Best Management Practices Evaluation


Nonpoint source pollution from logging practices has long been a concern of water quality managers and forestry officials alike. The three parameters generally associated with impacts from logging practices are changes in flow regime, temperature and turbidity (total suspended solids). Perhaps the most widely accepted best management practice (BMP) used to curb degradation is to leave an undisturbed vegetative buffer strip immediately adjacent to the stream. This riparian buffer can decrease sheet flow runoff and thereby reducing sedimentation. Wisconsin Office of Forestry currently has guidelines for riparian buffers along streams in timber harvest areas. These guidelines were largely based upon good science from other states, but as a follow up they should be empirically tested to determine if they provide adequate protection of stream resources unique to Wisconsin. This project will evaluate the changes in the three previously noted parameters generally associated with impacts from logging practices. Accurate measurement and estimation of water quality changes is dependent on the timing and frequency of data collection. This is particularly true for parameters such as suspended solids. For example, it is common in streams and rivers for most of the annual suspended sediment to be transported during a few, large runoff events. Automated data collection is essential to effectively capture such events. Although it is possible to rely solely on manual measurements, important flows are infrequent, unpredictable, and when they do occur, trained personnel may not be available to collect the required information. There is currently no practical method to directly measure the full range (submicron to 2 mm) of suspended sediment concentration (SSC) in the field. Pumped or manual samples must be transported to a laboratory for analysis. However, like the new generation of pressure transducers, a number of companies now offer turbidity sensors that can be deployed on a continuous basis in streams. These sensors use near-infrared light source to accurately measure the stream water's light scattering ability and are designed with a automated small wiper/cleaning device to keep the sensor surface clean from debris and biofouling.. These sensors generally possess highly accurate dynamic range (0-1500 NTUs). While turbidity cannot replace SSC, it can be of great benefit as an auxiliary measurement. The continuous turbidity record can reveal sediment pulses unrelated to flow, providing information about the timing and magnitude of sediment inputs The most rigorous evaluation of riparian buffers in timber harvest areas would be on landscapes with steep slopes and erodeable soils. We expect that if the buffers perform adequately in sensitive landscapes then they should be adequate for other landscape types as well. We propose to test buffer effectiveness in the Lake Superior clays region with the soils dominated by calcareous red clays and where topographic relief can frequently be 90 - 100 m/km. The Lake Superior clays region was identified from the USGS Quaternary Surficial Geology map. This region corresponds closely with Omernik et al. (2000) Level IV ecoregion Lake Superior Clay Plain. The effective study area shrinks considerably once focusing upon the forested land cover within the region. Ultimately we intend to sample streams in timber harvest areas using riparian buffer BMPs prescribed by Office of Forestry in the region.


The project objectives are: 1.) Evaluate the water quality impacts on small streams adjacent to two timber harvests employing current BMP standards. 2.) Provide a demonstration site to showcase new monitoring technologies for water quality staff.

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