If you still are considering a project, there are a couple of things to keep in mind. If you have not done so already, and you're not one yourself, consult with a professional trained in the field of stream habitat restoration. Diverting water from a stream to create a pond or wetland where one did not exist previously will likely not be viable or sustainable project. And you will create havoc for downstream neighbors and fish. Check before you get your feet wet.
Wetlands act as ecosystem sponges.
During seasonal flows, wetlands play a critical role in absorbing excess runoff. If wetlands are filled, not only is habitat destroying for fish, waterfowl and other creatures, significantly, flooding increases and everyone ends up paying for costly mistakes. Remember, plants are a vital part of a stream ecosystem, adding nutrients to the stream, preventing erosion and keeping water temperatures cool. Leave as large a riparian buffer around streams and wetlands as possible to ensure good water quality and to protect salmon habitat. At a minimum, follow buffer width guidelines prescribed by your city or county code.