2006 river cruise is a floating Chautauqua dedicated to TMDLs

On Thursday, August 24, 2006, about 100 guests were treated to the District's annual cruise down the Minnesota River. Along the way, from Savage's grain terminals to St. Paul's Harriet Island in the Mississippi, we soaked in the sights and sounds of the rainy Minnesota and Mississippi rivers while we listened to science professionals speak about the health of our rivers and streams as measured in TMDLs (Total Maximum Daily Loads of various pollutants).

Guests included stakeholders of the Lake Pepin region and professionals, along with various state legislators and city and county representatives.

Speakers included Norm Senjem, of the Minnesota Pollution Control Agency (MPCA), who summed up a Lake Pepin TMDL project; Carrie Jennings, of the Minnesota Geological Survey, who provided a trenchant geological background; Hal Runke, Barr Engineering, who talked about a Nine Mile Creek restoration project; John Anfinson, of the US Park Service, who gave an historical perspective on the rivers’ health; Dan Wilcox of the US Army Corps of Engineers; and Terry Schreiner of the US Fish and Wildlife Service, who discussed wetland flora and fauna.

In addition, two Metropolitan Council scientists, Cathy Larson and Kent Johnson, plus Dennis Wasley from the MPCA, conducted in-cruise measurements of Minnesota River water quality.

What's all the fuss about TMDLs?

In technical terms, TMDLs were the topic of the day — that is, Total Maximum Daily Loads of such polluting substances as phosphorus and sediment. As discussed in the District’s online newsletter, a May 2004 MPCA report lays out ways to decrease these polluting substances, whether they come from “point” sources like wastewater treatment plants or “nonpoint” sources like septic systems. As the MPCA's Larry Gunderson stated, we have to “put the Minnesota River on a diet for phosphorus” and other pollutants in order to see improvement.

The federal Clean Water Act of 1973 requires states to name “impaired” bodies of water, to evaluate sources of pollution, and to attempt to restore the bodies of water.

Highlights of the talks

• Norm Senjem, of the MPCA, talked about Lake Pepin impairments because of "excess nutrients," as from phosphorus from fertilizer, and turbidity. As a slow spot in the Mississippi, Lake Pepin keeps water longer and thus suffers "frequent and severe algae blooms." The Minnesota River, Senjem attested, contributes 80–90% of Lake Pepin's sediment, thus increasing algae growth at low flows and sediment-caused turbidity at high flows.
• Carrie Jenkins of the Minnesota Geological Survey discussed the sources of sediment in the Minnesota River basin, both geological and manmade. She characterized the basin as “young” in geological time, for just 10,000 years ago the Minnesota River channel “slashed” its way across the glacial basin. All rivers, including the Minnesota, she suggested, “want to create a completely drained landscape.” In the case of the Minnesota, such a natural desire would turn central Minnesota, around the metro area, into flat floodplains as in southeastern Minnesota. Man, of course, she continued, has contributed sediment, too, and we must decrease this sediment if we are to see improvements in the clarity of the river.
• Hal Runke, Barr Engineering, spoke about a Nine Mile Creek Watershed District TMDL analysis. Water quality data collected at three stations on the creek suggest impairments in terms of turbidity and excess chloride. Fish communities are also impaired, according to electrofishing analysis of the types of fish in the stream. But a recent restoration project, which installed riprap in curves, has stopped erosion and helped improve clarity and fish health in the stream.
• John Anfinson, a historian with the National Park Service, spoke intriguingly about the progress of the river, from the days of Zebulon Pike to the present. According to Pike’s 1805 journal, the Minnesota River, at the confluence with the Mississippi was clear and blue. By 1875, the river had become cloudy because of urban changes and deforestation. When Lock and Dam Number 1 was built in 1917, garbage and raw sewage would build up during the winter and create 12-foot sludge piles in the spring. It wasn’t till 1938 that the first wastewater treatment plant was built on the river, Pig’s Eye. Today, the Minnesota River contributes 6% of the nitrogen that goes into the Gulf of Mexico’s dead zone.
• Dan Wilcox of the St. Paul office of the Army Corps of Engineers discussed effects of navigation on the river, including the stirring up of sediments by commercial and recreational traffic. He also discussed the COE’s required dredging of the river, dredged material placement (guests saw the District’s new placement site at the I-35 bridge), and the effects of accidental spills on the river.
• Terry Schreiner, who’s with the US Fish and Wildlife Service at the Minnesota Valley National Wildlife Refuge, told us that the refuge’s 14,000 acres host more than 250 plant species. The flora of the refuge are mostly in wetlands, like Longmeadow Lake, which are fed by ground water, not river water. Wetland vegetation and macroinvertebrates are the source of food for insects and higher animals that traverse the entire refuge. Floods and excess sediment can smother and kill wetland plants, and yet, in part because of man’s technical clean-up efforts, plants in this “very rich organic system” are adaptable and can recover.
• Cathy Larson and Kent Johnson (Met Council), plus Dennis Wasley (MPCA), collected water samples at five points along our route on the Minnesota River. Here are the data from their experiment, comparing water quality in the Minnesota with that in the Mississippi and St. Croix rivers. (Abbreviations below: mg/L = milligrams per liter, where the dissolved oxygen standard is 5.0 mg/L or higher; NTU = nephelometric turbidity units, where the water quality standard is 25 or less; C = Centigrade; NA = not available.)
  
  

  Water quality in three rivers
  	Minnesota R.	Mississippi R.	St. Croix R.
  Dissolved oxygen	6.6–7.7 mg/L	8.1 mg/L	NA
  Temperature	23.4 C	22.9 C	NA
  Turbidity	27.7–31 NTU	16 NTU	4.1 NTU

  
  Larson also measured the Minnesota's transparency at about 7 inches. "That means," she said, "if you waded into the river up to mid-calf, you wouldn't be able to see your toes. Imagine what it's like for the fish and other aquatic life."
  

The pleasure of merely floating

The District’s guests were not quizzed, afterwards, on the talks. Indeed, while we absorbed the lessons of the guest speakers, we also took in, at the same time, the sights and sounds of the rainy rivers. (See video clips and photo album.) If the day was not perfect for boating, it was as good for us, finally, as it was for the plants, animals, and bodies of water. Cooling, cleansing, refreshing, the rain returned us to our daily lives in a better, more hopeful mood. And our speakers made us more aware of the need to be vigilant about our water resources.

* * *