THE VIRGINIAN-PILOT
Copyright (c) 1995, Landmark Communications, Inc.
DATE: Thursday, July 27, 1995 TAG: 9507270372
SECTION: LOCAL PAGE: B4 EDITION: FINAL
SOURCE: BY FRANCIE LATOUR, STAFF WRITER
DATELINE: CHESAPEAKE LENGTH: Medium: 75 lines
For only the second time since the city began tapping the Northwest River for drinking water, salt levels have tripled the recommended federal taste threshold.
Chlorides, which give the water a salty taste, reached 781 parts per million Wednesday. The federal standard for drinking water is 250 parts per million.
The only other time the city's supply had reached such heights was in an extended drought a decade ago. Most summers the high peaks at 363 parts per million.
Of more concern to city officials is the rise in the sodium content of the water. It was at 391 parts per million Wednesday - more than 15 times what doctors recommend for patients on severely restricted diets.
Chesapeake Health Department Director Nancy M. Welch issued a public health bulletin Wednesday alerting residents and physicians to the high sodium levels.
She advised that those with even moderately restricted diets use bottled water and check with their doctors.
Although sodium is tasteless, elevated levels pose a potential risk to those who suffer from high blood pressure or who are on severely sodium-restricted diets for other conditions, Welch said.
For most people, Welch said, the dramatic rise in chlorides and sodium in Chesapeake's drinking water will be merely ``an annoyance, because of the salty taste.''
How long that annoyance will last is unclear, city officials said Wednesday.
``Until the rainfall changes, there is no way of telling when it's going to let up,'' Public Utilities Director Amar Dwarkanath said.
Dwarkanath said the shortage of rainfall in July set the stage for the rising levels of chlorides and sodium. The city should have gotten between five and six inches of rain this month, but only one inch had fallen in and around the river.
The lack of fresh water has allowed salty water from the Currituck Sound to back up into the Northwest River.
The city first faced this dilemma in 1985 and '86. A severe drought through two summers sent sodium and chloride levels skyrocketing, topping out at more than 1,600 parts per million.
But that scenario, Dwarkanath said, isn't likely to be repeated: Since 1990, the city has had a storage system in place to supply fresh water in case of such emergencies.
Since Sunday, the city has been pumping about three million gallons of water a day from a 318-million-gallon underground reservoir.
``When we have surplus fresh water,'' Dwarkanath said, ``we push it deep into the ground and store it there. So when we need it, we pull it up like a straw and pump it into the system.''
That water, with a sodium content of 34 parts per million, is sometimes mixed with water from a well in Western Branch that is higher in sodium, bringing the average sodium content for the blend to 150 parts per million, Dwarkanath said, still above the recommended level for severely restricted diet patients.
Welch pointed out that Great Bridge, Greenbrier and some scattered locations in the Deep Creek area were still receiving Northwest River water, with its much higher sodium and chloride contents..
After an upgrade of the water treatment system that would be funded by a $72 million water bond referendum in November, Dwarkanath said, worries of salty taste and health concerns could be a thing of the past.
The improvements planned under the bond issue are designed to bring the Northwest River Treatment Plant in line with federal guidelines.
But the filter that will be used will also take the salt out of the water. The mesh of the filter is so fine, Dwarkanath said, that sodium and chloride molecules will not be able to get through.
KEYWORDS: WATER CHLORIDE SODIUM SALT CHESAPEAKE by CNB