Homeowners and designers can choose from a variety of bridge styles, railing types, and accessories to achieve the look they want. Bridges can arch high over pools to leave room for swimmers or sit low over koi ponds, reflecting light into the water from solar post caps. They can also be short or long, with a minimum span of 4 feet and a maximum length of 40 feet. Material options include California redwood and composite lumber. Redwood Garden Bridges for Koi Ponds. 559.325.2597. www.redwoodgardenbridges.com.