The Rainbow River has been the focus of many scholarly studies and management plans. Below is a collection of some of the major publications regarding this important spring run.
The Rainbow River was designated as a Registered Natural Landmark in 1972, an aquatic preserve inRainbow Springs Aquatic Management Plan
1986, and an Outstanding Florida Water in 1987. Additionally in 1989, SWFWMD adopted the Rainbow
River as a SWIM water body, and subsequently created a SWIM Plan for the river.
“The two greatest impacts to Florida’s springs over the past half-century are the decreased availability of clear flowing groundwater for discharge from the springs and the rise in concentrations of nitrate-nitrogen in the upper Floridan aquifer. There is compelling evidence that these stresses are the direct or indirect result of human activities rather than to natural variation in climate and regional ecology.”
“The TMDL adopted for Rainbow Springs Group, and Rainbow Springs Group Run in 2013 sets a target concentration of 0.35 milligrams per liter (mg/L) of nitrate (NO3 as N) and requires an 82% reduction in nitrate concentration for each of the impaired waterbodies.”
“This report presents the Total Maximum Daily Load (TMDL) for nitrate (NO3), which was determined to be a cause of the impairment of Rainbow Springs Group and Rainbow Springs Group Run within the Rainbow River Planning Unit of the Withlacoochee Basin. These waterbodies were verified by the Florida Department of Environmental Protection (Department) as impaired for nutrients (algal mats) and included on the Verified List of impaired waters for the Withlacoochee Basin that was adopted by Secretarial Order in November 2010.”
“Because updated groundwater modeling indicates that the predicted springflow decline for the Rainbow Springs Group under 2014 pumping conditions is approximately one percent, the proposed minimum flow is being met, and a recovery strategy is currently not required. Similarly, given a flow impact of 2.5 percent associated with withdrawals based on projected demand for 2035, implementation of a specific prevention strategy is also not warranted at this time.”
“The entire Rainbow Springs Springshed is vulnerable to groundwater contamination by nitrogen. Fertilizers and human/animal waste disposal practices within the springshed result in an average load of about 1,000 tons of nitrogen per year (917 MT/yr) discharging at Rainbow Springs at a concentration of more than 2 mg/L of nitrate nitrogen. A reduction of about 82% nitrate is needed to comply with state water quality standards.”
The primary issues affecting the ecology of the Rainbow River are elevated nitrate concentrations, reduced water clarity, long-term stream flow reduction, and an altered aquatic vegetation community. To address these issues and their drivers, the SWIM plan is organized into the following three focus areas: water quality, water quantity, and natural systems (habitat)
“Jones et al. (1996) identified 10 anthropogenic sources of nitrogen that contributed to ground water nitrate loading in the Rainbow Springs basin: septic tanks, residential turf fertilizer, golf courses, sewage effluent disposal, land disposal of sewage sludge, land disposal of septic sludge, row crops, cattle, horse farms, and pasture fertilization with inorganic nitrogen. Fertilization of pastures, horse farms, and cattle farms were reported to be the three largest sources…”
Technical Memorandum for the Chassahowitzka, Homosassa, and Rainbow Rivers Submerged Aquatic Vegetation Winter 2022 Data Collection
“SAV (submerged aquatic vegetation) taxa/groups designated as invasive were more abundant in the downstream half of the river, while desirable SAV taxa were more abundant in the upstream half of the river”
“We observed SAV and filamentous algal abundance to vary markedly along the length of Rainbow River. Consistent with previous observations, native Sagittaria kurziana abundance declines with downstream distance, as did most other SAV species. The notable exception was the invasive Hydrilla verticillata. Filamentous algae abundance also increased with downstream distance.”