Eliminating Runoff and Overspray

Water waste is unnecessary and illegal. Article X, Section 2 of the California Constitution specifies that the right to use water is limited and does not extend to waste or unreasonable method of use. State and local ordinances also explicitly prohibit wasting water.

Run-off occurs when water is applied too fast or in a greater amount than the soil can absorb. Most soils absorb water much slower than sprinkler systems apply the water to the landscape. It is recommended to use one of two methods to aid in decreasing or possibly eliminating run-off of water on a landscape. One option is to use low precipitation spray nozzles or drip irrigation which applies the water at a slower rate. This allows the soil time to absorb the water as it is being applied. If either of these irrigation devices is used, it should be on a separate irrigation valve and not combined onto one valve. A second option to aid in decreasing run-off is to use multiple cycles with short duration watering times for each station and allow enough time between each cycle (approximately one hour) for the water to soak into the soil. A good way to do this is turn on your system manually and time how long it takes for water to start running over the curb or down the driveway then set each station for that short period of time. After the cycle has finished you can run another one, and in hot weather a third or fourth. Remember to run the cycles on your designated day and times.

Terracing and shallow watering basins can help prevent run-off on areas that are sloped or poorly graded. Broad, shallow basins are generally better than deep, narrow ones; the wider the basin, the wider root area you can soak.

Runoff causing expensive damage

to asphalt.

runoff1

Runoff transporting pollutants to recharge and ponding basins, the

Wastewater Treatment Facility and local waterways.

Once your sprinkler system has run through all the cycles, let the landscape rest and have a chance to completely absorb the water before repeating the process. Determining the length and frequency of watering for your landscape is a simple process. Visit the Plant List and note the hydrozone designation (level of water use and sun/shade necessary) for each of your particular plants.

Overspray is simply the water that lands beyond the planted or target area. When the overspray lands on sidewalks, driveways, and other hard surfaces it can, and does, empty into the streets and local waterways. Garden beds and irrigation systems should be designed to avoid overspray onto impervious surfaces. Lawns should be held back from streets and driveways. Overhead irrigation should not be used in planting areas directly adjacent to streets, driveways, and sidewalks.

Water running off the landscape will carry pesticides and fertilizers used on that landscape. Once in the street, runoff may also pick up oil, trash, sediment, and other pollutants. Also, drained swimming pool water is chlorinated and can be deadly to aquatic life. In addition, the public is susceptible to safety and slip hazards from runoff and water puddles on walkways and roadways.

Most storm drains empty into ponding and groundwater recharge basins, however, a few connect to the wastewater treatment facility or discharge into nearby waterways. In all these cases, pollutants cause problems that must be dealt with in order to keep water clean and safe.

Unlike sewers, storm drains are not connected to treatment plants. Water and pollution that runs off of streets and land flow directly into rivers, creeks, sloughs, and the ocean without being filtered or treated. In inland areas, storm drain runoff is sometimes directed into open spaces where it percolates into the ground.

Water pollution is a serious problem because it causes changes in the biological, physical, and chemical characteristics of a water body. Some attributes of water that are affected by pollution are pH, acidity, dissolved oxygen content, nutrient or sediment load, and the presence or absence of pathogens. Changes in these attributes caused by pollution can harm aquatic life, create unpleasant odors, and in the case of pathogens, may cause disease in humans that come into contact with the water.

Allowing sprinklers to overwater your lawn or to spray onto sidewalks, driveways, or other hardscapes causes run-off that can carry pollutants into our watershed.

Pollution carried by the irrigation runoff can 1) enter the Wastewater Treatment Facility and cause problems in the processes of cleaning the water; 2) add to the street runoff during storm events that carries contaminants into ponding and recharge basins, and 3) in some cases empty directly into our San Joaquin River.

Image created by Dave Williams, Education Director, City of Fresno Water Conservation Program

This satellite image provides the big picture perspective of the San Joaquin River serving as the lifeblood to the greater Fresno / Madera area. Water deliveries enable agriculture to flourish in both counties, and the river provides the urban areas with drinking water and groundwater recharge. Keeping Our Watershed Clean includes protecting the approximate 25 miles of the river as it travels from Millerton Lake behind Friant Dam past the Highway 99 bridge west of Fresno. Blackstone Avenue divides the image in half vertically and the two major east-west arteries in the City, Herndon and Shaw Avenues, run across the bottom.

This infrared aerial image was created from data provided by the Landsat-4 TM satellite, and was processed in the GeoInformation Technology laboratory at CSU Fresno. While the color red is commonly used for vegetation in scientific analyses, here green has been substituted to produce an “infragreen” image in order to highlight the agricultural and urban plant growth.

Water features all appear in black. Note that at the time this area was imaged, the two large gated communities in north Fresno, Van Ness Lakes and Woodward Lakes (lower left and right middle, respectively) had not yet been built, but the lakes were already full. The small dark squares scattered throughout are recharge and stormwater ponding basins.

The large green areas north of the river and east of the river along the right edge of the image are agricultural fields. Small square and rectangle green areas in the urban sphere are mostly parks and school yards. The two large golf courses in the bottom lower left are the brightest green surface feature.

The various shades of pinkish-red (mostly in the northeast quadrant) denote different mixtures of surface materials that consist of bare soil, rocks, and dry grasses. Asphalt roadways in the urban areas, concrete, and large roofed areas appear in shades of purple.

Water from Millerton Lake and Pine Flat Lake is delivered through canals that provide agricultural water to farmers throughout the area and water to replenish what we pump from the underground aquifer for urban consumption.