Water Quality Concerns After Wildfire Author - Gene Surber, Extension Service, Montana State University, Editor - James E. Knight, Extension Service, Montana State University

General Impact of Wildfires Loss of vegetation canopies Increase in erosion

General Impacts, cont. Increase water temperature Lower water levels Soil and ash pollution Red Slurry

General Impacts – cont. Nutrient movement Nitrate, organic nitrogen, potassium, calcium, magnesium Returns to pre-burn levels within 1 to 2 years

Soil and Water Quality Changes in soil pore space Changes to infiltration rates Run off rates

Physical Water Quality Temperature More sunlight reaches streams and soil Aquatic life Livestock

Sediment and Turbidity Suspended sediment Bedload Turbidity

Algae Nearly all water have some form Increased temperatures, increases growth Blue-green alage

Chemical conditions - pH Neutral = 7 Over 7 = alkaline Under 7 = acidic

Chemical conditions - Alkalinity Ash in stream Above 8.5 – livestock problems

Chemical Conditions - Salinity NOT same as alkaline TSD (total dissolved solids) Abrupt changes, problems w/ livestock Expressed as ppm or mg/l

Nutrients - Nitrogen Nitrates – convert to nitrites Nitrites decrease oxygen carrying capacity of blood

Nutrients - Phosphorus Binds to soil Following storms – can wash into surface waters Eutrophication – aquatic plants

Nutrients – Dissolved Oxygen Cold water fisheries - between 8 and 13 mg/l Cold water holds more oxygen Soil temperatures increase after fire

Cyanide Red fire retardant slurry Acutely toxic to salmonids

Other Chemicals See table 3 - handout