Impacts to a Coastal River and Estuary from Rupture of a Large Swine Waste Holding Lagoon

Abstract

We tracked a swine waste spill (4.13 × 10 7 L) into a small receiving river and estuary. After 2 d, a 29‐km freshwater segment that the wastes had traversed was anoxic, with ca. 4000 dead fish floating and hung in shoreline vegetation. Suspended solids, nutrients, and fecal coliforms were 10‐ to 100‐fold higher at the plume's edge (71.7 mg SS/L, 39.6 mg NH + 4 ‐N/L, and >1 × 10 6 cfu/100 mL, respectively; cfu, colony forming units, SS; suspended solids) than in unaffected reference sites. Elevated nutrients and an oxygen sag from the plume reached the main estuary after ca. 5 d. Increased phytoplankton production was contributed by noxious algae, Synechococcus aeruginosa and Phaeocystis globosa (10 8 and 10 6 cells/mL, respectively) after 7 to 14 d. The toxic dinoflagellates, Pfiesteria piscicida and a second Pfiesteria ‐like species, increased to potentially lethal densities (10 3 cells/mL) that coincided with a fish kill and ulcerative epizootic. After 14 d, water‐column fecal coliforms generally were at 10 2 to 10 3 cfu/100 mL. But where the plume had hovered for the first 5 d, surface sediments mostly yielded ≥10 4 cfu/100 mL slurry, and after 61 d densities in surficial sediments were still at 10 3 to 10 4 cfu/100 mL. Dinoflagellate and euglenoid blooms developed and moved downestuary, where they were detected after 61 d. This study documented acute impacts to surfacewaters from a concentrated swine operation, and examined some environmental policies affecting the intensive animal operation industry.