# Presentation: 909384

## Lessons Learned from Monitoring Compliance with an Interim Phosphorus Standard in the Florida Everglades

**Garth Redfield, Nenad Iricanin, **
**Cheol Mo and Steven Hill**
- Environmental Resource Assessment Department,
- South Florida Water Management District,
- West Palm Beach,  Florida

## United States v. South Fla. Water Management Dist. et al., Case No 88-1886-Civ-Moreno (S.D. Fla.)

- Suit claimed violations of state water quality standards caused by runoff entering two areas of remnant Everglades: the Loxahatchee Refuge and Everglades National Park.
- Governor Chiles directed the State to settle the case and in 1992, the Court approved the Settlement Agreement among USA, FDEP, and SFWMD.

## Settlement Agreement  Phosphorus Control Programs

- Build 32,000 acres of Stormwater Treatment Areas (STA) to reduce phosphorus inflows to 50 ppb
- Implement Best Management Practices in the Everglades Agricultural Area to achieve a 25% load reduction in phosphorus discharges from the basin

## A.R.M. Loxahatchee National Wildlife Refuge in the Northern Everglades

**A.R.M. Loxahatchee National Wildlife Refuge in the Northern Everglades**

- Remnant Everglades marsh
- 125,000 acres
- Sawgrass plains with many tree islands
- Naturally low in nutrients
- Peripheral areas of enrichment

**Notes:**
Required by State:  35,100 acres

Required by Federal Government:  approx. 6,000 acres (STA 1 East)

TOTAL REQUIRED BY SETTLEMENT AGREEMENT:  aprox. 40,500

TOTAL CONSTRUCTED TO DATE:  over 41,000 acres

FLORIDA GOES ABOVE AND BEYOND:  State started construction this year on 20,000 more acres above and beyond Settlement Agreement requirements

## A.R.M. Loxahatchee National Wildlife Refuge in the Northern Everglades

**A.R.M. Loxahatchee National Wildlife Refuge in the Northern Everglades**

**Notes:**
Required by State:  35,100 acres

Required by Federal Government:  approx. 6,000 acres (STA 1 East)

TOTAL REQUIRED BY SETTLEMENT AGREEMENT:  aprox. 40,500

TOTAL CONSTRUCTED TO DATE:  over 41,000 acres

FLORIDA GOES ABOVE AND BEYOND:  State started construction this year on 20,000 more acres above and beyond Settlement Agreement requirements

## Loxahatchee National Wildlife Refuge(WCA-1)

**Water Quality Monitoring Stations (14) required in the Settlement Agreement**

**Locator Map**

**  ****LNWR**

## Schematic of Refuge Water Movement

**Notes:**
Required by State:  35,100 acres

Required by Federal Government:  approx. 6,000 acres (STA 1 East)

TOTAL REQUIRED BY SETTLEMENT AGREEMENT:  aprox. 40,500

TOTAL CONSTRUCTED TO DATE:  over 41,000 acres

FLORIDA GOES ABOVE AND BEYOND:  State started construction this year on 20,000 more acres above and beyond Settlement Agreement requirements

## Schematic of Refuge Water Movement

**Notes:**
Required by State:  35,100 acres

Required by Federal Government:  approx. 6,000 acres (STA 1 East)

TOTAL REQUIRED BY SETTLEMENT AGREEMENT:  aprox. 40,500

TOTAL CONSTRUCTED TO DATE:  over 41,000 acres

FLORIDA GOES ABOVE AND BEYOND:  State started construction this year on 20,000 more acres above and beyond Settlement Agreement requirements

## Settlement Agreement  Phosphorus Monitoring and Compliance

- For the Loxahatchee National Wildlife Refuge, phosphorus (TP) concentrations are measured at fourteen sites and compared to predicted values from equations (based on stage) in the Settlement Agreement.
- Interim Level equation was developed from 14 monthly geometric means during a baseline period for Outstanding Florida Waters.
- Interim Levels effective since 1999, and Long-Term Levels effective 01/01/07

## Compliance with Interim Phosphorus Levels for the Refuge

- An ‘excursion’ is when the marsh TP geomean is > the calculated value in one month
- An ‘exceedance’ or violation of the Agreement is when the TP geomean is > the calculated value two or more times in 12 months
- Premise is that external loads are linked to water quality at the 14 compliance sites
- If this assumption is not correct or the compliance system generates false positives, millions could be spent on unnecessary phosphorus control programs

## Compliance with the Interim Levels

- Miccosukee Tribe claimed violations of Interim TP Levels in the Refuge and asked a federal Court for judicial oversight of Everglades water quality programs
- Court found that ‘there is a violation of the Consent Decree due to exceedances in the Refuge’ and ordered additional hearings on compliance and potential remedies
- Let’s look at the evidence

## Total Phosphorus Concentrations 

**Seasonal Kendall’s Tau**
- Slope Statistic = -0.30
- p-Value = 0.01

**Total Phosphorus Concentrations **
**During the Compliance Period **
- (February 1999 to Present)

## Phosphorus Loads to the Refuge

## Long-Term Trends

- External loads and concentrations have dropped
- A decade of monitoring shows no systematic trend in TP concentrations
- Annual TP values are very low at < 9 ppb, at or below the baseline period
- So, why is the alarm going off?

## What is Causing Excursions Above the Interim Levels?

- Are TP inputs are causing the excursions
- Could they be caused by error in the compliance equation?
- Cause and effect chain of logic has weak links, let’s look at the chain of data sets

## Stage, Sampling and Excursions

## Stage, Sampling and Excursions

- Most excursions occur at higher stages
- If rising stages are associated with water flowing into the marsh from the peripheral canal, then external causes are supported
- Let’s look at potential for penetration of canal water into the marsh

**Stage, Sampling and Excursions**

## Periods of Potential Movement

**Periods of Potential Movement**
**of Canal Water into the Marsh**

- Days with Potential Outflow

- Days with Potential Inflow

## Periods of Potential Movement

**Periods of Potential Movement**
**of Canal Water into the Marsh**

- Days with Potential Inflow

- Days with Potential Outflow

## Periods of Potential Movement

**of Canal Water into the Marsh and**
**Excursions above the Interim Levels**

- Pattern is inconsistent and periods of penetration can occur without excursions
- Let’s look at other information that might link external inputs to marsh phosphorus concentrations
- Is there any correlation between loads coming in and phosphorus concentrations in the marsh?

## External Loads and Internal Concentrations

## Frail Logic Links Loads and Excursions

- Statistical correlation between monthly loads and TP geomeans is almost non-existent
- Data on loads, stage & marsh penetration help explain why:
- Loads are not correlated with stage due to water management of canals and marsh (open system)
- High stage is not consistently related to potential movement of canal water into the marsh; inflow can occur at any stage above 15.8 feet
- No sign that stations nearer canal drive excursions, in fact they show lower TP concentrations than those more interior

## External Loading and Refuge Excursions

- The longer-term temporal correspondence between loads and excursions is very weak.
- e.g., Huge hurricane loads in the September 2004 did not produce an excursion
- There has been no change in the frequency of excursions with years of loading reductions
- If not external loads, then could the equation be producing false positives?

## Excursion Pattern

- As mentioned earlier, excursions tend to occur at high and rising stages
- Pattern of excursions appears uneven
- 8 of 9 excursions occur at high and rising stages
- Counterintuitive: TP levels tend to be higher at lower stage and there is a greater chance of sampling problems

## Compliance and Change in WCA-1 Marsh Levels

**Excursion**

**In**
**Compliance**

*Above Interim Level*

*Below Interim Level*

***Marsh levels going down***

***Marsh levels going up***

*Stage < Previous Month*

*Stage > Previous Month*

**Compliance and Change in WCA-1 Marsh Levels**

## Performance of the Equation

- Potential for bias in the equation
- Based on limited data, 14 dates in five year period
- Sampling was never done in consecutive months
- Stage levels were lower than today
- Many changes have occurred in Refuge since 1978-79
- Why don’t we see hits at low or falling stages?

## Many high values at lower stages
Produces a strong TP stage relationship

- Produces a strong TP stage relationship

**Original 14 Data Points**

## Many high values at lower stages
Produces a strong TP stage relationship
De-trending lowered line but left a strong downward trend in TP-stage relationship

- Many high values at lower stages
- Produces a strong TP stage relationship
- De-trending lowered line but left a strong downward trend in TP-stage relationship

**Original 14 Data Points; ****9 were re-trended**

## Monthly geometric means from pre-compliance period
60 values taken sequentially
TP-Stage Relationship much weaker with a slight downward trend

- 60 values taken sequentially
- TP-Stage Relationship much weaker with a slight downward trend

**Data from 1994-1999 ****Tells Another Story**

## Differences in the TP-stage relationship has implications for 
   excursions

Most excursions at 
   higher stages 

Most excursions are 
   <1.5 ppb

Divergence of the curves at higher stages could lead to false positives: calculated levels are unrealistically low

-    excursions
- Most excursions at
-    higher stages
- Most excursions are
-    <1.5 ppb
- Divergence of the curves at higher stages could lead to false positives: calculated levels are unrealistically low

**Data from 1994-1999 ****Tells Another Story**

## Data from 2000 to 2006 Tells the Rest of the Story

- Rising stage is a surrogate for changing conditions
- When excursions occur, marsh almost always meets the Interim Level the next month
- Instantaneous response is unrealistic
- Equation had no sequential data

## The Story in Brief

- The implication of external loading is not supported by the facts:
- Loads uncorrelated with marsh levels
- High and rising stages are associated with excursions through the equation’s performance, not external loading
- Marsh TP levels are low and meet the Interim Levels within a month of changed conditions
- Weight of evidence says that excursions are false positives, not reflecting a water quality concern at the 14 compliance sites.

## Lessons from this TP Compliance System

*Prima facie* evidence isn’t always right
- Case of the fallacy: *Post hoc ergo propter hoc*
- Should have built-in a validation and updating process in the Agreement
- Five years of pre-compliance data would have shown that the original premise was not valid – TP at the 14 sites is not linked meaningfully to external loads
- Pre-compliance data are more representative and would have provided a more robust compliance system

## Lessons from this TP Compliance System

- Assessing compliance monthly is unrealistic in a large wetland
- FL  Phosphorus standard will correct with testing based on data from a network sampled over 1 to 5 years
- Long-term data sets are highly valuable
- Patterns in loads, concentrations, stages and marsh concentrations told the story

## Lessons Learned from Monitoring Compliance with an Interim Phosphorus Standard in the Florida Everglades

- Hearings on compliance have been held and the Court’s Special Master is writing an analysis as this presentation is given.
- Judge Moreno is a tough judge, so now is your last chance for questions!