Water flows downhill. We observe this frequently in nature, but sometimes forget that it happens in our own backyards. Your yard is its own micro-watershed where water flows down the path of least resistance. Rain coming off your roof, driveway, gutter, etc. should soak in when it reaches the ground, but if the ground is already full of water (saturated) the extra water will runoff to the lowest nearby area.
Runoff is not confined by nor does it follow property boundaries. If your neighbor’s yard is a lower elevation than yours, excess water runoff is going to flow there. If your neighbor’s yard is higher than yours, you might be receiving runoff.
In our communities, we get to know our neighbors and try to be considerate; we pick up pet waste, mow our lawns, plant flowers and trees, and generally take care of our place. Yet, there are many stories of homeowners putting in patios, home additions or other structures that change how water flows and increasing runoff to a neighbor’s yard. Others re-grade their yard simply so excess water flows off their property, sending the “water problem” off somewhere else. Lower lying neighbors are often unhappily stuck with a new problem they didn’t create, that damages their property, costs money and creates stress.
When homes are built, there is a grading plan that is used to make sure water drains through the property and the neighborhood efficiently and without causing problems. Grading plans are designed to protect neighbors, natural resources, prevent erosion, and reduce flooding. Changing the grading of a property changes how water flows on the property. However, so changes are needed because soil and buildings have settled or from other changes to the property.
For all grading projects, large or small, first check with your city to prevent any negative drainage issues. For smaller projects, the city engineer may be able to make design recommendations to you or may ask you to consult a landscape professional. For larger grading projects or ones that involve building a new structure you may need a permit. The city engineer can tell you if you need a permit and also how the project will change how water flows on your property. Most cities require permits for excavation of a certain square footage and forbid re-grading on drainage or utility easements.
There are other ways of dealing with excess water. If you have soggy areas in your lawn consider planting a native garden or raingarden with deep rooted plants to absorb help water soak in. There are many projects out there to help mitigate water problems. This website www.bluethumb.org is great for learning how native plants help keep waters blue.