WCA - Everglades Conditions Update

(April 22, 2008)

 

Rainfall:

Rain was limited across the system (see attached gif), where total rainfall ranged from 0.08 to 0.26 with the following distribution:

WCA-1:          0.13               WCA-3A:       0.09

WCA-2A:       0.25               WCA-3B:        0.02

WCA-2B:        0.26               ENP:               0.01

All areas received much less rain than the mean 7 day evapotranspiration for the region (1.81; see srs pdf).

 

 

Water Conservation Areas:

Low rainfall, high evapotranspiration and water management releases resulted in generally fair or good recession rates in WCA-1, WCA 2-A and WCA 3-A, but depths in most areas remain well above the 1 ft maximum threshold for wading bird foraging (see WCA_stages.xls). Stages in WCA-1 have declined and are now very close to Regulation Schedule (see WCA_reg_schedule.doc), WCA-2A marsh remains well above regulation, and WCA-3A stages have declined and closely tracked regulation schedule.

 

Everglades National Park:

 In contrast to recent weeks, ENP and FL Bay saw very little rainfall last week.  In ENP, water level declined by 4.3” over the 7 d period at Taylor Sl. Bridge (not an unusual recession rate at this station).   The southern part of Taylor Sl. (at Craighead Pond) & northern areas of Shark River Sl. (station P33) both saw weekly recession of 1.3”.  Reliable water level readings for the panhandle station at EVER6 were unavailable this, but at EPSW (west of EVER6) stage was down by 1.2” for the week (see ENP stages pdf).   

 

Salinity in Florida Bay increased last week.  Salinity rose above 30 psu again at Trout Ck and remained in the upper-20s at the mouth of L. Madeira Bay (see ENP salinity pdf).  In the Taylor ponds, salinity rose into the lower – mid-20s by the weekend at Pond 5 (USGS station) and Argyle Hendry (ENP station TR).  As of Sunday, 4/20, the 30d moving average concentration at TR (used for tracking the FL Bay MFL criterion) was at 17.5 psu (up from 16.7 psu last week, and while not unseasonably high, the highest concentration we have seen yet this dry season).  Salinity also increased in the northcentral Bay areas of McCormick Ck. & Terrapin Bay, where concentrations once again rose into the mid-30s by the week’s end.  At the central Bay station in Whipray Basin salinity increased slowly through the week, into the upper-30s.  These salinity concentrations across FL Bay are near seasonal norms.  The most notable change in salinity occurred in the upstream reaches of Shark River (Tarpon Bay platform), an area where salinity has remained very high for much of the dry season: the daily mean measurement here dropped again this week (probably in response to recent rain events), down into single digit concentrations (~ 9 psu) as of Sunday, 4/20, near its seasonal norm.  It has been > 3 mos. since salinity was this low in this part of the system.

 

Wildlife:

Water depths remain limiting to wading birds over much of the system, but this week’s strong recession rates resulted in a resurgence of foraging activity in some of the relatively shallow areas of the system. Last Friday’s survey of the Refuge and WCA-2A revealed large numbers of foraging White Ibis, spoonbills and Wood Storks along the western margin and extreme north tip of the Refuge, but no activity elsewhere in WCA-1 or 2A. The traditional nesting colonies in the Refuge remain devoid of White Ibis nests but continued good recession rates may yet stimulate some nesting in this species. 

 

Bear in mind that while current high stages may not be conducive to successful nesting, they may be necessary for recovering the populations of fish, crustacean and apple snail that were diminished by recent drought conditions.  

 

 

 


 

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