K-12 
Pocomoke River 
Pocomoke River segments had low sample size; however, most of the degraded 
samples in the lower Pocomoke were classified as contaminated. 
Pocomoke Sound 
Again, Pocomoke Sound had low sample size; however, 75% of the degraded 
samples were classified as contaminated by the benthic diagnostic tool. Twenty-five 
percent of the uncontaminated samples had insufficient abundance/biomass. Results 
suggest that benthic community degradation in this segment stems from a combina¬ 
tion of contaminants and low dissolved oxygen. 
Manokin River 
Of the Maryland small Eastern Tributaries, only the Manokin River (MANMH) had 
adequate sample size. Seventy-five percent of the degraded samples were classified 
as contaminated. Of the remaining uncontaminated and degraded samples, 25% had 
insufficient abundance/biomass. 
Maryland Upper Western Tributaries 
In the Gunpowder River (GUNOH), only 17% of the samples were classified as 
contaminated. Of the uncontaminated samples, 50% had insufficient 
abundance/biomass and another 17% had excessive abundance/biomass. The 
predominant source of stress to benthic communities in this segment appears to be 
low dissolved oxygen. In the Magothy River (MAGMH), 38% of the degraded 
samples were classified as contaminated. Excessive abundance/ biomass was 
observed in 13% and insufficient abundance/biomass in 50% of the uncontaminated 
degraded samples. Results suggest a mixed source of stress. In the Patapsco River 
(PATMH), 58% of the degraded samples were classified as contaminated. The 
remaining degraded samples had insufficient abundance/biomass, suggesting 
contaminants and low dissolved oxygen as sources of stress. In the Severn River 
(SEVMH), 60% of the degraded samples were classified as contaminated. An addi¬ 
tional 20% and 40% of the uncontaminated degraded samples had excessive and 
insufficient abundance/biomass, respectively. Results suggest a variety of sources of 
stress for this segment. 
Chesapeake Bay Mainstem 
Sixty-seven percent of the upper Chesapeake Bay (CB1TF) degraded samples had 
possible contaminant effects, and 17% of the remaining degraded samples had 
excessive abundance/biomass. Segment CB20H, on the other hand, had no degraded 
samples. In Segment CB3MH, 55% of the degraded samples were classified as 
contaminated while 32% of the remaining degraded samples had insufficient abun¬ 
dance/biomass. In Segment CB4MH, 35% of the degraded samples were classified 
as contaminated, 25% of the uncontaminated degraded samples had excessive 
appendix k • 2006 303(d) Assessment Methods for Chesapeake Bay Benthos 
