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NDEQ Ends Bacteria Sampling of Diverted Floodwaters; Bacteria Levels Return to Normal



Updated October 18, 2013 -- Due to the fact that some floodwaters from the South Platte and Platte River had been diverted into a number of Nebraska canals and reservoirs, the Nebraska Department of Environmental Quality (NDEQ) expanded and extended its weekly sampling plan for bacteria.

Most of the expanded sampling program concluded on October 11, 2013, after NDEQ determined that the most recent results demonstrated that floodwaters had subsided and bacteria levels had returned to levels below 235 colonies of bacteria per 100 ml of water. Followup samples taken Oct. 14 at Overton, Grand Island and Duncan also showed levels had greatly subsided.*

Sampling was conducted at three reservoirs with public swimming beaches – Sutherland Reservoir, Maloney Lake and Johnson Lake -- that are normally sampled weekly from May through September for bacteria and have results for toxic algae and bacteria posted on NDEQ’s web site. In addition, NDEQ established additional sampling locations which will provide weekly information about bacteria levels in the Tri-County Supply canal system, which includes the reservoirs of Jeffrey, Midway, East Midway, Gallagher, Plum Creek, Johnson, and Elwood. Samples were also taken at several locations along the Platte River.

Results are posted below. The tables were first posted on Sept. 27 and were updated on Oct. 4 and Oct. 11. Updates were also posted for Overton, Grand Island and Duncan on Oct. 18.

Bacteria readings above 235 colonies of bacteria per 100 ml of water are considered a higher risk, meaning that there may be a greater likelihood of developing an illness if you consume water containing bacteria above these levels. Bacteria in the lake or river water can cause gastrointestinal problems (such as diarrhea) if swallowed.

The tables below list the reservoirs and sampling locations that were sampled weekly for bacteria. Any readings that exceed 235 colonies of bacteria per 100 ml of water will be in red bold type.

Sutherland/Maloney Reservoirs
Sampling Location
Bacteria Results
9/19/2013
(pre-flood diversion)
Bacteria Results
9/27/2013
Bacteria Results
10/04/2013
Bacteria Results
10/11/2013
17
15
24
50
2
28
13
28

Tri-County Supply Canal (TCSC) System
(includes the reservoirs of Jeffrey, Midway , East Midway, Gallagher, Plum Creek, Johnson and Elwood)
Sampling Location
Bacteria Results
9/19/2013
(pre-flood diversion)
Bacteria Results
9/27/2013
Bacteria Results
10/04/2013
Bacteria Results
10/11/2013
TCSC near North Platte
NA
214
91
53
Jeffrey Reservoir
NA
179
31
59
TCSC south of Gothenburg
4
101
78
45
East Midway Reservoir
11
210
33
32
Plum Creek Reservoir
1
74
291
20
44
222
548
219

Platte River
Sampling Location
Bacteria Results
9/19/2013
(pre-flood diversion)
Bacteria Results
9/27/2013
Bacteria Results
10/04/2013
Bacteria Results
10/11/2013
Bacteria Results
10/18/2013
Brady
687
2522
133
102

Cozad
61
2419
78
73

Overton
dry
3654
99
NA
42
Grand Island
24
727
488
NA
56
Duncan
dry
dry
2419
NA
387*

*Note – Although Duncan’s results on Oct. 18 were above 235 counts per 100 ml, NDEQ considers these numbers to be within normal sampling levels for the Platte River, particularly since there had been considerable rain previous to sampling, which can elevate bacteria levels. The NDEQ concluded that further sampling for floodwaters’ impacts is not necessary.

Bacteria levels can become elevated during flooding and other heavy rainfall events. Click here for more information about bacteria and its potential health effects.