Final answer:
The primary issue with using groundwater to cool a power plant and then returning it to a nearby lake is thermal pollution. This causes oxygen levels to decrease and can be detrimental to aquatic life, affecting their survival and the ecosystem's health.
Step-by-step explanation:
Environmental Concerns with Water Recycling in Power Plants
The environmental concern involved with the method of recycling water by returning it to a lake after use in a power plant is thermal pollution. Thermal pollution occurs when water used as coolant is disposed of in natural bodies of water at a higher temperature, leading to adverse effects such as reduced dissolved oxygen levels. This can cause aquatic life to suffer from insufficient oxygen, and in the worst cases, suffocation. Additionally, the warmer water can create a layer that prevents oxygen from dissolving into the cooler water below, exacerbating the problem. Nonmammalian aquatic organisms, which are mostly cold-blooded, may also experience stress or death due to the deviation from their normal temperature range.
Efficient cooling systems implemented by power plants are essential to minimize thermal pollution and protect surrounding aquatic ecosystems. These systems ensure that the return water temperature remains close to the natural temperature of the water body, maintaining its ecological balance.