The 1st attraction to take up space in Lake Charles was Diamond Falls. It took up all of the cove between the Dodgem building and the north-eastern part of of the Safari Village lake front.
Keep in mind that when KECO opened Hurricane Reef in 1992, most of the water park was below the former surface water level of the lake. I am pretty sure the bottom of the splash pools for the slide complexes Baja Bends and Free-Stylin', as well as the bottom of the lazy river, were just 1-2 feet from the original lake bottom. The most fill-in occurred in the southwest corner of the former lake, nearest the arcade building, to create the "hill" for the Free-Stylin' tube slides. I guess that land rise is 14-16 feet above what was then the lake bottom.
I don't fully understand the reasons for the company placing the original water park where they did. Maybe Kings Entertainment Company was not sure how a water park, within the dry park, would be received. I don't think that many parks were a combination of dry/water back then. We take it for granted today; but, back then they might not have been certain if this combo would work.
It is easy to look at it now and say why didn't they build it completely south of the Rebel Yell. But, the animal safari and the steam train ride took up most of that land until Paramount took over. Then they eliminated the animal safari and steam train. Fianally, around 1999, Paramount expanded the water park to the south.
At this point, the only original slide complexes left north of the Rebel Yell are Baja Bends and Free Stylin' (and the lazy river). The other Hurricane Reef attractions were removed when the Stunt Coaster was constructed (Kid's area and the 4 Monsoon Chutes 50ft/70ft speed slides). Then, Torrential Twist, the twisted dual slides were removed in the mid-2000's. Finally, Shoot the Curl slides are on the way out this off season.