1. OVERVIEW OF SUMMER DISSOLVED OXYGEN & CHLOROPHYLL IN NARRAGANSETT BAY
CHRP Meeting
MAY 19, 2015
Heather Stoffel

2. % of Time Hypoxic Events Occur During Each Summer Month
Stations:
Providence River & Upper Bay
Greenwich Bay
West Passage
East Passage
Month PD BR CP NP GB SR MV QP PP MH
May
1.0
0.7
Jun
6.3 
18.0
 6.6
22.8
20.4
21.8
3.1
1.3
14.0
7.5
July/Aug
69.8 
63.0
 87.7
69.4
65.1
65.6
94.8
98.7
83.4
77.5
Sept
19.0 
19.0
 5.6
7.8
9.1
11.6
2.1
2.6
15.0
Oct
4.7 
4.4
0.3
NO hypoxic event have been observed in May until 2012 (May 21-25, 2012) GB & SR
October events occurred 8 of the 10 years of data at PD (latest 10/15/06 PD)
Hypoxic events occur when bottom waters are >14C

3. Data from 8 monitored rivers that discharge into Narragansett Bay (HR, BR,PR, TMR, WR, MR, TR, WR) Normalized to the 15 year seasonal total average

8. Conclusions 2015 was a “good year” (drier than average).
NP and MV appears to be showing a downward trend in oxygen exceedences, but more data is need to test for significance.
MH needs further examination. It is possible hypoxia is increasing in this area.