WCA - Everglades Conditions Update

(Jan. 15, 2008)

 

Rainfall:

Rainfall amounts were between 0.08” (WCA-2A) to 0.271” (WCA-3A) within the WCAs (see Raindar.gif).  Rainfall totals were very light across ENP & Florida Bay.  Most stations saw only trace amounts (< 0.1”), if any, rainfall over the 7 d period.  The exception to this was at P33 in Shark River Slough, where a quick moving shower dropped close to 0.4” of rain last Monday (1/7), & in Terrapin Bay where just over 0.5” of rain fell over a 3 hr period on Saturday morning (1/12).  The ENP basin spatially-averaged 7 d accumulation of only 0.03” reflects the generally dry trend (see attached RAINDAR image).  With an average pan evaporation of 0.71”, this was another deficit water budget week (see srs.pdf).

 

Water Conservation Areas:

Overall GOOD dry-season recession rates continue to dominate the region (see WCA_stages.xls). Northern and central WCA-3B continues to have FAIR recession rates due to little change over time.  Although recession rates were GOOD, the depths in the Everglades remain too deep for wading bird foraging. This is normally not an issue at this time of year because foraging in support of nesting behavior does not usually begin until February. Only the northern (north of I-75) sections of WCA-3A had proper depths and recession rates to support wading birds.  Stages in WCA-1 are slightly below Regulation, WCA-3 stages continue to be significantly below regulation, and WCA-2A remains above regulation (see WCA_reg_stages.doc).

 

Everglades National Park:

ENP wetland water levels continue to decline.  Taylor Slough Bridge saw the most substantial weekly drop of nearly 1.7”, which is not unusual for this station.  All other areas of the Park experienced a weekly decline of approx. 0.5” (areas including Shark River Slough at the P33 gage, the panhandle at the EVER6 gage, & Craighead Pond). 

 

Salinity concentrations either remained stable or increased slightly in Florida Bay last week.  Salinity crept slowly upwards at the creek sites, into the upper-20s at Trout Ck. and into the upper teens at the mouth of Taylor River.  Effects from a flow reversal were evident in the Taylor River ponds as salinity increased throughout the week, up to just over 10 psu at Pond 5 and near 8 psu at Argyle Hendry (station Taylor River) as of Sunday, 1/13.  The 30 d moving average concentration at Taylor River (used to monitor exceedances to the FL Bay MFL rule) is still low at just over 2 psu. Salinity concentrations at the Little Madeira Bay platform spent much of last week near 20 psu.  In the north-central Bay, salinity increased to 20 psu at McCormick Ck., and to 25 psu at Terrapin Bay.  The platform at Whipray Basin stopped sending data after 1/7, so cannot report on trends in the central Bay.  In the SRS outflow at Tarpon Bay, salinity was near 11 psu as of Sunday 1/13.  As of now, the Bay appears to be well buffered in terms of salinity for the dry season.

 

Wildlife:

Roseate Spoonbill: A follow-up on roseate spoonbill nesting status in Florida Bay from information provided by staff at Audubon’s Tavernier Science Center (thanks to Brynne Langan & Jerry Lorenz):  An incorrect statement from last week that few spoonbill chicks have yet hatched; rather, there are few chicks that have made it to branchling phase (21 d old).  No chicks have reached this stage in the NE Florida Bay colonies at Deer or S. Nest, where there are a total of 27 nests (note that there are still no spoonbills nesting at Tern Key, where, on average, there are close to 100 nests).  Audubon staff are actively monitoring just over 50 of the 80 nests at Sandy Key, typically the largest colony in northwest Florida Bay.  Seventeen of these monitored nests have branchling phase chicks; eleven of the 53 monitored nests have failed (this # is not particularly high).  Overall the big mystery continues to be the low nesting effort Bay-wide.  Audubon staff are scheduled to visit colonies at Frank & Clive Keys later this month.  It is possible that birds that normally nest in the NE Bay or at Sandy Key may have moved out to these western islands, it is unlikely there will be enough to make up for the deficit seen this year at Tern & Sandy.  

 

System wide nesting behavior surveys will begin in February.  For now, random foraging observations are qualitative, but important. Approximately two thousand birds (Spoonbills, Ibis, Egrets and Woodstorks) have been observed foraging in the very northern and northwest section of WCA-2A.  (Note: The topography in WCA-2A is such that despite depths over 1 ft at the 2-17 gauge, the depths for foraging can be FAIR to GOOD in the west and NW of WCA-2A).

 

On January 9th a number of District staff visited the USFWS service office in Vero Beach to discuss the process of getting WCA-1 and WCA-2A deviations.  One crucial metric in that process is the evaluation of endangered species that my potentially be utilizing these areas (specifically - Snail Kites and Woodstorks).  Wiley Kitchens (professor/research ecologist at the Florida Cooperative Fish and Wildlife Research Unit) gave an update on the current status of the Snail Kite.  During the 2001/2002 drought there were approximately 3400 birds before the drought and these number declined to approximately 1700 post drought.  A 2006/2007 survey shows there are still approximately 1600 snail kites remaining.  Wiley suggests that these bird numbers could potentially be reduced half again during this current drought.  Bottom line is that reproduction rates are very low with few birds making it to adults.  Conclusion is that the Snail Kite population is in peril.  District staff along with others in the ornithology community are trying to investigate whether there is enough information/data to develop a model that can help us in our decisions for water operations within the system.

 

Extensive fish kills along the northern Bay have been reported by several researchers following the recent cold snap.  Many species, including large tarpon, snook, goliath grouper, & barracuda were affected by water temperatures that reportedly dropped to 4oC in some of the coastal embayments.   

 


 

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