Troubled waters? STAFF PHOTO BY DAN PARKER Sunflowers hang over the marina at The Moorings, where water samples in canals have shown that nutrient concentrations have jumped after rains, possibly posing a threat to bay ecology. Port Aransas City Councilman Rick Pratt says bay waters off Mustang Island chronically suffer from fertilizer laden storm-water runoff, and he wants to possibly establish a program that will fix the problem before more serious environmental damage takes place.

"It has become apparent that runoff into our bay is causing a lot of trouble," Pratt said. "Eventually, it's going to really impact the fishing and birding" if not corrected.

The city council is scheduled to consider Pratt's proposal when the council meets at 5 p.m. today - Thursday, Sept. 18 - at the council chamber, 710 W. Avenue A.

Pratt said he has been working on the problem since four or five years ago, when fishermen began telling him that oyster reefs had grown so much in the east flats that it was getting hard to get boats through. The problem has persisted, he said.

CANAL WATERS COURSE BETWEEN ISLAND MOORINGS HOMES. PORT ARANSAS CITY COUNCILMAN RICK PRATT SAYS RUNOFF IN THE CANALS THREATENS THE BAY ENVIRONMENT. "These reefs are just proliferating like crazy where there used to be passages," Pratt said.

Pratt and several other concerned folks hired Dr. Ken Dunton to do a study on canal waters at Island Moorings, where runoff discharges into canals and Corpus Christi Bay. Dunton is a research scientist at the University of Texas at Austin Marine Science Institute in Port Aransas.

Pratt declined to identify those who helped fund the study, which Dunton did at a reduced fee.

"They want to remain private, and that's their call," Pratt said.

Dunton said he did the research in 2005. He said he took samples at about a dozen sites in Island Mooring canals during a period of drought and then took samples from the same sites during a rainy period after the drought.

The samples showed that nitrate levels went up two to three times higher than the previous levels; and ammonium concentrations shot up 10 times the previous levels.

Runoff from people's lawns is the most likely cause of the nutrient levels jumping that much, Dunton said.

Dunton has put his study results on his Web site at www.utmsi. utexas.edu/people/staff/dunton/ Research/IM%20Nutrient%20St udy%202005.pdf.

Speaking generally, algae feeds on nitrates and ammonium nutrients, so algae levels likely will increase when nutrient concentrations rise, Dunton said. Oysters feed on algae, he said.

Pratt said he believes runoff at Island Moorings has caused algae and oysters to multiply. Dunton's research did not specifically address that question.

Nutrient-heavy runoff likely would be bad for fish because dying algae robs waters of oxygen, Pratt said. And an algal bloom can cause such an imbalance in plant life that it would throw off the food chain and end up harming bird populations, Pratt said.

Pratt said a storm-water program should call on residents to voluntarily either reduce how much chemical fertilizer they use or completely replace their chemical fertilizers with organic fertilizers that won't cause such problems in the bay.

He said he is hoping the Port Aransas Garden Club will make those recommendations, too, and make organic fertilizers available to folks around town.

Shirley Page, a past president and current landscape co-chair of the garden club, said she believes the club likely would support Pratt's ideas.

Page lives at Island Moorings. She said she and a number of others in the community already are using organic fertilizers in efforts to avoid causing problems in the bay.

The garden club has created a book, Gardening in Port Aransas, that includes discussions of organic fertilizers, Page said. The book is available at various outlets around town.

Asked if he would favor an ordinance that would restrict how people fertilize, Pratt said, "That is something we will address if the voluntary measures don't work."

Pratt said he wants the council to send the storm-water program concept to the city's Planning and Zoning Commission to give folks a chance to chime in before it comes back before the council.

Island Moorings is the only bayside community in Port Aransas, but many more homes are planned on that side of the island.

"It's about time we started looking at the quality of runoff while it's still an easy fix," Pratt said.

"We have a special responsibility here," he said. "We have the best fishing in Texas. We need to take care of it."