By Jennifer Kotila
HOWARD LAKE, MN Implementing measures to control nutrients in lakes Ann and Emma, located about two miles south of Howard Lake, could cost as much as $2.5 million, according to a study by the Minnesota Pollution Control Agency (MPCA).
The agency is seeking public input on the recently-completed total maximum daily load (TMDL) study.
The study is part of a nationwide effort under the federal Clean Water Act to identify and clean up pollution in streams, rivers, and lakes.
A TMDL study is a scientific study that calculates the maximum amount of a pollutant a water body can receive (known as the loading capacity) without exceeding water quality standards.
The goal of the Lake Ann and Lake Emma TMDL study is to quantify the pollutant reductions needed in order for the lakes to meet state water quality standards for nutrients.
Findings and recommendations for lakes Ann and Emma have been compiled into a water quality improvement draft report from the MPCA.
Currently, the MPCA is seeking the public’s comments on the report through Wednesday, Sept. 28.
After receiving public comments, the MPCA will revise the Lake Ann and Lake Emma TMDL report and submit it to the US Environmental Protection Agency (EPA) for approval.
Following EPA approval of the study, a plan will be developed to reduce pollution throughout the Lake Ann and Lake Emma watersheds.
A link to the Lake Ann and Lake Emma TMDL draft report can be found at www.heraldjournal.com.
The report is also available at the MPCA’s St. Paul office, located at 520 Lafayette Road North.
Comments should be submitted to Maggie Leach, MPCA, 7678 College Rd, Suite 105, Baxter, MN 56425, or by e-mail to firstname.lastname@example.org.
For more information, call Leach at (218) 316-3895, or toll-free at (800) 657-3864.
Written comments must include a statement of your interest in the draft TMDL report; a statement of the action you wish the MPCA to take, including specific references to sections of the draft TMDL that you believe should be changed; and, specific reasons supporting your position.
For more information, a link to the Impaired Waters and TMDLs page on the MPCA website can be found at www.heraldjournal.com.
The need to improve the lakes’ water quality
Every two years, states are required to submit a list of impaired waters to the EPA.
Lake Ann, which has been monitored periodically for the last 20 years, was placed on Minnesota’s impaired waters list in 2002, because of excess nutrient levels, particularly phosphorus, according to the TMDL study.
Although it is not officially listed as impaired at this time, Lake Emma is scheduled to be placed on Minnesota’s impaired waters list in 2012.
Both lakes are part of the North Fork Crow River Watershed, and the Upper Mississippi River Basin, according to the study.
The TMDL study indicated that phosphorus loads will need to be reduced by 81 percent in Lake Ann, and 60 percent in Lake Emma, for the lakes to meet state water quality standards.
Phosphorus sources to Lake Ann include 68 percent watershed runoff, 30 percent internal sediment release of phosphorus, and the remaining phosphorus coming from atmospheric deposition (precipitation), according to the study.
Lake Emma receives 74 percent of its phosphorus from Lake Ann, 17 percent from internal loading, and 9 percent from the direct watershed.
Land use in the Lake Ann and Lake Emma watersheds is more than 90 percent agriculture, including row crops (corn and soybean rotation) and animal agriculture, according to the study.
Based on models used by the MPCA, the primary source of phosphorus in Lake Ann is from animal manure.
There are more than 9,000 animal units throughout the Lake Ann watershed, producing more than 1.4 million pounds of phosphorus per year, according to the TMDL study.
A large proportion of this manure is land-applied in the Lake Ann watershed, some of which eventually makes its way into surface waters.
Another source of phosphorus for both lakes is internal loading due to carp and curly-leaf pondweed infestations, according to the study.
Controlling the amount of phosphorus reaching the lakes will need to focus on manure management, as well as controlling the internal loading of phosphorus.
Because the primary source of phosphorus to Lake Emma is from Lake Ann, restoration of Lake Ann will benefit Lake Emma tremendously, according to the TMDL study.
Restoration options for lakes are numerous, with varying rates of success.
Each technology must be evaluated in light of the current understanding of physical and biological processes in that lake, according to the MPCA.
Potential actions for controlling nutrients in Lake Ann and Lake Emma, and their respective watersheds, will be further developed in an implementation plan, according to the MPCA.
The estimated cost of implementing nutrient controls in lakes Ann and Emma is $1,000,000 to $2,500,000.