| Mile | Location | Note |
| 0 | Spring Lake | Start |
| GPS: 29.893485,-97.930922 | ||
| Spring Lake Dam | Portage | |
| Portage island left, right, or middle with the middle being the most popular. Hazardous footing in some spots. Can only be seen on race day (private property). | ||
| 1.25 | Rio Vista Dam | Portage |
| Can be portaged left or right or can be run through small spillway in center of dam. It and the salt water barrier are the only dams that can be run. ALL OTHERS MUST BE PORTAGED. | ||
| 1.86 | Thompson's Island Dam | Portage |
| Approximately 1/4 mile past I-35 bridge, Thompson's Island Dam will be on river right with mill race continuing down left channel to Thompson's Island Bridge. You can portage the dam and get into old river stream or take left channel to Thompson's Island road bridge. | ||
| 2.2 | Thompson's Island Road Bridge | Portage |
| Portage right at end of mill race. Carry boat beside road to re-enter river above road bridge with yellow handrail. You cannot cross the road and must go under this bridge in the race. | ||
| 4.67 | Blanco River Confluence | |
| Obvious right turn at confluence. | ||
| 5.27 | Cummings Dam | Portage |
| Portage right or left around dam. | ||
| 5.86 | Westerfield Crossing | Low Clearance |
| Low clearance at higher water levels. River current increases with small rapids down to Cottonseed Rapids. | ||
| 9.12 | Cottonseed Rapids | Caution!!! |
| One of the best known on the San Marcos River. It can be run at most water levels. Can be scouted by stopping on river right when you see the old concrete dam. | ||
| 9.58 | Scull's Crossing | |
| Good clearance at all but extremely high water. | ||
| 10.66 | Martindale Dam | Portage |
| Must be portaged on the right. | ||
| 10.76 | Martindale Low Water Crossing | Low Clearance |
| Just past Martindale Dam, approach with caution. Fast current Portage Right leading up to and under bridge with rocks below bridge at low water. Portage right if necessary. | Portage Right | |
| 11.35 | FM 1979 | |
| This next section of river has some fast current with sweepers and small rapids. Still water the last two miles above Staples Dam. | ||
| 16.62 | Staples Dam FM 1977 | Checkpoint #1 |
| DEADLINE-YOU MUST REACH THIS CHECKPOINT BY 2:00PM FRIDAY | ||
| Staples dam fifty yards past bridge. Portage left over lip of dam or right down stairs. This is private property, please exercise courtesy. Fast current starts again with sweepers and two small rock dams that can be run at normal water levels but may need to be portaged at lower water, small log jams are possible from here to Luling 90 but are usually single, fallen trees. | ||
| GPS: 29.782312,-97.83131 | ||
| 26.05 | Fentress Hwy. 20 Bridge | |
| The river continues to be fast at average water levels with tight sweeping corners and stumps. | ||
| 29.15 | Prairie Lea Bridge #1 | Low Clearance |
| Low clearance and dangerous at high water levels. A sweeping left hand turn upstream of the bridge can make the approach difficult to see. At high water it should be approached with caution. Portage right if necessary. | ||
| 30.47 | Prairie Lea Private Bridge | Low Public Access |
| A private bridge. Currently to middle of the bridge is missing | Low Clearance | |
| 31.65 | Prairie Lea #2 | |
| 33.17 | Stairtown Bridge | |
| The river from here to Luling 90 continues to be tight and winding with logs and possible small jams. | ||
| 39.62 | Luling 90 | Checkpoint #2 |
| DEADLINE-YOU MUST REACH THIS CHECKPOINT BY 8:00PM FRIDAY | ||
| The river begins to slow and the possibility of larger log jams increases. Little or no current for the last three miles above Luling Dam. | ||
| GPS: 29.667722,-97.69978 | ||
| 45.56 | Luling (Zedler) Dam and Hwy 80 | Portage |
| The dam, about 400 yards past Luling water intake on left. Portage right. The portage is obvious in daylight. If dark, approach with caution, pulling over well above dam. | ||
| 49.68 | IH-10 | Difficult Access |
| The river below Luling Dam is similar to below Luling 90 with some current below the dam for a couple of miles then slowing. | ||
| 56.03 | Broken Dam Rapid (Son of Ottine) | Caution |
| An old broken rock dam that is runable at all but extremely low water. Run just right of center or far left. | ||
| 60.21 | Palmetto Bridge & Park | Portage |
| DEADLINE-YOU MUST REACH THIS CHECKPOINT BY 6:00AM SATURDAY | Checkpoint #3 | |
| A portage at most water levels, strong current just above the bridge; bridge may also have logs and debris on it. Approach with caution especially at night. River continues to have some current but fewer sweeping corners with more logs and some of the largest log jams possible in the next section of the river. | ||
| GPS: 29.589948,-97.585067 | ||
| 67.95 | Sladen Cemetary Bridge | |
| The river gets slower as you get closer to the confluence of the San Marcos and Guadalupe rivers. This is usually the last section for log jams. | ||
| 76.67 | Gonzales 90A | |
| The river gets slow and wide from here to Gonzales Dam. | ||
| 79.17 | Old Iron Bridge (Cone St.) | No Access |
| 81.26 | Guadalupe River Confluence | |
| The Guadalupe River flows in from the right, obvious left turn. Boils and eddies at high water. | ||
| 84.46 | Gonzales Dam | Portage on Left |
| DEADLINE-YOU MUST REACH THIS CHECKPOINT BY 2:00PM SATURDAY | Checkpoint #4 | |
| There is a cable strung 15-20 feet above the water 500 yards above the dam with a warning sign on it. Generating building on left side of the dam is usually well lit at night. Must portage on Left hand side. Take out at ramp. Carry up to access road. Turn in to gate on right. Follow trail to the river. There is quite a bit of rip rap so exercise caution. The next road crossing is 39 miles and this is the longest section on the race course. Make sure to have plenty of water. The dam is not conducive to team pulling over to sleep. Suggest going to Gravel Bar if planning to sleep. | ||
| GPS: 29.2949, -97.2718 | ||
| 85.79 | Gonzales 183 (Gravel Bar) | |
| At low water, there are gravel bars, sweeping turns and a few small rapids. At high water, boils and eddies. This is an appropriate place to sleep if needed. | ||
| 122.6 | Hochheim Hwy 183 | Checkpoint #5 |
| DEADLINE-YOU MUST REACH THISCHECKPOINT BY 4:00AM SUNDAY | ||
| Similar river conditions as the previous section. | ||
| GPS: 29.314262,-97.30321 | ||
| 147.4 | Cheapside Bridge (766) | Checkpoint #6 |
| DEADLINE-YOU MUST REACH THISCHECKPOINT BY 11:00AM SUNDAY | ||
| GPS: 29.147265,-97.317855 | ||
| 154 | FM 3402 / Heaton St. (Old Cuero-San Antonio Rd) | |
| 156.9 | Cuero Hwy 87 | |
| 161.2 | Cuero 236 | Checkpoint #7 |
| DEADLINE-YOU MUST REACH THISCHECKPOINT BY 3:00PM SUNDAY | ||
| This section is a lot like the previous one with a few sweepers and small rapids at low water and boils at high water. | ||
| GPS: 29.051293,-97.265117 | ||
| 178.1 | Thomaston Bridge | |
| This section has some rapids with standing waves at normal water level, but are usually washed out at high water. | ||
| 186.8 | Nursery (447) | |
| 199.8 | Victoria City Park Boat Ramp | Checkpoint #8 |
| DEADLINE-YOU MUST REACH THIS CHECKPOINT BY 6:00AM MONDAY | ||
| This and the next section are the last to have sweepers at low water levels. | ||
| GPS: 28.824706,-97.01542 | ||
| 212.1 | Hwy 59 Bypass (Old Victoria Loop 175 Bridge) | |
| As the river current slows there is a slight possibility of log jams in this section, but usually just fallen trees blocking a portion of the river. | ||
| 213.6 | Cornfield Cut | |
| A sharp cut to the left that leads nowhere. DO NOT TAKE ANY CUTS IN THIS SECTION OF RIVER. | ||
| 216.2 | Blue Bayou Cut | |
| Illegal cut that flows to the left at high water. Cuts are dangerous and congested with logs. | ||
| 221.4 | Coletto Creek Confluence | |
| Flowing in from the right it is a good landmark for time. It is the halfway point to Swinging Bridge (Dupont). | ||
| 231.3 | Swinging' Bridge (off Canal Road) | Checkpoint #9 |
| DEADLINE-YOU MUST REACH THIS CHECKPOINT BY 4:00PM MONDAY | ||
| Swingin' Bridge is privately held property. It will be open for the race, but for training runs there is no access. Log jams are possible in this next section, especially after the railroad bridge. | ||
| GPS: 28.651783,-96.962229 | ||
| 237.2 | Railroad Crossing | |
| This next section has the possibility of some of the largest log jams. Some years as many as several large jams. At high water, there are several cuts flowing off the river to the right. | ||
| 248.5 | Saltwater Barrier | |
| A dam that is raised at extremely low water to keep salt water out of Port Lavaca water intake just above the dam. It can have logs piled up in front of it that can be portaged right but is usually open and passable with boils around the pilings. | ||
| 251.2 | Tivoli Hwy 35 Bridge (Papa & Maga's Calhoun Riverside RV Retreat) | Checkpoint #10 |
| DEADLINE-YOU MUST REACH THIS CHECKPOINT BY 3:00AM TUESDAY | ||
| This section can have small log jams but is usually kept open by fishing boats. | ||
| GPS: 28.4766078,-96.8614860 | ||
| 255.1 | Traylor Cut | |
| It's a cut to the left that goes to the upper end of the San Antonio Bay. Usually not taken because of the increased time in the bay. Take the right channel and stay in the river. | ||
| 256.2 | Wooden Bridge | |
| The last public access point. | ||
| 258.7 | Guadalupe River and San Antonio Bay Confluence | |
| There are several routes to cross the bay. One course is to enter the bay turning right after 50-100 yards and follow the right shoreline to Foster Point, then angle left to the end of the spoil bank and around the island turning left to the Seadrift flagpole and pavilion on the seawall. Another course is to come out of the river and across straight to the opposite shore then turn right and follow the shoreline to end of the spoil bank. There are multiple cuts through the spoil island to the barge canal. Do not enter the barge canal but continue to the end of the spoil bank, then left to Seadrift. At the end of the spoil bank you will have to cross the barge canal. Make sure there are no barges coming down the canal. Let any boat pass before attempting to cross. The depth of the canal can make large waves and be dangerous to cross. At night a row of lights on the seawall and car lights on the road above the seawall are landmarks to look for. | ||
| 264.7 | Bill Sander Memorial Park – Seadrift | FINISH |
| DEADLINE 1:00 PM TUESDAY | ||
| 1522 Swan Point Rd, Seadrift, TX 77983 |