are dependent on the water, if they can’t swim away and if there’s no water then they die.”
The GBRA has had Stage 2 conservation measurements for residential customers in place since June 2022 meaning lake residents are limited to specific watering days based on their address. While Canyon Lake is low compared to its own history, it’s still relatively full as far as Texas lakes go, said Jonathan Stinson, the GBRA’s deputy general manager.
“From my perspective, I grew up in Austin on Lake Travis, which fluctuates much more than Canyon,” Stinson said. “While Canyon is a few feet low, it’s in a lot better shape than a lot of the area’s lakes.”
Canyon Lake has “plenty of water for our contracted water supply customers,” Stinson said.
Unbothered businesses
Despite the lake’s low levels, Canyon Lake locals remain optimistic.
With Labor Day just days away, the lake will see a good number of visitors this weekend, said the U.S. Army Corps of Engineers Canyon Lake Manager Marcus Schimank.
“That’s typically the last big summer holiday at the lake,” Schimank said. “So we anticipate having pretty good crowds out here.”
The low water hasn’t deterred people from coming out to the lake this summer, said Zack Pennell, founder and co-owner of Canyon Lake Adventures, a boat and jet ski rental company that has operated on the lake since 2014.
“It’s just making things more complicated as far as ramps — there’s only a few right now — but it’s not really affected business,” Pennell said.
Pennell said he still gets about four to six groups out on the lake every day. It’s made wait times slightly longer between groups due to the difficulties of getting boats in and out of the water with so few ramps available, he said.
Schimank said the U.S. Army Corps of Engineers closed the Potters Creek Boat Ramp 21 last week, leaving just three other ramps open.
However, all the lake needs is one good rainfall to come back up quickly, he said. As a flood-control lake, it refills fast by design, Schimank said.
“Hopefully the weather pattern will change where … we’ll get a good rainfall and … the lake will come back up,” he said.
