Legal Definitions - surface water

Surface water refers to water that exists on the Earth's surface, typically originating from precipitation (rain, snowmelt) or overflow, and flows across land without being contained within a defined natural channel like a river, stream, lake, or pond. It is often temporary, diffuse, and unconfined, moving across the ground until it evaporates, seeps into the soil to become groundwater, or eventually reaches a defined watercourse.

Here are some examples to illustrate the concept of surface water:

• Residential Property Drainage: Imagine a heavy thunderstorm that causes rainwater to accumulate on one homeowner's sloped backyard. This water then flows across the lawn, over the property line, and onto a neighbor's garden, creating a temporary puddle and potentially eroding some soil.

  This scenario illustrates surface water because the rainwater is not flowing in a ditch or stream; it is simply running off the land in a diffuse, unchanneled manner. Legal disputes can arise if this unmanaged surface water causes damage to the neighboring property.

• Agricultural Field Runoff: After a significant snowmelt in early spring, water begins to spread across a large, flat agricultural field. This melting snow forms shallow sheets of water that slowly move across the soil, eventually draining into a low-lying area at the edge of the field before soaking into the ground or evaporating.

  Here, the melting snow constitutes surface water. It is not confined to a specific channel but is broadly distributed across the field. Farmers often need to manage surface water to prevent soil erosion and ensure proper drainage for crops, sometimes leading to legal considerations regarding how this runoff impacts adjacent properties.

• Urban Development and Stormwater Management: A new commercial complex is built, featuring large parking lots and extensive building rooftops. During a rainstorm, the water that falls on these impervious surfaces cannot soak into the ground. Instead, it collects and flows rapidly across the concrete and asphalt, eventually being directed into a storm drain system.

  The water flowing across the parking lots and roofs before entering the storm drains is considered surface water. Urban planners and developers must design systems to manage this increased volume of surface water runoff to prevent flooding, pollution, and erosion in surrounding areas, often subject to specific environmental regulations.