406 The UMAP Journal 22. 4(2001) Lake b and lake c and determine the level of risk of successful zebra mussel invasion in these two lakes. We averaged the values together for all of the years We also assume that these two lakes are fairly uniform in chemical composition Table 3 Viability and density values for Lake B and Lake C pH [Ca] ITPl ITN Mg/L ng/L Lake b7.6311.56.02×10-30.182993874 Lake C 4.74 1.15 According to our Model 1, Lake B should not be at risk for a zebra mussel invasion because it is not a suitable habitat(V 10.4): this prediction makes sense because the average calcium concentration is 11.5 mg/L, which is below the 12 mg/L threshold. Lake C is in no danger to an invasion, since D=4.97, which corresponds to the fact that both the ph and the calcium concentration are far below the threshold values De-icing Policy for Community of Lake B De-icing compounds increase the solute concentration in the melted ice, lowering its freezing temperature and preventing the ice from reforming. Thus, de-icing compounds are water soluble and can easily enter the water supply The most commonly used de-icers are calcium chloride, calcium magnesium acetate, sodium chloride, and potassium acetate salts. Calcium magnesium ac- etate is popular because it has fewer negative environmental impacts, whereas calcium chloride is widely used because it lowers the freezing point of water more than sodium chloride Ithough these calcium containing compounds may be excellent choices for de-icing agents, our model indicates that using these compounds increases the risk of zebra mussel invasion. According to Model 2, if calcium levels increase in Lake b by 50%(D=9.9), a low density population of zebra mussels can exist Doubling the calcium levels(d= 11.0)will support a high density population De-icing agent can therefore have a significant impact on the zebra mussel population. We recommend that this community use sodium chloride or potassium acetate salts, or decrease the amount of calcium salts used by mixing them with the other noncalcium salts or sand. We also suggest pre-wetting the salts before they are applied to the roads, to reduce the amount entering the water system Lastly, the community should develop a strategy for anti-icing, applying de- icing agents before ice forms, thus decreasing the amount of de-icing ag used in each storm. These efforts should help prevent Lake B from becom habitable by zebra mussels406 The UMAP Journal 22.4 (2001) Lake B and Lake C and determine the level of risk of successful zebra mussel invasion in these two lakes. We averaged the values together for all of the years. We also assume that these two lakes are fairly uniform in chemical composition. Table 3. Viability and density values for Lake B and Lake C. pH [Ca] [TP] [TN] V D mg/L mg/L mg/L Lake B 7.63 11.5 6.02 × 10−3 0.182 9.93 8.74 Lake C 4.74 1.15 4.97 According to our Model 1, Lake B should not be at risk for a zebra mussel invasion because it is not a suitable habitat (V < 10.4); this prediction makes sense because the average calcium concentration is 11.5 mg/L, which is below the 12 mg/L threshold. Lake C is in no danger to an invasion, since D = 4.97, which corresponds to the fact that both the pH and the calcium concentration are far below the threshold values. De-icing Policy for Community of Lake B De-icing compounds increase the solute concentration in the melted ice, lowering its freezing temperature and preventing the ice from reforming. Thus, de-icing compounds are water soluble and can easily enter the water supply. The most commonly used de-icers are calcium chloride, calcium magnesium acetate, sodium chloride, and potassium acetate salts. Calcium magnesium ac￾etate is popular because it has fewer negative environmental impacts, whereas calcium chloride is widely used because it lowers the freezing point of water more than sodium chloride. Although these calcium containing compounds may be excellent choices for de-icing agents, our model indicates that using these compounds increases the risk of zebra mussel invasion. According to Model 2, if calcium levels increase in Lake B by 50% (D = 9.9), a low density population of zebra mussels can exist. Doubling the calcium levels (D = 11.0) will support a high density population. De-icing agent can therefore have a significant impact on the zebra mussel population. We recommend that this community use sodium chloride or potassium acetate salts, or decrease the amount of calcium salts used by mixing them with the other noncalcium salts or sand. We also suggest pre-wetting the salts before they are applied to the roads, to reduce the amount entering the water system. Lastly, the community should develop a strategy for anti-icing, applying de￾icing agents before ice forms, thus decreasing the amount of de-icing agent used in each storm. These efforts should help prevent Lake B from becoming habitable by zebra mussels