February 2011, Vol. 23, No.2
Study shows improvement in Everglades water quality
Water flowing into Everglades National Park in Florida contains fewer nutrients than it did three decades ago, according to a new study. The study, conducted by researchers at the University of Florida (Gainesville) Research and Education Centers and scientists at the South Florida Water Management District, describes variations in the quality of water feeding the park.
Researchers assessed data from 1977 to 2005 to find that overall levels of nitrogen and phosphorus from seven inflows to the park have declined since the 1970s. This improvement could be attributed to restoration methods completed in the areas surrounding the park, according to an American Society of Agronomy (Madison, Wis.) news release.
Environmental concerns in the area from agricultural and urban-area runoff, as well as canal and levee disruption of natural flow patterns, were raised as early as the 1960s, the news release says. Best management practices and other interventions were implemented regionally in the 1990s in the Everglades Agricultural Area and various urban areas. Also during this decade, Water Conservation Areas and Storm Water Treatment Areas, which supply water to Everglades National Park, control flooding, and repair water quality, were implemented to regulate and diminish the effect of human presence and activity in the region, the news release says.
The study’s results suggest that these types of water quality analyses could provide additional insight into the success of a restoration management plan and how monitoring may be modified for more efficient use of resources. A report on the study, “Water Quality Trends at Inflows to Everglades National Park, 1977–2005,” was published in the September–October 2010 issue of Journal of Environmental Quality.
Majority of stream and river flows significantly altered
The U.S. Geological Survey (USGS) has found that nearly 90% of flows in streams and rivers assessed nationwide have been significantly altered.
Flows altered by land- and water-management activities, such as reservoir creation, wastewater inputs, and impervious-surface construction, contribute to degraded ecosystems and loss of native species, a USGS news release says.
The extensive analysis, conducted by the USGS National Water Quality Assessment Program, identified more than 1000 unimpaired streams to use as reference points to create streamflow models. These models were used to estimate expected flows from 2888 additional streams where USGS had flow-monitoring gauges from 1980 to 2007. The estimated values were compared to actual measured flows to determine the degree to which streams have been altered, the news release says.
Study findings indicate that streams with diminished flow contained aquatic communities that prefer slow-moving currents characteristic of lake or pond habitats. The study also found that flow alteration differed in severity and type among regions because of natural landscape features, land practices, degree of development, and water demand.
Flow differences were especially large between arid and wet climates because of management practices. In wet climates, watershed management focuses on flood control, which can result in lower maximum flows and higher minimum flows. In dry climates, extremely low flows are the greatest concern, and waterways are affected by groundwater withdrawals and high water use for irrigation.
Cycles of water flows, particularly low flows, which maintain suitable habitat for aquatic life, and high flows, which replenish floodplains and flush out accumulated sediment that can degrade habitat, shape ecology in rivers and streams. Taking this into account provides an important consideration for sustaining and restoring the health of these aquatic ecosystems, the news release says.
The findings were reported in the journal of the Ecological Society of America (Washington, D.C.), Frontiers in Ecology and the Environment. For more information, see http://water.usgs.gov/nawqa.
©2011 Water Environment Federation. All rights reserved.