Saving the Arroyo: EPA accepts new watershed management plan

HARLINGEN — A new and improved plan to protect the Arroyo Colorado watershed has won the approval of the Environmental Protection Agency.

The green-lighting by the EPA means the new study replaces one adopted in 2007 and will provide a framework for cleaning up the heavily polluted waterway which also serves as a key flood-control feature for the Valley.

The update met the agency’s national guidelines for watershed-based plans, and outlines a strategy to improve the Arroyo’s two segments impaired by bacteria and low dissolved oxygen rates, Jaime Flores, Texas A&M AgriLife Extension Service program coordinator in Weslaco, said in a statement.

“The Arroyo Colorado Watershed Partnership has been working with local stakeholders and project partners for the last five years to conduct baseline monitoring, model best management practices and management measures, and complete the updated plan,” Flores said.

The Arroyo Colorado runs for 90 miles from Mission to the Laguna Madre near Arroyo City. The river is split into the upper, freshwater section, and the final 26 miles known as the tidal section due to saltwater intrusion from the Laguna Madre.

The tidal section of the Arroyo was initially listed as being among impaired water bodies in Texas due to low dissolved oxygen levels in 1978. In addition, both the upper and lower Arroyo contain high levels of bacteria that exceed the state’s human contact recreation standard.

“While great progress has been made in both urban and agricultural areas to reduce pollutant loads, we have not reached our goal of removing the Arroyo Colorado from the list of impaired water bodies,” Flores said. “This updated plan will guide us in that effort.”

Scoping out the problems

The new 157-page document reveals complexities in the Arroyo Colorado that belie its mere 90-mile length. The plan factors in soil types in the Valley, source points of pollution both natural and man-made, agricultural runoff problems and the impact of both colonias and urbanization in one of the nation’s fastest-growing regions.

Pollution problems in the Arroyo watershed include low dissolved oxygen levels, agricultural and lawn runoff and fecal material from both animals and humans, the latter primarily arriving via septic systems, the document says.

Nitrogen and phosphorus pollution of the Arroyo is primarily the result of agricultural and lawn runoff, with higher concentrations of phosphorus in the Mid and Upper Valley, and nitrogen spread throughout the watershed.

E. coli bacteria loads are lower in the Mid and Upper Valley and increase in density the closer one gets to the Laguna Madre.

Just less than 50 percent of E. coli pollution monitored at sampling stations along the Arroyo is attributable to non-avian wildlife like white-tailed deer, nilgai and javelina, the study says.

The study discounts any pollution impact from feral hogs, which in Texas number somewhere between two and three million.

“Fortunately, feral hogs have not yet become a major issue in the Arroyo as they have in many other watersheds in Texas,” the report states.

The report also downplays the impact of javelina along the length of the Arroyo, saying an estimated 100,000 javelina occupy 62 million acres of Texas rangelands and, extrapolating from these figures, the Arroyo holds “an estimated 127 javelina in the watershed.”

Avian contributions to pollutants in the Arroyo are a very significant pollution factor. Some 250 bird species frequent riparian areas along the river, with 70 percent of those being migratory species.

As far as E. coli is concerned, these birds contribute an estimated 18.2 percent of the total bacterial pollution found in samples of Arroyo waters.

Septic systems at 11.2 percent and cattle at 11.1 percent are the other big polluters when it comes to E. coli bacteria in the Arroyo watershed, the study says.

But the study’s authors say human fecal pollution is the primary risk factor for people.

“Despite significant E. coli contributions from wildlife, human fecal pollution still poses the greatest human health risk,” the study says, adding that human fecal material may well be under-reported in the sampling.

Into the future

Jude Benavides, chair of the Arroyo Colorado Watershed Partnership and Steering Committee, said the plan outlines the next phase of efforts to improve water quality in the Arroyo.

“This update to the plan represents the quintessential marathon effort,” said Benavides, an associate professor at the University of Texas Rio Grande Valley, Brownsville. “It is not the work of any one single individual. It is instead a direct outcome of the long-term commitment, continuous support and goal-oriented work of numerous individuals and organizations.

“We all look forward to helping put this plan into action in order to preserve and best manage the Arroyo Colorado for our current and future stakeholders,” he added.

John Tracy, Texas Water Resources Institute director in College Station, said those involved in the plan’s development were pleased with the EPA’s acceptance.

“Much work has gone into compiling the plan, and I believe it sets forth an effective approach to restoring the water quality in the Arroyo Colorado,” Tracy said.

Goals outlined

Among the ways to achieve a healthy watershed, the plan proposes to:

• Encourage voluntary BMP (best management practice) adoption on an additional 35,000 acres of cropland (i.e. 75 percent of cropland under a conservation plan), 10,000 acres of pastureland and 7,500 acres of rangeland.

• Improve the quality of treated effluent from WWTFs (wastewater treatment facilities), reduce sanitary sewer overflows (SSOs) and where possible, encourage voluntary implementation of enhanced biological treatment projects to remove nutrients from WWTF effluent.

• Increase wastewater and stormwater infrastructure development for rural and unincorporated low-income communities (i.e., colonias).

• Repair/replace 300 failing OSSFs (onsite sewage facilities) and provide colonia residents and homeowners with OSSFs information on how to properly inspect, maintain and service their septic systems.

• Pursue installation of three aeration structures (i.e. waterfalls) in the non-tidal segment.

• Pursue installation and operation of three to five aerators in the zone of DO (dissolved oxygen) impairment.

• Encourage adoption of landscaping, GI (green infrastructure), LID (low impact development) and urban forestry ordinances on new development and retrofitting of existing development.

• Reduce lawn fertilizer use by homeowners by 10 percent through educational and outreach (E&O).

• Reduce pet waste loading by 10 percent.

• Introduce and encourage alternative urban development designs and adding LID and drainage policies to LID code that help protect and restore water quality.

The watershed plan is currently available for download at http://arroyocolorado.org/

Development of the updated plan was funded through a Clean Water Act grant to the Texas Water Resources Institute, administered by the Texas Commission on Environmental Quality from the EPA.

The institute is part of Texas A&M AgriLife Research, AgriLife Extension and the College of Agriculture and Life Sciences at Texas A&M University.