The regional planning agency for Northern Virginia has urged that the seven governments in the Occoquan River Basin study a plan to share operating costs of the Upper Occoquan River Sewage Treatment Plant. At present the costs are being borne by only some of the residents served by the reservoir.

The unanimous recommendation came at a meeting last week of the Northern Virginia Planning District Commission. In addition, the commission has urged the seven areas to study ways outlying counties could help stop "nonpoint pollution." That pollution, which comes from water runoff from housing subdivisions, farms and construction, has become a major problem for the reservoir, according to some experts. The reservoir is the water supply for more than 600,000 area residents.

The regional agency has invited officials from the seven jurisdictions to meet next month to discuss the proposals. Among those invited are officials from Fairfax, Prince William, Loudoun and Fauquier counties; the cities of Alexandria, Manassas and Manassas Park; local water authorities, and the Northern Virginia Regional Park Authority, which owns all of the north bank of the Occoquan Reservoir.

The proposal to study the issues could result in a trade-off agreement, urged by the planning commission staff, in which the rural counties would require stricter controls over nonpoint pollution in exchange for urban areas -- such as Alexandria and eastern Prince William County -- paying a share of the costs of the new sewage treatment plant.

The plant contributes to the cleanliness of Occoquan's water since it provides much more advanced treatment for the wastewater. The cleansed effluent is dumped into streams feeding the reservoir.

The 2-year-old plant replaced 11 outdated sewage plants in western Prince William and Fairfax counties and the cities of Manassas and Manassas Park, whose residents now pay not only the plant's operating costs but a large share of its $82.3 million construction costs.

Sewer bills for Manassas and Manassas Park residents have jumped more than 200 per cent in some cases in the past two years. Bills of $100 to $150 every two months, residents say, are not uncommon because the costs are spread among few residents. The Fairfax County share is spread among all county residents, not just the relatively few served by the sewage plant. Prince William has several water and sewer districts with only those in western parts of the county paying higher sewer bills. Alexandria and eastern Prince William residents pay none of the sewage plant's costs.