WCA - Everglades Conditions Update – 06 April 2009

 

Rainfall:

Rainfall was light in the Greater Everglades last week (see Raindar image and below) but the regional pan evaporation of 1.49” (see srs pdf) produced continuing decreases in stage throughout the Greater Everglades.  Basin totals last week ranged from a trace in the Park to 0.39” in WCA-3B:

 

Rain:                            WCA-1:         0.31 in            WCA-3A:          0.17 in

                                    WCA-2A:      0.03 in             WCA-3B:          0.39 in

                                    WCA-2B:      0.08 in              ENP:               <0.01 in

 

Water Conservation Areas:

Recession rates have increased again, declining at rates considered Good or Fair throughout the WCAs (see WCA Stages spreadsheet).  WCA-2A and Northeast Shark River Slough are experiencing especially high recession rates, -0.31 and -0.33 ft, respectively, in one week:

 

Stage Change:             WCA-1:          -0.11 ft             WCA-3A:        - 0.10 ft

                                    WCA-2A:       -0.31 ft             WCA-3B:         - 0.11 ft

                                    WCA-2B:       -0.17 ft              NESRS:           - 0.33 ft

 

WCA-1 is still below its regulation schedule (about -0.2 ft).  WCA-2A canal stage (used from February to May) has fallen again to about -0.21 ft below schedule.  The WCA-3A marsh is below about -0.5 ft the bottom of Zone E1 (see Reg schedule).

 

The declining water levels are again reflected in this week’s water depths map (attached).  Large portions of WCA-1, WCA-2B, and WCA-3A are wet, but most of the rest of the Greater Everglades are dry.  Subsurface water depths continue to drop in the WCAs, Holeyland, Rotenberger, and in the Park, which has large areas with water levels once again below -2.5 ft (as it was a month ago).  The drying front continues to head southward through northern WCA-3A, and nearly all of WCA-2A is dry.  The northern Refuge is now dry, and nearly the entire Park except the coast is dry.  Water tables in Big Cypress Preserve have continued to dry; areas that are below -2.5 ft have expanded substantially from a month ago.

 

Wading bird feeding conditions are good in most of WCA-1, WCA-2B, middle WCA-3A, and southern WCA-3B (see Recession Index map), but water levels are below ground in WCA-2A, northern WCA-3A, and in the Park.  Recession rates are increasing with the higher evapotranspiration rates that are typical of this time of year.

 

The muck fire index (see attached map) indicates that most of the Greater Everglades are still in the low to moderate risk categories, except for parts of Holeyland, Rotenberger, WCA-2A, and a small portion of ENP.

 

Everglades National Park (ENP):

Only trace amounts of rain fell across ENP and Florida Bay last week.  Stations for which we receive data from ENP measured 0” – 0.3” of rainfall over the 7 day period, and the basin-wide spatially-averaged weekly RAINDAR total was 0.01 for the ENP and C-111 basins.

 

Stages continued to decline last week (see Stages pdf).  Water level at the Taylor Slough Bridge declined by 4.6” (NOTE: data problems last week at station P33 preclude reporting the water level trend at this site).  To the south, water levels in the ENP panhandle (EVER6) and at Craighead Pond declined by 1.7” and 1.2”, respectively (NOTE: water level has once again dropped below the marsh surface in the ENP panhandle).

 

Salinity remained steady or increased in Florida Bay last week (see Salinity pdf).  In the near shore eastern Bay, salinity was steady in the mid-30s in Long Sound and increased slightly from the low 30s to mid-30s at the Little Madeira Bay platform.  Farther into the Bay at Duck Key, salinity was steady in the mid-30s.  The 30 day moving average salinity at the Taylor River platform (used for tracking the Florida Bay MFL) increased from 18.9 psu (3/29) to 24.4 psu (4/5), and the daily mean salinity rose from 29.3 psu to 33.6 psu (4/5).  In the north central Bay, salinity increased slightly to 40 psu in Terrapin Bay, and following an early week decline to the mid 30s, salinity increased to near 40 psu in McCormick Creek.  At the central Bay platform in Whipray Basin, salinity remained at 40 psu.  To the west, in the upstream reaches of Shark River Slough, salinity increased slightly from 20 to 22 psu.

 

Please contact Kevin Cunniff (kcunniff@sfwmd.gov) for questions about the ENP/Florida Bay report.

 

Fires:

No fires were reported by FIRMS (the Fire Information for Resource Management System) in the WCAs or the Park for the week.

 

Wildlife:

All primary wading bird colonies in the WCAs were surveyed during the District’s monthly flight on 02 April.   2009 is shaping up to be a successful nesting year, at least in terms of number of nest starts.

 

Large numbers of white ibis nests are evident at all the major colonies, particularly New Colony 4 (WCA 1), Alley North (WCA 3a) and Hidden Colony (WCA 3A). District staff visited New Colony 4 on Friday by boat and many nests now have young nestlings (1-5 days old).

 

Wood stork nesting effort is also relatively high, probably the largest number of nest starts since 2004, and are estimated to be approximately 3000 nests throughout the WCAs and the Tamiami West colony.  Many nests at southern colonies have ‘ibis’ sized nestlings. Eggs in the refuge have not yet hatched.

 

Large mixed flocks were observed in eastern WCA 1 and western and central WCA 3A. WCA 2A is now too dry for foraging birds.

 

There are currently approx. 41,000 nests in the WCAs and ENP (31000 W. Ibis, 3225 stork and 7000 great/snowy egrets). We do not count the small dark herons.

 

Below is a summary of the nest numbers for each colony. Attached is a spreadsheet providing colony coordinates and a table for comparing nest numbers from 2006 through this year.

 

Alley North Colony:  Approximately 10,000 – 15,000 White Ibis nests 3000 Great Egret/Snowy Egrets nests

Cypress City:  Researchers in colony – not counted

6th Bridge:  700 Great Egret/Snowy Egrets nests, 50 White Ibis nests, and 40 Spoonbill (roosting)

Crossover:  5 Wood Stork nests, 7 Great Egrets nests

Jetport:  900 Wood Stork nests

Hidden:  1000 Great Egret nests, 6000 White Ibis nests

Tamiami West:  900 Wood Stork nests, 300 Great Egret nests, 800 White Ibis nests

Tamiami East:  40 Great Egret nests

Heron Alley:  No nests

3B Mud East:  90 Great Egret nests

Big Mel:  40 Great Egret nests

Colony 99:  1000 Great Egret/Snowy Egret nests, 3000 White Ibis nests

Colony 73:  55 Great Egret nests, 700 White Ibis nests

Colony 70:  0

Lox West:  500 Great Egret nests, 700 White Ibis nests

Colony 111:  0

New Colony 1:  0

New Colony 2:  400 Great Egret nests

New Colony 3:  0

New Colony 4:  800 Great Egret/Snowy Egret nests, 5000 White Ibis nests, 20 Wood Stork nests

Canal N:  0

 

Please contact Mark Cook (mcook@sfwmd.gov) with questions about the wading bird survey.

 


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