Based on the available information, the boat ramp named 30th Avenue Southwest Stark County in North Dakota is a concrete boat ramp that is approximately 12 feet wide. It services Lake Tschida, a reservoir located in southwestern North Dakota.

According to the website of the U.S. Army Corps of Engineers, which manages Lake Tschida, the reservoir is open to all types of watercraft, including motorized boats, sailboats, canoes, and kayaks. However, the website notes that restrictions may apply to certain areas of the lake, such as designated swimming beaches and areas near dams.

It is important to note that the information provided is accurate as of the time of writing, but it is always a good idea to check with local authorities or the managing agency before using any boat ramp or waterway to ensure that there are no closures, restrictions, or other changes that may affect your plans.