Consultant's Report - Minnesota State Legislature

MINNESOTA DEPARTMENT OF NATURAL RESOURCES
Feasibility Study to Limit the Spread of Zebra Mussels from Ossawinnamakee Lake
VI. ALTERNATIVES ANALYSIS AND RECOMMENDATIONS
Field sampling conducted by MN DNR has confinned adult zebra mussels within
Ossawinnamakee Lake and the upper portion of Pelican Brook, near the lake outlet structure.
While zebra mussels have not been encountered in other downstream areas ofPelican Brook, it is
possible that downstream dispersal could occur. Thus zebra mussels could eventually enter the
Pine River and disperse into the upper waters of the Mississippi River. Based on this possible
migration and the known life history and behavior of the zebra mussel, the project team
detennined that treatment alternatives should address the growing size of the zebra mussel
population in the lake, and movement ofzebra mussel larval stages in both the lake and brook.
This section ultimately provides an analysis ofthe treatment alternatives previously described in
Section V. Alternatives have been grouped into five categories, ranging from biological control
to physical control, and analyzed collectively. A numerical rating system that includes items
such as efficiency of the alternative, cost implicatio,ns, constructability and impacts to native
species was utilized to evaluate each alternative. Furthennore, the feasibility of treatment
alternatives is discussed relative to location in Ossawinnamakee Lake and Pelican Brook. The
section concludes with a list of objectives that could be utilized to limit the spread of zebra
mussels from the infested area.
Analysis of Potential Treatment Methods",
As previously mentioned, the treatment alternatives discussed in Section V and listed in Table
V-I were individually analyzed and scored with a numerical ranking system. In addition, several
combinations of alternatives were evaluated. Table VI-l contains the results from the analysis.
Three major evaluation criteria including effectiveness, economics, and environmental impacts
were used to make general inferences as to whether a particular treatment alternative could be
applied and capable of achieving the overall project objective. The scoring system utilized
numerals I through 6 to evaluate the overall effectiveness of each alternative, with "1"
designating the highest effectiveness and "6" designating poor effectiveness due to low
efficiency or high fe,asibility concerns. For simplicity, the remaining categories were rated as a
1, 2, or 3 with "1" being the best and "3" being the worst. The categories utilized to evaluate
treatment alternatives are outlined below.
Effectiveness
Reported EfficienCy - Theoretical treatment effectiveness as suggested by case, field, and
laboratory studies. Additionally, any efficiency claims made by product manufacturers were
considered.
Site Application/Implementation - Predicted treatment effectiveness and feasibility as suggested
by site-specific characteristics or limitations (e.g., implementation, contact time, flow rates, and
potential design requirements).
VI-I Alternatives Analysis and Recommendations