11-12-1985 Council Packet - Laserfiche WebLink

Home Browse Search

Soils - Any nutrient rich soils that are removed are basically topsoil that has eroded ovet the last several hundred years into the wetlands, it is very loeded with nutrients, by returning it to the uplands making for excellent topsoil which may well not need fertilization for many years. Wildlife - Proposed alteration should be more attractive to migratory water fowl than the existing mature "marsh". MONITORING Quality Indicators - The principal concern would be in the outflow increased nutrient or sediment loading would be detrimental to Lake Minnetonka. Actual flow is only a concern as it relates to gauging those nutr ent and sediment flows since the storm water ponding c:haractistics of the pond are being altered in a positive manner. Baseline - In order to appropriately establish a baseline it may take 3 or 4 years to do so in order to have a valid data for the average and extrodinary flows that may result from this wetlands. Princi_l measurements in addition to outflow would be some analysis of suspended solids and specific nutrients that would be considered detrimental. A mote complete analysis of specific reactivity diminsions of certain nutrients could also be done but would radically increase the price. For a full study which would go beyond deter- mining the detriment to the lake to do a study that would be worth- while would include monitoring estimates of approximately $10,000 a year for 3 to 4 year period possibly. WETLANDS ALTERATION PROJECT While the Gregory's property could be the focus of a study it is probably not of a magnitude or flow that would be the most appropriate for special study and it has been suggested and discussed that perhaps a study of a wetland that could be altered in 4 to 5 years that is of larger magnitude and flow may be more appropriate for study and may be of interest to such agencies as FWBI, Minnehaha Watershed, Cicy of Orono, etc. The study would possibly involve use of graduate student developing a thesis with ongoing monitoring and a very excellent readout of water flow, sediment and nutrient changes in loading from before and after the alteration. ON -GOING MONITORING Without a_ baseline: there is very li tie use in monitoring since there is nothing against which to compare the loads. Additionally if monitoring is done for only a short period of time it may not be at the appropriate points and may give a false reading together with the fact '..hat should future measurements of sediment and/or phosphorus contents increase 10 or 15% maybe considered by some significant but not by others, particularly in light of the magnitude of impact within the lake. (There is an on(joinq monitoring by Minnehaha Watershed which does keep ongoing data as to phorsphorus in Brown's Bay which will indicate substantial "out of range" changes.) RESTORATION/SFCURITY (,iv nFFie`magniFu-de risk and benefit fr�)m this proje•,t it is felt that the only additional oxponse incurred by the Gro(jory's relate to some