Building A Waterway Baseline in Florida
Massive flow of data will put science at the center
of standards debate |
by
Steve Werblow
The Florida Department of Environmental Protection (DEP) knows that
establishing dissolved oxygen (DO) and nutrient criteria for the state’s
water bodies is a challenge – both scientifically and politically.
To strengthen the scientific basis of its upcoming discussion of
nutrient and DO levels statewide, DEP has embarked on a comprehensive,
year-long study of those parameters in hundreds of Florida’s diverse
waterways, which range from natural to manmade water bodies and from
crystalline to tea-colored black water systems. The study draws upon
state-of-the-art sampling equipment and analytical tools, highly trained
analysts, and meticulous protocols. Grab-sample data will be augmented
by continuous monitoring data, providing an unprecedented level of
detail on the state’s water quality.
By the end of the study, the project’s 342 sampling sites will have
yielded more than a half-million data points and, officials hope,
perspective on nutrients and DO concentrations in the state’s waterways.
That perspective will be invaluable in establishing science-based
criteria for acceptable levels of DO and nutrients in the state’s
diverse water bodies.
“The purpose of this project is to help the state of Florida revise
its standards for dissolved oxygen and establish quantitative nutrient
criteria,” said Eric Livingston, chief of the DEP’s Bureau of Watershed
Management in Tallahassee, Fla. “To do that you need data – lots of
data.”
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BRA analysts calibrate YSI sondes in field |
An abundance of data translates into flexibility in setting the new
criteria. “We really are going into this without any preconceived
notions of what the standards will look like,” explained Garry Payne,
environmental manager at the DEP. “We’re leaving the doors open to look
at site-specific alternative criteria like we have in the Everglades for
DO, which depend on diurnal monitoring. We’ll have the data we need –
and we don’t want to have to do it again. We wanted to be able to do it
all in one shot.”
The need for science over politics wasn’t lost on state lawmakers.
“The Legislature recognized the importance of good data and allocated
the funds to undertake this study,” said Livingston. A good economic
return to the state is likely. That’s especially true in the form of
cost savings for businesses and residents of watersheds where Total
Maximum Daily Loads (TMDLs) will require Best Management Practices and
environmental safeguards that will hinge, in part, on the results of the
DEP research.
Divide and conquer
The first challenge was defining the kinds of water bodies that would be
studied and selecting enough sites to generate statistically significant
results. Working with Biological Research Associates (BRA) and its team
of sub-consultants to fine-tune the sampling site list, DEP developed a
list of water body types and targeted the number of sites to be sampled
in each:
- Large river (30 sites)
- General stream (45)
- Low-velocity stream (30)
- Urban stream (60)
- Natural lake (90)
- Urban lake (60)
- Canal (30).
Each of the sites is undergoing an intensive monitoring regimen, said
Doug Durbin, the BRA vice president who heads the study team for DEP’s
principal contractor on the project. Teams collect grab samples at each
site for total Kjeldahl nitrogen (TKN), ammonia, nitrate + nitrite,
total phosphorous, total organic carbon, chlorophyll a, and color.
Turbidity is measured in the field, and biological and sediment samples
are also collected for analysis during selected sampling trips.
“This is one of the biggest statewide efforts of this type I’ve ever
been involved in,” said Payne, who also worked on the high-profile
effort to set nutrient criteria for the Everglades. “The Everglades is
probably one of the most environmentally studied pieces of earth in the
world. We had probably 10 years’ or more of data for the Everglades to
set the standards down there. We just don’t have that kind of data for
the water bodies across the state. Our previous statewide ambient
monitoring data covered a lot fewer sites, one season out of the year, a
lot less intensively. To set the standards for the state, we knew we
needed a lot more data.”
Monitoring data
In the new effort, continuous monitoring data – shedding light on
diurnal cycles and reactions to different weather events – is a critical
part of the study. Every three months, analysts deploy YSI 6600EDS
sondes at each site at a half-meter depth. Each 6600EDS measures water
temperature, conductivity, pH, DO and depth every 15 minutes for four
days. When the sondes are deployed, another YSI 6600EDS – configured for
water column sampling – is used to grab a snapshot of the same data at
half-meter increments throughout the water column.
The sondes’ data is downloaded into YSI 650 dataloggers. Additional
data on the sampling site – including air and water temperature,
velocity, biological information, and who is present at the time – are
recorded in symbol personal data assistants (PDAs), and all equipment
and personnel identification codes are logged in with individual
barcodes to aid in QA/QC efforts.
Fortunately, data quality has been excellent, and even in challenging
extended deployment situations, the long-term unattended monitoring
equipment has performed quite reliably. Surviving challenging conditions
really says something – after all, in Florida, “challenging” deployments
range from hurricane surges to extensive fouling to alligator attacks.
(In fact, the BRA team has learned to wrap its buoys in heavy wire mesh
to discourage territorial ’gators from chewing up the floats and
dislodging the sondes.)
Every analyst has a favorite survival story about the sondes that
illustrates their durability.
“One sonde fell to the bottom in 20 ft of water,” recalled BRA Senior
Water Resource Analyst Kym Rouse Campbell. “It spent six days on the
bottom in the muck and collected data the whole time – and verified.”
In fact, she said, she has seen very few sondes come back from
deployment and fail to verify.
After Hurricane Katrina blew through south Florida in August, sonde
pickups were delayed for days beyond their scheduled four-day
deployments. The BRA team reports that after a full week in the field,
including the storm, the entire group of sondes picked up after the
hurricane stayed within DEP’s exacting +/- 0.3 mg/L tolerance standard
for DO.
Diligent maintenance protocols – along with the training and
follow-up tech support provided by YSI – help keep the equipment in top
shape and keep the complicated project moving ahead, said Durbin.
“The tech support from YSI turned out to be an incredible
money-saving factor,” he noted.
Drawn by the reliability and extensive data-gathering capabilities of
the probes, the BRA team and its subcontractors – who have experience
with an array of equipment – have become very attached to the YSI
sondes.
In fact, one contractor told Durbin that he wants to buy the
equipment from DEP at the end of the study. When BRA posed that question
to DEP, they were told that the department already had a number of
internal requests to use the sondes for other studies, so the state
wouldn’t part with them.
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Deploying 'gator-proofed’ sonde near Tampa |
Competing curves
BRA’s exhaustive efforts to collect accurate data and DEP’s carefully
considered protocol are yielding a comprehensive look at each sampling
site that takes into account the entire water column, an array of water
quality parameters, and how DO changes over time. Put them together and
water resource scientists should be able to understand how the water
bodies function, and how different systems compare and contrast.
“The state is well aware of the importance of considering the
differences among water bodies,” noted Durbin. “The thing this study is
trying to do is quantify the degree and variability of those
differences.”
Understanding the relationships among water bodies is no small
challenge, Durbin noted. As part of a QA/QC review for the project,
Durbin churned thousands of data points through YSI’s EcoWatch for
Windows to chart the monitored parameters over four-day study periods at
each study site.
The data crunching was surprisingly easy
“I could just click on the parameters I wanted and look at the
relationships, then pick out the ones of interest,” Durbin said. “It
took what might have been three days of data review and put it into one
day.”
But the charts hint at the challenges that face regulators and
stakeholders as they seek acceptable limits for DO and nutrients.
“It’s pretty astounding how much variability there can be,” he noted.
Some water bodies revealed strong diurnal cycles, with DO rising and
falling dramatically; others were remarkably stable. Among the sites
with significant peaks and valleys, some showed strong positive
correlations with temperature (and, consequently, daytime vs. nighttime)
while others displayed strong negative correlations. The bottom line,
said Durbin, is that DO patterns will need to be referenced against
other water quality parameters and physical factors to generate a more
complete understanding of the water body.
That knowledge will be vital. So will the unwavering confidence that
the data is accurate – accurate enough to stay at the center of
Florida’s effort to develop appropriate standards for nutrients and DO
across its extraordinarily diverse water bodies.
“We are collecting data that will be highly scrutinized by everyone
from USEPA to environmental groups to affected users in the watersheds,”
noted DEP’s Livingston. “We want to make sure that we have extremely
high-quality data, and lots of it, to make sure we make good decisions
when it comes to something as important as DO and nutrient standards.”
Added Payne, “One place we don’t want to leave ourselves open is
quality. When you know you’re going to be challenged, you want to cross
all your Ts and dot all your Is.”
YSI Inc
1725 Brannum Lane
Yellow Springs, OH 45387
P: 800-897-4151
F: 937-767-1058
environmental@ysi.com
www.ysi.com/environmental.htm |