Springs

Springs occur where groundwater emerges from an aquifer.  Once groundwater emerges it can form pools, (a.k.a, limnocrene or helocrene springs) or running water (a.k.a., rheocrene springs) systems that have strikingly different habitats and organisms from more typical ponds or streams that are not as directly influenced by groundwater.  Specific physical and chemical conditions of any particular spring depends mostly on the chemical and physical properties of the groundwater source.
Impacts		Dewatering for livestock (see middle picture above) or municipal water, introduction of exotic tropical pet fishes
Hydrology		Discharge regime- Generally constant, but shallow groundwater systems may fluctuate with snow melt. Water Temperatures- typically constant throughout the year.  Springs may be cold, warm or hot.
Habitat		Substrate varies from coarse to fine, but because of near constant seasonal flows, the substrate is stable and is thus conducive to the establishment of aquatic plants, moss and algae, especially in flowing water springs.
Aquatic invertebrate sampling equipment		dip nets, kick nets or Surber nets for outflow with coarse substrates, drift nets
Dominant functional feeding groups		Predators, scrapers
Invertebrates commonly found in cold springs		Amphipoda: Gammarus lacustris, Hyallela azteca, Stygobromus (rare blind amphipod) Coleoptera: Dytiscidae Diptera: Chironomidae, Tipulidae Ephemeroptera: Baetidae Baetis tricaudatus Plecoptera: Perlidae Hesperoperla pacifica Trichoptera: Glossosomatidae Anagapetus, Lepidostomatidae Lepidostoma, Limnephilidae Neophylax, Rhyacophilidae Rhyacophila, Uenoidae Neothremma,  Turbellaria (flatworms)  Hydracarina (mites)
Invertebrates commonly found in warm springs		Coleoptera: Dytiscidae, Hydrophilidae Diptera: Chironomidae, Ephydridae, Simuliidae, Stratiomyidae Hemiptera: Corixidae, Saldidae  Odonata: Coenagrionidae, Libellulidae Hydracarina (mites)