Twenty Reasons Why Saving Rodman Reservoir...

Twenty Reasons Why Saving Rodman Reservoir is the

Silver, Ocklawaha and St. Johns Rivers' Loss!

 

An Information & Opinion Report

Compiled by Ocklawahaman Paul Nosca

Revised:  25 October 2013

 

SILVER RIVER & MIDDLE OCKLAWAHA RIVER

(Silver Springs downstream 23 miles to Eureka)

 

Loss of FISH & WILDLIFE since 1968 completion of Rodman (Kirkpatrick) Dam:

(1)  Loss of the historic St. Johns River to Silver Springs unimpeded riverine connection for various migratory aquatic, estuarial & marine species. Florida's peninsula was blessed by the Creator with thousands of lakes but very few swift-flowing streams of any considerable length. The "pre-Rodman Dam" 56-mile long "Silver-Ocklawaha River" was unique in this state by virtue of having one of the world's greatest-flow 1st magnitude artesian spring groups (73-degree F Silver Springs) as its supreme headwaters with unimpeded access for fish & other aquatic life--located more than 50 miles above tidewater influence.

 

(2)  Loss of endemic STRIPED BASS (Morone saxatilis) normal migration, back & forth, from the St. Johns River which has destroyed the ability of these STRIPERS to successfully reproduce naturally--this was their only suitable spawning habitat (requires about 50 stream miles of swift current) in the entire St. Johns River Basin. Hatchery-raised striped bass are stocked into the St. Johns Basin--but not upstream of Rodman Dam & Buckman Lock. Very seldom, if at all, are stripers present anymore in the Ocklawaha River of Marion County upriver from Rodman Dam or Buckman Lock. Striped bass are an important riverine freshwater recreational fish owing not only to their excellent sporting & table qualities but also to the fact that stripers are voracious consumers of gizzard & threadfin shad--these shad are major contributors to the nutrient overload problem of the Ocklawaha River Basin along with many other Florida waters.

 

Striped bass have always had an extremely limited range in Florida due to their very strict survival requirements. Adult stripers need cool 70 to 80-degree F thermal refuge areas such as artesian springs or canopied streams to survive the heat of summertime--& they also require long continuous stretches of swift-flowing rivers to achieve a successful natural hatch during the springtime of the year. These two requirements are seldom met in any "Sunshine State" waters. In fact, a 1961 study by fisheries biologists found a self-sustaining population of striped bass in only two Florida river systems: the Apalachicola & the St. Johns. Striper replacement stocks in the St. Johns River Basin have been hatchery-bred since the advent of Rodman Dam--the lower Ocklawaha River amounts to only about 12 stream miles in length.

 

(3)  Loss of CHANNEL CATFISH (Ictalurus punctatus) & WHITE CATFISH (Ameiurus catus) normal migration, back & forth, from the St. Johns River--catfish & mullet formerly were the dominant fish species in Silver Springs. Catfish are important freshwater commercial & recreational fish species.

 

(4)  Loss of STRIPED MULLET a.k.a. BLACK MULLET (Mugil cephalus) normal migration, back & forth, from the St. Johns River--catfish & mullet formerly were the dominant fish species in Silver Springs. Mullet help clean water environments by removing detritus & microalgae. Striped mullet are an important marine catadromous commercial & recreational fish species.

 

(5)  Loss of AMERICAN EEL (Anguilla rostrata) normal migration, back & forth, from the St. Johns River. American eel are an important marine catadromous commercial fish species.

 

(6)  Loss of BIG CLAW RIVER SHRIMP a.k.a. GIANT RIVER PRAWN (Macrobrachium carcinus) normal migration, back & forth, from the St. Johns River. These extremely large crustaceans require access to brackish water for successful reproduction & were historically extant in Silver Springs but no longer appear to be present there.

 

(7)  Loss of Florida MANATEE (Trichechus manatus latirostris) normal migration, back & forth, from the St. Johns River. These "gentle giants" navigate rivers for feeding or for utilizing the warmth of artesian springs during cold-weather. The Florida manatee is protected by the Endangered Species Act of 1973.

 

Loss of OTHER RECREATION since 1968 completion of Rodman (Kirkpatrick) Dam:

(8)  Loss of traditional St. Johns River to Silver Springs unimpeded riverine navigation for recreational boating.

 

 

RODMAN RESERVOIR

(Eureka downstream 21 miles to Rodman Dam)

 

Loss of FISH & WILDLIFE since 1968 completion of Rodman (Kirkpatrick) Dam:

(9)  Loss of 21 river miles of cool & free-flowing riverine ecosystem that formerly was a travel route for various migratory aquatic, estuarial & marine species between the St. Johns River tidal estuary & Silver Springs.

 

(10)  Loss of necessary dissolved oxygen levels in the water results in fish kills from time to time. Among the causes is the man-made Rodman Reservoir's "thermal pollution"--elevated summertime water temperatures that are the result of damming a naturally cool, spring-fed, swift-flowing stream into a sluggish, sun-baked "backwater." Rodman Reservoir's summertime water temperature averages 83 to 84 degrees F (28.5 to 29 C) & probably even higher in its still-water shallows. Before Rodman Dam was built in 1968, summertime water temperatures averaged about 79 degrees F (26 C) in this section of the natural river--which is downstream of & fed by the Middle Ocklawaha River's usual summertime water temperature of 75 to 77 degrees F (24 to 25 C). Warmer water holds less of the dissolved oxygen that is required by largemouth bass & other fish for survival. To the fish, warmer water is a double "whammy"--it speeds up their metabolism which causes them to need more dissolved oxygen--just when there is less! Living aquatic plants--using the process known as photosynthesis--introduce dissolved oxygen into the water almost entirely during periods of sunshine & very little, if any, during night or heavily overcast conditions. Several mostly cloudy days in a row (e. g., hurricanes or tropical depressions / storms) during hot weather periods of the year "mixed-in" with the already warmer & less oxygenated lacustrine water is the "recipe" that can trigger fish kills in Rodman Reservoir.
 

(11)  Loss of the ability of Florida LARGEMOUTH BASS (Micropterus salmoides floridanus) in Rodman Reservoir to feed on the St. Johns River's expanded menu of estuarial prey species such as shrimp & small crabs or brackish-water/marine fish. Possibly because of this more varied forage supply, bigger largemouth bass (up to 18-lb 13-oz) have been caught from the St. Johns River since the 1968 creation of Rodman. The heaviest largemouth ever taken in Rodman was reportedly 17-lb 2-oz & ranks near the bottom of the list of the top-25 heaviest largemouth bass ever caught in Florida. Rodman Dam--which has strangled the free-flowing Ocklawaha River for over 40 years & has ended the natural spawning success of our native St. Johns Basin striped bass--has yet to produce a world record or Florida state record largemouth bass.

 

(12)  Loss of a continuous wildlife corridor connection for black bear or other non-aquatic mammals from the Ocala National Forest north to the Osceola National Forest & Okefenokee National Wildlife Refuge. The 100-foot wide Ocklawaha River is much easier for them to swim across than just about any of Rodman Reservoir.

 

Loss of FLOODPLAIN FOREST since 1968 completion of Rodman (Kirkpatrick) Dam:

(13)  Loss of 7500 acres, already destroyed, of floodplain mixed-hardwood/cypress swamp forest--valuable for utilizing nutrients from the river to grow long-living trees & as wildlife habitat/recreational hunting lands.

 

(14)  Loss of perhaps up to an additional 3000 acres, slowly drowning to death, of floodplain mixed-hardwood/cypress swamp forest--valuable for utilizing nutrients from the river to grow long-living trees & as wildlife habitat/recreational hunting lands.

 

Loss of MONEY $$$ since 1968 completion of Rodman (Kirkpatrick) Dam:

(15)  Loss of money for annual dam, lock & spillway maintenance costs of a man-manipulated reservoir system whereas a free-flowing river maintains itself naturally.

 

(16)  Loss of money for annual management costs to control run-away exotic aquatic plant growth. Hydrilla, water hyacinth, & water lettuce are thriving where native mixed-hardwood/cypress swamp forest should be growing. The non-native floating & submerged vegetation intakes nutrients from the water for maybe a year or so until its death when it sinks to the still-water lake bottom contributing to an ever deepening layer of enriched muck.

 

Loss of OTHER RECREATION since 1968 completion of Rodman (Kirkpatrick) Dam:

(17)  Loss of use of about 20 drowned artesian springs (some with "spring runs") for divers & swimmers.

 

(18)  Loss of use of summertime recreation areas (river channel & sandbars) for divers & swimmers.

 

 

LOWER OCKLAWAHA RIVER & ST. JOHNS RIVER

(Rodman Dam downstream 12 miles to St. Johns River)

 

Loss of WATER since 1968 completion of Rodman (Kirkpatrick) Dam:

(19)  Loss of a huge amount of the Ocklawaha River Basin's water discharge into the St. Johns River because of evapo-transpiration in Rodman Reservoir. Data from the USGS suggests that evaporation alone from a 10,000 acre lake in central Florida amounts to a water loss of over 50 cubic feet per second (CFS) annually. During some drought "water years" less CFS of water is discharged below Rodman Dam into the lower Ocklawaha River than is recorded as CFS of water entering the reservoir from the middle Ocklawaha River at the Eureka USGS gage station 21 miles upriver of Rodman Dam! ADDITIONAL CFS OF WATER, NOT LESS (than Eureka's), should be expected to exit out of the Rodman tailrace into the lower Ocklawaha River--as a result of all these tributary inflows that enter Rodman Reservoir DOWNSTREAM of the Eureka gage: Mill Creek, Orange Creek, Bruntbridge Brook, Deep Creek, Sweetwater Creek & Camp Branch in addition to some 20 drowned artesian springs.

 

Loss of WATER QUALITY since 1968 completion of Rodman (Kirkpatrick) Dam:

(20)  Loss of water quality in the lower Ocklawaha River because of the man-made Rodman Reservoir's "thermal pollution"--elevated summertime water temperatures flowing out of the lake through the dam downstream & on to the St. Johns River. Summertime water temperature below the dam averages 82 to 83 degrees F (28 to 28.5 C). Before Rodman Dam was built in 1968, it averaged 79 degrees F (26 C) at that site on the river--where the water temperature used to be influenced by the cool 73-degree F inflow of nearby "Blue Spring" & other now-drowned artesian springs along with the natural tree-shaded Ocklawaha River upstream. Warmer water holds less of the dissolved oxygen that is required by most desirable fish for survival & it speeds up their metabolism which causes them to need more dissolved oxygen.
 
 
 
 
REFERENCE AS:  Nosca, P. 2013. "Twenty reasons why saving Rodman Reservoir is the Silver, Ocklawaha and St. Johns Rivers' loss!" webpage report. "Ocklawahaman" website. Paul Nosca, Eureka, FL.
https://sites.google.com/site/ocklawahaman/twenty-reasons-why-saving-rodman-reservoir-is-the
 
 
 
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