Managing Low Water Levels in Farm Dams During Drought: What to Watch For

Q. Our dam water levels are dropping and we are concerned with what we should be doing to ensure the dams longevity.

ANSWER

Low water levels in a dam are common during droughts, high evaporation, increased usage, or reduced inflows. While low levels can expose more of the structure for inspection and sometimes reduce immediate overtopping risks, they introduce challenges like increased erosion, potential structural weaknesses, poorer water quality, impacts on aquatic life or livestock, and risks of seepage or instability as the dam “dries out” unevenly. Proper care focuses on safety, maintenance, water conservation, and long-term resilience.

1. Assess the Situation

Monitor water levels regularly

Perform inspections:

• Cracks, slumps, or settlement (especially on the dam wall as it dries).
• New or increased seepage (clear water is often okay if filtered; cloudy indicates soil loss.
• Erosion, rills, gullies, or animal burrows (rodents, etc.).
• Exposed roots, bare soil, or vegetation die-off.
• Spillway condition and any debris blocking outlets.

Check for hazards: Low water can concentrate pollutants, promote algal blooms, or allow livestock to access muddy edges and cause damage. Test water quality if used for drinking, irrigation, or stock (pH, nutrients, salinity, oxygen levels).

2. Carry out Structural Maintenance and Repairs

• Repair erosion and bare areas: Fill rills/gullies with compacted soil, then seed with appropriate grasses or vegetation for erosion control. Fertilize, mulch, and maintain good vegetative cover on the dam and spillway.
• Control burrowing animals: Fill burrows with compacted soil or gravel.
• Manage seepage: Minor seepage through or under the dam is common but monitor closely. If increasing, install or check filters/drains. For leaky farm dams, consider polymer sealers like Dam Stop Leak Professional.
• Clear vegetation strategically: Keep trees and large woody plants off the dam embankment (roots can create seepage paths), but allow appropriate native plants for stabilisation. Mow grass regularly but avoid over-clearing, which can worsen erosion.
• Inspect and maintain outlets/spillways: Ensure low-level outlets (if present) function for draining or controlled releases. Clear debris to prevent blockages during future rains.

3. Conserve and Manage Remaining Water

Reduce losses:

• Minimise unnecessary releases or withdrawals. If evaporation is high, consider using an anti-evaporation film , like Aquafilm to reduce surface evaporation.
• Balance inflows and outflows
• Stock management (for farm dams): Fence off the dam and provide alternative watering points (troughs) to prevent livestock trampling edges, causing erosion, nutrient runoff, and bogging in mud. This helps to improve water quality dramatically and makes maintenance easier.

Water quality care:

• Low levels concentrate nutrients, leading to algae, low oxygen, or odours. Aeration Fountains can help in smaller systems.

4. Prepare for Refilling and Long-Term Resilience

Plan for rain:

• Ensure the spillway and emergency spillway are clear and in good condition so sudden inflows don’t cause overtopping or erosion.
• Enhance the dam ecosystem: Plant native vegetation in zones (inflow, margins, dam wall) to stabilise soil, filter runoff, provide habitat, and improve water retention. Exclude stock and control weeds.

Build drought resilience:

• Install or upgrade monitoring equipment.
• Consider catchment improvements upstream (e.g., vegetation to reduce runoff speed and increase infiltration).
• For farm dams, explore sealers or liners for future water retention.