Table 1. Stressors or inter-tier interactions affecting Tier 1 Essential Ecosystem Characteristics (EEC) identified as an information need in the application of the conceptual model to case studies in the Canadian River (1), Colorado River (2), Columbia River (3), and Upper Mississippi and Illinois rivers (4).

	Tier 1 EEC
Stressor or inter-tier interaction	Hydrology	Channel Morphology/Hydraulics	Sediment Transport	Biogeochemistry/Thermodynamics
Altered Hydrologic Regime	1, 2, 3, 4	1	1, 2
Altered Hydraulic Regime		1, 3, 4	3
Altered Sediment Regime			3, 4
Altered Water Temperature Regime				1, 2, 3, 4
Altered Biogeochemical Regime				1, 3, 4
Channel forming processes		1, 2, 3, 4
Sediment transport dynamics		1, 2, 3, 4	1, 2, 3, 4
Sediment adsorption of contaminants and nutrients				1, 2, 3, 4

Tier 1 EECs are measurable characteristics that describe processes that can significantly alter the morphological or chemical characteristics within a river channel.