Because of the large volume of water pumped through the S-5A, this pump contributes the largest load of phosphorus to the Everglades of any of the pump stations. A third source of surface phosphorus is the Acme Drainage Basin to the east of the Refuge, which adds an estimated average of 5.39 tons to the refuge annually. These inflow waters tend to flow easier along the canals, unless the water level across the refuge is very high, which is rare. Thus, the cattails spread deeper into the refuge from the canals. They now cover over 6,000 acres.
Cattails are the most visible effect of the nutrient imbalance.
However, many detrimental changes in the abundance and diversity of algae, diatoms, desmids, and other microorganisms have already occurred by the time the cattail problem is evident. Changes such as these starting at the bottom of the food chain eventually work their way up to the more visible effects. A healthy Everglades system supports a wide variety of aquatic algae. The natural Everglades was a balanced ecosystem that required little in the way of nutrients to keep it healthy. Low growth rates, low primary productivity, and high dissolved oxygen levels characterize the oligotrophic Everglades.