Lake Lanier is the big tourist draw, with huge spans of water filling visitors’ views from many a vantage point.

But it’s the dozens of creeks and streams flowing in from every direction that ultimately support the lake, providing the full pools, wakes behind boats and children’s splashes in the water off sandy beaches.

And it’s why environmental groups regularly check the health of these water bodies. These groups include Gainesville’s environmental staff, a group from the University of North Georgia and the Chattahoochee Riverkeeper’s Neighborhood Water Watch program, where, every Friday, volunteers collect water samples at 15 area creeks and streams.

And there is cause for some concerns.

Fecal coliform, which is tied to human or animal waste, is the most common issue for Lanier’s streams — as it is for most of Georgia’s streams and rivers — but there are other woes, most notably troubled fish habitats and oxygen depletion, according to the U.S. Environmental Protection Agency.

Although they are generally not harmful themselves, coliforms indicate the possible presence of disease-causing bacteria.

“Several of the tributaries entering the lake are impaired for bacteria,” according to the Georgia Environmental Protection Division. “Plans to improve the bacteria levels in these tributaries have been developed and are being implemented.”

Officials said sources of the bacteria include failing septic tanks, broken sewer pipes, stormwater, pets, wildlife, wastewater treatment plants and agricultural operations where animals are kept and raised in confined conditions.

EPA data from 2012 shows that 358 miles of rivers and streams — each a basin unto themselves — are impaired in the Upper Chattahoochee River basin, which envelops Lanier.

Waters rated as “impaired” by the state cannot support one or more designated uses, such as swimming, drinking and fish protection.

“Many of these streams have limited habitat due to sedimentation,” according to the EPD.

“The sediment may be due to stormwater runoff from construction sites, wash-off from dirt roads, agricultural activities, bank destabilization and (long-ago) sediment.”

One of the lake’s most troubled tributaries is Flat Creek. Its main issues, according to EPA data, are fecal coliform and troubled fish habitats, and the probable cause is “unspecified urban stormwater.”

The 6-mile waterway travels through an industrial area, including poultry processing plants, and past homes in Gainesville on its way to emptying into Lanier west of McEver Road.

Environmentalists have long kept a keen eye on the creek, which flared up in the news in March when the EPA said that Pilgrim’s Pride had violated sections of the Clean Water Act.

Floating fats entering the city’s wastewater system, maggots on a pipe wall and blood on a trailer were just a few of the things found by federal investigators in an Aug. 27 inspection at the poultry plant.

“Flat Creek can show some really bad results, but not always, and a lot of it is weather-dependent,” said Robert Fuller, physics professor at the University of North Georgia in Dahlonega.

His lab regularly tests tributaries around Lanier.

Among the tributaries tested, Flat Creek had the highest fecal coliform count in 2014 at 811 colony-forming units per 100 milliliters of water, based on a geometric mean of 15 samples taken that year. The recreational standard is 200 per 100 milliliters.

An excessive amount was reported at sampling sites on all the other tributaries tested — Six Mile Creek, Balus Creek, Little River, Chattahoochee River, Chestatee River and Wahoo Creek.

“From a regulatory standpoint, to really tell people that they couldn’t use that water, you’d have to go back and do second and third tests, which we don’t do,” Fuller said.

“But when I see readings that are in the thousands, just a single reading, to me that’s a giant red flag.”

Bryan Barrett, area resource conservationist for the federal Natural Resources Conservation Service, said water sampling can show some “questionable numbers.”

“They are done off the side of roads, where (testers) have easy access to run down and get a water sample,” he said. “Well, most of these roads have bridges on them and you have a lot of wildlife ... that love to nest under bridges.”

He said he once saw a picture showing a colony of swallows roosting under a bridge, upstream from where water samples were taken.

“And that’s where it was determined the E. coli and fecal coliform numbers came from,” Barrett said.

E. coli is a bacteria that is commonly found in the gastrointestinal tract and feces of warm-blooded animals and humans. It’s part of the group of fecal coliforms.

EPD officials say that even though some tributaries may have fecal coliform levels that exceed the criteria, dilution in the lake and natural processes, including the effects of sunlight, result in an average fecal coliform level that meets or exceeds water quality standards.

Another issue Fuller considers is conductivity, or the amount of electricity that water will conduct.

“Water itself does not conduct electricity well at all — it takes dissolved minerals — so we interpret conductivity to mean the amount of dissolved minerals in the water,” Fuller said.

“There’s a multitude of things that might be dissolved in there. The most common things are going to be fertilizers that wash off people’s lawns, but there is some naturally occurring minerals. Limestone Creek, for example, as its name implies, has some limestone out there.”

Flat Creek “will always show a high conductivity,” he said.

Gainesville, which operates a wastewater treatment plant on Flat Creek, off Old Flowery Branch Road, is working to restore Flat Creek with a couple of projects.

One of them, involving its flows through an industrial section of Gainesville, is well underway.

An old fire pond that once served the century-old Gainesville Mill off Marler Street and Georgia Avenue has been drained and a pump building there has been demolished, said Horace Gee, Gainesville’s environmental services administrator.

Also, as part of the $1 million project, workers have started cleaning up the stream in the area around Hancock and Georgia avenues and between E.E. Butler and Queen City parkways.

They’ve also staked out an area where the creek will be moved from its old streambed but will still meander as it travels near the mill.

When the project is completed in late June or early July, the area will be transformed into a public amenity, with a chain-link fence removed and sidewalks and benches placed around the pond.

“And it will be used for flood control during (heavy) rain,” Gee said.

Another project is being done in tandem with the Army Corps of Engineers — and is expected to be the largest stream restoration project the city has done on Flat Creek.

They plan to restore about 3,300 feet of Flat Creek from Dorsey Street to Hilton Drive, including under Atlanta Highway. The project’s total cost would be $1.9 million, with the corps contributing more than $1.2 million and the city nearly $700,000.

Gainesville’s share would be paid for through the public utilities department’s capital projects fund.

Gee said the project could start in late summer or early fall, which is about the time a restoration project around the Gainesville Mill north of Queen City Parkway is wrapping up.

In the newest project, work will focus more on water flow and ecosystem restoration, including, as with previous work, “changing the meandering of the stream to prevent undercutting,” Gee has said.

“There won’t be as much beautification as we’ve done ... and making it a community park setting or whatever,” he said.

Mud Creek is another Lanier tributary that has struggled for the past couple of years.

Known for overflowing during a historic May 2013 flood and blowing out a couple of West Hall culverts, the creek also saw contamination this past winter.

Through the Neighborhood Water Watch, the Chattahoochee Riverkeeper found off-the-chart amounts of E. coli at Mud Creek off Stephens Road between November and January.

It turns out a Flowery Branch sewer line had been leaking into Mud Creek for an undetermined period of time. In February, Flowery Branch City Council approved up to $49,000 in repairs.

That episode led to some goodwill efforts between Flowery Branch and the environmental group, with a plan by the city to allow the group to use its lab facilities for testing or to see if the two parties “could coordinate testing,” City Manager Bill Andrew said.

EPD officials said that investments by watershed watchers and groups “can improve water quality in the lake’s tributaries.”

They pointed to a 29-mile section of the Soque River in Habersham County as a success story.

The stretch was polluted by animal waste and other sources of bacteria.

A grassroots group formed and, in partnership with the EPD, developed a plan to improve water quality.

Helping lead in that effort was Duncan Hughes, the Soque River Watershed Association’s watershed coordinator and Chattahoochee Riverkeeper’s headwaters outreach director in Gainesville.

“Over several years, the Soque River Alliance worked closely with farmers to fence cattle out of streams and implement other best management practices,” according to the EPD.

By 2012, monitoring data indicated that bacteria contamination had dropped and that this section of the river now meets bacteria standards, officials said that bacteria contamination had dropped and that this section of the river now meets bacteria standards, officials said.