Laserfiche WebLink
5 . What arc the relati~ e effects on shoreline and shallow Hater bottoms of (i) ens ironmental or a Bather conditi~~ns <br />.s. (ii) recreational boating? <br />Turbidity is affected by depth and basin shape, lack of aquatic plants, wind action, and <br />boating. Relative contributions of boats vs. wind are hard to assess. Studies that address this <br />issue are rare. A poster at the National Lake Conference (Nov. 96) described a study done in the <br />eastern US in which turbidity was measured along transects from shore to mid-lake at various <br />times of the day, and boat traffic was counted; traffic was correlated with increased turbidity (TN ). <br />Other potential factors contributing to turbidity were identified by SEH as rough fish and <br />inadequately-treated urban runoff. Most settling ponds work well to catch large materials that settle <br />in 1-2 days but fine sediments may not be caught. About 60% of Owasso's turbidit}' is due to <br />algae, and 40% to unknown cause(s), possibly a combination of factors. Wabasso receives flow <br />from Owasso but is much clearer; its non-algal turbidity is low. It has much less boat traffic and a <br />different depth and shape. Rough fish can migrate between Owasso and Wabasso (JSch); Owasso <br />does not have an excess of rough fish (carp and black bullhead) for a lake of its type (DZ). <br />6 . Discuss ~~ akes, turbulence, and bottom sediment disturbance as a function of craft t~ pe, hull hpe, speed, <br />propulsion s}stem, and t~~pe of boating acti~it<~. <br />Waves break when wave height = 80% of depth. Energ}' is lost as the wave breaks and then <br />on the shoreline, and runup pulls loose sediments off the shore. Sustained wave action is <br />correlated with shoreline damage (EM). Kinetic energy of waves is related to their size, not their <br />source. Soil characteristics of the shore are critical: silt anal clay are less erodable than sand or <br />gradel (TP, EM). Slowing for no-wake zones can generate large wakes (JSch). <br />Lake aeration by natural factors is far greater than that from boat or PWC operation (JSch). <br />Basin shape and wind direction affect the amount of natural aeration (DZj. <br />7. What is the relati~ e significance of factors affecting lake eater qualih and what is the expected lifetime of Lake <br />Ow-assn? What is it_s trophic status? <br />On a geological scale, lakes may last 10,000 yr. Human activity accelerates filling in of lakes. <br />which might occur in 7-8 generations (DZ). <br />A 50% reduction in the apparent supply of ground water contributed to a 1988 order b}' the <br />DNR Commissioner that lake augmentation (pumping] was a low priority use of ground water <br />(TN). Maintenance of lake level through pumping is now prohibited except in extenuating and <br />chronic circumstances (DZ), as for Snail lake (TN). The county has removed many pumptng <br />systems and will soon remove the well on N. Owasso (TN). <br />8 . Do the water qualit} goals for Lake OH-assn hay e an~~ rele~ ante to or impact on ~~ ater surface use regulatiem? <br />There would be changes in safety, in wave energy and erosion, and in plant disruption. More <br />plant. debris would wash up on shore. If "something" (e.g. no-wake buffer, watershed projects) is <br />changed, an impact will eventually be perceptible, but effects are not rapid (DZ). <br />The panel was unclear what regulattons were meant here anal preferred to answer #9. Also see <br />paragraph on MPCA goals, #9. <br />9 . Will changing the no-wake buffer zone from 300' to 150' ha~~e an}' impact on eater qualiq, erosion, weeds, or <br />algae? Will wide weed beds (- ] 50') be affected? <br />GW explained that the primary regulation at issue is a change from 300' to 150' no-wake <br />buffer. A change to 150' means the city can never return to 300' (DZ). Enforceability was <br />discussed: the sheriff thinks 150' is more enforceable and 150' in the SW end would allow > 1 <br />boat there at a time (GW); 300' has not been practiced or enforced (SP). Boaters might adjust their <br />non-compliance with no-wake buffers as drivers do to speed limits (PEj, ornon-compliance could <br />reflect an unreasonable law (GW). Kim Elverum of the DNR said. the number of boats on the lake <br />has probably not increased in 10 yr (PE). <br />Ability to use the lake is important; boats keep the lake open (DA). Access in the SW end is <br />not a problem, it will be created either by boat use or herbicides. Mechanical harvesting per DNR <br />3 <br />