Potomac River. But then again, the Patuxent River is a trickle 
relative to the Potomac. We’re up to about 38 million gallons 
of discharge per day right now. We anticipate by the year 2000 
as much as 60 million gallons a day. 
Now, one thing that needs to be mentioned about the Chesa¬ 
peake Bay, and the Patuxent is no exception as this applies 
equally as well, is that things vary tremedously depending on 
the climate, wet years, dry years, et cetera. 
On an annual basis, a greater percentage of phosphorus is 
derived from terrigeneous point sources (e.g., sewage effluent) 
and nitrogen from non-point sources (e.g. runoff). However, 
there's an important caveat: that the sediments in the estu¬ 
arine saline portions of the Chesapeake Bay and Patuxent River, 
of course, are in essence, seasonally very significant non-point 
sources of phosphorus that are often unaccounted for as non¬ 
point sources. They represent a source of phosphorus to the 
water column that can be very, very difficult to control. 
The sequence of nutrient enrichment is as shown in Figure 
2. When we add nutrients to a system, like the river, nutrient 
concentrations in the water column increase. This, in turn, 
stimulates the growth of algae. The algae block light out in 
the water column and the accumulated algae constitute increased 
particulate loads. This particulate organic matter settles to 
deep water and subsequently decays and consumes the oxygen. The 
anoxia that we presently see in the mainstem of the Chesapeake 
Bay is believed to be largely the result of decay of biomass 
from the local productivity of phytoplankton stimulated by the 
input of nutrients to the Bay and not by the decay of organic 
matter from terrigenous sources. We think it's getting worse 
because the nutrients are being added at a greater rate and the 
phytoplankton are growing faster in response. 
Now comes a very important point: The Chesapeake estuary is 
stratified. There is a lighter, freshwater layer on top. Most 
of the pollutants come in via a surface flow. The heavier, sal¬ 
tier water on the bottom, whose salt is derived from relatively 
"clean" ocean water, mixes in. Especially important is what I 
refer to extremely loosely as a "salinity transition zone," 
shown in Figure 3. I know my scientific colleagues might take 
me to task for that usage, which I use as a broad generaliza¬ 
tion. 
This is the zone, in particular, I think that we need to be 
worrying about right now. I would argue very strongly that 
while it’s certainly important to be concerned with the main 
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