program is the largest federal effort to date to monitor and assess the
conditions of rivers and streams throughout the United States. Fifty-one
major watersheds and aquifers
(referred to as “study units”) are being evaluated, representing 60%
of the nation's drinking water. The goal of NAWQA is to provide continuous water
quality assessments that identify and describe major water quality issues. The results
of the program will serve as the basis for understanding watershed ecosystems nationwide,
and for solving serious water quality problems. To this end, the USGS research staff
is measuring a wide variety of water chemistry parameters and physical habitat
in addition to identifying fish, benthic invertebrates and algae. Data are analyzed
on the watershed scale and also on a national scale. At the watershed scale, the
focus is on water quality issues pertaining to a particular watershed. National
scale syntheses address broader issues such as the distribution and concentration
of pesticides and nutrients among watersheds.
The USGS and the Patrick Center for Environmental Research have established a four-year
cooperative agreement. Patrick Center scientists in the Phycology Section analyze
algal samples collected by USGS biologists; this information is integrated with
chemistry, fish, insect, and geomorphologic data collected by NAWQA scientists.
The Patrick Center effort will contribute significantly to understanding water quality
issues nationwide, while emphasizing the importance of algal distribution and ecology.
Patrick Center scientists have been analyzing NAWQA algal samples since 1994. Under
the four-year cooperative agreement which began in 1999, the PCER role was expanded
to include data synthesis and interpretation, as well as the preparation and analysis
of about 500 samples per year. The Patrick Center subcontracts the analyses of some
of these samples to other phycology centers, primarily Dr. Jan Stevenson's lab at
Michigan State University.
All samples are collected from the surface of rocks and other natural substrates,
then preserved and shipped to Philadelphia. Subsamples of soft-algae, which include
green, red, and blue-green forms, and diatoms are analyzed. Accurate identification
of algae is rigorously documented with photographs taken through state-of-the art
microscopes. After the samples are analyzed, they are stored at the Academy for
future reference. The diatom slides are a major addition to the Academy's Diatom
Herbarium, already the largest in North America and a major resource for the scientific