Water Surveys


The Water Surveys Section was initially created as a part of the TMDL Program, sponsored by the Environmental Protection Agency (EPA). In 1972, the Clean Water Act (CWA), developed by the EPA, implemented pollution control programs such as setting water quality standards for all contaminants in surface waters. Total Maximum Daily Load (TMDL) is the amount of a pollutant a waterbody can assimilate without exceeding the established water quality standard for that pollutant. The Water Survey Section performs intensive surveys on impaired waterbodies of Louisiana, which are listed on the EPA's 303 (d) list.

During a survey on a watershed, a wide range of biological, physical, and chemical data is collected by Environmental Scientists and evaluated by DEQ's modelers. Environmental Scientists employ several methods of collecting data such as:

  • water quality (in-situ measurements and sample collection)
  • stream geometry
  • time-of-travel studies
  • discharges
  • stream flow

Assessment of data may eventually result in revisions in the water quality standards set or a delisting of a waterbody deemed to be meeting current standards.


The Water Surveys Section collaborates with LDEQ's Non-Point Source Section to help plan and execute several water quality projects through field data assessment and sample collection. Section 319 of the Clean Water Act required that the states develop a plan to reduce and control various types of NPS pollution, which comes in the form of agriculture and urban runoff, home sewage systems and many other sources. Water Surveys is tasked with reconnaisance of accessible and representative sites for each project, as well as adhering to monthly or bi-monthly water sample and flow measurement collection schedules. Their efforts provide a qualitative and quantitative assessment of a waterbody and help identify potential "hotspots" for non-point source pollution. With the help of Louisiana Department of Agriculture and Forestry (LDAF) and the implementation of Best Management Practices (BMPs), LDEQ is hoping to educate local entities of how their land use practices can adversely affect local waterbodies.

Bayou Chene - NP2012014 - Bayou Chene is listed as impaired for not meeting its designated use for fish and wildlife propagation due to low dissolved oxygen concentrations stemming from numerous agricultural practices. View the Watershed Implementation Plan here.

Queue de Tortue - NP2013001 - Bayou Queue de Tortue is fully meeting primary and secondary contact recreation uses but is impaired for fish and wildlife propagation because of high concentrations of nutrients, total suspended and dissolved solids, low dissolved oxygen, turbidity and mercury in fish. Agricultural practices are the suspected sources. View the Watershed Implementation Plan here.

Bayou Lafourche - NP2013003

Comite River - NP2013010 -
Comite River was selected by LDEQ, USDA, and LDAF as one of Louisiana's priority waterbodies to partially and/or fully restore by October 2022. Comite River is impaired for primary and secondary contact recreation because of fecal coliform. Suspected sources are on-site sewage treatment plants and sanitary sewer overflow. 

Big Creek North - NP2015002 - Louisiana's 2016 Integrated Report indicated that Big Creek was not supporting its designated use for fish and wildlife propagation (FWP); however, it was fully meeting SCR and PCR uses. The suspected cause of NPS impairment is turbidity from agricultural practices. BMPs are in the early stages of development as of April 2018.

Bayou des Cannes - NP2015003 -
Louisiana's 2014 Integrated Report indicated the bayou was not supporting its designated use for fish and wildlife propagation (FWP); however, it was fully meeting SCR and PCR uses. Currently, suspected causes of impairment include nitrate-nitrite, low dissolved oxygen, total phosphorus, and turbidity, due to agricultural and natural sources. BMPs to be implemented include irrigation land leveling, grade stabilization structures, residue management, irrigation water management/dry seeding of rice, and shallow water for wildlife. 

Hemphill Creek - NP2016002 - Louisiana's 2016 Integrated Report indicated that Hemphill Creek was not meeting its PCR designated use due to high concentrations of fecal coliform. The suspected sources include livestock and sewage discharge in unsewered areas. Since partnering with LDAF, LDEQ will continue long-term monitoring in conjunction with LDAF's implementation of BMPs. The addition of nutrient data will inform LDEQ's nutrient management strategy group of the state of nutrients in this watershed and will support the fecal coliform data by providing valuable information about the overall health of the watershed.  

Bayou Vermilion - NP2016003 -
According to the 2016 Integrated Report, Vermilion River is impaired for Fish and Wildlife Propagation (FWP) with suspected causes of Nitrate-Nitrite and Dissolved Oxygen. It is also impaired for Primary Contact Recreation (PCR) with a suspected cause of Fecal Coliform. The suspected sources for the FWP impairment of DO are agriculture and natural sources while the suspected causes for Nitrate-Nitrite are unknown. The Bayou Vermilion District (BVD) initiated the individual on-site waste disposal system (OSDS) inspection program in the Coulee Mine in July 2017. LDEQ Water Surveys initiated water quality monitoring from June 2016 through June 2017, establishing a baseline for Fecal Coliform. The overall intent of the inspection program is to improve the water quality of the Vermilion River within the urbanized and rural areas of Lafayette Parish by reducing or eliminating the effects of malfunctioning OSDSs in the area. This will be accomplished through continued public education and awareness campaign demonstrating maintenance of home sewage systems through OSDS inspections.

Bayou du Portage - NP2017002
- During LDEQ's ambient water quality monitoring of a site located on Bayou Portage, data collected indicated that dissolved oxygen, turbidity, and fecal coliforms violated the state's standards for fish and wildlife propagation and for primary and secondary contact recreation. Agriculture practices dominated by surgarcane, pasture, rice and aquaculture are suspected contributors.


Bayou Grosse Tete - NP2018001 - Bayou Grosse Tete is listed as impaired for Fish and Wildlife Propagation (FWP) with suspected causes of Dissolved Oxygen, Nitrate-Nitrite, and Total Phosphorus with agriculture as the suspected source. The waterbody is also impaired for Primary Contact Recreation (PCR) with Fecal Coliform as the suspected source from on-site treatment systems.

Bayou Maringouin - NP2018002 - Bayou Maringouin failed to support its PCR designated use due to high bacteria levels as indicated by fecal coliforms and a TDS exceedance during the 2015-2016 ambient water quality monitoring period. 

Through EPAs Hypoxia Task Force grant, Water Surveys' sampling efforts are helping DEQ's Nutrient Reduction and Management Strategy. To learn more, click here.


NEW VISION PROJECTS - CLEAN WATER ACT SECTION 303(D)Natalbany River - Subsegment 040503

Yellow Water River - Subsegment 040504

New River - Subsegment 040404

For information on LDEQ's Long-Term Vision for Assessment, Restoration, and Protection Program, click here.


Cyanobacteria Harmful Algal Bloom (CyanoHAB) Detection and Verification Pilot Study   

Starting in the Spring of 2021, LDEQ Water Surveys, in a cooperative effort with the Water Quality Standards and Assessment Section, began monitoring for CyanoHABs in a multi-regions, multi-lake survery where CyAN satellite imagery showed bloom activity. Three areas in coastal southeast Louisiana were identified as priority regions based on previous review of CyAN imagery products between 2017 and 2020: east of the Mississippi River (Lake Marurepas and Lake Pontchartrain), west of the Mississippi River ( Lac des Allemands, Lake Salvador, Lake Verret, and Lake Palourde), and coastal areas in Breton and Barataria bays. Monitoring efforts include water quality field and laboratory measurements (including cyanotoxins, nutrients, and pigment analysis) and total algal and cyanobacteria speciation and enumeration. EPA recommends monitoring for two common and well-studied toxins associated with CyanoHABs, Microsystins and Cylindrospermopsin.


Mercury Initiative Program

Video courtesy of Smith-Root


Evaluation of Dissolved Oxygen in Inland Rivers and Streams within Louisiana's Southern Plains Terrace and Flatwoods (SPTF) Ecoregion - DEQ is conducting a Use Attainability Analysis (UAA) in the SPTF ecoregion to determine appropriate water quality criteria to support the fish and wildlife propagation designated use. 

An ecoregion is a relatively homogeneous area of similar ecological characteristics such as:

  • climate
  • land use
  • soils
  • potential natural vegetation
  • hydrology
  • other ecologically relevant variables

Because of the similarity and homogeneity of ecological characteristics within an ecoregion, an ecoregional approach provides a framework for determining appropriate water quality standards by water body type on a regional basis.

Data collected at designated reference sites in the SPTF ecoregion will help develop ecoregion-wide dissolved oxygen criteria.


Nutrient Gradient Inland Lakes Project (NGIL)

During the summers of 2019-2022 the Louisiana Department of Environmental Quality (LDEQ) is conducting a study of nutrients and aquatic life in Louisiana’s inland, freshwater lakes. A total of 48 lakes, ponds, and reservoirs across four of the state’s inland ecoregions in central and northern Louisiana are planned to be sampled. Field crews will be using boats and hand-held equipment to collect water quality data; habitat characteristics; and biological communities including zooplankton, benthic macroinvertebrates, diatoms and algae, and fish. 

For further details about this study, please see the U.S. Environmental Protection Agency approved Quality Assurance Project Plan (QAPP) 3070: