I recently moved into a new subdivision and notice that the homeowners association or developer's landscaper planted a magnolia tree directly over my water service lateral.

I am concerned about roots invading the pipe and contaminating my water. I cannot get the association to remove the tree without citing code.

When we lived in the East Bay, the cities and county had codes (or design guidelines) that prohibited trees over water or sewer laterals (the minimum offset was 3 to 5 feet). I have contacted Sacramento County and Elk Grove, but neither Public Works nor Planning departments are aware of any such codes.

What is the possibility of the roots breaking into my water line, and is there an agency I can contact for more information?

– A. Dopson, Elk Grove

According to UC Master Gardener Bill Pierce, magnolias have root systems that are close to the surface and are not known to be invasive of water lines or sewer systems.

That includes both Magnolia grandiflora – the evergreen Southern magnolia – and deciduous Magnolia x soulangeana – the saucer magnolia often called a "tulip tree" because of the shape of its flowers.

If your tree is the evergreen type, you may have one of the six or so subspecies of Magnolia grandiflora that reach a mature height of not more than 20 feet. One variety, Samuel Sommer, matures at 30 feet. Thus, their root systems are much smaller than the full-sized magnolia tree that grows to 80 feet in height and has a spread of 60 feet.

Deciduous varieties generally have a height and spread of about 25 feet. According to University of California research, trees have more than 70 percent of their root system in the top 18 inches of soil.

Find out how deep your water line was buried when the subdivision was built.

The Sacramento Tree Foundation has lists of suitable trees for planting in a variety of situations and works with the various utilities to get appropriate trees planted in sensitive areas, for example, under power lines. Its website is www.sactree.com.

You also may want to contact the arborist at the city of Sacramento, (916) 808-6345.

The city of Elk Grove recently passed an ordinance regarding that city's arborist, so city staffers may have additional information since you talked with them.

GARDEN QUESTIONS?

Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties.

Send questions to Garden Detective, P.O. Box 15779, Sacramento, CA 95852. Send email to h&g@sacbee.com. Please put "Garden Detective" in the subject field and include your postal address.

To contact your UC Extension directly, call:

• Sacramento: (916) 875-6913; 9 a.m.-noon and 1-4 p.m. weekdays

• Amador: (209) 223-6838; 10 a.m.-noon Monday through Thursday; email ceamador.ucdavis.edu

• Butte: (530) 538-7201; 8 a.m.-noon and 1-5 p.m. weekdays

• El Dorado: (530) 621-5512; 9 a.m.-noon weekdays

• Placer: (530) 889-7388; 9 a.m.-noon on Tuesdays, Wednesday and Thursdays or leave a message and calls will be returned

• Nevada: (530) 273-0919; 9 a.m.-noon Tuesdays through Thursday or leave a message

• Shasta, Tehama, Trinity: (530) 225-4605

• Solano: (707) 784-1322; leave a message and calls will be returned

• Sutter, Yuba: (530) 822-7515; 9 a.m.-noon Mondays and Tuesdays and 1-4 p.m. Thursdays

• Yolo: (530) 666-8737; 9-11 a.m. Tuesdays and Fridays, or leave a message and calls will be returned

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