Department of Environment and Natural Resources Environmental Management Bureau

Regional Office No. IX-Zamboanga Peninsula

EMB 9 CONDUCTS MONTHLY WATER QUALITY MONITORING AT TUMAGA RIVER

Tumaga River is regarded as the most important inland river in Zamboanga City. It is a waterway which originates from the 10,107-hectare Pasonanca Watershed, flows in a north- westerly direction and curves out into Arena Blanco to empty its waters into the Moro Gulf. The River traverses several heavily populated areas of Zamboanga City including Pasonanca, Tumaga, Tetuan, Tugbungan and Mampang.

The Philippine Clean Water Act of 2004, otherwise known as RA 9275, mandates the DENR through the Environmental Management Bureau to designate certain areas as water quality management areas. In 2013, the Tumaga River Water Quality Management Area (WQMA) was officially designated through the signing of DENR Administrative Order No. 2013-01 by DENR Secretary Ramon J.P. Paje. The hydrologic unit comprises of the Tumaga River, its watershed, streams and creeks that drain into the river and contribute to the pollution load, and the land surrounding the River. The area encompasses nineteen (19) barangays in Zamboanga City. Attendant with the designation of the WQMA is the creation of its Governing Board that is chaired by the Regional Director of EMB 9, Jacqueline A. Caancan. The Board consists of 27 members from stakeholders such as the Office of the City Mayor, concerned barangays, NGA, NGO, water district, business/industry sector, and the academe. The governing rules for the organization and operations of the TR WQMA Governing Board provides for the creation and operation of a multi-sectoral group (MSG) for water quality monitoring and surveillance.

Good water quality is beneficial for many different uses. Water quality criteria established under DENR Administrative Order No. 34, series of 1990, protect the beneficial uses of surface waters in the country. Based on its beneficial uses, Tumaga River is classified into three categories namely: Class A for drinking purposes, Class B for recreational purposes and Class C for industries and irrigation.

Being a requirement of the WQMA program, monthly water quality monitoring is conducted to assess the present condition of the Tumaga River in terms of its physical, chemical and biological characteristics. Nine sampling stations were established for the monitoring of the River, namely:

Station 1 – Tugbungan Bridge, Tugbungan, 5,530 m N88°W from the mouth Station 1a – Jumbo Bridge, Guiwan, 1,723 m N83°W from Sta. 1 Station 2 – San Bernardino Bridge, Guiwan, 798 m N79°W from Sta. 1a Station 2a – Between Pasonanca and Tumaga boundary, 2,146 m N23°W from Sta. 2 Station 2b – Philippine Public Safety College, Pasonanca, 1,150 m N5°W from Sta. 2a Station 3 – Spillway, Kilometer 7, Upper Pasonanca, 866 m N19°W from Sta 2b Station 4 – Intake, Upper Pasonanca, 1,416.60 m N22°W from Sta 3 Station 5 – Intake, Upper Pasonanca, 386 m N11°W from Sta 4 Station 6 – Intake, Upper Pasonanca, 767.25 N6°W from Sta 5

Each classification has three (3) sampling stations as described below:

Class C: Estuary through Stations 1, 1a, and 2 (downstream) Class B: Upstream of Station 2 through Stations 2a, 2b, and 3 (midstream) Class A: Upstream of Station 3 through Stations 4, 5, and 6 up to the watershed (upstream)

Women wash their laundry at the Tumaga The water quality checker enables the field - Pasonanca boundary section of the River. personnel of EMB 9 to take onsite Parameters that are measurement of water quality parameters. monitored are pH, dissolved oxygen (DO), five-day biochemical oxygen demand (BOD 5), total suspended solids (TSS), total coliform, and fecal coliform.

The potential of hydrogen or pH is a measure of the acidic or basic nature of a solution. The concentration of the hydrogen ion [H +] activity in a solution determines the pH. The standard for pH as stipulated under DAO 34, series of 1990, is the range 6.5-8.5 which is the range that appears to provide protection to the survival of freshwater fish and bottom dwelling invertebrates. Runoff from agricultural, domestic, and industrial areas may contain iron, aluminum, ammonia, mercury, or other elements. The pH of the water will determine the toxic effects, if any, of these substances. For example, 4 mg/L of iron would not present a toxic effect at a pH of 4.8, however, as little as 0.9 mg/L of iron at a pH of 5.5 can cause fish to die.

For the 4th quarter of 2015, the average values of pH in all stations are within the given criteria (please refer to Figure 1). Results also show increasing pH values (linear correlation coefficient r = 0.6659) from station 1 to station 6, which indicate that the water is slightly more alkaline in the upstream section than the downstream section.

9.00 8.00 7.00 6.00 5.00 y = 0.0472x + 7.5597 R = 0.6659 4.00

pH values 3.00 2.00 1.00 0.00 Sta 1 Sta 1a Sta 2 Sta 2a Sta 2b Sta 3 Sta 4 Sta 5 Sta 6 Minimum 6.50 6.50 6.50 6.50 6.50 6.50 6.50 6.50 6.50 pH 7.61 7.48 7.56 7.92 7.99 7.97 7.95 7.84 7.84 Maximum 8.50 8.50 8.50 8.50 8.50 8.50 8.50 8.50 8.50 Sampling Station

Minimum pH Maximum Linear (pH)

Figure 1 Average pH values for the 4th quarter of 2015

Fish, invertebrates, plants, and aerobic bacteria all require oxygen for respiration. Much of the dissolved oxygen in water comes from the atmosphere. After dissolving at the surface, oxygen is distributed by current and turbulence. Algae and rooted aquatic plants also deliver oxygen to water through photosynthesis. The main factor contributing to changes in dissolved oxygen levels is the build-up of organic wastes. Decay of organic wastes consumes oxygen and is often concentrated in summer, when aquatic animals require more oxygen to support higher metabolisms. Depletions in dissolved oxygen can cause major shifts in the kinds of aquatic organisms found in water bodies. The DO concentration should not fall below 5.0 mg/L.

Results of the water quality sampling during the 4 th quarter of 2015 show that the average DO concentrations did not exceed the standards except for stations 1 and 2, which are located at the downstream section (please refer to Figure 2). This could be due to the decreased water level of the River during the months of November and December, hence the decreased water flow and DO concentrations, as well as the present of discharges at the midstream and downstream sections. Results also indicate increasing DO concentrations from station 1 to 6 (linear correlation coefficient, r = 0.8023).

10 9 8 7 y = 0.4897x + 4.3439 6 R = 0.8023 5 4 DO, mg/L 3 2 1 0 Sta 1 Sta 1a Sta 2 Sta 2a Sta 2b Sta 3 Sta 4 Sta 5 Sta 6 Criteria 5 5 5 5 5 5 5 5 5 DO 3.81 4.27 6.10 8.07 8.02 7.51 7.73 7.75 7.87 Sampling Station

Criteria DO Linear (DO)

th Figure 2 Average DO concentration for the 4 quarter of 2015

Wastewater from sewage treatment plants often contains organic materials that are decomposed by microorganisms, which use oxygen in the process. Other sources of oxygen- consuming waste include stormwater runoff from farmland or urban streets, feedlots, and failing septic systems. The amount of oxygen consumed by microorganisms in breaking down the waste is known as the biochemical oxygen demand or BOD. The term also refers to a chemical procedure for determining this amount. This is not a precise quantitative test, although it is widely used as an indication of the organic quality of water. The BOD value is most commonly expressed in milligrams of oxygen consumed per liter of sample during 5 days of incubation at 20 °C.

For Class A and B fresh waters, the BOD 5 concentration should not exceed 5 mg/L while th for Class C fresh waters, the criteria is 7 mg/L. During the 4 quarter, the average BOD 5 concentrations did not exceed the designated criteria in all stations (see Figure 3). The BOD 5 concentrations were also shown to decrease from the downstream to the upstream section (linear correlation coefficient, r = -0.9667).

4 y = -0.7483x + 6.825 3 R = -0.9667 BOD5, mg/L 2

0 Sta 1 Sta 1a Sta 2 Sta 2a Sta 2b Sta 3 Sta 4 Sta 5 Sta 6 Criteria 7 7 7 5 5 5 5 5 5 BOD5 5.67 5.87 5.30 3.90 2.40 1.67 1.27 1.00 0.67 Sampling Station

Criteria BOD5 Linear (BOD5)

th Figure 3 Average BOD 5 concentration for the 4 quarter of 2015 Another source of water pollution is suspended solids. When these suspended particles settle to the bottom of a water body, they become sediments. Suspended solids consist of an inorganic fraction such as silts and clays and an organic fraction such as algae, zooplankton, bacteria, and detritus that are carried along by water as it runs off the land. The inorganic portion is usually considerably higher than the organic but both contribute to turbidity, or cloudiness of the water. Waters with high sediment loads are obvious because of their "muddy" appearance. This is especially evident in rivers, where the force of moving water keeps the sediment particles suspended. Suspended solids can clog fish gills, either killing them or reducing their growth rate. They also reduce light penetration and this, in turn, reduces the ability of algae to produce food and oxygen. When the water slows down, as when it enters a reservoir, the suspended sediment settles out and drops to the bottom, a process called siltation. This causes the water to clear, but as the silt or sediment settles it may change the bottom environment.

For Class C fresh waters, the TSS concentration should not exceed more than 30 mg/L increase from the baseline data while for Class B, the TSS concentration should not exceed more than 30% increase. For Class A fresh waters, the TSS concentration should not exceed 50 mg/L.

For the 4th quarter of 2015, the average TSS values conformed to the criteria in all stations and a decreasing trend in the concentration from station 1 to 6 was observed as seen in the figure below (linear correlation coefficient, r = -0.6878).

TSS, TSS, mg/L 30 y = -1.6173x + 20.642 20 R = -0.6878

- Sta 1 Sta 1a Sta 2 Sta 2a Sta 2b Sta 3 Sta 4 Sta 5 Sta 6 Criteria 68 75 60 28 36 26 50 50 50 TSS 20.67 9.67 21.67 19.00 6.33 14.33 7.33 8.00 6.00 Sampling Station

Criteria TSS Linear (TSS)

th Figure 4 Average TSS concentration for the 4 quarter of 2015

Coliforms are bacteria that are always present in the digestive tracts of animals, including humans, and are found in their wastes. They are also found in plant and soil material. The most basic test for bacterial contamination of a water supply is the test for total coliform bacteria. Total coliform counts give a general indication of the sanitary condition of a water supply. Total coliforms include bacteria that are found in the soil, in water that has been influenced by surface water, and in human or animal waste. The water quality criteria for total coliform for Class A and B inland waters is 1,000 MPN/100 mL while it is 5,000 MPN/100 mL for Class C.

The average total coliform concentration in all stations during the 4 th quarter of 2015 exceeded the criteria (please refer to Figure 5).

100000

80000

60000

40000 y = -10954x + 88268 R = -0.8907 20000

0 Total Coliform, MPN/100 mL

-20000 Sta 1 Sta 1a Sta 2 Sta 2a Sta 2b Sta 3 Sta 4 Sta 5 Sta 6 Criteria 5000 5000 5000 1000 1000 1000 1000 1000 1000 Total Coliform 89,495.1 44,479.6 82582.4 40000.0 18120.6 20645.6 1955.7 2064.6 2154.4 Sampling Station

Criteria Total Coliform Linear (Total Coliform)

th Figure 5 Average Total Coliform concentration for the 4 quarter of 2015

Fecal coliforms are the group of the total coliforms that are considered to be present specifically in the gut and feces of warm-blooded animals. Because the origins of fecal coliforms are more specific than the origins of the more general total coliform group of bacteria, fecal coliforms are considered a more accurate indication of animal or human waste contamination than the total coliforms. Fecal coliforms are measured in rivers to determine the risk of infection and disease to people who come in contact with the water while fishing, swimming, or bathing. There are many sources of bacteria in rivers, including humans (from recreation or failing septic systems) and wildlife. On agricultural lands, fecal coliform comes from livestock waste, either deposited directly into waterways or carried to waterways via runoff and soil erosion.

At the midstream section, the average fecal coliform concentrations exceeded the standard of 200 MPN/100 mL in all stations during the 4th quarter of 2015. The average fecal coliform concentrations at the upstream section also exceeded the standard of 100 MPN/100 mL. No criteria was set for Class C inland waters.

9000 8000 7000 6000 5000 4000 3000 2000 1000

Fecal Fecal Coliform, MPN/100 mL 0 -1000 Sta 1 Sta 1a Sta 2 Sta 2a Sta 2b Sta 3 Sta 4 Sta 5 Sta 6 Criteria 200 200 200 100 100 100 Fecal Coliform 8522 4258 3399 5450 1694 2568 816 706 816 Sampling Station

Criteria Fecal Coliform Linear (Fecal Coliform)

Figure 6 Average Fecal Coliform concentration for the 4th quarter of 2015 The table below shows the summary of compliance with the water quality criteria at the upstream, midstream, and downstream sections of the Tumaga River. It can be seen that the River failed the designated water quality criteria for DO (stations 1 and 1a), total coliform, and fecal coliform. This indicates that the Tumaga River partially complies with the designated water quality criteria and only partially supports its intended beneficial uses. The results specifically indicate that the River received discharges from human and/or animal fecal wastes and suggest risk of contamination from water-related diseases. The River is typically used by people for bathing and swimming particularly at the midstream and upstream sections. The downstream section of the River where the DO level is generally below the desired water quality criteria becomes unsuitable for the optimum growth and survival of many aquatic organisms.

Table 1 Compliance with the water quality criteria Total Fecal Section Station pH DO BOD TSS 5 Coliform Coliform 1 passed failed passed passed failed - Downstream 1a passed failed passed passed failed - 2 passed passed passed passed failed - 2a passed passed passed passed failed failed Midstream 2b passed passed passed passed failed failed 3 passed passed passed passed failed failed 4 passed passed passed passed failed failed Upstream 5 passed passed passed passed failed failed 6 passed passed passed passed failed failed