An airboat takes DNR staff to water quality sampling sites in winter on Pool 8 of the Mississippi River near La Crosse.
Mississippi River monitoring
A story in long–term teamwork
DNR water quality specialist Shawn Giblin peers intently through the snow–covered plastic window of the airboat as it bounces along the snow and ice–covered surface of Pool 8 of the Upper Mississippi River near La Crosse.
The temperature on this late January day is a "balmy" 22 degrees with a gusty northwest wind. He eases his foot off the accelerator and keeps his eye on the GPS unit as the airboat approaches the first sampling site. Timing is important. The crew onboard has to be within 15 feet of the coordinates for the study site.
At the last moment, Giblin spins the airboat around to pack down the snow. John Kalas, a DNR water quality technician, quickly gets out the ice auger and goes to work drilling the first hole. The dull, low–pitched roar of the auger cuts through the air as snow falls. He is careful not to drill all the way through. He doesn't want to stir the water column with the action of the auger.
Giblin chips out the last few inches of ice in the hole with a spud and then scoops out the loose ice. He inserts the probe of the Hydrolab Data Sonde into the hole. This equipment measures four components and the data is immediately transmitted to the field computer. Giblin measures the snow depth and moves over to the second hole where he works with Kalas to collect a water sample; measure ice thickness, water depth and river current velocity; and determine water clarity using a Secchi disk.
By the time they finish collecting this information the Data Sonde has finished its task. The Sonde is then safely stored in the airboat, the velocity meter is tucked into the pizza box warmer to keep it at a working temperature on this cold day, and they are off to the next site.
This routine will be repeated many times before the day is over. Giblin and Kalas work as a well–coordinated team with no wasted motion and little conversation. They have 150 sites to visit in two weeks.
Giblin and Kalas' water quality work is part of the Upper Mississippi River Restoration Long–Term Resource Monitoring Program (LTRMP). Six study reaches are monitored annually by LTRMP. The Pool 8 reach near La Crosse is monitored by DNR staff from the Mississippi River Monitoring Field Station.
The team samples water quality, and monitors fish and aquatic vegetation using strict protocols. Data has been collected on Pool 8 and the other five study reaches since 1993 using standardized monitoring techniques which provide valuable information that is used by research scientists, resource managers and planners to understand and restore this globally significant large river.
"It's a monitoring system that is unmatched both nationally and internationally," explains Jim Fischer, DNR Mississippi River Team leader and field station supervisor. The program has attracted the attention of other countries. China, for example, is using the LTRMP as a model to develop a scientific monitoring system for the Yangtze River.
Twenty years ago when the standardized monitoring began, data was collected using individual instruments and the scientists recorded data on paper data sheets for manual data entry when they returned to the office.
Today, a Data Sonde measures dissolved oxygen, pH (acidity), temperature and conductivity simultaneously and transfers the data to a laptop in the field. The evolution of equipment over the last 20 years has been dramatic, but no less than the changes Giblin has observed on the Mississippi River.
Giblin has been the LTRMP water quality specialist for only seven years but knows the area very well having grown up on the banks of the river in Brice Prairie, a township just north of La Crosse.
"We have observed dramatic ecological shifts in the river during the LTRMP sampling," Giblin says. "What we are learning about the river could not be achieved with a series of short–term studies. Water quality is measured by determining dissolved oxygen concentrations, total suspended solids, chlorophyll, phosphorus, nitrogen and water clarity."
Each of these components has implications for plants, fish and wildlife. Dissolved oxygen is critical to sustain aquatic life, insects and fish. Excessive suspended solids (sediment or soil particles in the water) limit plant growth by blocking light and thus affecting aquatic insect behavior and fish by reducing feeding efficiency and smothering spawning habitat.
Chlorophyll is an indicator of algae in the water. Algae and duckweed can form thick green mats on the surface and cause problems for anglers, boaters, swimmers and other plants and fish by blocking light for plants and reducing dissolved oxygen as the plants decompose. Reduced dissolved oxygen can force fish out of the backwaters and into the main river channel. Phosphorus and nitrogen are the nutrients that fuel the excessive growth of algae.
On a positive note, water clarity in Pool 8 has increased dramatically over the past 20 years.
"Suspended solids are declining and have reached a healthy level," says Giblin. "We have observed a shift from a turbid state to a clear state."
Algae and duckweed fueled by excess phosphorus and nitrogen in the water column, though, continue to be a problem.
"The improvement in water clarity has resulted in an increase in aquatic vegetation, in particular wild celery and wild rice," explains Heidi Langrehr, an aquatic plant specialist. "These two plants are important as a food source for migrating waterfowl."
Aquatic plants provide food and shelter for other birds, fish and invertebrates including larval forms of insects, worms and snails. Aquatic plants are sampled by visiting 450 random sites scattered through– out Pool 8 during warmer months.
"Unusually high water levels during the growing seasons in 2011 through 2014 created more difficult growing conditions for some species," Langrehr says. "Generally plants have increased, both in the number of species and in abundance, from 1998 to 2010."
The increase in vegetation resulted in a cascade of effects that led to a dramatic improvement in the fish community.
To monitor the fish community, staff uses six sampling methods including electrofishing, a variety of nets and otter trawls, explains Andy Bartels, a DNR fish specialist.
Fish sampling is conducted from June 15 to Oct. 31. In 2012, 64 species were recorded in Pool 8.
"Overall, catch rates in 2012 were the highest observed since 2007 and ranked fourth highest over the 20 years of sampling," says Bartels.
Some species appear stable over time including walleye, catfish and black crappie.
"Catch rates for backwater–oriented species like yellow perch, largemouth bass and bluegill have greatly increased over the last 20 years," Bartels adds. "Whereas, catch rates for species such as carp, buffalo and white bass, which are more riverine fish, have decreased."
The positive changes in the fisheries are reflected in the increasing popularity of the river for recreational fishing by bass anglers, family fishing and bass tournaments as well as ice fishing for panfish.
Data collected through the LTRMP efforts document the changes in the river that have resulted from changes in human practices in the watershed. The data has also shown that high flows in the river caused by precipitation events are the key variables that influence water quality and life in the river. Floods result in more sediment and nutrients carried by the river as they enter the river in runoff from the land.
There is more work to be done to improve water quality in the Mississippi River, but perhaps these intricate connections between the land, the people and the river are why Giblin's favorite quote is one by John Muir, "When we try to pick out anything by itself we find it hitched to everything else in the universe."
The official results from 20 years of standardized water quality and fisheries monitoring, and 15 years of standardized aquatic vegetation monitoring in Pool 8 of the Upper Mississippi River were published in the "2012 Pool 8 State of the Ecosystem Report" available online at dnr.wi.gov.
Ruth Nissen is stationed in La Crosse and works with the Mississippi River Team in the Department of Natural Resources.