Artificial Recharge Helps Replenish Groundwater Supply

Demand for water has increased awareness towards use of artificial recharge to augment groundwater supplies. Artificial recharge is a process by which excess surface water is directed into the ground to replenish an aquifer. When water is proactively returned to the ground and put into storage, it helps to ensure a sustainable groundwater supply.

Groundwater is an important source of water in the Fresno area, and the City of Fresno is committed to protecting the groundwater quality and to ensuring that groundwater is available to the community now and for the future.

Fresno’s Groundwater Recharge Program

Surface water is currently used to replace lost groundwater through the City’s artificial recharge program at the City-owned Leaky Acres and smaller facilities in Southeast Fresno. In addition, Fresno Irrigation District (FID) and Fresno Metropolitan Flood Control District (FMFCD), also play a critical role in our water supply through their partnership with the City. During the summer and fall the City’s surface water entitlement is delivered via canals by FID to the FMFCD recharge basins located throughout the urban area where it percolates through the soil to replenish groundwater. The City is working with its regional partners to fully utilize the sites already developed and is developing new sites such as a recharge basin in southeast Fresno.

Flood irrigation of surface water applied to surrounding farmlands is also a vital source of groundwater recharge. As agricultural land is converted to urban use, total water consumption within the region actually drops, but the recharge impact of deep percolation from flood irrigation is lost. Identifying sites for additional groundwater recharge is essential to keeping our water supplies balanced.

What is Leaky Acres?
Leaky Acres is a water recharge basin located at 4111 N. Winery near the Fresno Yosemite International Airport.

What is the purpose of Leaky Acres?
In 1970, the Leaky Acres facility, which is currently comprised of 26 ponds covering 200 acres, was built to store water that is percolated into the underground aquifer for the purpose of recharging the groundwater supply.

Where does the water come from?
The City of Fresno has a contract with the U.S. Bureau of Reclamation which entitles the City to 60,000 acre feet of water each year from the San Joaquin River. This is known as Class I water and is delivered from Millerton Lake.

The City also receive water from the Kings River via the Fresno Irrigation District canals that is referred to as Class II water and it is delivered from Pine Flat Lake. We have entitlement to 21% of FID's yearly allotment which is determined by the amount of seasonal rainfall. Example: If FID receives a total allotment of 500,000 acre feet, then the City would be entitled to 105,000 acre feet.

What determines if the water comes from Millerton Lake or Pine Flat Lake?
As a general rule, we try to use our Class I water (Millerton) early in the season and then rely on our Class II (Pine Flat) water to finish out the year. Occasionally, FID will switch sources to avoid too large of a balance stored behind either dam.

How much water is put into Leaky Acres?
Over the past five years, we have received on average 55 acre feet per day which is equivalent to approximately 18 million gallons.

Can the recharge results be seen in the surrounding area?
Yes, there is a significant difference at Pump Station #80 located on Chestnut diagonal at Winery. The static water level at this location can rise as much as 10 feet when we are recharging. When we stop recharging, it will return to its original level.

How deep are the ponds?
It varies, but the average is 3 to 4 1/2 feet.

How long do we run water into Leaky Acres?
Nearly year around.

Are the soil conditions in Leaky Acres favorable for effective recharge?
Yes, however, the soil conditions are especially effective in the southern region.

Is Leaky Acres disked when it is dry?
No, disking only causes the silts to be further incorporated into the soils. The silts tend to form a barrier that prevents good percolation. As the silts build, they are removed.

Would placing holes or wells in Leaky Acres help water percolate faster?
There are about 100 test wells around the site that were developed by the Department of Agriculture. They were testing to find out how fast water percolates and its effectiveness. While we do not have statistics on their findings, it is generally accepted that the wells were not successful in helping water percolate faster because of the silt buildup and continual maintenance of the holes.

Are there other recharge basins in Fresno?
There are many others. We have an agreement to use some of FMFCD basins for the same purpose. However, they are not available year-round. Recharge operations usually begin in March and run until about October. The FMFCD must keep their basins available for storm water during the rainy season to minimize the chances of local flooding.

Are other recharge basins being planned?
The Southeast Recharge Basin located near Chestnut between Church and Jensen has been added. That site has two 10-acre recharge sites.

What sort of wildlife comes into the area?
Pelicans, Canadian geese, Mallard ducks, Pacific Ocean Pin Tail ducks, swans and Chinese Horn Bill geese are among some of the waterfowl spotted at Leaky Acres. Additionally there are jackrabbits, a few Red Foxes and even a bobcat that have been spotted in the last few years.

Do fish swim in the ponds?
The Mosquito Abatement District plants minnows to control mosquitoes. Other fish have managed to make it into Leaky Acres, but they are few in numbers . FID treats the canal system with Magnacide to control weed and algae growth. They must do this several times during the delivery season, unfortunately, this practice also kills the fish that may be present in the FID canals. All basins are closed temporarily while the canals are treated.

Can kids swim or fish in Leaky Acres?
Swimming and fishing is prohibited.

What are the responsibilities of Water Division employees for Leaky Acres?
Employees perform general maintenance including weed control and levee maintenance. When FID water is not running, they remove silts with heavy equipment. The employees also monitor the water levels, and make adjustments to pond levels so that the greatest amount of water can be recharged.
Are other local water purveyors participating in a recharge program?
It is our understanding that the City of Clovis, Bakman Water Company, and Malaga Water District are also participating in a recharge program.

Are other cities participating in a recharge program?
Other California communities, including Orange County and Coachella Valley Water District, are using the same type of program as the City of Fresno. Phoenix, Arizona also operates a similar recharge program. Many cities currently use surface water instead of wells for drinking water. Some cities are surrounded by canals and water is recharged in that way. Residents in those areas are sometimes charged on their tax bill for recharge.

How much does the water cost?
In FY 2006, it is estimated that the Water Division will pay a total of $7.4 million for the surface water used to recharge Leaky Acres and other basins throughout the City. Of this amount, $5.9 million will go to the US Bureau of Reclamation for 60,000 acre feet (contract for water delivery renewed in July 2005 for forty years) and $1.5 million will be paid to the FID for the City's available allotment of a projected 90,000 acre feet that year.

TOURS OF LEAKY ACRES

Public tours of Leaky Acres and other City of Fresno water operations are available. Contact the Water Division at: 621-5300 or 621-5480.

For more photographs, click: Leaky Acres Photos