Permanent Water Impoundments
A list of common advice regarding permanent water gathering spaces.
1. Ponds may be any shape but should not have small coves or irregularities around their perimeters.
2. Ponds should be designed to be emptied by gravity or pumping for cleaning or drying and have graded bottoms so all water can be removed.
3. Side slopes of excavations and levees should be as steep as possible, consistent with soil characteristics and risk factors of slope failure.
4. Where steep side slopes cannot be economically achieved, the slopes should be lined with suitable material such as concrete to 3 feet below the water line or sterilized to achieve weed control.
5. The top width of embankments should be a minimum of 12 feet and should be adequately constructed to support maintenance vehicular traffic.
6 An access ramp should be provided on an inside slope for launching a small boat for mosquito control.
7. Ponds designed for long term storage should have a minimum storage depth of four feet.
8. A maintenance program for weed and erosion control along inner slopes is essential.
9. All accumulation of dead algae, vegetation and debris should be routinely removed from the impounded water surface and properly disposed.
Water Conveyance Facilities
1. Ditches must be maintained free of emergent, marginal and floating vegetation.
2. Ditches should be sized and graded for adequate flow and must not be used for water storage.
3. Unpressurized and low pressure pipelines, commonly used in irrigation distribution systems, should be designed to be emptied when not in use and should not be used for water storage because of the mosquito breeding potential in the partially filled pipes.
The preceding mosquito prevention criteria are intended only to offer guidance when considering the development of design options during the planning process for projects. Be advised that these practices have been found to be effective, however, once the project has been completed it is essential that conscientious maintenance and management practices be followed to help ensure the successful prevention of mosquito production.
Be further advised that under the California Health and Safety Code (Sections 2274 et. seq.) the responsibility for the cost of mosquito control may fall on the property owner.