| San Marcos Springs | |
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 The Wetlands Boardwalk encircles Spring Lake at San Marcos Springs | |
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| Location | San Marcos,Texas,U.S.A.[1] |
| Coordinates | 29°53′35″N97°55′53″W / 29.89304°N 97.93128°W /29.89304; -97.93128 |
| Spring source | Edwards Aquifer |
| Elevation | 570 ft (174 m) abovesea level |
| Type | Karst spring |
| Provides water for | San Marcos River |
| Magnitude | 1 |
| Discharge | 152 ft³/s (4300 L/s) |
San Marcos Springs is the second largest natural cluster ofsprings inTexas. The springs are located in the city ofSan Marcos, Texas, about 30 miles (48 km) southwest ofAustin and 46 miles (74 km) northeast ofSan Antonio.
Although Spring Lake is highly protected, it is accessible to visitors through theMeadows Center for Water and the Environment, a program ofTexas State University, which offers glass-bottom boat tours among other opportunities to explore and learn about the ecosystem.[2]
The San Marcos Springs is an area ofartesian outflow from theEdwards Aquifer along theBalcones Escarpment. More than 200 springs flow from three large fissures and other smaller openings in the rock. The springs provide most of the water for theSan Marcos River, which flows southward from the springs' location.
The springs have never been known to stop flowing. The average flow is 152 ft³/s (4,300 liters/s); the lowest recorded flow of 46 ft³/s (1,302 L/s) occurred in 1956.
In 1849, formerRepublic of Texas vice presidentEdward Burleson built a dam just downstream from the springs; the resulting lake, known as Spring Lake, inundated the springs.
Archaeologists[3] believe that the San Marcos Springs area may be the oldest continually inhabited site in North America, with sediment core evidence of human activity dating back approximately 11,500 years.[4] Excavations at this location uncoveredPaleo Indian artifacts dating back as much as 19,000 years. TheCoahuiltecan refer to these springs as their origin, and called them "Ajehuac Yana" ("spirit spring"). TheTonkawa called the springsCanocanayesatetlo ("warm water"), a reference to the springs' relatively warm 72 °F (22 °C) year-round temperature.
The first Europeans to see the springs were probably members of the Espinosa-Olivares-Aguirre expedition of 1709. Later, theSpanish mission San Xavier and the failed settlement ofSan Marcos de Neve were situated there.White Americans began settling the area in 1835, and the springs became a major stop on theChisholm Trail. From 1928 until 1996, a resort and amusement park known asAquarena Springs was located at the site.Texas State University-San Marcos purchased the surrounding area in 1994, and the site is now known asThe Meadows Center for Water and the Environment.
This region is a dividing line for certain species' occurrences. For example, the iconicCalifornia Fan Palm,Washingtonia filifera is found only west of theBalcones Fault,[5] which runs through San Marcos Springs.
San Marcos Springs is home to eight threatened orendangered species: theFountain darter, theTexas Blind Salamander, theSan Marcos Salamander, theSan Marcos Gambusia,Texas Wild Rice, theComal Springs Dryopid Beetle, theComal Springs Riffle Beetle, and thePeck's Cave Amphipod.[6] Federal requirements to protect the species' environment, and the resulting demands those requirements place on water from the Edwards Aquifer, have led to several legal and political battles throughout the region.
Pursuant to the Edwards Aquifer Habitat Restoration Plan, researchers and volunteers operating out of theTexas State UniversityMeadows Center for Water and the Environment remove non-native species of aquatic vegetation and re-plant native species such asTexas wild rice, resulting in a 53% increase inTexas wild rice since 2015.[7]
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