Opponents of Ocklawaha River Restoration Are Citing Studies Out of Context

These two authors, much more qualified than their critics, are writing to correct the misinformation in the full-page ad in the Sun, placed by members of Save Rodman Reservoir.

Read the complete article here in the Gainesville Sun.

Comments by OSFR historian Jim Tatum.
jim.tatum@oursantaferiver.org
– A river is like a life: once taken,
it cannot be brought back © Jim Tatum

Opponents of Ocklawaha River Restoration Are Citing Studies Out of Context

Recent citation of our work, on Rodman Reservoir specifically and aquifer contamination more generally, seem taken out of context, so here we seek to clarify and contextualize that information to ensure the science we have done is accurately conveyed.

The main contention of a recent advertisement in this newspaper by Save Rodman Reservoir is that the reservoir protects downstream water quality. Uncertainty in early estimates of downstream nutrient delivery related to the restoration, and an emphasis to establish Total Maximum Daily Loads (TMDL) for the lower St. Johns River estuary, two decades ago led the Florida Department of Environmental Protection to hold in abeyance its restoration permit until such time that the downstream effects on water quality could be more accurately characterized.

Now, 20 years later, the lower St. Johns River TMDLs are established and water quality is trending toward recovery. With improved data and models, along with significant investment in restoration projects to reduce nutrient loads from the upper Ocklawaha lakes, the St. Johns River Water Management District re-examined the effects of a free-flowing Ocklawaha River on the lower St. Johns…..

Advocates for keeping the reservoir cite its capacity for assimilation of elevated concentrations of nitrogen (as nitrate) in the Floridan Aquifer, emerging principally from Silver Springs. This information was provided without two important caveats.

First, while excessive nitrogen pollution is detrimental, when it is low relative to the phosphorus supply it may actually promote nuisance blooms of blue-green algae, owing to their adaptive advantage to obtain (fix) nitrogen from the air. Indeed, years of phytoplankton monitoring data suggest that a balanced nitrogen supply and resumption of the natural supply of silica (which the reservoir currently sequesters) may benefit the food web in the lower St. Johns by favoring phytoplankton species preferred as food by grazing zooplankton.

While rising pollutant concentrations in groundwater are a serious concern, a half-century of water quality restoration has taught us that pollution is most cost-effectively controlled at the source. A pollution control approach that relies upon river impoundments to trap nutrients downstream of those sources is essentially converting shared ecological resource into stormwater retention ponds. This approach is both inefficient and unethical, since it perpetuates ecological impacts to the water and biota of Ocklawaha River, its previously magnificent floodplain and the myriad springs that have been submerged by the reservoir.

While science cannot directly inform the ethics of our stewardship decisions, it also cannot and should not be used out of context to justify keeping the dam.

John Hendrickson, former supervising environmental scientist with the St. Johns River Water Management District, lives in Fernandina Beach. Dr. Matthew Cohen, a professor in the School of Forest, Fisheries and Geomatics Sciences at the University of Florida, lives in Gainesville.