Start below Spring Lake Dam
You cannot fish the source. The San Marcos rises from more than 200 artesian openings under Spring Lake, which TSHA calls the second largest natural spring cluster in Texas, and the Meadows Center at Texas State says public swimming, fishing and unauthorized boats are not permitted on the lake; access is by tour. The river you can fish starts below Spring Lake Dam and runs past City Park, Rio Vista and Ramon Lucio parks, picks up the Blanco about four miles down, and travels seventy-five miles to the Guadalupe near Gonzales.
The springs are why the river fishes the way it does. The city and the Meadows Center both put the water at a constant 72 degrees, so there is no winter shutdown and no summer kill, and the fish are always at least somewhat awake. Spring flow depends on the Edwards Aquifer. In 2025, the Edwards Aquifer Habitat Conservation Plan's annual report says, San Marcos springflow averaged 89 cfs and bottomed at 77, the third straight year of extreme drought. No one publishes a fishing flow for the San Marcos gauge, so the 90 to 180 cfs range on this page runs from that 2025 average up to the long-term USGS daily medians, which sit between 146 and 176 cfs through the year.
Wild-rice, booms and the 120 cfs line
Texas wild-rice grows only in this river, in its upper two miles according to TPWD, and has been listed as endangered since 1978. The fountain darter was listed in 1970 and the San Marcos salamander as threatened in 1980. In December 2012 the Parks and Wildlife Commission made the upper river a State Scientific Area, from near Spring Lake Dam to near the city's water treatment plant. Inside it you may not uproot wild-rice or tamper with a boundary sign or buoy, and when the USGS San Marcos gauge reads 120 cfs or less, TPWD may close stands with booms, buoys or signs. Entering a marked area is an offense.
That trigger is live. Every monthly mean at the gauge from June 2025 through April 2026 was under 120 cfs, and it read 91 cfs on September 24, 2026. So wading in town means walking gravel and open runs, going around the rice, and treating any boom as a wall. City parks open at 6 a.m. and close at 11 p.m., ban alcohol, and since May 1, 2024 allow only reusable drink containers on the river and its banks outside designated Go Zones. From June 20 through September 7, Rio Vista charges out-of-area visitors on weekends and holidays, and the gate takes no cash.
Cummings Dam to Martindale, by the Water Safari's miles
Below the Blanco the river leaves town and the banks turn private. TPWD classifies the San Marcos as navigable, so the bed is public and the banks may be used only to portage. The Texas Water Safari's course log is the best map: Rio Vista Dam at mile 1.25 can be run through its center spillway, Thompson's Island at 1.86, the Blanco at 4.67, Cummings Dam at 5.27 is a portage, Westerfield Crossing at 5.86 has low clearance, Cottonseed Rapids at 9.12, Scull's Crossing at 9.58, Martindale Dam at 10.66 and Staples Dam at 16.62. The race notes that Rio Vista and the coastal saltwater barrier are the only dams that can be run.
TPWD leases two sites in this stretch. San Marcos River Retreat, on the north bank in Caldwell County, has about 1,300 feet of frontage and charges $5 a person to bank fish or $3 to launch a paddle craft, by reservation. Scull Road Bridge on the west bank near Martindale is the take-out for a 3-mile float from the Retreat through Cottonseed Rapids, which the Safari says can be run at most water levels; text 512-787-5574 for the gate code, and portage Martindale Dam if you carry on 1.85 miles to Spencer Canoes. TPWD's River Grove site near Fentress is closed.
Luling's six miles
Farther down, the only official TPWD paddling trail on the river runs 6.0 miles from the State Highway 90 crossing about 5 miles west of Luling to Zedler Mill Park, 2 to 4 hours depending on flow, with small Class I rapids and nothing man-made in the way until the dam beyond the mill, which is why you watch for the take-out. TPWD lists largemouth and smallmouth, gar, sunfish and catfish here and recommends small jigs, plastic worms, spinnerbaits and light line. The Luling gauge, 08172000, read 86.2 cfs the same morning the San Marcos gauge read 91.
Statewide limits, a catch-and-release request, and the cichlids
The San Marcos is not on TPWD's list of exceptions, so statewide limits apply: five black bass a day in any combination, 14 inches for largemouth and smallmouth, no minimum on Guadalupe or spotted bass, and no limit on sunfish. A resident freshwater license package is $30. TPWD's lease pages ask anglers to release sportfish on this river, especially largemouth and Guadalupe bass. Tilapia and other listed exotics have to be killed, gutted or iced before you keep them.
The Texas Freshwater Fly Fishing blog, written on this river, calls the bass fishing amazing and says Rio Grande cichlids grow to great size here. Its cichlid rig is a floating line, a 6 to 7 foot leader and a foot of 3X to 5X fluorocarbon, with small crayfish and jig patterns such as Pat's Hot Tail Mini-Craw and a jigged Foxy Clouser fished slow near the bottom. For summer bass it uses SMPs in baby-bass or sunfish colors, poppers, divers, Clouser Minnows and a salamander pattern first tied for this river and dragged along the bottom in the heat. With the water at 72 degrees, the real season is the crowd: weekends from April to September belong to tubes, and weekday mornings do not.