Excess Runoff Contribution to Daily Discharge Frequency of Channel Catfish Farms in Alabama

Journal of the World Aquaculture Society
Boyd, Claude E.;Pine, ;Boyd, C;Hulcher,
Water Quality & Water Management
Pub ID:
Aquaculture facilities producing more than 45,454 kg/yr and discharging 30 d or more annually,
excluding excess runoff, are designated concentrated aquatic animal production facilities by the
United States Environmental Protection Agency (USEPA), and they require National Pollutant
Discharge Elimination System permits. Three individual ponds and three of four channel catfish
farms in Alabama discharged 30 d or more annually. USEPA did not define excess runoff or explain
how to adjust for it. There is normally at least 7.6 cm storage depth in ponds when rainfall begins.
Runoff that causes overflow should be considered excess runoff. The year in Alabama can be divided
into three soil moisture epochs. The 24-h rainfall amounts necessary to cause ponds to overflow under
normal conditions for each epoch were estimated by water budgeting. For watershed ponds, daily
rainfall greater than amounts given below could cause excess runoff:

Period BlacklandPrairieRegion(cm) OtherRegions(cm)
December to April 2 3.3
May to August 3.8 5.8
September to November 5.6 7.5

Daily rainfall above 7.5 cm could cause overflow during any soil moisture epoch from embankment
ponds in all regions. Ponds discharged for 2

PDF File:
excess runoff contribution to daily discharge.pdf

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