By the time these words reach print, the year 2000 will be closer ahead than 1996 is behind us. We are closing in on a year with many implications. For the Chesapeake Bay Program, it is the delivery date of our most famous goal — to reduce by 40 percent from 1985 the levels of controllable phosphorous and nitrogen entering the Bay from its rivers.

Last year, after an extensive reevaluation effort, we concluded that the phosphorous goal would be met, but that further steps were needed to close the gap for nitrogen.

Since that time, progress has been made on a number of fronts. Maryland’s new nutrient management law will speed up plans on farms. In Virginia, new funds have been made available for both treatment plants and agricultural improvements; and the local response from treatment plants on the Potomac, which has first priority, has been universally enthusiastic. Virginia has also set up a program of bonus grants for improvements achievable by 2000. And plans are moving forward for trading programs to obtain greater than the 40 percent goal by 2000 at the two largest treatment plants in the system, Blue Plains in Washington and Back River in Baltimore.

All this is encouraging progress, but it leaves open the question of what happens after 2000, when, according to the Directives of the Chesapeake Executive Council, there shall be no increase in total nutrient loadings. In other words, in 2000 the goal becomes a permanent cap on nitrogen and phosphorous in the system.

What does it mean to maintain this cap? In simplest terms, it means that there should be no increase in the pounds of these two nutrients entering the Chesapeake from its 10 major tributaries. But how does this get done? Time is running out on getting a system to do this designed, agreed to and put in place.

One thing that is clear is that after 2000, there will be new sources of nutrients coming on line. There are no signs that population growth and the spread of urban areas out across the landscape will come to an abrupt halt. Despite efforts toward low-impact development and investment in cities, there will continue to be a need for sewage treatment plants to serve new housing, and even the best current technologies require the release of some nutrients. Likewise, there will be new industries and processing plants adding nutrients through wastewater discharges. And there are no signs to suggest any lessening in the movement of animal agriculture to larger and more concentrated facilities in the watershed. All of these will mean increases to the system which must be accommodated.

But take heart. On the other side of the ledger, there will be some areas where we will continue to make progress reducing the flow of nutrients. Some of these reflect the continuation of existing efforts. Just because the calendar turns to 2000, we don’t expect to stop preparing nutrient management plans for farms or funding other management practices. As in “The Sorcerer’s Apprentice,” the brooms will continue to carry the buckets of water for us, and that is to the good. In addition, the EPA is pursuing a national strategy on Consolidated Animal Feeding Operations, which could mean controls and permits on a substantial number of larger operations for the first time.

Other gains will come about as the Bay Program pursues its agenda for nutrients. For example, areas of nutrient concern will be identified for further reductions under a directive signed last year by the Executive Council. These could be either areas that fall short of the 40 percent goal, or areas where more effort is needed. Either way, they will bring additional reductions. And when the Northern Virginia and Patapsco facilities come on line with nutrient reduction in 2002 and beyond, it will “free up” the removal capacity at Blue Plains and Back River being used as an interim offset for these facilities.

We will also benefit from other source reductions. At present, air deposition accounts for more than 20 percent of the nitrogen entering the Chesapeake. Major reductions in emissions from power plants and other stationary sources are scheduled for the next decade. And while air sources were left out of the formula of “controllable sources” drawn up for the 40 percent reduction goal in the early ’90s, it is clear that current knowledge needs to be factored into our decisions related to maintaining the nutrient cap.

Finally, there are gains anticipated in nutrient reduction from new stormwater permits that are being issued to cities and large facilities. While these are intended to deal with more than nutrients, the measures likely to be required will result in nutrient benefits.

A final consideration in all this is new technologies. As was shown by the reaction to last summer’s pfiesteria outbreaks in Eastern Shore tidal rivers, there are a great many ideas under development to deal with nutrients at all levels — from preventing their introduction to reducing their impacts to removing their effects. As these technologies mature, they may provide additional help in maintaining the cap, although it would be foolish to lay all our hopes on this solution.

So there are clearly a plethora of “puts” and “takes” in store for the Chesapeake watershed after 2000. The question is how are we to deal with them. Some sort of agreed-upon accounting system seems to be a “must.”

Beyond that arise questions of how to keep the “puts” and “takes” in the system in balance. Should this involve some sort of allocation system? Should it involve trades, as is done more and more to hold the caps on air pollution? Should it be incentive or market-based? Do we need some sort of exchange or bank to keep the books and handle the exchanges?

These are all tough questions. But failure to deal with them raises even more serious ones. Are we prepared to squander the efforts of the last 15 years because we failed to think through how we will maintain our gains? Or will we get the gray matter stirred up and figure this one out?