tidal fresh portion of the estuary. The estuary narrows upstream of about 25 km from the mouth and 
there was limited sampling upstream of this region. There were limited historic data for water clarity 
(secchi depth) and as a result we were unable to assess trends in water clarity. All of the chlorophyll a 
data compiled were obtained using spectrophotometric or fluorometric methods. 
Table 4.1 Sampling frequency for cruise data collected by U.S. EPA from 1998-2006. 
Sampling 
# of Sampling 
Distance from mouth 
Year 
Month 
Frequency 
Locations 
of Estuary (km) 
1998 
Jun, Jul, Sept, Nov 
Once a Month 
35 
2-21 
1999 
Jan-Dec 
Once a Month 
Varied 5-35 
2-21 
2000 
Jan-Dec 
Once a Month 
Varied 5-36 
2-21 
2001 
Mar, Apr, Aug-Oct 
Once a Month 
Varied 5-36 
2-21 
May-Jul 
Twice a Month 
Varied 12-34 
2-21 
Apr-Sept 
Weekly 
12 
2-21 
2002 
Jan, Feb, Mar, Oct 
Twice a Month 
12 
2-21 
Nov, Dec 
Once a Month 
12 
2-21 
Apr-Sept 
Weekly 
12 
2-26 
2003 
Jan, Feb, Dec 
Once a Month 
12 
2-26 
Mar, Oct 
Twice a Month 
12 
2-26 
2004 
April-September 
Twice a Month 
12 
3-26 
2006 
F ebruary-December 
Once a Month 
12 
3-35 
28 
