Class: IV-; Ave. Gradient: 12 m/km; Portages: could be; Length: 30 km; Time: 6:00
Season: June to October; rafts? lower bits; Highlights: gorgeous jungle scenery; Crux move: twisting mini-gorge
Water Quality: decent; Water Temperature: not noted
PI: Chapultepec bridge (elev: 480 m); TO: Río Huehuetán bridge on coastal highway
Description: (click here for general notes about my descriptions)
The Río Mejapa is a narrow volcanic gutter in an especially verdant fold of the coastal mountains, and a micro-creeker's delight. With it's lush jungle scenery and squawking parrots everywhere, it's a true tropical garden, and with over 1000 feet of elevation drop, kayakers get to experience its fun as well as its beauty.
The creek starts off very small and boat abusive with class IV- micro-creeky rapids. In the first half hour there are 2 small low-head dams, both of which may be runnable. By about the 1:45 mark you encounter what is probably the crux rapid, a twisty mini-gorge requiring a scout and possibly a portage (see photo above).
The tight rapids continue a half hour more to a picturesque finca bridge. Here the river starts to widen a bit, wide enough for shredders. As above, there is a lot of wood to watch out for. Around the 4 hour mark, you will arrive at the confluence of the Río Santo Domingo entering river-right, where the river widens noticeably more. You can expect 1.5 hours more of class II/III paddling down to the coastal highway. You could shorten the trip by getting out at the Guadalupe access about 1.5 km (20 minutes) down from the Santo Domingo confluence.
Flash Flood Danger: normal to high, put on early.
Descent History: The only descent I know about was mine on 31.8.07.
Flow Notes: It is not easy to catch a boatable flow at the upper PI. There is an on-line gage just downstream of the confluence with the Huehuetán (linked below) though it's been out of commission for a few years now. Scouting at the TO bridge will give you the quickest measure but not much indication of what you'll have at the PI. Another guide is you'll want to see at least 1000 cfs in the larger rivers in the area (Cahoa, Coatán, Huehuetán) to make it worth the drive upstream. My impressions are from a low water run, with ~100/2000cfs at the PI/TO. Historical data from INEGI (from the gage point) is included below.
Shuttle Notes: The PI is on the way to the Río Huehuetán PI: drive north out of Tapachula on 8a Avenida which is Highway 18, and go pretty much straight to km marker 18 (passing over the Coatán bridge at km 8.5). The (lower) TO is at the coastal highway, km 268.7 (west-bound markers). Getting to other access points is left as an exercise for the reader. Note also that there is no regular public transport to the PI.
Accommodations: Tapachula makes a convenient base for this run.
Nearby Tourist Attractions: Proto-Mayan ruins at Izapa; Tacaná volcano; Puerto Madero beach.