Groundwater versus Stormwater
Groundwater is the water that is found underground. It is found in the cracks and spaces in soil, sand, and rock. Some groundwater comes from infiltration. When it rains, some of the rainwater soaks into the ground, or infiltrates. The portion of the water that does not soak in, but runs off, is stormwater.
Groundwater issues are related, but not directly linked, to surface and stormwater. They do interact, but the degree to which they interact is different for different locations and situations.
Groundwater's Role in the Watershed Studies
Groundwater is acknowledged in the watershed studies, but is not included in the evaluation. For example, when talking to residents that flooded in August 2018, many reported they had water in their basement. The water came up through the foundation, not from overflowing from a door or window. This means the water is from groundwater and not from flooding.
Groundwater evaluation is a different type of study. Groundwater typically covers a much larger area than a watershed study area. Groundwater modeling uses different modeling software and different information.
In a separate effort, the City is working with area agencies to understand groundwater impacts and planning accordingly.
Groundwater Recharge through Infiltration
Infiltration (water soaking into the ground) is one component of the water cycle that recharges groundwater in certain areas. Some of the proposed solutions include an infiltration component. The infiltration from these solutions may or may not affect groundwater levels. It should be noted that creating large amounts of infiltration in areas that have not had infiltration in decades and were not designed for it can have unintended consequences and infiltrated water can end up in adjacent basements.