We have measured the shear viscosity of solutions of ethanol and hydrazine in water into the supercooled region. Two techniques were used: Poiseuille flow measurements in the range 75°-17.5°C and photon correlation spectroscopy of light scattered from diffusing microspheres suspended in the solutions in the range from 20 °C down to nucleation. We have found that addition of hydrazine tends to diminish any anomalous increase in the viscosity of supercooled water, an effect similar to that seen in other types of measurements. Addition to ethanol, on the other hand, enhanced the viscosity. This was interpreted to indicate that the cagelike clathrate structures known to be found in aqueous ethanol solutions are also found in pure water and may be responsible for the anomalous properties of supercooled water which have recently been discussed in the literature.