Water Quality Assessment of the St. Lucie River Watershed – Water Year 2017 – DRAFT- Gary Goforth, P.E., PhD. SLR/IRL

Dr. Gary Goforth ready to tour the SLR & Lake O.

It is a journey the state, federal, and local agencies don’t always wish to take–a journey to face the numbers of our watershed…

Today, Dr Gary Goforth (http://garygoforth.net) shares his most recent report, “Water Quality Assessment of the St Lucie River Watershed, For Water Year 2017, DRAFT.”

Mind you, for non-scientist people like myself, a “water year” is reported from May of one year, through April the next year, as opposed to a calendar year.

The full report is linked at the bottom of the post and contains numerous helpful charts. I have just included the key findings below.

Dr Goforth wanted to get the draft assessment out before the Florida Department of Environmental Protection’s  Basin Management Action Plan workshop scheduled for this Friday Aug. 25th at 10:00 am at Martin County Building Permits Office, 900 Southeast Ruhnke Street, Stuart, FL 34994, Conference Rooms A & B because this is where the rubber hits the road! FDEP: (http://www.dep.state.fl.us/central/Home/Watershed/BMAP.htm)

Reflections in the St Lucie River, JTL

Water Quality Assessment of the St. Lucie River Watershed –Water Year 2017 – DRAFT Gary Goforth, P.E., Ph.D.

Quis custodiet ipsos custodes? (Who watches the Watchers?)

Key Findings:
1. Over the last water year (May 2016 – April 2017), the surface water entering the St. Lucie River and Estuary (SLRE) in general was of poor water quality. The best water quality entering the SLRE was from the highly urbanized Tidal Basins. The largest source of phosphorus, nitrogen and sediment pollution to the SLRE was Lake Okeechobee discharges. The C-44 Canal Basin contributed poor water quality, and was the only basin demonstrating a worsening in water quality over the last ten years.

2. It was estimated that stormwater runoff from agricultural land use contributed more flow and nutrient pollution than any other land use, even contributing more flow than Lake Okeechobee discharges.

3. The annual Basin Management Action Plan (BMAP) progress reports produced by the Florida Department of Environmental Protection continue to indicate water quality conditions in the tributaries of the SLRE are better than they actually are. Examples of flaws in the BMAP assessment process include the omission of Lake Okeechobee pollution loads, the use of simulated data instead of observed data, the inability to account for hydrologic variability, and the inability to assess individually each of the major basins contributing to the SLRE.

4. An alternative to the assessment approach presented in the BMAP progress reports was developed and used to evaluate water quality conditions of major inflows to the SLRE and to assess progress towards achieving the Total Maximum Daily Load (TMDL) load reduction goals. This alternative approach uses observed data, includes Lake discharges, accounts for hydrologic variability, and is applied to each of the major basins contributing pollution loads to the SLRE. For WY2017, observed nitrogen loads to the SLRE exceeded the Phase 1 BMAP target loads (adjusted for hydrologic variability) by 77 percent. Observed phosphorus loads exceeded the Phase 1 BMAP target loads (adjusted for hydrologic variability) by 53 percent.

5. The largest single source of total nitrogen, total phosphorus and sediment load to the SLRE was Lake Okeechobee discharges. In addition, total phosphorus concentrations in Lake Okeechobee discharges to the SLRE remained almost four times the lake’s TMDL in-lake target concentration of 40 parts per billion (ppb). In 2017, the South Florida Water Management District (SFWMD) reported that phosphorus loading to the lake from surrounding watersheds was almost 5 times the Lake’s TMDL of 105 metric tons, yet staff acknowledged the agency does not enforce permits that set numeric limits on phosphorus discharges to the lake[1] (SFWMD 2016, SFWMD 2017). Unfortunately, despite the continued and well-publicized pollution of the lake, the Florida legislature in 2016 enacted a water bill that pushed back deadlines for achieving the lake’s TMDL by decades (Ch. 2016-1).

6. The best water quality entering the SLRE during WY2017 was observed in the highly urbanized Tidal Basins, with concentrations of 97 ppb and 819 ppb for TP and TN, respectively. Each of the remaining source basins, except the C-44 Canal Basin[2], exhibited a slight improvement in nutrient levels compared to their base periods, however, collectively these WY2017 loads did not achieve the alternative BMAP Phase 1 load target (Figures ES-1 and ES-2). The C-23 and Tidal Basins met the alternative BMAP Phase 1 target for TP, while the C-23, C-24 and Tidal Basins met the alternative BMAP Phase 1 target for TN. The predominantly agricultural C-44 Canal Basin exhibited poor nutrient conditions, and in fact, continued a trend of deteriorating nutrient conditions compared to its 1996-2005 base period. As a whole, the water quality entering the SLRE remains poor, although a slight improvement over the 1996-2005 period was observed.

FULL REPORT below: the complete report can be seen/downloaded from Dr Goforth’s website under “Estuaries and Lake Okeechobee:” http://www.garygoforth.net/DRAFT%20-%20Water%20Quality%20Assessment%20of%20the%20SLRW%20-%20Water%20Year%202017.pdf

Dr Goforth’s website:(http://garygoforth.net)

Army Corp of Engineer Structure S-80 releases water from Lake Okeechobee in the the C-44 Canal that leads to the St Lucie River. JTL
Lake Okeechobee.
basins of SLR/IRL SFWMD

 

4 thoughts on “Water Quality Assessment of the St. Lucie River Watershed – Water Year 2017 – DRAFT- Gary Goforth, P.E., PhD. SLR/IRL

  1. Relatively good study of a complex situations n. Please note the absence of water from the EAA. The local run off is the major source of fresh water and nutrients to the St Lucie 24/7/365 for most years. The occasional rain events cause havoc with additional high flows of fresh water from Lake O, water from the Kissimmee basin mostly, which are mixed with corresponding high local basin runoff. The “perfect storm” for algae blooms in the St Lucie.

    Sent from my iPhone

    >

    Liked by 1 person

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