Steel, E. Ashley2011-08-182011-08-181999-01http://hdl.handle.net/1773/17079This fact sheet describes horizontal viewing discs, which are devices for measuring underwater visibility in moving waters. The fact sheet provides step-by-step instructions for building your own horizontal viewing disc and provides references.en-USmeasuring deviceslotic systemsriversstreamslimnologystream flowclarityoptical propertiestubiditywatermeasurementequipmentcustom-made equipmentTechnical Report