The Maryland Department of the Environment is trying to find out how bacteria are getting into Union Bridge's town well, although water from the well remains safe to drink.
"There is no incidence of any illness, no danger, but we're being cautious and trying to find the source of this so we can fix it," said MDE spokesman Quentin W. Banks.
State workers started dye tests in Little Pipe Creek and Sam's Creek in mid-September, and testing will continue for a month, Mr. Banks said.
The tests involve putting a harmless red dye into the creeks to learn whether creek water is carried through porous underground limestone into the town well, located near Town Hall on Locust Street.
Other possible sources are town sewer lines, which could be leaking, or the underground water tapped by the well, Mr. Banks said.
Results from tests of the town well in May and June showed low levels of coliform bacteria, Mr. Banks said. The bacteria do not cause disease, but serve as an indicator that disease-causing bacteria may be present.
Depending on the dye test results, Union Bridge may be required to install a filtration system. Although water treatment kills the bacteria, public water systems that have the organisms also are required by law to filter the water, Mr. Banks said.
"The first thing we've got to do is find out where it's coming from," he said.
If a filtration system is required, Union Bridge can ask the state to supplement a $200,000 water system grant that the town received in November, said Brenda Dinne, a county planner who is assigned as the department's liaison for Union Bridge.
The grant is for a new well house and chlorination system and other improvements to the water system, Ms. Dinne said. She said MDE declined to release the grant money until staff members tested the well for possible surface water infiltration.
Union Bridge will be required to contribute 12.5 percent toward the total cost of the improvements; the state's share is 87.5 percent, Ms. Dinne said.
Town government will acquire an additional water supply well as part of its agreement to annex a 175-acre tract known as the Phillips property. More than 400 housing units are planned for the Route 175 site.
A 1992 annexation agreement includes a provision that the town will not issue building permits until the developer provides an additional well.