Amistad National Recreation Area - Environmental Factors

Amistad National Recreation Area by National Parks Service

Storms can arise at a moments notice (NPS Photo) Amistad National Recreation Area contains some of the finest examples of natural and cultural heritage found in the United States. The primary goal of park staff is to preserve the resources of the area while providing recreational opportunities to visitors. This goal can be difficult because of the special environmental factors encountered at Amistad. The natural resources of the area are subject to a range of threats, including exotic species, water degradation, and flooding. The problem of biological invasion is not new. Many species have been introduced by man while others are the result of natural range expansion. Up to 100% of introduced species are able to adapt to a new environment and 2-3% will become invasive and possibly destructive.

Each month a water quality test is performed on samples of Lake Amistad water. Levels of pH and water oxygenation affect all the organisms that live in the lake. If oxygen levels in the water fall too low, the balance of plant and animal life at Lake Amistad can be jeopardized. By keeping track of the water quality in previous months and years, trends can be noted and steps can be taken to improve water quality. However, the lake is generally very clean and has glassy, blue-green water. Fluctuations in water levels are an almost daily challenge for park managers. The elevation of the surface of Lake Amistad is measured from sea level. An elevation of 1117' is considered the "conservation pool," and park boundaries are generally set at 1144'. However, water levels have gone down as far as 1056'.

While a falling water level strands boat docks "high and dry", it also exposes a great deal of previously inundated land. Vegetation quickly establishes itself in the fertile lake mud and becomes home to a variety of wildlife. Climbing water levels then flood these areas. This constant shift between lake and dry land makes the preservation of natural and cultural resources difficult.