Headwaters reservoirs: Water management provides flood risk reduction, recreation
March 12, 2013
Regulating the Mississippi River Headwaters reservoirs takes a lot of coordination, monitoring and science, according to Brian Johnson, Mississippi River Headwaters water control engineer.
Johnson is responsible for managing the six Headwaters reservoirs -- Lake Winnibigoshish, Leech Lake, Pokegama Lake, Big Sandy Lake, Cross Lake and Gull Lake -- as well as managing Red Lake, the largest lake located entirely within Minnesota.
Johnson said reservoir management is determined by manuals for each respective reservoir. "We regulate according to an approved water control manual," said Johnson. "The current manual was approved in January 2003, and it is currently being updated to incorporate the changes from the 2009 Reservoir Operating Plan Evaluation, or ROPE, study."
The Mississippi Valley Division, St. Paul District's higher headquarters, is responsible for approving any changes to the water control manual, he said. Traditionally, the manual is updated every 10 years.
To help with the reservoir management, Johnson said, he relies on a lot of coordination with the district's park rangers, as well as other federal agencies. "I'm always looking at each of our sites for information," he said. "From snow depths, precipitation and snow water equivalents measurements to ice thickness and frost depths, their measurements and the data they collect provide valuable information to me to determine winter drawdown levels."
The park rangers provide information during the summer, too. The staff provides daily precipitation, lake and dam levels. Johnson said, the data is critical in the process of regulating the reservoir levels.
Johnson relies on more than the district's park rangers to get the information he needs. He said managing the reservoirs requires direct coordination with other agencies as well. "I talk with meteorologists at the National Weather Service, or NWS, on a regular basis," he said. He added that he looks to them for their five-day forecasts, their snow depth monitoring, precipitation locations and the total amounts for each storm. "You have to consider all of the information to make the best judgments," he said. "Monitoring is the big thing. We look at it every day. We look at weather conditions, water levels and forecasts."
In addition to all of the data collected by the district staff and federal partners, Johnson said he uses historic data to help determine trends. It's another tool in the tool box, he added.
"I use the historic information to help me determine when to make changes to reach certain levels," said Johnson. "The goal is to reach the summer operating bands, which begin prior to the fishing opener and end after Labor Day."
The drawdown levels vary according to each reservoir, but Johnson said, the goal for each of them is to create storage for the spring runoff. He added that drawdown amount is determined, in part, on weather conditions, such as the snow water equivalents or amount of water contained within the snowpack.
According to the Headwaters control manual, "A considerable amount of hydrologic judgment is required during the drawdown process. Considering the myriad number of variables, there will be years when, even with the best of intentions, the ideal drawdown situation will not be achieved."
Looking at historical data, weather reports and guide curves are not the only challenges Johnson faces as the Headwaters water manager. He said one of the most challenging aspects of his job is dealing with the floods and droughts. "It requires the most work and coordination," he said. "During a flood or drought, we do day-to-day monitoring trying to figure out high the reservoirs will raise or fall, and it involves a lot of teamwork from the park rangers and other agencies. We are constantly trying to get accurate information to help people make informed decisions."
Providing information to the public is usually done through federal partnerships with agencies such as the NWS. Johnson said, "We provide our reservoir release plans to them, so they can provide a forecast to the city of Aitkin, Minn., among other things."
Diane Cooper, NWS meteorologist, said, "The close partnership between the National Weather Service and U.S. Army Corps of Engineers is vital, especially during floods and droughts." Specifically, she said, the Corps provides information on reservoir releases, which directly influences the NWS' river forecasts. She added that the Corps provides daily snow totals water content amounts, as well as rainfall and temperature data through the NWS Cooperative Observing Program. Cooper said, "These observations are key to our spring flood outlook products, as well as the seven-day river forecasts. The partnership between the Corps and U.S. Geological Survey to support river gauges allows the NWS to provide location specific river forecast services, too."