LOCKPORT — A second round of water tests in Eighteen Mile Creek last month confirmed the results of the first, seeming to point the blame away from Lockport’s sewage treatment plant for the frequent closures of Krull Park Beach in Olcott.

The Niagara County Health Department still says it will need to run DNA tests on the bacteria to prove the source, but it can’t do that until the spring for technical and budgetary reasons.

However, health officials suspect that sea gull droppings coating the 500-foot-long concrete piers on either side of the creek mouth and the 100- foot wooden piers beside the beach might be the source of the bacteria that forced them to close the beach seven times in less than two months this summer.

The Health Department last week released the results of tests taken Oct. 20 at 18 locations from Lockport to Lake Ontario.

County Public Health Director Daniel J. Stapleton said, “It’s not showing that [the closures] are primarily due to the wastewater treatment plant.”

The trend was the same as the tests taken at 14 locations Aug. 31: high levels of E. coli and fecal coliform bacteria near the Lockport wastewater treatment plant, dissipating to almost nothing during Eighteen Mile Creek’s 13-mile flow to the lake.

However, the numbers rise slightly again between the creek mouth and Krull Park Beach, 1,600 feet to the east.

State bathing beach standards require closure if water tests at a beach show more than 235 “colony forming units,” or CFUs, of E. coli bacteria in a 100-milliliter sample of water.

Also, a beach must be closed if there are more than 1,000 CFUs of fecal coliform in a sample.

The Aug. 31 tests were taken during dry weather. The Oct. 20 tests followed a daylong rain.

The new tests showed more than 10,000 CFUs of both types of bacteria right at the sewage plant’s outflow pipe. But at the creek mouth and in the “plume” of creek water seen in satellite photos of the lake, the readings were below 50 CFUs.

The E. coli figures did rise slightly from 10 CFUs at the creek mouth to 40 at the beach.

In August, the readings were 20 CFUs of E. coli at the creek mouth, 160 at the beach.

County Environmental Health Director James J. Devald said the readings were probably higher in the summer than in the fall because the weather was warmer and because there was more seaweed during the summer near the beach.

“The seaweed holds the bacteria and allows it to proliferate,” Devald said.

Fecal coliform bacteria are found throughout the environment, but E. coli comes only from the guts of humans or animals.

If human DNA is found in the bacteria at the beach, the Lockport sewage plant is probably to blame. But if it’s animal DNA, the sea gulls could be guilty.

Devald said testing will resume about a month before the beach opens to swimmers on Memorial Day weekend.