The Beta Dam is a model present in the original PS2 and PS3 releases of Shadow of the Colossus, as well as the PSU Preview and Preview Version demos of the game. The leftover asset is not present in the PS4 version.
With a distinct orange-brick texture, the model features a winding pathway emerging from a cave, trailing along a mountain ridge before wrapping around to a two-leveled walkway.
The upper level prominently features a partially smashed causeway, highly reminiscent of the ones found leading to Hydrus' lake. Below, a narrow bridge overlooks the surrounding void, bearing a resemblance to the bridge seen in the Gondola level in Ico.
At the end of the bridge, the path opens up to a sprawling green field lined by cliffs to the south before being jarringly cut off at the quadrant's western edge. To the north of the range, a ruined arch can be found, scattered about with rubble and ruins. Three steps are within the ground just before the archway, suggesting there might have once been more to the structure at one point.
Located at quadrant I2, the Beta Dam is distinct in that it is the only prominently complete structure to be found. The majority of adjacent quadrant zones are largely empty, leaving the stranded model floating largely alone in the void.
The Beta Dam was first discovered by Games F&Q forums user Pikol on February 9th, 2009, while searching for the lands seen in the opening intro cutscene. Sadly, his original channel no longer exists, but a copy of his video has been archived and re-uploaded by the legendary Shadow of the Colossus fan Nomad Colossus.
Originally believed to be a leftover model from either Barba's arena or a rejected concept for the waterfall at Pelagia's oasis, it would be later discovered by Nomad Colossus that the I2 quadrant was the dam's proper location. It, along with the rest of the beta mountains, were in fact remnants of a much earlier version of the game that included a larger, more complete landscape.
While the exact purpose of the Dam is unknown, the most plausible theory proposes that it was a backdrop to the Devil colossus' battle. In one of the early Devil screenshots, orange-brick structures and steps can be observed in the background, similar to the ruined archway that stands a close distance to the Dam. The models do not match perfectly, but it is plausible that the model left behind in the game had underwent further refinement from the early pictures seen in the game's artbook and guidebook.
The cave at the southern side of the Beta Dam appears to have once led further south into the I3 quadrant, where it is believed that an early permeation of Basaran was once tested. Alternative theories propose that the feature observed at I3 may have been the lake the Phoenix would be driven into to extinguish its flames given the feature's close presence to the Dam, which may have once filled the area with water.
On September 28th, 2018 Nomad Colossus unveiled a video titled Shadow of the Colossus - The Beta Dam with collisions. In this, the Beta Dam was showcased with the addition of collision detection manually added back to the asset with the assistance of "Wisi".
A short while later, a follow-up video was uploaded, titled Shadow of the Colossus - Beta Dam playable ISO. The video was much the same as the first: showcasing the now-solid beta dam - but with the new addition of patching several small voids in the incomplete structure. Additionally; a playable version of the preview version demo of the game was included in the video's description, with the game modified to include the solid dam.
Although unrelated to Nomad and Wisi's Beta Dam ISO file, current efforts are underway to finish restoring the removed half of the beta dam's landscape by a small team of developers, as well as recreate the various other removed lands scattered across the game.