pH is a measurement of the hydrogen concentration in water and indicates the acidity or alkalinity of a substance. pH ranges from 0 (highly acidic) to 14 (highly alkaline), with 7 being a neutral pH (Figure 8). The pH of precipitation is slightly acidic (usually near 6), influencing the pH of receiving waters. A pH range of 6.5-8.5 is best for most organisms, and aquatic life is impacted at pH values outside of this range. Both acute (3.0 mg/l) and chronic (4.8 mg/l) standards for pH have been established by the New York Department of Environmental Conservation.